Trans Slipping - HELP!!

**coolken84** · 04-09-2008

I have a 2001GT -w- the 4T65E Transaxle. I've just started getting what seems like sliping in 1st gear in the last month, and It's pulling around 3500 rpm in 4th to maintain 75mph level grade. It still seems to pull hard if I get on it, but slips if I go like half throttle. Also every once in awhile going from 1st to 2nd it slams in prety hard. I have replaced fluid twice in the last 6 months, including slick50 trans treatment the first time, and lucas trans treatment the last weekend. Not much difference. Ordered and got the 1-2 3-4 solenoids and have a manual on it, but I'm unsure if while I have the tranny out if I shouldn't just do a complete rebuild, or roll the dice with the solenoids?
Any Help will be appreciated!

**Trannyman95** · 04-09-2008

Replacing the shift solenoids isnt going to help your problem. It sounds like pressure problems and possibly a stripped 4th clutch shaft. Slipping in 1st and slamming between 1-2 shift could be a lot of things internal. Pressure control solenoids are the most common problem for pressure issues in these transmissions and the only way to verify that is if you had a trans tech look at your car and drive it, hook up a pressure gauge and scanner and see what is going on. Installing just shift solenoids is a great deal of work and you arent going to gain anything from it. Your trans is just likely tired and in need of rebuild or replacement

**coolken84** · 04-18-2008

Hey trannyman, Another ? - I have a transmission available from a 99 gtp that I can pick up for $400, has 90k on it - wondering if it would work on my car & what modifications it would need? Followed your advice, but I'm unsure of who to trust - certified transmissions said they scanned my current tranny and it's not going into 4th gear, but said it was low on fluid, and that was causing the slipping. I added fluid to the trans hot and it is at the top of the full range - still slipping in first, but when I start slow and accelerate slowly I hear it shift through 4 gears. It's like it goes into 4th and slips back into 3rd. Any more sage advice?

**Trannyman95** · 04-18-2008

A 99 GTP trans wont be a direct bolt-in for your car. That trans has a larger differential which requires a HD/Supercharged specific passenger side axle, has a 2.93 overall gear ratio VS your stock 3.29 overall gear ratio, and the cooler line fittings on the 99 will be for thread-in style cooler lines and your 01 car will have a quick connect line. Without custom pcm reprogramming or some extra work to make the gear ratio change work correctly you will throw a trouble code for incorrect gear ratio and put the trans in limp mode and it wont work right. The cooler line fittings will be a coin toss, some 99 cases had the correct sized threads that would allow for quick connect fittings to work and some cases did not. As for your current trans feeling like it has 4 gears you are probably just feeling the torque converter lock up after it shifts into 3rd gear which will feel like another gear but isnt. No forth gear explains your high rpms at 75mph and is a common problem with the pre 03 transmissions as there is a clutch hub for 4th gear that the splines strip out on which leaves the trans working ok except no 4th.

**coolken84** · 04-18-2008

Thanks for the quick reply! Sounds like the gtp trans would be more trouble than it's worth. Ok, say it's the 4th output shaft splines stripped out; I saw other posts in the forum where people have replaced it without completely pulling the trans...I can do the work, but I'm wondering if I'm just buying potential for other issues not just pulling it and doing a complete rebuild? Also the 4th gear output shaft still doesn't explain the slipping issue in low gears. Thoughts?

**coolken84** · 04-18-2008

P.S. I have carefully inspected my used trans fluid from the past 3 changes - never have seen ANY metal fragments at all.

**Trannyman95** · 04-19-2008

The slippage could be a lot of problems, and if you trans has over 80K on it then it may need rebuilt to fix it or at least torn apart to find the cause. The pressure control solenoid is a common cause of pressure problems on the 02 and earlier 4T65E transmissions and that is something that would be accessable if you did try to tackle installing a 4th clutch shaft.

**coolken84** · 06-10-2008

Started the hub replacement finally - due to work only been able to work on it 1 day so far. You were right trannyman...that hubs splines were GONE! Replacing all solenoids as well...I'm hoping I can get away without a full bore rebuild - don't wanna take the tranny completely out if I don't need to.

**Trannyman95** · 06-10-2008

Glad to hear you found your problem ok! I would definately replace the pressure control solenoid also while you are in there.

**coolken84** · 06-23-2008

Just wanted to drop you a note Trannyman, finished the work on the transmission & replaced all the solenoids - working great...I have 4th gear again!!! Thanks for all your advice on this, and anybody wanting to attempt this can ping me for advice on doing this -w- the tranny in the car. Not as hard as I thought it might be.

**coolken84** · 06-25-2008

Well..this is insane - worked for 2 days and yesterday driving to work I lost 4th gear, then it started throwing the tcc solenoid stuck on error code and the 2-3 solenoid stuck error - Does go into 4th again, but when going uphill sometimes the engine revvs wildly...I'm about 10 seconds from making a road trip to northeastern Iowa for a trannyman special! This thing is killin me.

**coolken84** · 07-19-2008

Just an update Dave, Removed the tranny today and have disassembled it - good thing I did, found metal shavings in the reverse servo and various other places - speed sensor.. (would have sucked to ruin your good work on the valvebody with that crap).. The good news, all of my planetarys and gears look brand new - haven't found so much as a chip anywhere. I start reassembly in the morning. Looks like the hardest part is going to be just getting it back in...was a pain w/o a lift. Quick ??...Should I add transmission fluid to the new torque converter ya sent me? Looks like it has some in it already, But I've read you need to add a quart before assembly.

**Trannyman95** · 07-19-2008

I generally dont put any fluid in converters but if you can get a quart in before you put it on the trans it is best. It will take quite a while to do this so dont plan to do it right before installing the trans, and some is going to leak right back out when you tip up the converter to put it on the trans. Just make sure when you start the car up you already have 6-7 quarts in the trans and immediately poor in the rest, it will hold roughly 13 quarts give or take a bit.

**beno420** · 06-01-2011

my car has no 4th gear. 1998 gtp. when yours went bad did it slip in 4th or just tottaly bypass the gear? mine wont go into 4th to slip lol if i let off the gas it will drop into 4th but the instant i touch the gaspedal its back in 3rd gear. i know its going into 4th becuse if im in 3rd and let off the gas and put in 4th (drive) u feel it shift and then if u drop back into 3rd you feel it downshift. was your car slipping in 4th? or just bypassing the gear?