is my clutch slipping?

L

louis

Member
 the exotic far east
dear all,

was chasing a red alfa GT yesterday(not really relevant) when i think i experienced some clutch slip... but i'm not too sure.

basically, i didn't notice anything amiss with first gear but when i changed to 2nd and 3rd gear, revs climbed from 4000-ish to my redline at around 6500 at a "normal-ish" rate; although i did feel that acceleration was not as strong as it felt once i changed to 4th gear. so is this the tacho-speedo disparity that's symptomatic of a slipping clutch?


several other pieces of info that may or may not be relevant towards reaching a diagnosis:

1) DTC lights did not light up at any point in time. although my DTC fault lights did come on a month ago(went away after a day and dealer's diagnostic unit showed no fault codes stored)
2) car feels normal in daily driving, but i seldom rev beyond 3000rpm in DD anyway.
3) didn't feel this "lag in acceleration" in 1st or 4th gear, only 2nd and 3rd. didn't try 5th gear at that rpm range as it would have been irresponsibly fast for public roads.
4) i couldn't smell any burnt clutch even with my convertible top down.
5) i thought the engine sounded different from 4000-6500rpm in 2nd and 3rd (it sounded like it was free revving.... you know, like when you're gunning the engine in neutral gear)
6) i still have my CDV installed as i haven't had a problem with it.
7) my 2005 car has a little more power/torque than the average 2.5L Z4.
8 ) my sport button was on when the incident happened. DTC was, presumably, still active.


sooo....... is this clutch slip? if so, why didn't i feel it in 1st and 4th?

or is this a tire traction issue(perhaps TC didn't activate because of an electronic gremlin)? if so, shouldn't it be worst in 1st gear?

or is it a combi of both or something else altogether?

thanks for any feedback you may have.
 
louis, has it repeated itself again?

Have a look at these -

http://www.ehow.com/how_7687_diagnose-s ... lutch.html
http://www.carspace.com/guides/How-to-T ... ing-Clutch
 
Wondermike,

thanks for the links. i found an empty stretch of road today and tried to reproduce the problem but couldn't. perhaps its my cdv afterall... which is a good thing i suppose, because i've had lots of problems finding an aftermarket replacement for the smaller 228mm clutch that's found in the 2.5L.

most companies only carry clutch upgrades for the 240mm clutch that's found in the 3.0L Z4, either that, or they only have a clutch + lightweight flywheel upgrade kit that'll replace my stock flywheel with a lighter 240mm one.

my last hope lies with sachs but i've been unable to contact their local representative.

will update you guys if i learn anything new.
 
hi guys, just a quick update on my situation:

i think i've got the problem pinned down. i found an empty stretch of road and did a few straight line acceleration runs to see if i could replicate the problem. i didn't drop the clutch for any of the starts, i just got my car moving in first gear up to a speed of abt 10-20km/h and only mashed the gas pedal to the floor after the clutch had been fully released.

the first two runs were faultless, good strong acceleration, no obvious signs of slip, no smell of burnt clutch, i stopped after redlining in 4th both times.

on the third run however, 1st to 2nd gear were normal but there was obvious and unmistakable slip as i shifted into 3rd and 4th. the revs just climbed more quickly than it did in the lower gears and i could hear the engine scream but yet at the same time, i could sense the drop in torque and see the stagnant speedo needle. couldn't smell any burnt clutch though.

i cruised around for abt 5 mins to cool the engine/clutch/brakes down before i started the 4th run and the same thing happened again.

so my conclusion: probably a combination of poor shifting technique, cdv slowing the clutch engagement and susceptibility of the organic clutch lining to overheating that caused the clutch to overheat, glaze and slip by the time i started my 3rd run.

solution: i've placed an order for a custom stage 3 OFE clutch from a company in the US called southbend clutches. it's been gaining favour over in some of the audi forums and it's supposed to retain OEM clutch pedal effort despite higher torque capacity.

as is typical of most of my internet purchases from the US though, initial email replies were speedy and courteous but once payment had been made, replies were scarce and delivery has since been delayed by close to a week from the promised "1-day for the clutch to ship out" :thumbsdown: also, although i purchased it as part of an internet group buy, not only was i not eligible for the 15% discount, but i had to pay more than what the others did for my clutch since the company said it was a custom setup. 450USD for this southbend OFE versus roughly 350USD for a sachs HD and 250USD for the sachs OEM replacement.

gripes about my purchasing experience aside, i'm looking forward to the arrival of my new clutch so stay tuned for a review.

cheers
 
Well sounds like you'll cure the problem soon. Bit of a bummer about the service you're getting though, I reckon I would've just gone for the sachs HD clutch. Let us know what it's like once you get it.
 
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