frankvan

About to dive headfirst into a clutch replacement and curious if anyone has any comments on Centerforce or any other "performance" brand clutches vice the stock Sachs kit.

I've had a Centerforce in a previous vehicle and the thing was pretty much bullet proof - I put twice as many miles on it as the stock unit took, and I wasn't kind to it either!
OTOH, the stock unit in my 89 has over 200,000 miles which is quite impressive in its own right. But I had noticed even before my clutch started slipping last fall that it would not engage completely on quick and hard shifts (which probably isn't good for the tranny either) and was thinking something like a centerforce might alleviate that.

Indycam

I have not seen the centerforce in person , but I think its disc is a "normal" spring type , where the Sachs has a big chunk of rubber .

herman maire

Head first.... thats the way to go .

200k miles is pretty impressive. Cant really suggest a clutch but I am buying a LWF+sachs motorsport RS clutch set up for my 993.... The 31lbs Dual mass flywheel is just crazy heavy. 12lbs for the RS flywheel.

frankvan

Luckily I've got the 89 without the DMF so I already have a MWF
(can't remember the weight of it - it's in a post here somewhere - but it's alot less than the DMF!)

Indycam

"I do not have a precise scale for small weights, but I believe the starter ring is ~2lb
I believe the flywheel is ~10.5 lbs" KirkF


"Ok here is some more info: Measured Weights & heights. Accuracy is +/- 100g

964 Porsche Clutch & Flywheel Data

PART#/1989 STOCK/RS STOCK
------------------------------------------------------------------------------------------
Flywheel & Pilot/4900g(10.8lb)/~5000g(11.0lb)
Clutch Disc/2200g/2000g
Pressure Plate + T.O. bearing/10050g(22.15l)/4750g(10.5lb)
Starter Ring/950g/750g
Guide Tube Height/49.05mm/63.30mm

Total Rotational Mass/15900g/10500g
(Clutch Disc Excluded)/35.05lb/23.15lb" KirkF

frankvan

Thanks Indycam!

Finally found the one I was thinking of (and it's also from KirkF!)

For the 89 I wonder if the Centerforce PP is lighter than the Sachs? Or if the other year PP's (4750 g) would work with the 89 clutch disc?

Of course the location of the rotating mass is imortant too (radius from axis to center of rotating mass providing angular inertia). Given two setups of identical mass but having the center of rotating mass say 5 cm vs 10 cm out from the axis would have a different effect.
If I remember correctly:
I= 1/12m[3r2 + h2)] (sorry the "2"s are supposed to be squares but couldn't figure out the superscript on the editor)
But that's beyond me.

Indycam

I was just on the phone with R Warner at centerforce , I asked for the parts to be weighed , but they have none in their hands at the moment . They may have some coming in in a few weeks .

"Or if the other year PP's (4750 g) would work with the 89 clutch disc?"
I'll bet a real good beer that mixing and matching the parts will not work .

"Of course the location of the rotating mass is imortant too"
Yes but I'm not going to do the tests to find the results .

KirkF

Sadly as I am ripping out my DMF to put the LWF back in this has become a relevent topic for me.
(supercharger project requires a LWF)

Where are you looking at the centerforce stuff? got a website?

Kirk

KirkF

ahh
www.centerforce.com

Sadly it doesnt look like they make anything special for the RS LWF setup. Everything they list says W/DMF.

Kirk

Indycam

"Most disc. Weigh around 5 lbs.
Part number DF021044 weighs 27.6 lbs.
Regards,"

LARRY CLARK
Senior Account Representative
Sales - Customer Service - Catalogs
CENTERFORCE PERFORMANCE CLUTCHES
Division of Midway Industries
Bus. 928/771-8422 ext. 30
Fax. 928/771-8322
larryc@centerforce.com

frankvan

Kirk, I notice that your sig says your C4 is an 89, yet you mention "ripping out the DMF" - Am I correct in assuming you put a DMF setup into the 89 housing? Any reason for the DMF choice?

KirkF

When my car was 3 years old the original owner replaced the transmission with a new one. (Possibly done under Porsche Warranty)
When they did it they changed it out for a newer transmission (DMF) style.

Trust me when I tell you I went through alot of confusion when I was initially ordering the clutch parts, and then found out that none of them fit.

Kirk

frankvan

Just as a follow up to my original question I wound up getting the "Power Friction" disc from Vertex (no affiliation, yada, yada, etc...). It looks like a standard clutch disc with four springs in the hub instead of the rubber center. And it was about half the price!

It seems to grab well but I am still getting shudder on takeoff. I'm not sure if this is a difference in the design from the rubber center or if the friction material needs to be broken in or if the clutch slave needs to be bled again. I've bled the slave twice and both times the shudder has been reduced but that may just be a placebo effect.

HoBoJoe

When I put a spec clutch in my 944T it had a bit of shudder at takeoff. However, it got much better after the break in period.

On a side note I had a Centerforce dual-friction clutch kit in my Talon turbo awd, it was terrible...

altarchsa

[QUOTE=Indycam;5146759]"Or if the other year PP's (4750 g) would work with the 89 clutch disc?"
I'll bet a real good beer that mixing and matching the parts will not work . QUOTE]

I just went throught the "oredering the wrong clutch kit" routine and my understanding is the '89 is a one year only different diameter.

I have correct clutch in the car now and a new in-box 90-94 sitting on the floor.