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-   -   A good 930 clutch for my turbo conversion. (http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1064712-good-930-clutch-my-turbo-conversion.html)

kamaro 06-19-2020 04:30 AM

A good 930 clutch for my turbo conversion.
 
I'm now shopping for a good clutch that would hold good for 10 psi of boost and still street friendly, do you think the stock Sachs clutch and PP can hold for that power? or do I need to step up to something like Centerforce or Spec?, speaking of both, I kept reading not so great opinions on Spec clutches being not so street friendly and hard on the leg, but I have not hear anything about Centerforce. I'm looking for some feedback from guys running them on 930s. Thanks!

RarlyL8 06-19-2020 04:51 AM

Love the Sachs Sport clutch, have used many of these. Hate the KEP clutch but was a one and done on that experience. Never used Centerforce.

356911930 06-19-2020 07:27 AM

Not to hijack this thread but I'm still gathering parts for the rebuild of my 1976 930...three plus years now:rolleyes:

New parts include BL WUR, SC Sport cams, K27, Rarlyl8 headers and muffler.

Will the stock, early 930 clutch and pressure plate be adequate for the modifications or should I go to the Sachs Sport Clutch and pressure plate?

Rahl

GJF 06-19-2020 10:47 AM

At 10psi a fresh stock clutch will hold for a decent time before it starts to slip due to wear.
KEP typically is used with high HP cars but heavy on the leg.
Centerforce is modified clutch and work well.
Sachs always work from stock to sport to their 934/935 clutches for high HP, and are the smoothest actuating stock dimension packaged clutches.
If you want the most reliable package... SACHS.
Stock will be fine if you stay below 10psi.
Sport, KEP Stage 1 or Centerforce for a little extra holding power up to 15psi.
Over 15psi KEP Stage 2 or 934/935 will be required.
Beyond 25psi will require custom multidisc clutch assemblies.

As for SPEC, I have not one thing good to comment on them. So I leave it at that. ;)

quattrorunner 06-20-2020 08:43 AM

Assuming you were talking about a 930 transmission, the stock clutch should be fine with less than stock boost pressure. If you’re talking about using the 915 transmission in your converted car then the center force is a pretty good option although heavier than the aluminum versions of the sachs clutch. As stated before the sport clutch for the 915 could hold 10 psi pretty well.
With the stock 930 clutch, even stock boost pressure in colder climates can overrun the pressure plate. I wasn’t very impressed with the stock clutch holding power Of a well running 930 engine.
Are used three different clutches in my 915 to try to hold the power, one was a power clutch which held pretty well with about 10 psi next I tried a sport clutch I believe it was and then finally it was a center force and the Centerforce held the power the best at over .8bar.

Kraftday 06-20-2020 10:35 AM

Well if you are coverting the 1987 911 (shown in your tag) to turbo, then equipped with the G50.01 transaxle. My favorite option is a KEP Stage 1 which features an aluminum pressure plate cover. This will save some weight and pedal will be easy as it is hydraulic slave actuation. Excellent, very durable clutch and matched with stock or KEP 930/G50 sprung hub disc.

If 1978-88 930 4 Speed trans (deep bell housing) is used, the best clutch I would suggest is the Centerforce DF255255 with the MODE adapters. This is a very durable, lightweight (~54% weight reduction) and easy pedal clutch. It is a reworked Sachs 76 911 Turbo clutch (low profile alum). The next option is the Sachs RE "Ruf 5 Speed" performance clutch and disc with little stiffer pedal but will hold ~650ft lbs tq. Also requires MODE adapters.

Next option for 930 78-88 is the Centerforce DF252252 which is a reworked stock OEM Sach clutch. It features original cast iron heavy. The "rework" involves some tech that makes the clutch easier to operate and higher clamplaod.

Next for 930 a KEP Stage I aluminum. Pedal will be little stiffer than stock but reduced mass due to alum pp cover.

+++
G50 KEP Stage 1 with 911 3.2L flywheel. Notice DME trigger teeth and stepped refister on flywheel to pp interfaces.
http://forums.pelicanparts.com/uploa...1592676284.jpg
http://forums.pelicanparts.com/uploa...1592676284.jpg
+++

Centerforce DF255255 : Low profile lightweight = excellent performance option.
http://forums.pelicanparts.com/uploa...1592676284.jpg
http://forums.pelicanparts.com/uploa...1592676284.jpg
http://forums.pelicanparts.com/uploa...1592677655.jpg
+++

Sachs Ruf 5 Speed, ultimate clutch for RS, Autox or 500+hp street.
http://forums.pelicanparts.com/uploa...1592676284.jpg
+++

Centerforce DF252252 clutch cover reworked Sachs cast iron. Heavy duty with easy pedal.
http://forums.pelicanparts.com/uploa...1592676284.jpg
+++

KEP 930 Stage 1 Alum.
http://forums.pelicanparts.com/uploa...1592676284.jpg
http://forums.pelicanparts.com/uploa...1592676284.jpg

MTN930 07-07-2020 02:45 PM

Liking the advice on this thread. I'm in a similar situation where the stock clutch won't hold any longer so it needs to be replaced. Heavily modified 930 3.3L, twin plug, beefed up K27 and runs well at 1.4 - 1.5 bar of boost. Looking for something that'll hold w/o slipping.

What do the experts say? BTW - don't track or race... just like to accelerate a bit from time to time.

TurboKraft 07-09-2020 02:30 PM

Quote:

Originally Posted by kamaro (Post 10912124)
I'm now shopping for a good clutch that would hold good for 10 psi of boost and still street friendly, do you think the stock Sachs clutch and PP can hold for that power? or do I need to step up to something like Centerforce or Spec?, speaking of both, I kept reading not so great opinions on Spec clutches being not so street friendly and hard on the leg, but I have not hear anything about Centerforce. I'm looking for some feedback from guys running them on 930s. Thanks!

A new stock G50 should hold, for a while. It is an iron clutch plate, so heavy.
Just say "no" to Spec.
Centerforce would be an option for more clamping torque. They are modifying new Sachs clutches.
KEP Stage-1 would hold for sure, and being aluminum it is lighter weight. Downsides:
* They don't always fit into the flywheel correctly, shaving off aluminum as they are torqued down. Not cool. No fun trying to measure all the way around whether it's truly 100% seated (and if it isn't, then uneven clamping, warping parts...)
* Pedal effort -- much more than stock. Getting caught in stop-and-go traffic sucks. KEP Stage-2 is the worst.


Quote:

Originally Posted by MTN930 (Post 10937058)
Liking the advice on this thread. I'm in a similar situation where the stock clutch won't hold any longer so it needs to be replaced. Heavily modified 930 3.3L, twin plug, beefed up K27 and runs well at 1.4 - 1.5 bar of boost. Looking for something that'll hold w/o slipping.

What do the experts say? BTW - don't track or race... just like to accelerate a bit from time to time.

I think we talked about this on the phone 2-3 days ago?
Again, skip the Spec stuff.
A low-profile aluminum Centerforce is an option, but this is basically a 1976-77 aluminum clutch (now pricey) with a re-worked disc, we don't see it as a great value. And in our experience, if you slip the clutch once, the disc glazes over and never grips properly again. No bueno.
KEP -- same issues as their G50 version above.
For up to 475wtq, the Sachs "Ruf" clutch is the best way to go. Sport disc, MODE aluminum spacer + stainless release bearing extension. Reliable, only had 2 bad ones in 26 years. Pedal effort as easy as an all-stock clutch, and it's lightweight aluminum and saves about 13lb.

http://forums.pelicanparts.com/uploa...1594331168.JPG

http://forums.pelicanparts.com/uploa...1594333520.JPG

Oheggem 07-10-2020 08:24 AM

Chris, can you let me know why the Specs are bad? Even on PM if you feel you trash them or something.
I did research before i got mine and seemed very good. Then suddenly i see a few here saying otherwise but no explanation. If it`s because they are "bitey" then that`s just how they are i guess. Speed Academy installed it and is happy with it. I got it also bc of price so not expecting world class. Just wondering :)

Sorry if this is a highjack but i believe it`s on topic and useful info being they are hald the price. SmileWavy

TurboKraft 07-10-2020 01:30 PM

Hi, not bashing Spec at all; I am saying that in our experience they don't work well in these cars.
"Speed Academy installed it" -- okay, really *we* installed it :-) and ultimately no, not happy with it. It had a high torque rating advertised and failed to come anywhere near that, slipping on both the dyno and the street. We had to keep the boost turned down on Pete's car.

Another customer brought his near-stock 1986 3.3L in for a simple 3.4L rebuild with sport cams and the typical performance bolt-ons. It had a Spec clutch rated for far more torque than the CIS would support, but again, it slipped. That was a CIS-injected engine, not EFI. The client obviously wasn't pleased, so we had to pull it back out and put in a Sachs clutch. Expensive, yes, but:
(a) much lighter, so rev-happy, better gear shifts as the engine's more responsive
(b) still as-stock pedal effort
(c) as-stock driveability -- not "bitey," no chatter, no issues.

Like Centerforce, most of Spec's "upgrading" comes in modifying the disc: stripping off the existing friction surface (which is currently very good from Sachs) and replacing it with their own. Last I checked, most of their different levels are just differences in the disc type. I know Centerforce also modifies the tall pressure plates a little for more clamping (not the low profile ones, last I checked), but I don't know Spec does anything to the clutch plates other than paint them blue.
Regardless, they haven't been good for cars we've built.

We'd make more profit selling Spec and Centerforce, and the KEP should be the easiest solution -- but the Sachs Race Engineering clutches fit perfectly, work perfectly, are very light, always hold, have a reasonably long service life, and have no increased pedal effort. I really don't see what more a person could want from a clutch.
When everything just works, I think it's worth the extra cost.

Oheggem 07-10-2020 11:22 PM

oof. wish i knew that before. I`ll just have to see how it turns out and report. Guess i will get what i paid for but I might be lucky and it`s ok though so will not start crying just yet.

I followed the whole of Petes build but thought i`d not say you`d installed it because it was obviously his choice. He said in a new video that his clutch was slipping on dyno but not in the street. Kinda understood that as it`s slipping but he`s lowering boost and not ripping it. That`s why i wanted confirmation.

Thx for the info SmileWavy

kamaro 07-10-2020 11:23 PM

I thank all of you that have replied to me in this thread, with special thanks to Chris (TurboKraft), I went a head and bought a Sachs clutch kit which will arrive next week (hopefully). I have always hate any "performance" clutch that would act as "on-off" and chatter when ever the car moves, in the muscle cars field I use clutches made by Mantic (Australian made) and they absolutely the best clutch you will ever use, period. they are easy on pedal, yet would hold a ton of torque, I wish they would come up with something for the Porsche community.

TurboKraft 07-11-2020 10:10 AM

Quote:

Originally Posted by Oheggem (Post 10941621)
I followed the whole of Petes build but thought i`d not say you`d installed it because it was obviously his choice. He said in a new video that his clutch was slipping on dyno but not in the street. Kinda understood that as it`s slipping but he`s lowering boost and not ripping it.

He has to walk a balance when he gets the parts for free.

We don't get parts for free. I'll tell you if it's good or not.

smurfbus 07-13-2020 08:26 AM

Just got this for no guessing option. My current stock 77 pp is barely holding 1bar so this should solve all clutch problems even with future mods.http://forums.pelicanparts.com/uploa...1594657412.jpg

quattrorunner 07-13-2020 10:38 AM

is that the 934 clutch?

TurboKraft 07-13-2020 11:53 AM

No, that's the "Ruf" clutch plate + current version street/sport disc.

The 934 clutch uses a similar-looking aluminum pressure plate, includes a release bearing, and requires a special 8.5mm thick clutch disc (also organic lining, spring hub).
It, too, is fully streetable, easy in stop-and-go traffic but won't slip with 600tq+ at the wheels. :-)

Porsche 935 07-13-2020 12:01 PM

I contacted Sach's last year when I replaced my 934 clutch disc. They said it was 7.8mm thickness new. And it will not hold 600tq at the wheels, even when new and boken in. Have to move up to the 4 or 6 hub racing disc.

smurfbus 07-13-2020 09:56 PM

Fuuuukmii, Now that I looked at the #numbers and my receipt, I think they sent me wrong pressure plate after all! I ordered 999574.999615 and the box had 594 + 615 which don't even match!

Kraftday 07-14-2020 12:39 AM

http://forums.pelicanparts.com/911-930-turbo-super-charging-forum/1037103-strange-change-my-clutch-behaviour-iirc-kep1-2-kevlar-disk.html

Kraftday 07-14-2020 01:11 AM

Sachs Performance / RE clutches have many reinforcement features, are made with higher quality materials in limited production. The OE parts from a 76 Turbo are usually not upto the task of a modified 930.

Centerforce is a brand and company I trust with 100s of experiences hooking people up proper. They rework the stock clutch covers and the discs... more than just orange paint.

KEP, also USA have their own tech and great clutches.

One very important feature is the thicker or tripple limit straps. Think how this helps with hard downshifts.



http://forums.pelicanparts.com/uploa...1594716014.jpg

http://forums.pelicanparts.com/uploa...1594716292.jpg


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