944Hybrids: 924/944/968 and 928 V8 Conversions
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HOW TO DO AN ADVANCED SEARCH.

Mon Jul 08, 2013 3:56 pm by Admin


For the benefit of 944Hybrids users there are two search functions available for you to use.
The purpose of this sticky is to explain the "Advanced Search" function because it is much more powerful and is the best choice when researching information.

When you log on to the site a list of options is shown in a line at the top of the page. One option is labelled "Search", use this option (NOT the search box lower down on the right).

After you click on the upper search option, a drop down box appears. At the bottom of this box is a radio button marked "Advanced …

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Clutch disc for LS7 FW/PP assembly

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Clutch disc for LS7 FW/PP assembly Empty Clutch disc for LS7 FW/PP assembly

Post  Brucebe on Mon Nov 19, 2018 6:42 pm

Hello,

We have been supporting a client who recently asked us install a new LS3 in his LS2-powered 1987 944.  Previously, a SPEC stage 1 kit was used (SPEC part number:SC091-8 ). As some may know, the SPEC system utilizes a flat flywheel, and a "flat" organic clutch disc. This setup functioned with the LS2, but, the engagement was not smooth, and it had the heavy pedal that SPEC is sort of known for.  The clutch was also not very tolerant of faster shifting, and an examination of the clutch parts upon disassembly indicated a bit of interference between the clutch disc and the pilot bearing adapter.

The LS7 clutch setup is an obvious candidate, as the capacity is sufficient, and GM has done an excellent job on the clutch pedal effort and engagement for a wide variety of driving scenarios.  The pressure plate is self-adjusting, and the flywheel geometry helps prevent the potential issue of the clutch disc hub contacting the pilot bearing adapter (the surface of the flywheel is about 3mm further away from the crank than the SPEC unit).

A standard LS7 clutch disc has a slightly smaller O.D. than the older SPEC disc that we removed from the LS2.  This particular SPEC disc had an O.D. of 11 5/8" - larger than the LS7 OE unit, but still fitting within the LS7 stepped flywheel without interference.

Here's the problem:  SPEC now use an 11 3/4" facing blank for their clutch discs, which will NOT fit within the stepped LS7 flywheel.

Is anyone aware of another clutch disc, besides the Chrysler application discussed elsewhere on this forum, that is dimensionally identical to the "old" SPEC disc?  This would be:

  • O.D. - 11 5/8" (or slightly less)
  • Thickness - 0.350"
  • Hub - 23-spline PORSCHE (not Chrysler)
  • Long hub - ~1.2"
  • Flat profile


In parallel, we are now working with a very reputable sport/motorsport clutch manufacturer to develop a clutch disc that will be compatible with the LS7 PP/FW assembly.

-Bruce Beachman
Beachman Racing

Brucebe

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Post  948 on Tue Nov 20, 2018 8:38 am

I have had custom clutch discs made by Clutchnet, now California Clutch. The current disc I have in my 944 conversion was made by McLeod for me, back when Red was still running things - this was before we had manufacturers like Spec making parts for our conversions. I would try contacting California Clutch, they have been one of the few clutch disc manufacturers, in the U.S, for decades.
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Post  Brucebe on Tue Nov 20, 2018 4:19 pm

Thanks for the reference. Based on the lack of replies, I'm guessing that with the exception of the Chrysler disc (and variants), and the SPEC disc (now no longer compatible with the LS7 PP/FW), there are no other turn-key options.

-Bruce

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Post  948 on Tue Nov 20, 2018 5:50 pm

Mine was made from a Chevy disc, 10.5", and a Porsche 944 splined hub.
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Post  Brucebe on Tue Nov 20, 2018 6:29 pm

That's about a 26% reduction in area, over an 11.5" disc (assuming the same I.D.).  Probably just fine for stock-ish LS1 power levels. The Chevrolet Performance LS3s have outputs similar to the LS7, so we want to use all of the available surface area, to get the rated torque capacity out of the clutch assembly.

-Bruce

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Post  sharkey on Tue Nov 20, 2018 10:17 pm

seeing spec makes the disc specifically for the other ls conversions im sure they can put you together a disc that will work with the ls7 flywheel.

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Post  948 on Wed Nov 21, 2018 4:47 pm

I shared my specs only to illustrate the fact that you can have whatever you want made...
Brucebe wrote:That's about a 26% reduction in area, over an 11.5" disc (assuming the same I.D.).  Probably just fine for stock-ish LS1 power levels. The Chevrolet Performance LS3s have outputs similar to the LS7, so we want to use all of the available surface area, to get the rated torque capacity out of the clutch assembly.

-Bruce
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Post  MCharlebois on Thu Feb 27, 2020 1:46 pm

Bruce, I know it's been a while you posted, but I was curious to know what setup you ended up choosing?
Thanks,
Mathieu

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