UKKid35

I am getting the friction plate of my S4 relined, but the reliners need to know the original thickness. Any help much appreciated. The cost is going to be 30% of the price of a new disc via Porsche.

UKKid35

Anyone have new clutch disc they can measure for me?

Thanks in advance

Rob Edwards

Paul-

Till someone comes up with a new one to measure, I pulled the clutch on my GT last weekend, and the friction disc has 2000 miles on it. It measured, on average, 10.3 mm, but some spots were closer to 10.4. Hopefully someone can chime in with a truly new disc.

UKKid35

That's great - many thanks!

jon928se

I just measured a new one, had to rely on my old vernier calipers and convert from imperial as my digital caliper battery has died. The thickness of a new unused Sachs varies as with Rob's measurements but in general 10.4mm (odd high spot was 10.5 possibly) Rivets are 1.5mm below the friction surface and I couldn't reliably measure the wear grooves but Ild estimate about 0.3mm belwo the surface.

UKKid35

Brilliant thanks!

That concurs with info from Marton in the WSM:
I'll post details of the Reliner once I have the disc back and fitted.

Thanks again

cfc928gt

Paul,

I'm glad to hear you're doing this. I'm not sure why Porsche thinks these discs are made of gold but the $250+ price of a S4 disc is ridiculous especially since they're such a simple design. Please keep us posted on how this works out.

UKKid35

Roger can beat the dealer price so it's worth contacting him before buying new from Porsche.

cfc928gt

Not a problem, I bought a spare before last years big price increase. However, I would think one of our vendors would jump on the relining idea as a lower cost alternative.

Mrmerlin

Fred, one thing to consider is the fact that a simple relign wont rep-lace the splined collar portion and since this portions need to be perfect to operate I would rather have a new disc than a relined unit.
Usually the discs can be in service for many years before being removed and as you know corrosion will damage the splines once they get corroded than the original tolerances are lost and then this will contribute to possibly sticking or dragging of the clutch when its released.
Thats why when you install new parts its important to use a new stub shaft and new discs along with the correct hi temp Porsche grease.

UKKid35

Jon - please can you measure the thickness of the friction material itself?

The disc was returned to me by the reliner within 48hrs, I had given him the overall thickness of 10.5mm, but the returned disc was about 9.6mm. He explained that the friction material was available in various thicknesses and he chose 4mm, because the 5mm would have resulted in an overall thickness outside my spec. He also said that the 10.5mm disc would probably compress to about 10mm, whereas I had noticed that the returned disc did not seem to have much compression. That would make the difference nearer 0.5mm.

If I can find out the thickness of the friction material on a new disc then I'll be able to get a better idea of whether this was a successful exercise or not. I also need to fit the disc!

jon928se

Yes

Give me a couple of minutes

jon928se

Looks like it's your lucky day. Go and buy a lottery ticket now.

The friction stuff has a very thin metal backing plate between it and the the structural "disc" . Total thickness of the friction stuff and thin metal plate is about 3.8-3.9 mm. The thin metal plate seems to act like a bit of a spring which keeps the friction stuff separated from the structural disc.

So I gently clamped the friction disc in the vise until the gap between the friction stuff, thin plates and structural disc closed up (No real vise pressure - just a little finger turning the vise) Total thickness is now about 9.6-9.7mm measured right next to the clamped stuff.

UKKid35

Many thanks Jon, seems like that was £78 (inc tax & p&p) well spent.

I'll post of pic of the disc later.

UKKid35

For anyone interested in the UK the reline was by Jim Jack Services in N Lanarkshire.