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Clutchs - is there much difference?
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Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Mon Nov 21, 2005 10:42 am    Post subject: Clutchs - is there much difference? Reply with quote

Is there much between these three?

Sachs
Centerforce
Spec

I'm installing a Bae turbo, and my cheap LUK clutch couldn't even handle the standard power, so it's time to upgrade, but how far do I need to go?
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1977 RX924 rally car
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ideola  



Joined: 01 Oct 2004
Posts: 15451
Location: Woodstock IL

PostPosted: Mon Nov 21, 2005 11:10 am    Post subject: Reply with quote

I was exchanging several emails with a couple of board members on this very topic. Here is what I accumulated from their collective knowledge:

By several accounts, the centerforce are junk and not recommended for racing. Another board member mentioned this possibility as well:

Quote:
It is known that the 911 SC pressure plate and disc work on the 931, and that the stock PP for that car is 2X the clamping force of the 931 PP, one could easily use the 911 PP, Ford Bronco II disc, and the OE bearings and all that and come up with a nice upgrade using mostly OEM parts.


Apparently John Heaney in NZ knows the correct 911 part number. Mating the Sachs disc plus OEM bearings and you have all Porsche parts.

I can't comment on the Spec clutch kits from experience (yet), but everything I've heard and read is very positive. I am fairly certain that I will be putting a Stage III in my wide body conversion, but this part of the project is still a ways off.
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My924gtc  



Joined: 14 Aug 2004
Posts: 1362
Location: 248

PostPosted: Mon Nov 21, 2005 11:15 am    Post subject: Re: Clutchs - is there much difference? Reply with quote

Andrew NZ wrote:
Is there much between these three?

Sachs
Centerforce
Spec

I'm installing a Bae turbo, and my cheap LUK clutch couldn't even handle the standard power, so it's time to upgrade, but how far do I need to go?


Sachs = Very good, no upgrades for our cars
Centerforce = Bad rep from what I have read
Spec = Been told by many Euro Tuning Specialist that this is all they use, especially in hi-po situations.

I don't think the BAE kit will outwork your standard Sachs replacement so you could go there.

I personally can't wait to get a Spec kit and test one out. I need to do the clutch in the 931 and will be mating the Spec Stage III up to a Fidanza flywheel when the time comes, but all funds are allocated towards the projects right now.
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MJ
'81 924 2.0L T
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My924gtc  



Joined: 14 Aug 2004
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PostPosted: Mon Nov 21, 2005 11:18 am    Post subject: Reply with quote

Good points Dan but Andrew drives a 924, not a 931. No 215mm parts for him to swap around that I know of.

Andrew I say kick the Stage II or III Spec kit. Not any more expensive than stock replacement and should have 2X - 3X the clamping force but still be fairly smooth engagement..
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Andrew NZ  



Joined: 22 Jun 2004
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Location: New Zealand

PostPosted: Mon Nov 21, 2005 11:27 am    Post subject: Reply with quote

Thanks.
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gohim  



Joined: 02 Nov 2002
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Location: Rialto, CA

PostPosted: Mon Nov 21, 2005 12:16 pm    Post subject: Reply with quote

Since the firewall is known to crack where the clutch slave in bolted-on, I would be concerned about the extra stress on the sheetmetal caused by the heaier springing of an upgraded clutch assembly.

I would take extra care to make sure that everything is in adjustment, and would consider reinforcing the firewall before the cracking occurs.
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My924gtc  



Joined: 14 Aug 2004
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PostPosted: Mon Nov 21, 2005 12:28 pm    Post subject: Reply with quote

gohim wrote:
Since the firewall is known to crack where the clutch slave in bolted-on, I would be concerned about the extra stress on the sheetmetal caused by the heaier springing of an upgraded clutch assembly.

I would take extra care to make sure that everything is in adjustment, and would consider reinforcing the firewall before the cracking occurs.


Is this cracking scenario also true on cars not equiped with a slave cylinder?

As I am certain that your advice was directed towards those of us that have 931's and not AndrewNZ since he clearly drives a '77 924.

I have em all so I am curious myself.
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'81 924 2.0L T
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Andrew NZ  



Joined: 22 Jun 2004
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Location: New Zealand

PostPosted: Mon Nov 21, 2005 1:19 pm    Post subject: Reply with quote

My924gtc wrote:
gohim wrote:
Since the firewall is known to crack where the clutch slave in bolted-on, I would be concerned about the extra stress on the sheetmetal caused by the heaier springing of an upgraded clutch assembly.

I would take extra care to make sure that everything is in adjustment, and would consider reinforcing the firewall before the cracking occurs.


Is this cracking scenario also true on cars not equiped with a slave cylinder?

As I am certain that your advice was directed towards those of us that have 931's and not AndrewNZ since he clearly drives a '77 924.

I have em all so I am curious myself.


Mines RHD too, so I'm not sure if that makes a difference??

I'll keep an eye on it and weld a reinforcement plate in if needed.

Mark, I'd heard that centerforce had a really good reputation - have you had problems with them? (It's certainly a brand name that's known in this part of the world anyway).
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My924gtc  



Joined: 14 Aug 2004
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PostPosted: Mon Nov 21, 2005 1:34 pm    Post subject: Reply with quote

Andrew NZ wrote:
Mark, I'd heard that centerforce had a really good reputation - have you had problems with them? (It's certainly a brand name that's known in this part of the world anyway).


Nope no personal experience with them at all. Just what I have heard from a couple guys here (Vaughan being one of them), and from others on different boards I frequent. Everyone has different experiences with products though.

Tha main reason I suggest going Spec is because of the upgrades, and the fact that I have not had a single person that I have talked to about this tell me anything negative. Just that they are very nice, well built kits, and that they grip like hell.
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Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Mon Nov 21, 2005 1:44 pm    Post subject: Reply with quote

Fair enough!
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ideola  



Joined: 01 Oct 2004
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PostPosted: Mon Nov 21, 2005 1:48 pm    Post subject: Reply with quote

Quote:
Andrew drives a 924, not a 931




Details, details

Sorry Andrew
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Andrew NZ  



Joined: 22 Jun 2004
Posts: 744
Location: New Zealand

PostPosted: Mon Nov 21, 2005 2:02 pm    Post subject: Reply with quote

ideola wrote:
Quote:
Andrew drives a 924, not a 931




Details, details

Sorry Andrew


Not a problem - I really appreciate everyone trying to help little old me down here at the bottom of the earth
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gohim  



Joined: 02 Nov 2002
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PostPosted: Mon Nov 21, 2005 2:33 pm    Post subject: Reply with quote

Most turbo conversions also include the transmission and the clutch set. I would not expect the smaller diameter NA disc and pressure plate to take kindly to the increase in hp.
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Andrew NZ  



Joined: 22 Jun 2004
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PostPosted: Mon Nov 21, 2005 2:43 pm    Post subject: Reply with quote

gohim wrote:
Most turbo conversions also include the transmission and the clutch set. I would not expect the smaller diameter NA disc and pressure plate to take kindly to the increase in hp.


I'll be keeping it quite tame until I can afford to upgrade the transmission etc. Turbo transmissions are rare and expensive down here, and the freight would be rediculous from the States. I know that the gearbox won't take more than about 150, but my LUK clutch slips if you push it off the line with 125hp, so something better will be required for a while.
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My924gtc  



Joined: 14 Aug 2004
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PostPosted: Mon Nov 21, 2005 3:04 pm    Post subject: Reply with quote

gohim wrote:
Most turbo conversions also include the transmission and the clutch set. I would not expect the smaller diameter NA disc and pressure plate to take kindly to the increase in hp.


I'm sure the NA clutch can handle another 30 hp especially when considering 3X's the clamping pressure, and much better disc materials.
As a matter of fact I am expecting it to handle 60 bonus hp minimum in my configuration. You are only talking about 10mm difference in diameter.

But fear not, I'll test the theory for you, then we'll know for sure.
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'81 924 2.0L T
'82 924 2.3L SC/EFI <---online fall '06

Sponsor of the 944 Cup and Super Cup
Sponsor of the "2006 Battle in the Badlands"
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