Yep, I bought the first tranny from someone in California posing as an art carr dealer. Asked me my vin# and said he would get one out of a camaro or firebird to rebuild for me. Recieved the tranny and the tailshaft housing was smooth with no holes like the 4l60e out of our cars have to mount the bar from the rear end. Pulled the tailshaft housing from my old tranny and installed it in on my new one, everything seemed to work ok except the tranny had a vibration in it at a certain rpm in gear and in neutral. 3rd gear clutches get soft and start slipping, then the car bounces off the rev limiter before shifting every time into 3rd. Had a mechanic at one of our dealerships I work at rebuild the tranny and it worked ok for about 2000 miles and then started not shifting into 3rd at part throttle and hitting the rev limiter before shifting at WOT. Bought a kit from pro-built.net and ended up buying most of the hard parts inside the tranny since the old ones were shot "new drum and I can't remember the other parts". Holy crap, the tranny shifted fast and very firm from 1-2, but still hit the rev limiter before shifting at WOT into 3rd, and wouldn't shift into 3rd at part throttle about half the time. Sometimes it shifts into 3rd very softly at part throttle and slips really bad but if it revs enough it will grab 2nd gear, not downshift just grab. If I manually select third gear it holds just fine and doesn't slip, noone seems to have a clue as to what is wrong with this thing. I replaced both shift solenoids and it has a brand new vigilante converter. Fluid had a little discolorization kinda looked like clutch material, but not too bad.

The original new tranny obviously didn't come out of a firebird or camaro. Are there any internal electronic parts that may be different than our 4l60e's that could be conflicting with the obd1 pcm in my car. Since I put my new motor in and got it running last monday the car refuses to downshift on its own.

 

Dude finally i have the same problem let me know if you get an answer thanks
Smokey_3917@hotmail.com

 

Bad Throttle position sensor was the upshift problem at part throttle, didn't find out until it finally gave out completely and didn't set the SES light, I only noticed it while running datamaster.

 

Bad TPS was a problem with 3 gear upshift and slippage? How it was seen in DataMaster. I'm asking because I have very similar problem with my 4l60e.

 

thanks man your right i did mine and it shifts like new

 

Datamaster didn't see it as a problem until it completely went bad and then it would just register a throttle opening percentage of 0-3% and the voltage stayed the same and never moved even though I was revving the engine.

EDIT:The slipping problem is still present because of unknown internal problems or the partial shifting nuked the clutches. I still have vibrations while driving around 2500rpm in every gear and while in neutral with or without the flywheel connected and with a different converter and new sun shell and input shaft. I think I'm gonna just get a whole new tranny and scrap this one when I can afford it.

 

That's great Firebird84, i'm glad it fixed your problem. From what I've read this has been a mystery to everyone why these trannies do this. It's no wonder though because it didn't give an SES light or any indication in Datamaster that it was getting bad readings until it finally completely went out.

If an admin comes across this post it may be a great help to make some kinda sticky out of it so others don't ruin as many transmissions as I did.

 

I was asked to make this a "sticky" and will leave it up for a while.

Rich

 

my trans did the same thing for about 5 rebuilds... finally had the builder call CPT and apparently they worked out the problem.. dont know for sure what ended up fixin it, but now the car shifts like a pro (havent gotten a whole lot of miles on it yet though cause it was wrecked right after he got teh trans straight....) but anyway they may be able to help you out! mine was doing it on 1-2 and 2-3 shifts though.. really only 2-3.. then it started doin it on the 1-2 after i had the 3.73 installed... he didnt think it was a problem until then either

 

I have a vibration mainly noticable @ about 2100 RPM. Since yours does it without the flywheel attached, you may want to check the rubber sandwiched between the 2 halves of the vibration damper on the front of the crankshaft, although my vibration damper looks fine. So if that's not your problem and you find out what is, please post what you find so I can try the same remedy. I recently rebuilt my transmission and checked for cracks in the flexplate but found nothing.

I had a problem with my 2-3 shift trying to hang on to 2nd gear after the rebuild and installed a TH400 coasting band spring in place of the servo return spring which seemed to help out a lot on the 2-3 shift lag problem. You can install it with the tranny in place, although it's pretty tight between the floorboard. I bent my floorpan in a little with a pry bar to gain better access. The TH400 coasting band part # is shown here and as you can see with the 2 shown side-by-side here it has almost twice the return pressure therefore releasing pressure on the 2-4 servo / band much quicker.
Hope that helps.

 

BTW: I ordered the TH400 coasting band spring through my local GM dealer, who I buy a lot of special order parts from, wholesale, but after 2 weeks they had not been able to aquire this part. I ended up getting one from Dacco Detroit in Memphis. I don't think they have a website, but they will ship you one if you call. The # is: Dacco Detroit of Memphis
(901) 345-1266

 

Good info! But here's the question?? How do you re-program the new throttle position sensor????

 

Thanks mike for the info, Pro-built is who I bought the kit from and he pm'd me and I'm gonna call him tomorow and see what he thinks I should do. I still think it's the inexperience of the builder and the fact that the TPS sensor was bad that led to my current tranny problems, the guy at pro-built has been extremely helpful and where the tranny shifts properly I am very impressed with its performance.

NZ12'S: I didn't reprogram the new TPS sensor, if the first one wasn't modified to get a different reading then you should just be able to put the new one back in. You can check in datamaster while at idle and it should read somewhere around .80 volts, I'm not sure thats exactly correct but just do a search and you find plenty of reference.

 

Very good info. I'll have to try this. Did it solve upshift problem completly?

 

OK I see a few problems here...

Sorry I haven't been a round for a while, but it looks like they sent you a tranny from another vehicle and possible a different year. This could pose a problem since there were different electronics for different years and vehicles...

The wiring for 94 was different, the 94 has an on-off tcc solenoid, the 95 and newer use pwm (pulse width modulated) signal to run the tcc apply. Those are just a few of the differences, I believe there are more. Ask Dana @ Pro-built when you talk to him or call Frank @ CPT and I am sure you can get it figured out...