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Clevelands Rule.
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1,671 Posts
Discussion Starter #1
Hi,
My race only C4 transmission with billet brake valve has never had more than 165psi at high revs.
Recently after a rebuild by a different trans shop to the guy who first built it, he fitted a new rollerized billet P.A pump and full P.A rebuild kit with new kevlar band and clutch plates.
It worked great on the first 3 passes then slipped in top gear on the 4th pass and second on the fifth pass.
Car only weighs 1650lbs.
We changed the oil and shimmed the press reg spring with as many washers as we could get in there, pressure came up to 175 and slip went away.
Does someone do a spring upgrade kit?
I have seen others on here say their transmission run at 225psi, are they still using the stock spring?
Thanks
Rod.
 

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My c4 is at 225psi but it came that way when i got it. If you fine somewhere to get one i would like to no because i have a spare c4 with a brake and it only has 165psi.
 

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Billy438Stroker
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5,634 Posts
When i talked to PA a few weeks ago about that , they said not mess with the spring , put the TransBrake in and your set to go...
 

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Clevelands Rule.
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Discussion Starter #6
I also have a PA transbrake and the spring in that valve seems alot stiffer than the spring in my valve.
 

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Some of the transbrakes and manual valvebodies like P.A amd Broader only use the one heavier spring, smaller diameter than a factory type that has the inner + outer spring
 

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What type spring is in there now ? Is it a smaller diameter spring like the P.A one ? I'll check i may have some the same as the Broader ones that give around 220-230
 

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Clevelands Rule.
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1,671 Posts
Discussion Starter #12
Greg,
Currently it has 2 springs in the press reg valve, a larger od, with a shorter spring inside it.
I will need to pull the valve back off to get exact dimensions, then I will come back to you.
Thanks
 

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our p r spring is a larger dia. to use it in a p. a. valve body, the pres. reg. bore has to be modified. i said earlier that we run 275 psi line pres.thats for guys w/big power pushing the limites of a c-4. 200-225 psi is o. k. for the avg. racer. all our c-4 vbs are set at 350 psi on the brake to stop any creeping in the lights. yes we do make a foreward pattern-brake c-4.
 

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I know this is an old thread but my question is what can i use to shim the spring and how much can i shim the spring? I have a stock vb body with a B&M shift kit and its not hitting on much!

Thanks
 

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Try a 14mm spark plug washer. Depending on spring, each one adds 10psi is what I was told. I have not tried it though.
 
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