Clutch plates

[Jim Christian]

I'm sure we all realise that the life span of clutch plates vary wildly with different drivers, but with the cars I maintain it's beginning to look like these have a life in the neighborhood of 2000 to 2500 miles. What are you guys seeing?
Jim

[smcqueen]

I went right at one year on my clutch plates. That would be ten race weekends with practice day on most and a few other practice days thrown in. I don't use the clutch on the track so virtually all of the wear is moving around in the paddock.

My clutch was still working when I changed it, but was right at the recommended wear limit. I wasn't sure how far before it goes so I changed it. By the way, I only changed the plates. Is that the norm, or do others change the whole clutch?

scott

[chuckj]

From what I am seeing about a season....i.e. 10 - 11 race weekends, and a few practice/track days. My somewhat educated guess is that the majority of the wear is in the paddock, even if you up and down shift using the clutch it is just a stab, not slipping it like you see in the paddock. From my experience the wear at the end of that period puts the discs right at the minimum specification (no paperwork in front of me at the time, I think that is .090") and I think the discs would go quite a bit longer. I only change the discs unless there are signs of excessive wear on the fingers, burning or grooving on the other parts.
Chuck

[dmiller]

I'm changing my right now, I was right at the limit (.09 and .095 ) on the disks with about 10 three day weekends on them. I use the clutch for both up and down shifts. Interesting is that the wear limit is higher for the same disk if it is in the single disk clutch (.075), so I suspect that we could go farther? -darius

[smcqueen]

Darius, the wear limit is dictated by the required compression on the disc(or clamping force), not the disc thickness. So the total wear, or loss of compression, is the same for a single disc or double disc.

I had one disc at .090" and one disc at .088 without any slippage. I would be interested if anyone had more wear than that.

scott

[Paul LeCain]

The other wear-related thing you have to watch is that the release fingers will move toward the throwout bearing as the plates wear. Make sure you have the required free-play here. Required free-play varies, but is usually around 0.2".

[SCOTTY81]

Discs should be replaced when a total pack wears .030.
On a 2 disc set up this will be at .089 per disc max wear.

If the discs have been in for more than a year,check closely for cracks in the disc.

The pressure plate ,floater plate and heat shield are also critical items here.
If any of these items has a warpage of more than .008 ,then they need to be replaced.
This can be checked by laying a straight edge across the plate ,and slipping a feeler gauge between the two.

All of these items will affect the clamping force of the clutch.

Scotty
Taylor Race Engineering

[Evl]

I have one at .100" and one at .103". Is there any reason I shouldn't reassemble with them in the opposite order (each disc spinning the other way) to try and even out the wear?

[smcqueen]

I don't know about changine the stack on the discs, but they should not slip with the thickness mentioned. You just need to figure the remaining life on the discs based upon your track time to date, then decide if you want to take the car back apart when the clutch is due.

I just changed my clutch discs again at about ten weekends.

scott