J. Patterson

My theory proved correct. When my new to me on second day instructor suggested that I change my 5-4-3 sequential downshift to a 5-3 downshift skipping 4th . I did not consider that if that downshift were done early in the braking that the clutch disc would be accelerated to extremely high rpms by the trans synchros, if 3rd were selected while still traveling at 100+ mph. I shifted 5th to 3rd at the same point that I had been shifting 5th to 4th with the intention of keeping the clutch released until braking brought my speed down to 3rd gear appropriate rpms. Bad plan. (give me a break, kind of busy driving to analyze all this at that point.) Below are pics of the (expensive ) result.


Pressure plate and Dual mass flywheel look good except for a bit of heat discoloration that had happened over the course of the cars previous 80,000 miles.

<img src="http://pictureposter.audiworld.com/74232/road_atlanta_july_08_022.jpg">

Clutch disc looks perfect on back side but on the side you see the lining was separated from the disc by the extreem centrifugal force of the high rpms while the clutch was released but 3rd gear was selected while still traveling too fast.
<img src="http://pictureposter.audiworld.com/74232/road_atlanta_july_08_021.jpg">

The sad part is that the lining that did not fail is still at 75+ % thickness. This clutch would have outlasted the car if I had not killed it.

The car is being reassembled as we speak. We are doing a flywheel and pressure plate and slave too despite the fact that they looked good enough to use again. It is a long job to get to the clutch and don't ever want to do it again. Lesson learned. Thoroughly.

Basttion

One downshift can destroy our clutch?

the Quiet sTTorm...

ouch. glad that was the only thing lost

J. Patterson

Yes.If you choose a too low gear while traveling too fast.The disc can be spun above it's rpm limit.

J. Patterson

Well there WAS my pride.

carsluTT

good call on the slave, there a pain to have to fix down the road....

TTinCT

ouch........did you rev match????

adminisTerTurbo

yeah?

J. Patterson

While I always rev match when doing a single gear downshift, this skip 4th downshift was new to me. I did my normal side of foot tap to the gas as I downshifted but thinking it through , no way would that match engine rpm to the rpm the clutch disc reached while being shifted to third gear while still traveling so fast. (3rd gear 100+---- what would that be---10,000 rpm? ) AND--- there is always the possibility that I missed 3rd and was pushing against the 1st gear synchro -- didn't go in gear anyway, no way to know for sure, but THAT could spin the clutch disc to unheard of rpm. Glad I still have my feet.

roadyTT

Drop 3rd @ 100 would've broken redline big time