pressure plate problems
Thread Starter
Teching In
Joined: Jan 2014
Posts: 35
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From: Iowa
pressure plate problems I am putting a muncie four speed behind my ls 6.0 and am having problems with the preasure plate bolts stripping out. I have the sachs 1050 with a spec stage 3 clutch for a big block. Everything lines up and looks good untill i try to torque the bolts on the pressure plate. They are factory bolts for a 3500 silverado and this is what the flywheel is for. The bolts are 25mm long and only catch half the threads so i think this the problem but unsure. I have all arp bolts on everything else but not these because i ordred the wrong ones and just ran to the dealer for the gm bolts. From what i can tell it looks like the arp bolts are only 25mm. What should i do? Maybe 30-35mm grade 10 bolts from harware store? I have stripped the bolt holes on two flywheels already.Thanks
The good stuff from the hardware store should be OK but nothing beats ARP. The dealership bolts should be good though. Have you compared the pressure plate thickness to the item the dealer has for the same vehicle you got the bolts for? Are you using an alignment tool and minding the dowels to make sure the pressure plate is getting as close to the flywheel as it should? I have the same setup save for unknown ~12" clutch and would be happy to compare dimensions. What us your pressure plate thickness at the bolt holes? Does the PP sit flat against the flywheel when you are tightening the bolts?
Moved to transmission section for more help.
I think the ARP bolts are probably the same size. You may need some longer bolts. I know ARP makes longer bolts for the automatic transmission guys with thicker flexplates. They might work for you.
I think the ARP bolts are probably the same size. You may need some longer bolts. I know ARP makes longer bolts for the automatic transmission guys with thicker flexplates. They might work for you.
Thread Starter
Teching In
Joined: Jan 2014
Posts: 35
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From: Iowa
Got it! I used the hardware store bolts that are 10.9 grade. 10mm x1.50 and 30mm instead of the factory 20-25mm length. Everything tightened down perfect. I guess the spec flyeheel must be thicker than a stock one but not sure. Thanks for the help guys.
How would the flywheel being thicker affect bolts? Do the threads not start right at the edge of the flywheel? That could be the problem right there. Glad you found a way around it.
Thread Starter
Teching In
Joined: Jan 2014
Posts: 35
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From: Iowa
Its a sachs 1050 and the threads are counter sunk prob 10mm. The gm bolts dont have threads to the end of the bolt. This combined with the threads being counter sunk makes the boltd catch half the threads. I went with round allen head bolts with threads to the end of the bolts. When they are tightened they are flush with back side of flywheel. I have know idea why the factory gm bolts are so short. I read many threads with this combo for mounting a ls to a muncie and no mention of this bolt problem. Not sure why not because there is no way it will work without longer bolts.
That is strange that the bolt holes would be countersunk so much. Perhaps they were hoping to help with alignment when changing a clutch under a car..but got a little too excited and did 10mm. That mfg should send longer bolts if they are going to require it.
