Last week at the track (on my 9th pass), I had a strange problem with my '95 Camaro off the starting line. It felt like the car was spinning when it launched, so I backed out of the throttle then immediately went back to WOT. The car then felt like it was bogging down and after 2 seconds the RPM's shot up to 6100rpm (still in first gear) so I backed out of it thinking I lost my forward gears. It drove fine down the return lanes though, all gears felt good. It still managed a 9.39 @ 70mph

I had my laptop hooked up to the car using TTS Datamaster, so it made it a bit easier to see what was going on with the car. After I got back in the throttle, it shows that it took the motor about 2 seconds to go from 4100rpm to 4600rpm and still managed to go from 16 - 44mph in that span. At one point it shows 48mph @ 4881rpm with the transmission showing -2197 slip RPM. I dont see how that's even possible. The transmission temp also went way up during this pass. I normally only show 4-5 degrees of temp increase from start to finish, but on this run I went from 181 degrees while staging to 200 while turning off the track. The transmission was actually about 3/4 a quart low, so I topped it off and drove home. It ran great on the way home and I drove it to work the following 2 days and it didnt have any problems.

The transmission has broken 2 pump rotors in the past year, it's got a billet rotor in there now. I bought a transmission pressure gauge and ran it up through the center console so I could see it while driving. I have about 80psi at idle and when I roll away from a stop, it jumps to 250psi and immediately starts dropping to 150. It stays between 150-175psi while cruising down the road in all gears.

The transmission is a Pro Race build from CPT and the transmission pressure wasn't adjusted in the car's tune.

Anyone out there have an idea as to what's going on with this thing? Also, what should I be looking for in terms of transmission pressure? I called Andre at Edge converters and was told that since the car is driving fine now that it likely isn't the converter.

 

sounds like maybe the forward input drum clutches may have been slipping

 

no dtc's? sounds like it might be a sprag going bad. no noises?

 

Nope, no noises or DTC's. It's been driving flawlessly ever since.
That's the only thing I could think of, but if there was clutch slippage I would have figured there would be some degradation in how the car drives. All I can think of is there may have been some major slippage either in the converter or transmission because of the heat from almost 4 hours of idling or from being 3/4 of a quart low.

What kind of trans pressure numbers should I be expecting from a modified transmission? I have a book, but it references a stock transmission, so I can't really go by that unfortunately.

Thanks for the responses.

 

From everything I see here, it looks like you might have picked some air. Which could account for, from what you have stated, the peculiar results.

 

eh I was afraid of that I broke 2 pump rotor/slides last year so the pessimistic side of me thinks my slide might be cracked again.

Is there any reason my transmission pressure would rapidly bounce between 150-175psi at around 3,000rpm while slowly accelerating in overdrive?

Thanks for the response

 

are you running 13 or 10 vane pump rotors? Also, do you have the transmission to engine dowel pins in there? If not this will cause repeated pump issues. Sometimes its just a matter of misaligned pump halves. Also make sure you run hardened pump rings.

 

I'm using a 10 vane pump, right now I have a billet pump rotor. I had hardened rings in there everytime. I also have the engine dowel pins in place.

The first failure, I dont think I had the converter engaged far enough into the rotor. I did my burnout with the selector in overdrive and went up through the gears without paying attention and we think somewhere in the process the converter pushed against the flywheel and disengaged, then smacked hte rotor, but this was just a guess. It broke coming out of the burnout.

I'm pretty sure the 2nd failure was due to the damn bellhousing bolts backing out on me. I've changed enough transmissions to know you always double check that **** after a few hundred miles, but I didnt in this case on this one, it looked like the pump slide cracked first then the rotor busted as a result.

My crankshaft endplay was within spec and I sent the converter out after the first failure to have it checked out and it was fine.

Though with my current issue, I'm starting to notice that under wide open throttle, the car slips out of gear and immediately back in gear between 4-5k rpm in first gear (shifter in overdrive) and in manual first gear, it feels like the e-brake is on.

It drives great under part throttle conditions, not sure what the hell is going on. I have no idea what to look for on the line pressure gauge.

 

Put the pressure guage on it and see what happens when the problem occurs.

 

The 2nd time it slipped on me the other day, the pressure gauge was right at 200psi and didn't seem to react at all. Next clear weekendwe have down here, I may just take it to the local track during test and tune and see what it does, even if it means I'll kill it at least then I'll know what to fix.

 

A good pressure at WOT should be at a minimum 220 lbs. - 240 lbs. maximum. I like 235 lbs. at WOT. See what you have when you go to the drags.