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ACT not keeping up

4thStroke

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Joined
Oct 22, 2007
Messages
1,864
Location
Vancouver, WA
Anyone else pushing high(er) HP numbers with a single disc clutch and having clutch issues?

My car dynod 557hp/455tq on a fresh (after properly broken in) ACT 2600/sprung 6 puck. This was maybe a thousand miles ago. It did ok, but when it was brought up to 9k RPMs, the clutch wouldnt disengage until the RPMs dropped below 7k. I never did cruise around with it cranked up this high. I had no intention on wringing out the motor to 9k on the street so I figured it should be fine for a while. Nope!

I was driving around the street with about 530whp and things have quickly been going down hill. My boost is now down to 25psi (from 31ish, well under the 500hp mark) and the clutch wont disengage with I bring it just past 7k RPM, it takes a while for it to pull out of gear after that. The clutch instantly goes soft at this point, too.

I knew I was taxing the clutch, but I really didnt think it would go downhill so quickly.

I really should start paying more attention to what Ive been told by respected members of the DSM/VR4 community... /ubbthreads/images/graemlins/smirk.gif

The search for a twin disc begins.
 

Can't really post on the clutch issue cas I have never had a 557WHP car with a clutch was on an auto /ubbthreads/images/graemlins/smile.gif. But man that much out of you GVR4 congrast /ubbthreads/images/graemlins/shocked.gif
 

4thStroke

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Oct 22, 2007
Messages
1,864
Location
Vancouver, WA
I wonder how the 2900/unsprung 6 puck would do. Just thinking out loud.

Thanks man, its a lot of fun. There is more to go, I just need a few more grand for L19s, Fel-Pro head gasket, 1650s, and the twin disc.
 

belize1334

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Joined
Nov 18, 2003
Messages
3,313
Location
Dundee, Scotland, UK
It may be that the clutch is only part of the problem. What kind of transmission do you have that you expect it to shift at 9k?
 

4thStroke

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Joined
Oct 22, 2007
Messages
1,864
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Vancouver, WA
The tranny is a fresh full rebuild by English racing, double cone 2nd, 3rd, and 4th.

On the dyno, he was bringing it to 9k for tuning purposes. On the street, its seen 9k maybe 3 times, but I have no reason to bring it that far. The car doesnt start dropping power until just after 8000rpm.
 

turbowop

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Joined
Apr 29, 2001
Messages
11,971
Location
Yakima, WA
Quoting 4thStroke:


The search for a twin disc begins.



Are all the vendors out of stock or something? Hurry up and buy!!

Or are you trying to find a used one?
 

4thStroke

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Oct 22, 2007
Messages
1,864
Location
Vancouver, WA
Waiting for a good deal to pop up, used (would have to be in good shape), or not. I will probably just end up buying from Lucas.
 

4thStroke

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Joined
Oct 22, 2007
Messages
1,864
Location
Vancouver, WA
Added security when running 32+ psi. I dont want the head to be lifting on me, especially since its my daily driver. We even held off on timing down low to help keep the head down.
 

Brianawd

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Joined
Apr 18, 2005
Messages
2,117
Location
Portland OR,
Quote:
Why do you need L-19's???



Because the regular 8740 head studs suck ass. I know I know, People have made 700+ with them but that is short lived. Why not just put them in with a good head gasket and forget about it.

On my 95/90 motor I was lifting the head with the 8740 studs. So I replaced the head gasket with a fel-pro mls had the head surfaced and then check and hand lapped the block. I again used 8740 studs. Motor was good for a few more months then started lifting the head again. It was after that I choose to never use the 8740 studs. Why spend $85 for a set of throw away studs when you can spend a little more and get something that you can use over and over and don't have to think about. Thats just me.
 

To tell you the truth, I have been running the standard stud forever and have never had a problem(35psi) but it may be the way we o-ring the block. Mike Reichen still runs the standard head studs with 45+psi. We were having an issue but we ended up milling the head out and welding it up solid under the exhaust port were it was blowing out and we haven't had any issues since. I've also done an evo 8 head like that also.


 

Brianawd

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Apr 18, 2005
Messages
2,117
Location
Portland OR,
Quote:
To tell you the truth, I have been running the standard stud forever and have never had a problem(35psi) but it may be the way we o-ring the block. Mike Reichen still runs the standard head studs with 45+psi. We were having an issue but we ended up milling the head out and welding it up solid under the exhaust port were it was blowing out and we haven't had any issues since. I've also done an evo 8 head like that also.



No o-rings here. I thought about doing on this build but for some reason did not. Maybe next time.
 

We press the o-rings into the block and then mill the tops off so they stick up about .005. It seems to work the best and then copper coat everything real good.
 

chvtec33

Active member
Joined
May 21, 2009
Messages
29
Location
Tolland, Ct
I have seen clutches not hold up well before from spinning so fast that centrifugal force on the clutch is so great that the pressure plate wont release completely. Ive seen it on our dyno when the clutch was under rated for the power of the engine, but that was on a drag race engine pushing 950hp and spinning 9k or so. Just a thought.
 

iLLeffeKt vr-4

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Jul 26, 2004
Messages
2,153
Location
NYC
How much torque is your clutch setup rated for?
 

1badgvr4

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Jul 2, 2006
Messages
1,242
Location
georgia
What setup are you running. I don't know if it just me, but my twin disc is VERY harsh. On decel it feels as if im breaking something. I love the way it sounds tho /ubbthreads/images/graemlins/rofl.gif
 

4thStroke

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Joined
Oct 22, 2007
Messages
1,864
Location
Vancouver, WA
The 2600/6 puck setups are rated at 513ftlbs per ACT. So I must be really pushing that number, but I would think that it would do a little better. I am under 450ftlbs at the wheels.

Setup as far as what? Power mods? Drivetrain mods?
 

1badgvr4

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Joined
Jul 2, 2006
Messages
1,242
Location
georgia
I was asking about power. I had a 2900 6 puck with LW Flywheel and it was great. If my trans ever comes back out ill put that setup back in it.
 

Brianawd

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Joined
Apr 18, 2005
Messages
2,117
Location
Portland OR,
Go twin or go home /ubbthreads/images/graemlins/hsugh.gif
 

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