Slipping Clutch

[twoweelz]

I just noticed a slipping clutch on the wife's '03 Z4 yesterday under moderate to heavy throttle going up a hill. It has 107k miles so I'm assuming the clutch is original. No mods to car. Here are some questions I have in mind. Please give me your thoughts on some or all. Thanks!

- Does flywheel need to be replaced or resurfaced?

- I've heard of others using Luk or Sachs parts instead of OEM. Opinions?

- What other parts should be replaced while the tranny is off? Slave cyl?

- Delete the CDV valve while it's at the shop? Car is lightly driven. I hear it helps drivability.

- Anything else I should know before calling around for prices?

Thanks so much for any info!

[gas-can]

- Does flywheel need to be replaced or resurfaced?
I don't believe a flywheel needs to be replaced by default unless you notice cracks, warping once you have the tranny off. Do you have any weird vibrations/chatter during clutch use? I can't recall what kind of flywheel you have in the 03 plate, but if it's lightweight, I would probably recommend against resurfacing, due to the already reduced mass (reducing it more may cause it to crack during use/heating cycles).

- I've heard of others using Luk or Sachs parts instead of OEM. Opinions?
No idea on this. Others will chime in I'm sure.

- What other parts should be replaced while the tranny is off? Slave cyl?
Recommend doing the throwout bearing at same time, as all the labor is already done to access it. BMW calls the MT oil lifetime, but it may not be a bad idea to check the quality of the oil while under the car to see if it may be able to use a new batch.

- Delete the CDV valve while it's at the shop? Car is lightly driven. I hear it helps drivability.
This seems personal, but I highly recommend it. If you are a good shifter, you shouldn't need the small protection it provides to the drivetrain. This may also be one of the reasons for the rather quick clutch wear on your car- this valve wears the clutch faster as it increases slip during engagement. 100k is quite low for a clutch. Are all the people that drive this car experienced?

- Anything else I should know before calling around for prices?
Make sure it's a reputable place. You should be able to ask the mechanics these kinds of questions and get good answers before you pay them anything.

good luck
-gc

[twoweelz]

gas-can, thanks for the info.

I am experienced but my wife is new to manuals and is the primary driver. There is some life left in this clutch for normal driving so I hope she is out of the beginner stage by the time the clutch is slipping under normal loads. I was wondering why it is taking her so long to learn the clutch engagement. It must be the CDV. I did notice it is slightly harder to drive versus other manuals I've owned but nothing that can't be learned quickly.

[pokeybritches]

The flywheel is considered a wear item. Check to see if it's out of spec. There are many E46 threads on this, so don't limit your searches to the Z4. At 107k miles, flywheel replacement is a definite possibility. I'm about to do mine at 130k miles, ditching the dual mass for a single mass flywheel and sprung hub clutch.

[twoweelz]

Thanks for the info, Pokey. Can you recommend brands and vendors for the single mass/sprung hub setup? Is it more or less $$ to go this route? Any benefit for just a stock daily driver?

[DerekSelmanRacing]

Once it starts to slip, it will go fast and burn the flywheel, making replacement necessary if it isn't already necessary. I'd also replace the pivot pin, pilot bearing, rear main seal and possibly input shaft seal. Check also shift linkage bushings and there is probably a seal at the top of the trans for the shifter.

[seank]

Is Derek Selman still Racing? I haven't seen him in a long while.

[DerekSelmanRacing]

No, just haven't changed the log in name. This is Joel, his Dad. I run the Z4 pictured in NASA time trial regularly.