6 series tech session - Strictly BMW Independent Service

Puget Sound BMW CCA Tech
Session:
The 6-Series
Hosted by: Strictly BMW, Bellevue, WA
Documentation By: Erik Brannfors
(All information within was collected from the internet and was created by and is the property of the various original authors and photographers)
Table of Contents:
Internet Sites
Steering Box Bracket Repair
Power Steering Filter R&R
Steering Adjustment
Warm Starting Problem
Ignition Upgrade for Idle Improvement
ICV Cleaning
M6 ICV and TPS
AFM Cleaning and Repair
Brake Booster/Master Cylinder Leak
Brake Warning Light/Accumulator Diagnosis
Power Brake Booster Rebuild
Headrest Fix
Sunroof Drain Cleanout
Heater Control Valve R&R
Heater Blower Resistor R&R
OBC Backlight Replacement
Service Indicator Reset
Upgrading Rear Sway Bar Mounts
Strut Spacer description and Install
Guibo Upgrade from e34 M5
Useful Internet Sites for your e24:
Brakes:
750, e34 M5 Calipers and Rotors, Steve D'Geralamo @ the "Ultimate Garage":
http://www.ultimategarage.com/
Upper/Lower Control Arm Urethane Bushings:
http://www.gruntsbushings.com/index.html Paul Gray
http://www.bimmerworld.com/catalog/urethane.htm Bimmerworld
General Parts:
http://www.bmwpartsplace.com/e24_m6.htm
http://www.bimmerworld.com/,
http://www.eap4parts.com/,
http://www.frankfaheymotorsports.com/door/, Fahey Motorsports
http://www.ground-control.com/,
http://www.hmsmotorsport.com/,
http://www.kormanfastbmw.com/index.htm - Korman
http://www.partsforbmws.com/ - Maximillian
http://www.metricmechanic.com/
http://www.mesaperformance.com/index.html
http://www.rogueengineering.com/
http://www.stevehaygood.com/
http://www.turnermotorsport.com/html/index.asp - Turner Motorsports
http://www.uucmotorwerks.com/ - UUC
http://www.vacmotorsports.com/
General Info:
http://www.nmia.com/~dgnrg/page_2.htm Repair information
http://www.normgrills.net/bcg - Big Coupe Group
http://www.bmwpugetsound.com/ - Local Club
http://teamdfl.com/bmw/e28/e28home.html - 5 and 6 series modifications
http://www.josejuantorres.com/ - 6 series racing/rallying
http://www.lexam.net/peter/carnut/bmw635.html - 6 series modifications
http://www.dnjmoran.com/bcg/reg1.htm - Sharks in the wild
http://home.attbi.com/~russelc/swaybar/swaybars.htm - Dinan Sway Bar Mounts
Steering Box Bracket Breakage
As reported by many, the steering gear box support bracket likes to break off the
subframe, causing erratic steering and clunking noises in the front end.
After getting a quote for $500 to fix it -- remove subframe, reinforce and weld a
new bracket on to the subframe, reinstall, etc. -- I decided to give it a go.
I followed more or less what I had remembered reading about 2 years ago.
1. Purchased a new bolt about 1.5" longer then the one used and a lock nut.
Be sure it is of the rating (8.8)
2. Purchased 13 washers (~0.1" think) of the correct center hole size for the
bolt - about 1" in diam.
3. Procured 2 washers about 2" in diameter and about 0.15" thick with also
the correct center hole size.
4. Removed the bolt, 2 washers, nut and broken bracket from subframe -work done under car -- with car on ramps.
5. Installed new bolt with old 1" washer thru hole in subframe --- AND installed
one of the 2" washer inside the subframe, between subframe and
washer/head of new bolt. One has to slip and align the large washer thru a
slot in the subframe -- easy to do with needle nose pliers.
6. Installed second 2" washer above the subframe and on the bolt.
7. Installed 12 of the 1" washers on the bolt -- this a little tricky -- but by
rotating steering gear upward one can get sufficient clearance.
8. Push bolt thru steering gear hole -- install top washer and self
locking nut. Torque adequately.
Note the I had to use a broom stick to pound the steering gear box back down to
allow the bolt to slip into the hole in the steering box. Also note that the 13
washers equal the height of the bracket that broke off -- this insured that the
steering box was aligned as per original design.
Power Steering Filter
I just replaced that filter. Mine had started to come apart. You can'tbelieve the
noise the PS pump makes when it can't suck properly. Whenthey first start to go,
the pump starts to make just a little noise. Hard to isolate the cause, but chances
are, it is the filter. Call "All BMW Discount Parts" 800.590.7770, try part # 32 41 1
128 167 (ZF) or 32 41 1 128 919 (Benteler). They have a free small catalogue
with part #s and related drawings for our 6's.
6 Series Steering Adjustment
I have replaced one box and simply adjusted another on 85 735i. The
replacement was not necessary.
Adjusting is fairly easy:
* raise front of car on jack stands, so steering is unloaded
* Turn steering wheel about 1 full turn CCW (front wheels point left).
* Look down at steering box under hood (bonnet?) beside engine:
- adjustment is a large screwdriver slot, with lock nut around it.
* loosen the lock nut (CCW)
* tighten slot (CW)
* turn steering wheel 2 full turns CW (front wheels point to right).
- you should notice slight increase in resistance as steering goes thru straightahead.
- if no resistance increase is noted, then tighten slot (CW) a little more and rotate
steering wheel back through straight-ahead to test resistance.
- if too much resistance, loosen slot (CCW).
* tighten lock nut (CW), while ensuring slot does not move.
* If the steering feels too numb when driving after this adjustment, then it is too
tight.
* I think the official adjustment procedure disconnects the steering linkage, using
a special gauge to measure the steering resistance.
This adjustment was enough to cure sloppy steering for an 85 735i with 225,000
miles (about 360,000 km).
I have done the same with success also for an E21 and E24 steering box. Some
steering boxes also have adjustment for "end play" of the worm gear. This "end
play" adjustment is on the end of the box, opposite from the steering column.
Replacing the steering box is best accomplished with the engine removed. At
least, the motor mount and stabilizer need to be disconnected so the engine can
be raised for clearance.
Before removing the old steering box(es), be sure to mark exactly what spines
match to the arm and column joint, so that the straight-ahead position can be
restored. The Pittman arm may be difficult to remove without a Pittman arm
puller.
The steering boxes for 5 and 6 series of similar vintage have matching splines for
the input and output shafts, and have a faster ratio for more responsive steering.
However, these boxes are smaller (perhaps not strong enough?) and completely
different mounting than the E23 steering box that would require cutting away the
old mount and welding new ones, which could be dangerous if not expertly
engineered and fabricated.
The replacement steering box will probably need adjustment, particularly if it is
obtained from another old car.
Warm Starting Problem
- - when cold it started on the first turn
- - when hot it would start immediately after being shut off but....
- - if it had soaked for 1/2 hour or more when hot it would require 4 to 8 seconds
of cranking... but would always start, eventually
Diagnosis:
The check valve in the main fuel pump was leaking allowing the fuel injector rail
residual pressure to bleed off resulting in formation of a huge fuel vapour bubble
in the fuel rail and back down the fuel line toward the pump. The extra cranking
time was needed by the fuel pump to recompress and eliminate the fuel vapour
bubble in the line and repressurize the fuel injector rail.
I could have replaced the fuel pump for $200 but I fixed the problem by putting a
$10 brass check valve (3/8") in the fuel line near the pump. I bought the check
valve from a Dayton Electric outlet. I can get the part number if you're interested.
I also bought a pair of small brass hose barbs, some teflon joint tape and two
small stainless hose clamps to complete the installation. Total cost was about
$15 and 1/2 hour of my labor.
Now the engine starts on first turn, hot or cold, overnight or after standing for a
while ....ie it always starts easily and immediately, even after soaking in Houston
sunshine while hot.
Ignition Upgrade for Idle Improvements
Your 1982-1984 U.S. model 633 (also applies to 533 and 733) may have had an
upgrade performed by the dealer to address idle problems. Technical Service
Bulletin TSB 13 07 86 (1162) discuss these changes.
The major components of the upgrade were to:
(1) Replace the ignition system (coil, cap, rotor, wires) with the 30 kv components
(the type in the 635) and adding a rotor adaptor;
(2) Install a 35 degree C thermotime switch;
(3) Replace the idle control unit with the green unit (or may be a black unit with
green tape);
(4) Install a purge control module;
(5) install an external resistor in the wire for the temperature sensor that feeds
the Motronics (should be the one with the light grey connector) Resistor type is
270 ohm, 1/2 watt, "Gold Band" metal film resistor for Motronics Control Units
with a Bosch code date of 342 or higher (production date after 9/83) and for
Motronics 341 and lower (9/81-9/83 production dates), it is a 560 ohm, 1/2 watt
"Gold Band" metal film resistor .
This upgrade was performed at no charge, but may not have been done on your
vehicle. If you have the slip on rotor instead of the bolt on type, the full upgrade
was not done, but you may still have the external resistor installed under TSB 11
11 84 (920), which was only added to address a complaint of "hesitation/poor
throttle response" during several minutes of operation after starting a cold or
warm engine at an ambient temp above 75 degrees F.
A few things on these model years because of these changes.
First, when replacing ignition components, make sure you are getting the correct
coil, cap, rotor and wires, depending on whether your car has the upgraded
components. If the upgrade was not done, a rotor adaptor (PN 11 31 1 718 761)
is still available if you choose to upgrade to the 30 kv components.
Second, if your car is not running right and you have questions, make sure to
specifiy whether your car has had the upgrades.
Third, the external resistor may be the source of a "no run" condition, if the solder
connection breaks from handling the temperature sensor connector. This resistor
is usually soldered just behi nd the connector and may be concealed under the
rubber boot. A broken or bad solder connection will mean that your car will not
start or run, and this could be an intermittent problem because of engine
vibration. In an emergency, you can disconnect a wire to the short 2 prong
temperature sensor that feeds the idle control module, and the car will run, but
the idle will surge hard. It may be better to carry a short wire with small insulated
alligator clips on both ends in your tool kit to do a roadside repair.
Idle Improvement
1. Throw out the Bosch Platinum plugs - they're basically not compatible with this
car. Spend about $4/each for the Silver ones that are ESPECIALLY made for just
this engine (check a BOSCH cross-reference book - guess what? The only
engine using these plugs is the big 6!).
2. Set them to 0.032" minimum gap. Even to 0.035-38" won't hurt, the ignition
system can easily handle it.
3. Install and TORQUE them in with no anti-seeze. 20 fl/lbs is about right.
4. Adjust valves to minimum of +0.002 over spec. +0.004 isn't even noisy and will
help even more.
5. Run mega-dose of techron full strength stuff (not the watered down k-mart
stuff) [mega-dose = 2 16oz can's in the last 1/4 tank. Run until almost empty. Fill
up. Change oil!!).
6. Run the heck out of it. It will like it.
Problems with the '86-88 big six engine idle is related to exceeding (vastly) the
EPA emissions standards. The things run VERY lean at idle (CO is almost
unmeasureable at the tailpipe). None of them idle great - but the above can make
it tolerable - and not embarrassing at a stop light (car rocking and rolling). The
biggest change is made by opening up the valve adjustment, followed by the
correct plugs and a wide gap. You'll notice as these open up with normal wear,
the car runs better and better - I'm often disappointed after I tune BOHICA up,
'cause it runs WORSE - and end up resetting the new plugs to the gap the ones
that came out were at - and doing the valves again. I'm currently running the
valves at 0.014 +.001 - .000 - this seems to work well, and with BOHICA gonna
reach 100,000 miles TOMORROW - the cam and lifters look JUST LIKE NEW the car uses no oil, and the compression is excellent, and very even. It won't hurt
the engine to run these wider - and will greatly improve the idle.
What do I set the valve clearance (lash) to on my '87 535i? The answer is
'usually 0.02" over specs' - which are 0.012" cold. So the answer is 0.014"
clearance.
The reason - it helps the crappy idle these engines are afflicted with due to
BMW's attempts to meet emission regs from around 1985-88 (they actually FAR
exceeded them.. there is NO measureable CO at my tailpipe - have to go back to
the exhaust manifold to see a reading).
If the car IS tuned to specs - it idles very poorly and tends to intermittently stall.
Not all of this may be due to the valve clearance and plug gap - but using the
wider settings sure helps.
Don Eilenberger says: What do I set the plug gap to on my '87 535i? I also set
the plug gaps oversize - same reason again - in this case, spec is 0.028" - I
typically use 0.032" If the car IS tuned to specs - it idles very poorly and tends to
intermittently stall. Not all of this may be due to the valve clearance and plug gap
- but using the wider settings sure helps.
Idle Control Valve Cleaning
Have had a couple of requests to add this procedure to the FAQ, so herewith is
what I did to clean the idle control valve on my '86 to solve idle surging from
normal to 1500rpm on warm-engine startup.
The valve on my '86 is a round metallic cylinder about 1" long toward the back
center of the top of the engine. The valve plugs into about the center of the black
fuel injection boot, firewall side, and in turn has a black Bosch electronic unit
plugged into it. Touch the valve when the ignition is on without starting the
engine, and you should feel it humming.
1. To remove the valve, loosen the hose clamp under the valve that attaches it to
a small rubber hose.
2. Remove the little nut that attaches the valve's metal support to the engine
valve cover.
3. Unplug the black Bosch unit from the rear of the valve by squeezing the Bosch
unit's wire lock together with your thumb & forefinger.
4. Remove the valve with the support attached, and then remove the support by
squeezing in on one of the two little rubber plugs attaching the valve to the
support.
5. Spray carb cleaner or penetrant liberally into one of the valve's two inlets, and
it will run out the other. Spray into both inlets, and then let the spray all run out
before reinstalling the valve. It may take a few minutes running the engine for the
valve to fully loosen so it won't surge, but either carb cleaner or a good penitrant
(not WD40 - one I like is Popular Mechanics "All Purpose Lubricant" available at
Walmart) should do the job.
6. Reattach valve.
This procedure might prevent or postpone having to buy a new valve. It worked
for me. Good luck.
Alternator Bushing Replacement - [email protected]
This is a step by step detailing of the removal and replacement of the alternator
bushings in my 1985 635csi. Wherever required I will include the reason why I
did something in a particular way. If it is possible, use the urethane bushings
instead of the rubber ones from BMW. Read the directions through a few times
before you begin. The job took me 2 hours, most of which was spent cleaning the
old bushings out of the alternator. As I am a DIY hacker and in no way a certified
mechanic I must add that the usual disclaimers apply.
Tools used:
Ratchet
adjustable wrench
slip-wrench (to remove fan)
13mm wrench selection of metric and SAE sockets (see steps 17-20)
large vise (opens wide enough to span the alternator, with several inches to
spare)
various screw drivers
C-clip pliers (a must).
1. Disconnect the battery.
2. Remove the alternator belt. This is accomplished by loosening the backside
nut on the upper mount, and then turning the front side bolt head such that the
toothed mechanism moves the alternator toward the engine block. When the belt
is loose enough, remove the belt.
3. Turn the large bolt head such that the alternator moves back to its original
position. This may seem unnecessary, however I found it makes it easier to
perform the next step (no obstructions).
4. Remove the bolt through the upper mount by removing the backside nut and
then sliding the bolt out of the mount. Note that the large front side nut is not
really a nut but a cogged wheel which slides on to the bolt. Make sure you do not
drop this cogged wheel or any washers when you remove the bolt.
5. In order to make some room, move the slotted arm to which the upper mount
was attached, out of the way (toward the engine block). If it is anything like mine
was, IT WILL BE STIFF. You may wish to spray some penetrating oil on the bolt
point to help.
6. This step is optional, though it may save some skin from you knuckles.
Remove the fan assembly and the radiator fan shroud. Note that the fan shroud
may interfere with removal of the lower mount bolt if it is not removed.
7. Using a 13mm wrench on the backside nut and a 13mm long socket on the
front bolt head, remove the bolt from the lower mount, taking care not to loose
any washers.
8. Gently pull the alternator from its position and twist it such that the back of the
unit is facing up. Place it carefully on the top of the power steering pump. This
allows easy access to the wiring connections on the back. Pry back the rubber
boots, and remove the connections. Mark the connections where necessary to
ensure proper assembly later on.
9. Take the alternator out of the engine bay and take it to a well lit work area (this
makes it easier to find the C-clips when they are inadvertently launched, I speak
from experience)
10. Using C-clip removing pliers (HIGHLY RECOMMENDED), remove the Cclips from both the upper and lower bushings. Be careful as they can easily fly off
the pliers. Put these in a safe place along with the new bushings and the flat
washers which are below the C-clips.
11. Remove the bushings by tapping and/or prying out the metal sleeves. This
may or may not be easy depending upon the condition of the rubber bushings.
My upper sleeve came out with not much effort, but the lower sleeve was a lot
more difficult due to the gooey nature of the rubber bushings.
12. With the sleeves removed, remove the rubber bushings or what is left of
them. I used a hardwood dowel, slightly smaller in diameter than the inside
diameter of the mount bore, to scrape out the gooey remnants. It is very
important that the inner walls of the mount bores and the outside surfaces of the
metal sleeves be clean and smooth. Believe me, this may take some work.
13. It is now time to reassemble the unit.
14. In order to ease assembly, coat the inside of the mount bores, the rubber
bushings and the outside of metal sleeves with a suitable lubricant which will not
attack the rubber. I used a liberal coating of graphite.
15. Starting with either the lower or upper mount (both are assembled in the
same way), insert the rubber bushings into the mount bores. Push the metal
sleeve back in, inserting it from the front side of the alternator. It is only
necessary to get the sleeve partially inserted into the back bushing.
16. Place the alternator in a vise (or use large slip-pliers), being careful to protect
the surface of the metal sleeve and the rear rubber b ushing. Slowly compress the
vise until the metal is inserted as far as it can go (ie. sleeve is hitting the back jaw
of the vise).
17. Open the vise very wide. Now place a socket of such a size that the inside of
the socket just clears the metal, on the rear rubber bushing. Close the vise again
(gently). This should insert the rubber bushing far enough that approximately 1/4"
of metal sleeve is visible.
18. Once again open the vise. Over the exposed part of the metal sleeve place
the flat washer and, using the C-clip pliers, place the C-clip on the sleeve.
19. Carefully place the socket back on the sleeve (it should be making contact
with the c-clip, if not, use a smaller socket). Using the vise, compress the
bushings until the c-clip snaps into the groove i n the metal sleeve. One mount is
now finished.
20. Repeat for the other mount.
21. Once this is finished, re-attach the alternator by reversing steps 1-8.
M6 Idle Control Valve
On close examination, the M6 has its idle control valve tucked in under the first
two throttle bodies. The ICV used on this engine is a very nicely made item,
having a steel outer case and die-cast aluminum valve parts - unlike the mostly
plastic units used on most other engines.
To remove the ICV for cleaning, first remove the intake manifold by removing the
12 nuts holding the 6 necks to the 6 throttle bodies. Use a magnet to get the
washers off so they don't get lost. Loosen two hoses, one from the valve cover,
the other from the ICV. Disconnect the large flex boot to the airflow meter (don't
need to loosen the throttle body boots). As the manifold with boots and necks, is
lifted up and out, pull off the tube at the bottom running to the crankcase. The
connector is barbed so it may work better to cut the first 3/4" off this tube if it
won't cooperate.
With the manifold out of the way, unplug and take the ICV out of it's rubber holder
and disconnect the hoses. By looking into the ports you can tell right away if this
valve is free or gummed up. It can be cleaned with carb cleaner - but don't soak
the electrical end. If you have compressed air, blow it out afterward. Shake the
valve (twisting motion) to check that the internals move freely. Installation is
straightforward. As the manifold is put back, check the o-rings at the necks and
wipe all mating surfaces clean. Use care in reattaching the throttle/cruise control
cable bracket. Check that the linkage returns to the full rest position.
M6 THROTTLE SWITCH
The throttle switch on the M6 is at the top and front of the engine, at the e nd of
the throttle shaft. The switch has a three-wire connector ( 3 18 2 ). Take off the
plug and measure ohms between the center (18) and the bottom (2) terminal. It
should be 0 ohms at closed throttle, and should go to open circuit as the throttles
start to open. If this switch does not connect terminals 2 and 18 at closed throttle,
the ICV doesn't get the right signal so idle will hang and come down slowly
instead of dropping normally. (The other function of the switch is to connect 3
and 18 at high throttle opening - but this is obviously unrelated to idle
performance)
With the engine off you can hear the micro-switch mechanism as the throttle
linkage is moved on and off the rest. But it may sound ok and still not be making
contact. Use an ohmmeter to be sure. The switch can be removed and taken
apart for cleaning (which I did ), this is tricky - the case is glued together and the
inner switch is soldered in.
If you take the switch out, be sure to adjust it for proper function when putting it
back. The closed circuit between 2 and 18 at rest should open very soon on
opening the throttles.
Air Flow Meter Pointer Repositioning and Repair
Correcting Idle Fallout due to air flow meter carbon band wear on L Jetronic and
Motronic models:
The problem of intermittent stutter at mid throttle, failure to hold idle, and the
engine responding when the throttle is depresses as if it were out of gas very
often is due to wear on the carbon band within the Air Flow Meter.
The dealers will say replace the AFM. That can cost you a few hundred dollars or
more. Instead of that, try the following procedure. My old 84 318 still had the
original AFM at228,000 miles because of doing this procedure several times, and
I'm pretty sure that AFM is still in action, now somewhere out in Minnesota:
Remove the black plastic lid. Notice the carbon dust on the pointer tracks on the
carbon band. VERY GENTLY, ever so lightly lift up the pointer from the band
using a small bladed screwdriver or thin hook tipped nose pliers. Blow the dust
away, compressed air is preferred. If you don't have a compressor, see below.
To verify band wear or loss of pointer tension is the problem, hold the pointer at
about the place it would be at idle. If you are not familiar with this, try about a
centimeter from the resting end. Then try to start the car. If just by pressing down
on the pointer at the right spot gets the car to hold idle, then you have found the
cause of your problem.
Now to regain tension at the pointer:
1. Notice the end of the copper pointer arm where it joins the pivot.
2. Notice where the arm is a double V shape, with an open slot between the inner
and outer sections of the V
3. Press down on the arm, only on one side of the V, just away from the pivot
until you just feel a little chance of it bending a bit. Now do the other side of the
V, again just away from the pivot.
4. Pressing down GENTLY on the tip of the pointer with a fingertip, move the
pointer forward and back across the range of movement of the carbon band.
5. START YOUR ENGINE.
You may not get it exactly right at first, but once you get the idea and can see
exactly what you need to do, a little more or less pressure exerted on either side
of the pointer arm will restore full contact over the full range of throttle motion.
You may then need to adjust the pointer position a tooth leaner or richer because
of the slightly different resistance at any given point. This is done by moving that
big black gear a tooth forward or backward. The gear retainer is easily lifted by a
screwdriver. Be sure to put a dab of white-out or something to mark the original
position so you can go back to initial setting if you need to.
The goal of this bending and repositioning of the arm and pointer is to both:
A. restore tension to the arm so it presses down sufficiently on the carbon
band again and
B. reposition the pointer ever so little further inward or outward so that it is
now rubbing across an unworn part of the carbon band. You may then
need to adjust the pointer position a tooth leaner because of the slightly
different resistance at any given point.
Brake Boost/Master Cylinder Leak
Had the same problem with the hydraulic leak from the brake booster on my '87
635. The leak is from a failed "O" ring inside the booster. The ring is about 2" in
diameter and goes around the plastic plug in the front of the booster. The screw
you feel under the booster is the retaining screw for the plug which, by the way,
has a fairly strong spring behind it. Be careful if you take it apart. I took the
booster out myself and got a replacement "O" ring from Steve Haygood, the guy
who runs the 6 Series Register.
Addendum:
This O-ring is a 3mmX38mm (ID) and can be found at Pep Boys.
Brake Light Flashes/ Accumulator Diagnosis
According to relevant past digests, this is symptomatic with one of two things:
either a particular switch, or (more likely) the more expensive brake pressure
accumulator.
(1) Bad switch
An old digest mentioned having a similar problem on a 535i. The brake warning
light came on under rapid braking. The problem was a switch on the high
pressure manifold (part # 34331150922, $22.29).
(2) Symptoms of bad brake pressure accumulator
The symptom is that when you press the brakes quickly, the brake warning light
lights up for a moment and then goes out again. If you press on the brake pedal
slowly, it never lights up.
Try a panic stop. If the brakes are real hard (like nothing is going to happen) then
feel normal, there is no built up hydraulic pressure.
Pay careful attention to steering and stopping at the same time. Since the brakes
and the power steering both run off the power steering pump, they borrow each
other's power. When it gives up, you can feel the brakes (or steering) change the
effort required when you use the steering (or brakes).
The valve and the attached pressurized sphere used as a brake power reservoir
will set you back $700, I think (anyone?). They need replacement around every
150,000 miles.
(3) Background and maintenance of brake pressure accumulators
The pressure accumulator is the round black ball under the power steering /
power brake regulator valve.
The purpose of the accumulator is to supply the needed hydraulic pressure for
the power brakes to make several stops in the case of loss of engine. It just
stores pressure (about 1000psi of it) against a cushion of air - separated my a
diaphragm. If the diaphragm goes bad, the air goes away, and the storage never
takes place.
The 6-series (and some later E28 5-series?) uses the same power brake system
as the 7-series, where the power brakes run off the power steering pump, not off
manifold vacuum like most cars.
Accumulators go bad over time. This is accelerated significantly if the little known
filter in the bottom of the power steering reservoir is starting to deteriorate. The
screen at the top of the canister is held in by a C clip, remove the screen. Drain
the fluid by either disconnecting a hose (kinda hard, but gets more fluid out) or
sucking or siphoning the fluid. Remove as much fluid as possible, discard of
properly. Towards the bottom of the shaft in the reservoir is another C clip, this is
holding down the filter with a plate. This is a doughnut shaped filter made of
something similar to pumice. It degrades over time and contaminates the fluid.
Put a new filter in. Also, change out the accumulator (bomb). I did mine by
removing the valve block it's attached to. This of course drained more fluid. I also
changed the block out, but I don't remember why at this time. Brakes work great
ever since.
(4) Are you sure there's enough fluid, and the sensor works?
The immediate cause of the flashing brake warning light is the lower sensor on
the hydraulic pressure regulator/accumulator. It could just be that the low-fluidlevel sensor has died. I don't know how to test it.
The hydraulic fluid might be low. If you check the level without relieving the
pressure in the system, it will appear low. And by topping it up you will
OVERFILL it.
To relieve the pressure, press the brake pedal about 15-20 times, engine OFF,
until it becomes VERY hard - which is a sign the hydraulic accumulator (if yours
is OK) has bled it's pressure back into the system. At this point, the correct level
is about half an inch below the top lip of the container. When you start the car,
the level should sink at least three inches.
If not, the brake pressure accumulator (the bomb) has gone south. Not
expensive, but a PITA to replace. If when you turn the engine off, the pedal is
immediately hard, this is also a symptom that the accumulator has gone south
and you have no reserve pressure.
Power Brake Booster Rebuild
Here you go. The O-ring in question is 38MM inner diameter and 44 MM O.D.
Black rubber. Any hydraulic O-ring that will withstand ATF should be fine.
Remember: clean is always good with hydraulic systems. Clean things as yo u go
and try to avoid getting dirt into any parts.
1. Inside the car, pump the brake pedal until the pressure is discharged. About
20+ times until the pedal get hard. Go ahead and remove the under dash fascia
under the driver's side. Four or five screws. Disconnect the chime and temp
sensor connections. Remember what goes to what and/or mark them if you want.
2. Drain and remove the coolant over flow tank. Two body screws - one on top
and one hidden underneath. The lower screw doesn't have to come completely
out. Mount tab is slotted to fit this screw. Just loosen and pull the tank up. Route
all the hoses and connectors safely out of the way.
3. Drain and remove the brake fluid reservoir. Route the electrical connectors out
of the way. Just rock this reservoir back and forth and left/right as you pull up. It
may be tough to pull out but it will come off eventually. You may need to replace
the rubber grommets that the reservoir slips into in the top ports of the master.
Carefully wipe the master cylinder clean and cover the top ports with Saran wrap
or something similar to keep crap out of the M.C. You will need to grab the M.C.
for leverage.
3. Break the two brake line connections off the left side of the M.C. with a
wrench. You should see two bolts that connect the M.C. to the power brake
booster (PBB). These are lok-tite sealed. Put a wrench on one and hold the MC
with your other hand and break the seal. Careful, they are tough to break and will
let go with a SNAP. Same with the second. Remove and carefully separate the
MC from the PBB. Careful! There is a push rod in there that will try to come out.
Observe the correct orientation of this push rod. One end is machined down from
the rod diameter and rounded off; the other is simply rounded off from the rod
diameter. Lay the MC and rod aside on a clean surface. Stop and wipe any brake
fluid that may have gotten on your paint off with a clean rag.
4. From inside the car: remove the clip that hold the clevis pin through the brake
pedal/PBB actuating rod. Spread with a flat screwdriver and pull the clip forward.
Take the return spring off the clevis pin on the opposite side of the pin. Pull the
pin out and put the clip/pin safely away. The PBB is held to the firewall by four
nuts visible around the actuating rod. Remove all four.
5. Back outside, grab the PBB and wiggle and pull forward to break it loose from
the firewall. Once it will wiggle pretty good, remove the low pressure return line to
the PBB (forward fitting, hose clamp). Tuck it away against the side of the ATF
reservoir. ATF will leak if its too low. Clean the area around the high pressure
fitting behind the return hose. Now comes the fun part: the high pressure flare
fitting behind the return line is a 17MM as I recall. Break it free with a wrench.
Then its a matter of turn a tiny amount, flip wrench, turn a tiny amount. flip
wrench. Well . . you get the idea. Until you get this backed out. It may help to
remove some of the hose support clips that may be on the high pressure line to
secure other hoses near it. Once free, it will lift and barely clear the PBB. Lift the
high pressure fitting clear and pull the PBB forward. There will be some
resistance but it will come out finally. Careful, its full of ATF and will drain when
the forward end is dipped down.
6. Drain the PPB of ATF and wipe it off with a clean cloth. Look in the forward
end and you will see a black plastic cup inserted into the PBB body. On the
bottom of the PBB lip there is a drain slot that aligns with a similar slot in the
black cup. This is where the ATF has been leaking. On the bottom of the PBB
body just aft of the slot is a strange looking bolt. This retains the black plastic cup
and spring inside. Get a medium sized cardboard box and line it with clean
newspaper. Stand the PBB open end down on the bottom of the box and back
this bolt out with a pair of vise-grips or pliers. Just a little. Hold downward
pressure on the PBB while you do this. The retainer bolt will release the black
plastic cup and the spring. Its not too strong, just be ready. Observe the parts as
they are released. viz.: Black plastic cup/O-ring on black plastic cup/steel
retaining washer on O-ring/spring/spring seat on back end of spring. Look at the
black plastic piece. The O-ring sits on a "shelf" on the black plastic cup. The steel
washer sits on the O-ring, the spring sits on the steel washer, etc. The black
plastic cup has two slots in the bottom portion: the first is for the retaining bolt,
the second provides for ATF leaks for your amusement. Replace the O-ring.
Lube it with a little ATF of which there should now be plenty on you/your
garage/box bottom, etc. Reassemble the PBB. You can just push the assembly
back in with your hand and screw the retaining bolt back into the PBB. Make sure
you line up the slot for the bolt. Don't rest the PBB on the actuating rod - it makes
the spring mad and difficult to deal with.
7. Got it all back together? Now look at the PBB high pressure port. On mine
there was a second fitting screwed into this port that the flare fitting screwed into.
Break it loose while you have the PBB out and remove it. Clean it up with a rag
and clean the threads too. Clean the PBB around the port well also. Clean is
good for this system. Take this fitting over to the car and spin it onto the high
pressure flare fitting. Don't tighten it, just spin it close to tight. You want to be able
to still turn the flare nut on the metal hose.
8. Reassemble the Master and the PBB. Make sure you put the rod back in the
assembly the right way. Use lok-tite (blue, but any will do) on the MC/PBB bolts.
Pull the bolts down completely to firm tight. The lok-tite will keep them there.
There shouldn't be any significant gap between the MC and PBB.
9. Take it back to the car and stick the assembly through the hole in the firewall.
Don't yet force the bolts into their holes. Wiggle it around until you can start the
High Pressure fitting into its hole on the PBB. This may take several tries and it
was tough. Make sure not to CROSS-THREAD. Hand tighten until you are
certain that you have it right. Run it down to almost snug.
10. Push the PBB back into place through the firewall. This will take some effort
to force the bolts through their holes: wiggle, push; wiggle push. You'll know
when it goes. Once its in, clean up and go under the dash and replace the nuts.
Tighten and hook up the brake pedal, replace the pin, clip, and return spring.
11. Back outside, tighten down the two high pressure fittings. Turn/flip - just like
before. Replace the PBB return line and hose clamp THIS TIME orienting the
clamp so you can get to it unlike the gorilla at the factory.
12. Reconnect the two brake lines to the side of the master. PITA, but you gotta
do it. Don't cross-thread them .Clean the master carefully with a rag. Clean the
brake fluid reservoir on the outside with a rag. Supporting the MC underneath,
press the brake fluid reservoir back into the MC. Fill it with new brake fluid. Clean
the filler cup, replace, and cap the reservoir. Reconnect the electrical
connections.
13. Replace the coolant overflow tank. Reconnect hoses and place clamps. Refill
to normal level with coolant. Reconnect the electrical leads to the level switch.
14. Clean the ATF reservoir and refill to about 10MM below the top. Close it up
and secure it.
15. Stop. Look over everything you have done and make sure you did it right and
tightened everything you loosened. Think about it for a while.
16. Remove things from the engine compartment, clean up. Start the car and turn
the wheel back and forth a few times. Pump the brake pedal a few times. Stop
the motor. Pump the pressure down and check the ATF level. Top off and repeat
until all bubbles are gone and fluid level drops no further. Replace under dash
fascia. Reconnect the chime connections and the interior temp sensor.
17. Now you have to bleed the brakes to get the air out and hopefully all will be
well. Please be certain that you want to do this before you start. It can be tough
the first time around and very frustrating at times.
Headrest Fix
If your headrests fail to move up and down but you can hear the motor turning,
there is a potential fix which is very simple. The way the motor is located in the
seat back, the cable hangs more or less vertically. It appears that the cable
"shrinks" and when it does it follows gravity and settles in to the motor end and
coming out of the headrest drive. The easy fix for this is:
1) Remove the seat back by taking two screws out of the bottom corners of the
seat back UNDER the seat back.
2) Slide the seat back down to disengage the two clips at the top and remove the
seat back. The motor is now exposed.
3) Remove the motor from it's bracket allowing removal of the cable from the
motor.
4) Cut a piece of coat hanger wire 1/4 - 3/8" long and drop it into the motor
square ho le drive. Make sure there is enough of a gap between the end of the
wire and the top of the square drive for the cable to make a good engagement
with the motor. Shorten the wire if necessary.
5) Spin the cable, pushing it upward to engage the headrest drive, making sure
enough sticks out the bottom end to engage the motor drive.
6) Re-assemble the motor into the seat back and test for correct operation.
7) Re-install the seat back in reverse order and proceed to do the other one.
8) Volunteer to help a friend whose headrests are malfunctioning and be a hero!
E24 Sunroof Drain Clean Out
Just thought I would pass along a preventive maintenance suggestion in hopes
that it may help some of you to avoid an unfortunate little occurrence I recently
had with my E24 (an '83 633 CSi).
The sunroof channel has four water drains, one in each corner of the roof. The
front two lead down to the rocker panels and drain out of holes formed in the joint
between the rocker panel and the sill (it appears there is one set of holes not far
behind the front wheel wells, and another set about midway between the front
and rear wheel wells), while the rear two lead down to drain behind the trim piece
at the rear edge of the rear windows.
For some time, I had been experiencing a condition whereby leakage from the
roof into the passenger compartment would occur under certain heavy rainfall
conditions (with the rarity of rainfall in southern California, this condition has
actually existed for a year or two without my paying it much attention). What I
hadn't realized was that the leakage was sufficient enough to drip onto the
driver's side rear seat bucket, eventually enough to cause the leather on the seat
bottom to dry out and tear >8^(. Realizing this, and with the onset of a bit of rain
recently, I decided to finally get off my duff and find the source of the leak.
As it turns out, the driver's side rear drain hose was simply plugged with
sediment, an easily remedied problem. The front drain holes are of course in
plain view when the sunroof is opened, and can easily be first snaked with an
appropriate gauge and length wire, and then blown out with air and/or water
pressure. Access to the rear drain holes, because they are shielded by the
sunroof and roof panels, is not possible. However, with removal of the headliner
trim piece from the 'B' pillar rearward, the headliner can be dropped enough to
allow access to the drain hose. The factory installed Keystone style clamp will
need to be cut off with a pair of side cutters (and later replaced with a worm style
or whatever-your-preference clamp), but then the hose can be disengaged from
the drain nipple and brought over almost to the window, allowing easy snaking
and subsequent attachment of air and then water hoses for clean out.
Heater Control Valve Part Number
If your heating system fails or is acting up, the first thing you should
check/change is the heater control valve. When this valve starts acting up you
will get symptoms from heat constantly on to it warms in stop-and-go traffic and
cools at highway speed. The swap out is pretty simple and, if you work carefully
and quickly, it is NOT necessary to drain any coolant before you change the
core. Loosen the valve assembly from the firewall and lift it up as high as
possible. A bungie chord can be used to hold it up. It is not necessary to buy the
entire valve.
The part number for the core is:64-11-8-390-132
Heater Runs Only on High
Problem:
If you have an infinitely variable blower control and the heater blower runs only
when the control is in the max setting, but DOES work when you turn the A/C
switch on, then you probably have a blown heater blower speed transistor.
Background:
The heater blower did not work unless the fan control was turned to the max
setting. The A/C fan (A/C button pushed in) is controlled correctly. This means
the control knob and electronics are ok, and the fact that the fan runs at the max
setting (transistor bypassed) means the heater blower is ok.
Procedure:
1)Open the hood and remove the heater blower cover. It's the black metal cover
in the cowl area. It's held on by 4 to 6 sheet metal screws.
2) remove the four "C" clips on the blower cage plastic covers. Two per cover,
one on each side, towards the passenger compartment.
3) Undo the clip on the back (passenger) side of each blower cover, and take the
top half off.
4) Undo the strap in the center that holds the motor down. Lift the motor up (take
care with the blower cages, they're not real sturdy), remove the two electrical
connections, and set the blower motor and cages aside in a safe place.
5) Looking into the passenger side blower vent, you'll see a transistor mounted
on a metal bracket (about 1" x 3") with three wires attached to it. That's the
blower transistor. To remove it, you need a 7mm wrench for the nuts on top, and
a stubby flat head screwdriver.
6) At this point, I just swapped in a replacement unit. The transistor, however is a
2N3055, same as in the A/C FAQ. It's a little easier to replace since it is bolted to
the heatsink/bracket instead of riveted. Replacement looks pretty easy: undo two
bolts/nuts, unsolder two leads, remove the old transistor and bolt in the new,
solder its leads, and you're done.
7) Installing the replacement is straightforward: the three leads are sized and
sexed so you can't mix them up. Just take you time when mounting the transistor
back in place - space is tight, and you don't want to drop any of the small
hardware into the HVAC ducts.
8) You may want to vacuum out the cowl area at this time to suck up any leaves
or other debris.
9) Reconnect the heater blower and place back into it holder (in the same
orientation as you removed it), and fasten its restraining strap. Spin the motor
and make sure it spins freely. If not, loosen the strap and jockey it around a bit to
eliminate the binding.
10) Put the blower cage covers back on. There's a flat spot on the side covers
that matches up with the "floor" of the cowl opening. Put the four "C" clips back
on.
11) You may want to try the blower control at this point. If it runs fine, put the
cowl cover back on, and you're done.
OBC BACK LIGHT REPLACEMENT
I haven't seen a repair FAQ specifically designated for the 6 series on the topic of
OBC Backlight Repair/Replacement, so I decided to create one
myself. I tackled the job tonight, and found that it isn't as difficult as it is often
made out to be. (At least for the six series, it is not too
complicated, just tedious) My mechanic quoted me $80 to do the job, I did it for
$2.50 and all it took was a few hours! Anyways, here is my step by step
instructions on how to replace your backlight on your e24. (NOTE- These
backlights DO burn out, if you've never done this or seen it done, SAVE this
message, you may need it in the future!)
Parts needed-OEM Backlight Replacement. (You can obtain from dealer, or parts house...it's
made by VDO I think. Costs about $20 roughly)
-- OR -- If you're handy with a soldering iron, you can buy the replacement bulbs from
Radio Shack. (Which is what I did, costs about $2.50) Radio Shack parts
number 272-1140. They are six volt bulbs, 1 volt more than the old bulbs. (No
problem, the circuit board can handle 19 volts max.) Buy 2 of these bulbs. You
may need one or both.
Tools needed-Flashlight or worklamp (if you're working in your garage or at night.)
-Phillips head screwdriver
-Philips head screwdriver with a small handle and shaft(to reach in the tiny spots)
-Needlenose pliers
-Rachet with long neck, and a 7mm socket
-Tiny, tiny flathead screwdriver to pop plastic plates. (head has to be paper thin
so you don't damage the plastic!)
Instructions1. Remove the radio, this makes the job a heck of alot easier! You can pull it from
the car, or leave it resting next to the gearshift, your choice.
2. First of all, you need to remove all the screws that attach the center console to
the dashboard/car. If you already know how to do that, skip to step
3. If not, read on.....
a. Lower the glovebox, and remove phillips screw on the right side of the center
console. (It is visible)
b. Remove screw in carpeting, just below the glovebox.
c. On the glovebox side(not under the glovebox), there is a screw where the
center console meets the dash. It is tipped upside down and tucked out of sight,
but if you stick your head and look up underneath, you should see it. Remove it.
d. Pop the leather shift boot off the console (it's clipped in, gently pull it) and lift
up the gray insulation. (note- you don't need to tear it out, just move it out of the
way.) There is a screw to the south of the gear shifter. Remove.
e. Next comes the fun part, you have to remove the plastic case underneath the
steering wheel on the drivers side. (It stretches from the door to the center
console, right above the pedals, you can't miss it) All of these screws are visible,
you just have to stick your head in there and look for them. (Work light comes in
handy here) There are 5 total, I believe, all Phillips head. After you get all of the
screws removed, it should be able to just fall to the floor. Good. Leave it there,
you don't need to pull it from the car. When you're removing it, be careful not to
pull any wiring or disconnect the circuit breaker switch. Now, you can remove the
2 screws on the left side, and the one in the upper corner. (Screws are in the
same location as the right side.)
f. Now, you need to loosen the parking brake plastic housing. (where the electric
seat controls are -- if you have them) This is where the very small flathead and
ratchet comes in. Take the mini flathead, and pop the 2 plastic covers off the
back of the housing. These covers are visible, and are slightly off color to the rest
of the plastic. Take great care in removing them, you don't want to poke any
holes in the plastic. Straight down, there should be a nut in each hole. Remove
the nuts, and gently slide the housing back toward rear seat. Once again, we're
making room for the center console to slide forward, so we don't need to remove
this from the car.(PS-Be careful when removing the nuts, they can fall down in
the seat railing.)
3. With the housing clear, gently slide the console forward. All you need is
enough space to get at the 2 screws on top. So, maybe 5-7 inches. No need to
yank it out.
4. Remove the 2 top screws on both sides. These screws support the black
plastic centerpiece that the radio, balance control and computer are attached
to. There is also a screw directly below the black centerpiece, right above the
ashtray. It's on the outside, so just feel underneath for it. Use the small headed
Phillips to remove this one. (Don't forget to put it back!)
5.There is also a screw behind the console, but you can't get to it. It's just a little
one that sort of supports the centerpiece. You should be able to remove the
centerpiece without removing the screw, because it is barely attached.
6.With the centerpiece removed, now you can finally get at the OBC! Remove the
4 Phillips screws that attach it to the centerpiece.
7. The OBC will break free from the centerpiece, and on the right hand side there
is a white plastic piece with a picture of a light bulb on it. This is the backlight.
Take your needle nose pliers and *gently* (what's your hurry?)pull it out. Now....
a. If you bought the backlight replacement part from your dealer or parts supplier,
slide it back in where the old one was. Turn on the car to test. Reverse the
removal instructions to get everything back together, and you’re done!
b. If you bought the replacement bulbs to solder in, check to see if one or both
bulbs are burned out. The way the circuitry is designed, if one bulb burns out, the
other does not function. If you're going to do one, might as well do the other. The
circuit board is fragile, so be careful. Un-solder the old bulb(s) and solder in the
new! For those with little or no experience with soldering The solder points
should be cleanly soldered. Make sure there is no solder run off un to the other
connections, this will cause a short and the backlights will not function. Reattach,
and reinsert into OBC. Reverse the removal instructions to get everything back
together, and you're through!
a. Replace the OBC buttons light this one is one back of the unit and is
recessed. You need to purchase this bulb assembly from the dealer or similar. It
is a bulb in a plastic holder.
b. PS: if you ever need to replace just this bulb, see the instructions on how to do
in an other FAQ.
SI Reset:
Short pins #7 and #19 of connector on the right. Turn on ignition. After about 10
seconds, the SI will reset.
1. Ground
4. Temperature sensor
7. Reset
8. TDC sensor yellow
9. TDC sensor shield
10.TDC sensor black
11.Start signal
12.Alternator charging excitation voltage
13.Ignition coil
14.Alternator charging supply current
15.Oxygen sensor output to test with.
Upgraded rear sway bar mounts
A couple pics of the Dinan mod sway bar mounts o n the rear. These broke often
until Dinan fixed them permanently.
E24 and E28 Steering Arm to Strut Spacers
Lowering these cars moves the front suspension out of the best part of the
dynamic camber gain curve. Once lowered, the car gains very little
camber. When the car rolls slightly in turns, the outside wheel does not camber
enough to offset body roll. You can always set the car up with static negative
camber to compensate but then you have too much negative camber while
traveling in a straight line which wears out the inside shoulder of the tire. Also,
bump steer rears its ugly head on lowered cars. I found these for about $120
including longer grade 10.9 bolts and Loctite. They were offered in 15mm (I think)
and 22mm. The 22's don't fit with most 15 inch wheels so you have to run the
thinner spacers with 15 inch wheels. This trick has been used in the past for
2002’s and can be purchased for a 2002 from places such as Korman.
The complete kit. The included Loctite is greatly appreciated.
To install:
1) Remove the 3 bolts holding the steering arm to the strut housing.
Separate strut housing from steering arm
I used a large flat bladed screw driver to help separate the parts
Reassemble with the spacers in place. I found it easiest to put the spacers on the
bottom of the strut housing first as the key along the top of the spacer was a
snug fit into the groove on the strut. Don't forget to use the Loctite on the bolt
threads.
Note the clearance between the lower control arm and the iside of the 16 inc h
wheel. Imagine how little space there would be with 15's. Now I understand the
need for 2 different sizes.
If you were sharp, you noticed that the bolts pictured at the top of the page are
not the ones I installed. For some reason, I thought the torque spec on these
bolts was about 80 ft-lbs instead of the spec 48 ft-lbs. While torquing one of the
bolts, I snapped the head off leaving most of the shank threaded into the strut.
Oops!
Luckily, I bought an SK stud remover a couple weeks ago so I had no problem
pulling the bolt shank out.
I decided against using any of the remaining hex head screws because of the
possibility of unseen damage I may have caused b y overtorquing. I found some
grade 12.9 socket head cap screws to replace them and torqued them to 48 ftlbs.
There is a factory alternative to the E30 M3 Guibo in
the form of the similar unit from the E34 M5. As is
clear from the photograph, the E34 M5 piece is
substantially thicker. This is especially so in the
"web" region between the six mounting bolts. This is
the region that carries most of the torque from the
transmission output shaft to the driveshaft.
On the E34 M5 Guibo the web region is 21.0 mm
thick vs. only 15.5 mm for the stock E30 M3 mount.
Also, the region of the bolt holes is thicker on the
E34 M5 Guibo (35.0 mm vs. 30.0 mm). The 5 mm
extra length is easily accommodated by the splined
section that connects the two driveshaft halves.
The list price for the E34 M5 Guibo is $95.75 but you
can find it cheaper if you scratch around a bit.
The part number for the E34 M5 Guibo is:
p/n 26 11 2 226 527
6 Series Ground Control Coil Conversion Experience
I have a 1988 M6 which had load leveling eliminated (Dinan Stage 1 conversion) and the
stock sway bars replaced with larger adjustable ones (25mm/19mm). When I decided to
convert to GC, I decided to do it so that if I wanated to swap the Dinan suspension back
in I could do so easily. This meant buying new front strut assemblies, Koni adjustable
shocks, new front and rear upper strut mounts, and 550/450 springs.
The front conversion was complicated. I bought a new set of front strut housings (which
have the spindle attached) and shipped them to GC for modification. They cut off the
stock spring perch, welded on a support ring for the threaded sleeve, cut about an inch
off the top of the strut tube, and reinforced/welded the sway bar mount, the bottom of the
tube so that the shock won't punch through it, and welded a gusset into place to attach
the top of the spindle assembly to the strut tube for added rigidity. At the top, I bought
their camber/caster mounts to get as much adjustability as I could.
The rear conversion was easier. Simply replace the existing Bilstein coil overs with the
GS setup. Upper strut mount and all.
Here's the fine tuning part and the problems I had, most of them tuning.
First problem was that the rear upper strut mounts were too large (diameter) to fit into
the recessed holes in the rear end. I had to have GC send up a new pair that they had
machined off ~3/4 inch of the diameter. After swapping the upper mounts, the
assemblies went in easily; 3 nuts at the top, one bolt at the bottom.
Second problem was the springs. After talking w/ several e24 coil over owners and Jay
@ GC, I decided to go 550F/450R as the car will see alot of track use with R-compound
tires. He sent 6 inch springs for the front and 8 inch springs for the rear. With that spring
setup, the front adjustment perches were screwed all the way up and the front of the car
was still ~1.5 inches lower. The rear perches were adjusted all the way down and the car
was ~3/4 inch higher than it was to start with! So, I had Jay send me 7 inch replacement
springs all around - longer in the front, shorter in the rear - to allow adjustability to corner
weight the car. This setup is better. From the ground to the center of the wheel well
openings is ~24 inches in front and ~25 inches in the rear (with 17 inch rims and 235/45
tires) - dropping the ride height ~1.25 inches all around. But I still have very little
adjustability in the rear, so I will be calling Jay back to get a set of 6 inch springs for the
rear.
Third problem was the holes in the front fender wells for the adjustable plates. The GC
plates will fit in the stock openings just fine, but if you want the full adjustability of the
plates you HAVE to cut the opening. This is not for the faint of heart, for once you cut,
there's no going back. In my case, the M6 is becoming more of a track car than a street
car, so I cut. Used a sawzall, very carefully, along lines I had drawn on the fender. You
have to worry about the support and rigidity of the opening in the fender after you do
this, but as I have a front stressbar the mounting rings seems to offer enough support for
now.
Last issue I have is with the front strut housings. The metal ring that GC welded onto the
strut housing is lower than where the stock perch was. This puts it into the area of the
sidewall of the tire. With 235/45 Yokohama A032R's mounted, there is less than 1/4 inch
of clearance between the sidewall and the welded ring. In order to be comfortable with
the situation I am going to have to grind the edge of the support ring down a bit so that
there is less of a chance of tire rub in the corners.
The suspension has transformed the car. I can dial in understeer and oversteer at will. I
can balance the car properly. I can adjust the Koni's for wet and dry track conditions.
The sway bars can be adjusted to compliment the suspension settings and track
condition. The car has no dive, no squat, no body roll. Combine that with the Sparco
Evo2 seats and Sparco 5 point harnesses and the soon to be fabricated and installed
rollbar (may end up being a 6 point cage) and the M6 is turning into a hell of a track car.