slowfive0

Ok, put a transmission in my truck that was proven and a new converter and on the launch, it acts like you threw it in neutral. Makes a nasty bang noise (like I dropped the d/s out of the truck) and hits the rev limiter. No tire spin either. I let off and the truck drives normal. The only time it will do this is on a hard launch from a stop or very slow roll. Any other time it is fine. Initially, I thought the converter was bad, but it was just ckd out and is fine. My next suspect was the low/reverse clutch or maybe the forward sprag....but they both look pretty good. In fact better than my old trans (3/4 clutch went out in that). The trans is full and the filter was in place. Thoughts????? I'll be putting it back together this weekend and I'm not comfortable not having found something concrete.....

pasadenaman

iTrader: (3)

My tranny guy says your sprag might be bad or backwords. U might want to get the 29 metal double sprag if they are bad.

slowfive0

It has a 29 element sprag and it looks pretty good

pasadenaman

iTrader: (3)

I mentioned this to him and he suspects the sprag is in backwords. He had to step out to finish rebuilding his sons tranny.

slowfive0

The trans had a 1000 miles on it and was working fine in a faster truck. I put it in and drove it and it shifted fine and worked perfect except for a hard launch or a WOT start from 10 mph or slower. If I did that, it would exhibit the concern I mentioned. The trans is built and has a 29 element double caged sprag. I inspected it and the low roller clutch and both look good. They show some wear, but look better than the units in my original trans (which wasn't giving me any problems other than the 3/4 clutch smoked). Thanks for the feedback---keep em coming.

FLT

iTrader: (1)

I think that you might be loosing fluid pressure in the input drum area. I would air check the forward clutch circuit through the shaft and also through the pump. One thing that might be happening is that the input shaft might be floating in the drum or you have a damaged stator tube. Also check your forward accumulator piston located in the valve body. There is a possibility that it is cracked. By chance did you install a pressure gauge on the unit to see whet pressure does when it does this neutral condition? Vince

slowfive0

Unfortunately, I was unable to do that as the trans broke less then a day later. Basically, the converter would slam extremely hard on low rpm lockup. I tried putting the pwm in to stock settings with no change so I would assume the trans shop disabled that function. Shifts felt great though (crisp, not harsh), but that lockup was nasty.

Anyways, I got on it a little from a light to merge and it did it's bang slam deal and then would hardly move. Once you came to a stop it would hardly take off unless you reved it way up---felt like it was taking off in 3rd and no torque multiplication.

I got it apart and it blew both the forward and 3/4 snap rings out of the input drum. It also twisted the splines on the reaction carrier shaft. I attribute this to the high pressures. Found out that the trans had valvebody tuning as well as the pressure solenoid was tweaked a little due to the extreme application it was in before. Add to that that I had a tune with slightly elevated pressures over stock and I "think" this is why I had the failure (high pressures plus triple disc converter locking up). The converter lockup at lower rpms felt like it does when you side step a clutch. Very harsh!

Anyways, I was expecting either a problem with the stator in the converter (converter guy called yesterday and said it's perfect) or a problem with the low roller clutch or forward sprag. Both show show some signs of wear, but actually look better then then units that came out of my original trans (it failed the 3/4 clutch).

I just inspected the stator shaft and pistons and found some interesting things. The forward piston has a ripped section (inside seal) and there are some weird lines in the stator shaft @ where the forward apply section would be.....It's not a groove like you would expect to see from wear, but almost like lines on about 1/3 of the circumference that you can feel with your finger. I would think this would effect sealing and may be my original problem? I'm thinking the torn forward clutch piston is due to the piston over extending when the snap rings blew out....

Oh, and all of the accumulators are perfect.

Any thoughts would be most appreciated!!! Thanks

slowfive0

Just to close the loop for those who might run into something similar.....

I changed the forward clutch piston (had a tear in the seal) and fixed the other damage and the trans works great. I installed my stocker pressure control solenoid (no tweaks to that one) and reprogrammed the pcm to stock pressure settings. Also, removed the ball the builder had in the PWM TCC circuit so that the pcm can pwm the tcc again. Lastly, left the ball in the input shaft for the tcc return fluid.

Trans shifts awesome! Nice and crisp, but not harsh. Converter was acting funny with stock PWM settings for the lockup. In 4th at low rpms (1200) when it was locked a steady throttle, it would flare up and down between 1200 and 1400 rpm. It would do this at other low rpms too, but most noticeable at low low speeds like that. I raised the minimum tcc lockup values and the problem was solved. Converter locks up now with a nice bump, but not harsh.

Very happy with the trans and new triple disc Circle D converter (Thanks Chris!!!!). Can't wait to go to the track!

Thanks for the suggestions on this problem PT!!!!

2004SSS

iTrader: (25)

glad you got it working right this thing should be solid from here on out.

slowfive0

Yep, pia to be sure, but worth it in the end. That's why they call it hot rodding---lol!

I love this trans and I would highly recommend it to anyone. The "Toy Shop" transmissions in Pomona, CA built it. Very solid trans ---- I've rode in some vehicles where the shifts would rattle your molars!!! This is completely different. Very clean precise shifts---Awesome!

The best part was the customer service those guys give. Kendall helped me out on several occasions and went above and beyond. Something hard to find in this day and age. I'll plug those guys whenver I get a chance. Thanks.

Coverter stall was a little off the first time (Circle D), but Chris nailed it the 2nd time around. I'm sure the info from my combo will help with subsequent customers. Very pleased with his customer assistance as well.

Thanks PT for a great forum. I don't get near enough time to hang out here, but I can always get great info here when I need it. Hopefully, my feedback helps someone else out.