350-400 hp clutch for the NA

[944noob]

I'm swapping to turbo internals and megasquirting for a boosted build, but am having trouble finding organized and credible information about any off the shelf clutch components for the NA. Everything is significantly overpriced and nothing seems to be rated for any specific amount of power. Can anyone point me in the right direction? Thanks!

[zedsn]

Do you plan on running a turbo flywheel and bellhousing as well? If so did you look into Kep? They have different stages of clutches.

[944noob]

I'm hoping to run the standard flywheel and bell housing and that seems to be causing my problem. I've found that I can run a starion disc which I can get cheaply and can be a big upgrade, but without a matching pressure plate I won't be able to take advantage of the better disc.

[porschetub]

Originally Posted by 944noob

I'm hoping to run the standard flywheel and bell housing and that seems to be causing my problem. I've found that I can run a starion disc which I can get cheaply and can be a big upgrade, but without a matching pressure plate I won't be able to take advantage of the better disc.

Thought the starion disc was a budget fix for the n/a cars ?don't know if you could spin that power thru a stock size 944 flywheel anyway.
To be honest I wouldn't describe the stock 944 clutch as that strong its just adequate for the job.
Have you looked @ the Centreforce kits @ Patrick motorsports,which ever way you go you need to spend a lot of $$$ as you don't want to be changing too many
Best to go to a turbo set-up there are more performance bits for them for starters and they are larger and stronger from the get go.

[944noob]

The diameter isn't the real issue, it's all about friction material and clamping force. I can get a sintered multipuck disc that could easily deal with the power for peanuts, but if I can't clamp it I'm screwed. I need to track down a pressure plate so I can see if there are any ways to change the fulcrum, add a diaphragm spring, or get my hands on a stronger spring that would fit. I'm thinking that a super tough clutch can be assembled for around $100 bucks (plus bearings) with the right mix of parts.

[petrolhead611]

Well let us all know your $100 solution please

[944noob]

I'm fairly certain there is one, I just haven't figured out what it is yet. My guess is that it will require a sintered multipuck disc from a starion (this alone would add 30% or more load holding with the capacity to hold 300% more power if it can be clamped well) and a heavier diaphragm spring or a second "helper" spring. I need to get my hands on a pressure plate so I can do a little research on the spring situation, and with any luck also move the fulcrum so that this clutch doesn't end up being too stiff to operate.

[RM512]

If you're going to be putting down that kind of power, you should also be looking for a turbo transaxle.

[jhowell371]

Or an S2 transaxle depending on what overall axle ratio you desire.

[DannoXYZ]

Back in '95 when I got my first '86 951, it had 125k-miles on the odo. During the next couple years, I did the usual chips, turbo, MAP, standalone EFI upgrades to 420rwhp and went through a couple of clutches. Here's what I found:

1. stock clutch died at 5k-miles with 325rwhp
2. Cup clutch (grippier disc) lasted 40k with 365rwhp
3. KEP clutch & disk lasted 60k with 395rwhp
4. Centerforce clutch & disk, 25% @ 40k with +400rwhp

I blew the engine getting to that last 400rwhp mark. The Centerforce clutch was only 25% worn out with 40k-miles on the clock. Better than any other clutch I used. And it wasn't as tiring to use in traffic as the KEP clutch as it has stock feel. The centrifugal weights really help tighten down the clamping pressure as RPMs increase. Given how much time & money I spent installing clutches, I would've gone with the Centerforce from the start if I knew then what I know now.

[PorscheNut924]

Can you direct me to the source of a Centerforce clutch? I'm putting an LS1 in a 1989 944 N/A and that sounds like a good way to go for longevity's sake. Would I get a clutch specifically for the 944 or do I need a special one because of the LS1 engine?

Also what do y'all think about keeping the original transaxle in the '89 with about 350 hp? I'm sure I could leave it and see how it goes and swap it for a turbo or S2 transaxle if I need something better. But if I'm going to be doing that anyway, I'd rather not risk breaking one that I could sell to help offset the cost.

[DannoXYZ]

The 944na tranny has weakness in R&P and cracks after a hard-life. Many autocrossers have reported this. Haven't heard of this failure in 951/S2 models. Not sure about the 2.7L '89 944na, what's the transmission Type and Code# on it?

Clutch-disc needs to fit the drive-shaft in the torque-tube, so if you've got 944/951 torque-tube, use a 944/951-specific disc.

The clutch pressure-plate needs to match diameter of clutch-disc and flywheel. Pressure-plate doesn't care what engine the flywheel is attached to.

Trick is activating the pressure-plate. The stock system works well, although the throw-out bearing and fork can be expensive to replace (rarely needed, just use a bearing-greaser to flush in new grease when doing the clutch). Franken-clutches can use a hydraulic throwout-bearing when mechanical-arms don't match up.

Here's some sources for Centreforce clutches:
Andy's Autosport
Autoplicity
Summit Racing

[PorscheNut924]

Originally Posted by DannoXYZ

The 944na tranny has weakness in R&P and cracks after a hard-life. Many autocrossers have reported this. Haven't heard of this failure in 951/S2 models. Not sure about the 2.7L '89 944na, what's the transmission Type and Code# on it?

Clutch-disc needs to fit the drive-shaft in the torque-tube, so if you've got 944/951 torque-tube, use a 944/951-specific disc.

The clutch pressure-plate needs to match diameter of clutch-disc and flywheel. Pressure-plate doesn't care what engine the flywheel is attached to.

Trick is activating the pressure-plate. The stock system works well, although the throw-out bearing and fork can be expensive to replace (rarely needed, just use a bearing-greaser to flush in new grease when doing the clutch). Franken-clutches can use a hydraulic throwout-bearing when mechanical-arms don't match up.

Here's some sources for Centreforce clutches:
Andy's Autosport
Autoplicity
Summit Racing

Thanks for the info.

I've been looking at this kit: LS1-Basic-Installation-Kit

It does have a clutch disc included. Would I need to make sure I have anything else if I used that kit?

[944noob]

Originally Posted by DannoXYZ

Back in '95 when I got my first '86 951, it had 125k-miles on the odo. During the next couple years, I did the usual chips, turbo, MAP, standalone EFI upgrades to 420rwhp and went through a couple of clutches. Here's what I found:

1. stock clutch died at 5k-miles with 325rwhp
2. Cup clutch (grippier disc) lasted 40k with 365rwhp
3. KEP clutch & disk lasted 60k with 395rwhp
4. Centerforce clutch & disk, 25% @ 40k with +400rwhp

I blew the engine getting to that last 400rwhp mark. The Centerforce clutch was only 25% worn out with 40k-miles on the clock. Better than any other clutch I used. And it wasn't as tiring to use in traffic as the KEP clutch as it has stock feel. The centrifugal weights really help tighten down the clamping pressure as RPMs increase. Given how much time & money I spent installing clutches, I would've gone with the Centerforce from the start if I knew then what I know now.

Thanks for the info! I just can't for the life of me figure out why they want $700-800 for a clutch. I've had much lower production vehicles and paid a fraction of that. The 944 is fairly common, it should be a lot cheaper.

[DannoXYZ]

Originally Posted by 944noob

Thanks for the info! I just can't for the life of me figure out why they want $700-800 for a clutch. I've had much lower production vehicles and paid a fraction of that. The 944 is fairly common, it should be a lot cheaper.

Not that common. Probably 100-500x more Mustangs, Mitsu Eclipses and Datsun Zs out there. Not to mention how many 944 owners will actually buy a Centerforce clutch versus those other makes. Heck, just on a per-car basis, Mustang owners probably buy them at 20x the rate of 944 owners. Adjusted for differences in numbers of Mustangs vs 944, you're probably looking at 2000-4000x more sales to Mustangs.

Then again, see how much it costs for a Centerforce clutch for Ford Diesel truck.

[v2rocket_aka944]

Well the NA uses the same disc as the S2 which is more power to start with and some people get away with it when they turbo those cars...