Ok i know these nv3500 trans are not good with High HP or TQ!!!! I have an 88 stepside with a 468 BB, HP and TQ are questionable.... I bought the truck and it had TBI and just didnt run good, so i took off all the factory stuff and replaced the intake, cam, distributor, shorty edelbrock headers and added a holley.... Truck sat for 2 months while doing this and I had only driven it for a month prior to that.. Motor was new and I bought a $400 heavy duty clutch from GM ..

I had no problems with it till yesterday(1st day of driving it).. It doesnt slip even if i get on it at a dead stop in 1st or 2nd gear... But going down the hIghway it slips in 4th and 5th gear. and thats barely touching the gas.... What gives???

 

The age old method for testing whether a clutch is slipping or not is to do load it up in high gear. The lower gears ease the strain, sans an all-out clutch dump, due to the physics of the gear ratios. When in high gear and you mash it, the clutch has to clamp for all it's worth to keep stuff from slipping.

You, sir, have a classic case of a slipping clutch it sounds like.

 

This all happened right after the original post..\

So its not the header about an inch from the slave cylinder and fluid line? Wont that make a difference cause the brakes get worse as i drive it also.. on the lift trying to get the exhaust leaks fixed i noticed my brake lines hot hot.(not a ground issue) and the fluid was leaking out of the rear drums and front calipers.. engine temp was only 190.. open the brake reservoir and it was steamy... this is running in traffic for about 3 miles catching 3 light and it took 7 to 8 minutes to drive it also at about 98 degrees outside.. I have let the truck idle for 40 to 45 minutes charging the a/c yesterday , and no problems.. Guess the hood being open then helped the temp thing???

but then on the way home after getting the exhaust fixxed even the engine got hot when i pulled in my driveway.. engine temp was 190 then climbed to 235 in about 30 seconds and boiling out into the radiator reservoir... had me boiling too...

remember only 800 miles on clutch and it has been babied.. I only got on it one time to race a vet.. before all the mods..

I think its too much heat from these shorty headers.. but thats why i am asking you all. maybe i should wrap them or something maybe flush the brakes also.. and replace everything.... forget it im probably going to rip out the motor and trans. sell or trade for 4 an LS1 motor or something... but just in case i keep it.. all help would be appreciated..

But yes pathfinderjr it will only slip in high gear 4 or 5 but it still bites in 3rd.. in 3rd gear at about 2000 rpm and at 30mph roll out and almost 1/2 throttle , leaves 2 40 yard black marks. 295/50 r15 bf goodrich tires in back.... it only got too 3700rpm..

 

What about just putting in a hays racing clutch for $250??? Think it would hold??? Figure flywheel and plate should be good just add a new throw out bearing and slave cylinder...

 

well, if the fluid is getting hot, that is only going to affect the clutch disengagement via the pedal. The fluid is not what keeps the clutch pressed against the flywheel. If your fluid is indeed steaming, you either have some shitty fluid in there or water has gotten in and is boiling. Hydraulic fluid generally has a higher boiling point (>250*F) than water unless it has been contaminated. But again, that is not gonna affect how hard your clutch clamps down.

Now all this residual heat could be radiating through and soaking into the clutch which could affect it. Hot clutches don't hold worth a damn. Do you smell burnt clutch very often?

Is the clutch aligned correctly? If not, it could be clamping irregularly around the flywheel which of course won't yield optimal results.

And about the hays racing clutch, I don't know a damn thing about their quality with respect to anything else, so I can't help you there.

 

No i dont let it slip enough to smell it... I just putter around.. but just a slight throttle in high gear and its slipping.. I tried when it was cold too and it still slipped but maybe your right and the extra heat is frying the clutch..

just stinks, it was fine when i parked it and the first night driving it when i pulled out of the driveway it was bad...

 

once a clutch is glazed over from heat or what not, it's chances of miraculously coming back and working are pretty slim. Instead of chunking the whole thing, upon removal you could always try lightly scuffing up the friction material and resurface the flywheel if it got warped some and go from there. It's quite a bit of time and effort but it might be worth not having to buy the parts. Kinda up to you on what you want to do..

 

i will probably just clean and scuff flywheel and pressure plate if not to bad and get me a racing clutch disc for it...i will probably wrap the headers, flush brake system, and etc etc.

thanks man. guess i aint got much choice

 

Yeah, sounds like a not fun, kinda crappy situation. Good luck, dude!

 

thanks man.. i fear it will be a constant problem.. maybe i should probably just go get a ls1, put on a carb, cam and get a 4L80E w/manual valve body... They say the kit makes 508HP 57?TQ. cheaper then fuel injected stuff.. but i dont know.. it will take me a few days to decide what i am gonna do... thanks again..