Slipping clutch
- Thread starter ovrkll
- Start date
So this will be done in multiple parts. Sorry guys, just the way it goes. Can't type fast enough for this 'net.
Anyways, left the driveway and realised that the actuation point was much higher and that my clutch was slipping through all gears (significant RPM increase with no increase in speed). Looked through various forums and found that we have a self-adjusting clutch.
hmmmm.
I played with the car for a bit and realised that it was slowly changing the engage point.
Anyways, left the driveway and realised that the actuation point was much higher and that my clutch was slipping through all gears (significant RPM increase with no increase in speed). Looked through various forums and found that we have a self-adjusting clutch.
hmmmm.
I played with the car for a bit and realised that it was slowly changing the engage point.
I am just shy of the dreaded 100K mile threshold, so I was wondering if there was a checklist item that was missed......Nope, we are good!
Apparently I had "glazed" the clutch plate by doing a little bit of "spirited driving" and not returning to a normal pace before putting her up for the night.
Spirited driving in this case means shifting at 5500 RPM at flat out gas....that is the highest point of our torque curve before is heads south. Racing?......you figure it out :evil:
A little bit of moderate driving this afternoon, it seems that I have worn off the glaze and the clutch grab is back to normal. I will probably still have my Indy take a look and see if there is any abnormal wear.
Anyone that has been around for a while does know that my car has been on the dragstrip around here, and is a candidate for early tranny failure. End of self-disclosure. 8)
Apparently I had "glazed" the clutch plate by doing a little bit of "spirited driving" and not returning to a normal pace before putting her up for the night.
Spirited driving in this case means shifting at 5500 RPM at flat out gas....that is the highest point of our torque curve before is heads south. Racing?......you figure it out :evil:
A little bit of moderate driving this afternoon, it seems that I have worn off the glaze and the clutch grab is back to normal. I will probably still have my Indy take a look and see if there is any abnormal wear.
Anyone that has been around for a while does know that my car has been on the dragstrip around here, and is a candidate for early tranny failure. End of self-disclosure. 8)
How to check if the clutch is slipping:
Start off at a slow speed and put it in 6th gear, apply a modest amount of acceleration. Did the vehicle increase in RPM without a noticeable increase in speed? RPM should remain equal with increase in speed.
Glazed (From my experience)
Have the car in any gear and hit the torque band. Any noticeable difference in RPM/MPH? Yep, there is the problem. Try driving like a normal person for a bit, and it may sort itself out. Otherwise see a good Indy for a clutch assy. replacement
Start off at a slow speed and put it in 6th gear, apply a modest amount of acceleration. Did the vehicle increase in RPM without a noticeable increase in speed? RPM should remain equal with increase in speed.
Glazed (From my experience)
Have the car in any gear and hit the torque band. Any noticeable difference in RPM/MPH? Yep, there is the problem. Try driving like a normal person for a bit, and it may sort itself out. Otherwise see a good Indy for a clutch assy. replacement
Liverpool
Not experienced it yet in the Z4, but mine's 'only' on 63k miles.
However, I had it on one of my M5s, and it felt just as you described. You'd be in a racy mood and you'd change up quickly only to find the revs rose a bit faster than usual, and the car accelerated slower than usual. Mine went back to normal almost instantly, but I booked it in to get checked out (two week/1200 mile wait), and found I'd worn some of the dual-mass flywheel away too, which turned a £400 job into a £1000 job.
Sometimes it's just a case of not having your foot fully off the clutch before hitting the throttle - and if you were trying to do 'no-lift' changes than that certainly could have cause momentary slippage.
You can do another test for slippage by parking the car, putting the handbrake on, and trying to slowly move the car forward in 1st gear. If the car moves then the clutch is fine for now (or the handbrake isn't fully on). If it doesn't move even when the clutch pedal is completely released then your clutch is on its way out.
However, I had it on one of my M5s, and it felt just as you described. You'd be in a racy mood and you'd change up quickly only to find the revs rose a bit faster than usual, and the car accelerated slower than usual. Mine went back to normal almost instantly, but I booked it in to get checked out (two week/1200 mile wait), and found I'd worn some of the dual-mass flywheel away too, which turned a £400 job into a £1000 job.
Sometimes it's just a case of not having your foot fully off the clutch before hitting the throttle - and if you were trying to do 'no-lift' changes than that certainly could have cause momentary slippage.
You can do another test for slippage by parking the car, putting the handbrake on, and trying to slowly move the car forward in 1st gear. If the car moves then the clutch is fine for now (or the handbrake isn't fully on). If it doesn't move even when the clutch pedal is completely released then your clutch is on its way out.
lacroupade
Veteran
Easiest (and most traditional) way to check is drive briskly at constant speed in top gear, then floor the clutch pedal and release quickly. Revs should come back almost immediately - if its slipping you'll know by the way it struggles to recover.
But regarding this 'glazing' business, I thought the CDV should take preclude that sort of thing? Or did you?...you did, didn't you....!
But regarding this 'glazing' business, I thought the CDV should take preclude that sort of thing? Or did you?...you did, didn't you....!
Follow up. Yep the clutch was pretty much done. Indy had it done in 5 hours and it feels so much better, and the nanny lights are kicking on a lot more often :lol:
Apparently the pressure plate had found the near-end of its life, and the plastic pin on the fork release was sheared.
All sorted for $800 USD
Apparently the pressure plate had found the near-end of its life, and the plastic pin on the fork release was sheared.
All sorted for $800 USD
The Cdv will actually make things worse by allowing some slip which is why the friction plate overheats and glazes.lacroupade said:Easiest (and most traditional) way to check is drive briskly at constant speed in top gear, then floor the clutch pedal and release quickly. Revs should come back almost immediately - if its slipping you'll know by the way it struggles to recover.
But regarding this 'glazing' business, I thought the CDV should take preclude that sort of thing? Or did you?...you did, didn't you....!
You will 'glaze' a clutch near the end of its life as the pressure plate isn't able to give full linear application to the friction material. In this car and you do slip it, then it will wear exceedingly quickly. My old evo had a twin plate clutch which needed to be overhauled instead of replaced, very gripped The thing to be careful on the Z4M's is i believe they have a dual mass flywheel and thus if you replace the clutch, you can't properly skim them - which as you can inevitably work out would mean a new flywheel too.
The thing to be careful on the Z4M's is i believe they have a dual mass flywheel and thus if you replace the clutch, you can't properly skim them - which as you can inevitably work out would mean a new flywheel too.Plastic clutch parts? Really BMW?ovrkll said:
Hypothetical question, I'm no where near needing a new flywheel. If available, why couldn't I put in a traditional solid flywheel? I know how to drive, I don't need no stinking spring loaded flywheel, guibo, CDV, etc. Just clutch disc springs will suffice. That's all I've had on every other car I've owned.