Z3 M Coupe Clutch and Lightweight Flywheel Job - Tips, experience, part list

[calimanusa]

I recently performed a clutch job on my 1999 M Coupe and thought I'd share some of my experience. There are a lot of excellent resources out there (listed below), so this isn't supposed to be a complete DIY, but rather just some tips and thoughts about my experience. I also replaced the shifter bushings, transmission bushings, and center support bearing. I would recommend replacing your guibo too if necessary (I did mine a few months ago). Other than the flywheel which I bought directly from Gripforce, I sourced all of my parts from Pelican Parts, FCP Euro, and AutohausAZ.

The installation was pretty straightforward, however it is very involved. I was working at a DIY garage with a lift and many professional tools (bearing puller, transmission jack, air tools, etc.) which made the job a lot easier. If you're in the LA area, I highly recommend performing the work at urdreamgarage.com. It's a great place where you can rent a lift and tools by the hour or day.

Overview
Gripforce FX Racing Chromoly Flywheel - 14.5 lbs
Sachs E34 Sprung Clutch Disc (21212226594) - 3.9 lbs
Sachs OEM Pressure plate - 11.9 lbs



The stock dual mass flywheel weighs 22.8 lbs and and unsprung clutch disc weighs 2.5 lbs so this setup contributes to about 7 lbs savings total. The chatter is barely noticeable when idling; I can hear it but can't feel it. It sounds sort of like water running through pipes on the inside of your house if you were to put your ear up to the wall. However, the noise level is minimal and you'll probably only notice it if you're listening for it.

I haven't broken in the clutch yet (500 mi) so I can't comment on the acceleration but I have noticed the car revs much more freely. So far happy with this setup, cost was under $500.

Some install tips

Dropping the exhaust
You don't have to drop the entire exhaust, just the center pipes as per Vinci's DIY.

Infamous "bitch" clip
This clip was indeed a "bitch" to take off, however a good understanding of how it works allowed me to do it in about 5 minutes. Lowering the tranny helps give your hands clearance and a small screwdriver to jam between the "tang" will help with the job.
http://www.unofficialbmw.com/e36/dri...itch_clip.html The pelican DIY on shifter bushings also has some good advice on removing the clip.

Undoing the tranmission bolts
You will need a 2-3 foot extension, u-joints, a breaker bar, and female torx sockets for the job. Some of these were difficult to access and I ended up stripping one of the bolts. Had to replace it with a new one which set me back a day. You may want to consider buying an extra set of bolts before you start the job. You can always return them.

Separating the transmission
This was the most difficult part. It took a lot of work to get the transmission separated from the engine. Between me and a helper, it probably took 30 minutes of wiggling, pulling, and delicate prying to separate it. A transmission jack proved to be very helpful.

Flywheel and Clutch install
You'll need a pilot bearing puller to replace the pilot bearing and if you buy your parts separately (no kit) make sure you have a clutch alignment tool as well. There are some tools people have come up with to hold the flywheel in place while torquing the bolts. I didn't have them and had to make do with a pry bar and an assistant. I screwed in a transmission bolt to push against with the pry bar while torquing. Remember to thoroughly clean the flywheel and pressure plate surfaces with brake cleaner immediately prior to installing. Gloves get greasy and you don't want any impurities on the surfaces. Since my aftermarket flywheel bolts didn't come with threadlocker on them, I applied blue loctite before installing. The sprung clutch disc has "gearbox side" printed on one side of it. Following the advice of others, I installed it backwards with the "gearbox side" facing the front of the car. I also compared this orientation to the stock disc and it seems to make sense. Haven't had a problem so far.

Bell housing internals
I thoroughly cleaned off the inside of the bell housing with brake cleaner and installed the parts dry. After doing some research, this seemed the way to go since the moving parts other than the fork are plastic. A dry lubricant could also be used but didn't seem necessary. This step was also the step I felt least confident about, so when performing this job, be sure to take a good look the internals of the bell housing before you disassemble the parts. Also, after a lot of deliberation I decided to use a OEM plastic pivot pin instead of an upgraded metal one. I figure it worked fine before.

Seals
Other than the selector rod seal (as part of the shifter bushing overhaul), I didn't replace any of the seals since they weren't leaking and I read that a lot of people had leaks after replacing old seals with new ones. Not sure if that just speaks to a job poorly performed, but I decided to take my chances and deal with the leak when it occurs.

Reattaching the transmission to the Engine
This wasn't nearly as difficult as removing it however you'll still need helper. Also, it's good to have someone holding on the the bolts while you're torquing them to ensure they don't slip off. Lastly, bear in mind that two of the bolts screw into the starter. I had to hold the starter in position while my helper guided the bolts in.

Shifter Bushings
This job was more time consuming than I expected, plan for a couple hours. The most difficult part was the shifter ball bushing (25111469397). I understand there is a tool designed to remove this however I didn't have one on hand so I tried using 90 degree pliers but finally resorted to the good ol' dremel. The carrier bushing was quite easily removed and a new one pressed in with a vice. There are kits out there but I don't recommend replacing every single part. The list below is what I replaced, got them individually from autohausaz. As for the difference, the shifter bushings definitely made operation a little smoother, and 5th is less sticky now.

Shift Pins
I decided against doing this job. Not sure what kind of improvement I'd see after replacing the shift pins, but it's shifting better than before and I didn't really have any issues previously, so I'm happy.

E21 Transmission Mounts
Looking for a little extra performance, I went with E21 OEM transmission mounts. I looked at some aftermarket parts but ultimately decided these were cheap and met the performance-comfort balance I was looking for. To install these you'll need to increase the diameter of the holes in the cross member where the mounts bolt into since bolts of the E21 mounts are thicker. A drill press worked perfectly for this job. You'll also need to ensure you buy nuts and washers to fit. Lastly, the cross member has a couple of nubs for fitting purposes that will prevent the E21 mounts from sitting flush. You'll need to grind these flat using a dremel or some other tool. This mod was very easy.

Center Support Bearing
The bearing is a tight fit. You'll need a bearing puller kit (http://www.harborfreight.com/bearing...set-93980.html) to get it off. Also, there's a good chance you'll screw up the backing plate while removing so I would plan on replacing that too. I also replaced the lock ring, seemed prudent. To get the bearing back on, I used a short piece of 1 1/4" PVC pipe and a club hammer.

Centering Sleeve
On a whim, I decided to replace this part as well. It probably wasn't necessary and it was a lot of work to get it out. Since the bushing has rubber on the inside and metal on the outside, my pilot bearing puller ended up just tearing up the rubber instead of pulling the whole sleeve out. After trying many different approaches, I used a dremel to remove the rubber on two sides after which the bearing puller was able to do its job. I then used a press to get the new sleeve in. It's a very tight fit!

Part List - Clutch
Gripforce FX Racing Chromoly Flywheel
21212226594 - E34 M5 Sprung Clutch Disc (install backwards)
21212228065 - Sachs stock pressure plate
21512226729 - Sachs stock throw-out bearing
11211720310 - Pilot Bearing (I went with Genuine BMW)
07119906045 - Pressure plate bolts (you'll need 6)
11222243051 - OEM flywheel bolts (if you're sticking with the OEM flywheel, you'll need 8. My LWFW came with shorter bolts)
21511223328 - Pivot Pin
21517570284 - Spring clip
26127536563 - Flex Joint Lock Nuts (one-time use, you'll need 6)
18301716888 - Exhaust Gasket (one-time use, you'll need 2)
25111221849 - Locking pin for shift lever support arm bushing (aka bitch clip, there's a good chance you'll screw up your old one when removing it)

Other parts to replace (while in there)
23711109173 - E21 transmission mounts (buy nuts and washers to fit)
26122227278 - Center support bearing
26111226553 - Backing plate for CSB
26123648156 - Lock-ring for CSB
26111226552 - Dust cover for CSB (I didn't replace mine, just cleaned off the old one)
26112226527 - Flex disc guibo
26117526611 - Centering sleeve (see my experience above)

Part List - Shifter Bushings
25111220439 - Plastic washer (you'll need 4)
25117507695 - Shifter bushing at shift level support
23411466118 - Shifter rod coupler bushing (pretty sure it's made of foam, you'll almost certainly need a new one of these)
25111469397 - Shifter ball bushing (very difficult to get off, I would reconsider replacing if the current one looks ok)
25111221700 - Rubber shift boot (I replaced mine, not sure it was necessary)
25111222015 - Rear shifter arm bushing (probably good to replace)
25117571899 - Shifter circlip (you'll need 2 of these, probably could reuse, but it's a cheap part)
23111204223 - Shift shaft seal (I replaced mine, not sure it was necessary)

Clutch DIY's
http://webspace.ringling.edu/~dplassma/cj/cj.html
http://www.bimmerforums.com/forum/sh...hmasters+sachs
http://www.pelicanparts.com/bmw/tech...ch_Replace.htm

Torque Values
http://www.autoevolution.com/news/bm...diy-55108.html

Shifter Bushing DIY
http://www.pelicanparts.com/bmw/tech...t_Bushings.htm

Book
http://www.amazon.com/Performance-Pr...mw+project+101

Part diagrams
http://www.realoem.com/bmw/partgrp.do?model=CM93

[BenFenner]

[calimanusa]

Update

The clutch is fully broken in now and I'm still happy with the setup. It held up perfectly fine during my last track day. I haven't noticed any significant difference in acceleration but as expected, it does rev a good amount freer thanks to the lightened flywheel which makes heel & toe shifts a bit easier to execute.

Also, following UUC's transmission and differential fluid recommendation for warm climates (http://www.uucmotorwerks.com/html_te...nny_rattle.htm) I replaced my fluids with:

Transmission: 1 quart Redline 75W140NS and the remainder with Redline MT-90
Differential: Redline 75W140 (non-NS)

I'm happy to report this recipe reduced chatter compared to the 1 year old Royal Purple fluids I had from before. Now when the transmission is cool, the chatter is negligible. After it heats up, I can hear it, but it's about half as loud as before. Very liveable for a daily driver.

[rf900rkw]

I do this job fairly often in my garage, on stands, by myself.

The correct "E" sockets are essential. E8, E10, E12, pan, starter, bell respectively. I have a univeral E12 just for the top bolts. Do not attempt this with the recent spate of "spline drive" sockets that are trying to replace the E torx.

Getting the starter off it's locating dowel is normally the biggest fight. Top starter and bell bolts are easier to reach from under the hood, a Z3 exclusive.

I **never** disconnect the center pipe. Depending on the job combinations (like driveshaft), I may take the back cans off. But never the center pipe. You can get a 6sp in and out with the pipe in place, the 5sp has gobs of room.

[gomanual]

This is a great write up; thanks for doing it and thanks for linking it in the FAQ. I just installed the JBR steel SMF with a Sachs HD sprung hub clutch and pressure plate, which looks like a very similar set of parts to what is discussed here.

I just wanted to add that I’ve read in several places that the disk should be installed “backwards”. The Sachs clutch disk was not labeled at all, so “backwards” was difficult to figure out. Put the spring pack toward the engine. If the spring pack faces the transmission the throw out bearing guide sleeve can contact the hub of the clutch disk. If you assemble it that way you’ll get to find out how much easier it is to take the transmission out the second time.

-Dan

[325bob]

This is a great write up; thanks for doing it and thanks for linking it in the FAQ. I just installed the JBR steel SMF with a Sachs HD sprung hub clutch and pressure plate, which looks like a very similar set of parts to what is discussed here.

I just wanted to add that I’ve read in several places that the disk should be installed “backwards”. The Sachs clutch disk was not labeled at all, so “backwards” was difficult to figure out. Put the spring pack toward the engine. If the spring pack faces the transmission the throw out bearing guide sleeve can contact the hub of the clutch disk. If you assemble it that way you’ll get to find out how much easier it is to take the transmission out the second time.

-Dan

Is the E34 M5 disc being used instead of a stock Z3 part the reasoning for installing it backwards, against the stickers warning?

[gomanual]

Is the E34 M5 disc being used instead of a stock Z3 part the reasoning for installing it backwards, against the stickers warning?

My understanding is that BMW decided the DMF had enough damping in it to skip the sprung hub clutch disk. Converting to a single mass flywheel eliminates this damping, so I wanted to switch to a sprung clutch to minimize NVH as much as I could. Since the stock disks are rigid they are thinner (no spring pack in the middle).

The single mass aftermarket flywheel I bought has a hollow area in the middle to accommodate the extra thickness of the spring pack. That's not how they are mounted on most cars that are designed for sprung clutches though since it's easier to accommodate the spring pack in the bell housing than in the flywheel.

- Dan

Sent from my Pixel XL using Tapatalk

[rf900rkw]

Yes but. The sprung hub is asymmetrical. Putting the disc in backwards pretty much negates the springs.

[Master Crash]

this thread is awesome. I love this forum.