Thread: 99 gtp trans issues

hey new here, not sure if this has been covered, if so can someone point me in the right direction.
Just bought this 99 gtp 2 weeks ago and have been fixing things on it to make it nice again. Things i have noticed before today, while driving, never seemed to shift into what i thought was 4th until after 45 mph. and torque converter when you let of gas would drop to idle- less than 1000 rpms. thinking this is normal with this. noticed delayed shift from 1st to second sometimes, looked at trans adapts and found to be around 20 psi. so i know i at least need a pressure control solenoid, was going to do that and filter and gaskets this week once they came in.
well today went for a drive for a couple of hours and it started something new once warm. found it would shift from 1st to second and then would just stay in second. played with shifter, went to neutral and the manual lows and eventually would go into 4th im assuming. doesnt seem like it ever goes into 3rd. did this a few times and then drove home for 30 minutes with no issues. car has 174,000 miles on it. fluid is red, smells ok and is full. Ive been in multiple 4t65e, as im a gm transmission tech. never ran into this 3rd gear issue and not shifting though. have done a ton of torque converters and pc solenoids and reverse issues and what not. but never had one that would not shift to 3rd. no codes have set. any help would be appreciated.

These drop into OD around 45mph, so that's normal. I'm not a 4T65E guru by any means, but I just changed out the fluid/filter on my 00 GT and installed a Transgo shift kit and so far it has really made a difference. Not only are the shifts quicker but it seems to be much better once the TC locks up as it used to fluctuate whenunder a load. Maybe check out tripleedgeperformace.com for the issues with it not going into gear correctly. There is a lot of info on there that may help you out.

Thanks guys, probably rebuild it, should look into what I should replace once in there.

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depends on how long you intend on keeping it. ALWAYS replace the afl valve and 4th clutch with hardened and ALL solenoids. Everything else is mostly optional if it looks good, but why do a partial rebuild? The ebay 4T65E rebuild dvd is the best thingI found hands down for rebuilding

that's the one! Used that along with this: https://www.google.com/url?sa=t&source=web&rct=j&url=http://shop.ukrtrans.biz/wp-content/uploads/catalogs/4T65E.pdf&ved=0ahUKEwjK1-PAz4rXAhUE2oMKHT-hCLMQFgh4MA0&usg=AOvVaw3ObOFg0bVO1rfMDz9xYTVD

Only special tool you need is: https://m.ebay.com/itm/Automatic-Tra...-/172235262701

If you're pondering whether or not to dig into things, check this video out (note, he makes this look easy) https://www.youtube.com/watch?v=31Q8qJvBn-M

Forgot to mention to be careful with that tool I mentioned, I usually improvise with parts of "modified" steels. Basically, one the second clutch piston spring, you'll usually bend it with this tool unless you "extend" it with some metal ring (you'll see what I'm talking about on the rebuild dvd).

The biggest advice I can give though is to be EXTREMELY organized and take pictures of EVERY step. Pay special attention to the spring colors and such when removing. I wasted hours on my first rebuild because I didn't do this (so learn from my mistakes!). Clean everything as you go (a parts cleaner helps a lot, pick up the cheap desktop one at harbor freight, some brushes, and tack cloths) and label/bag it as you go too. Organization is key.

It's not a necessity, but I'd have a good set of six sided sockets because some of the bolts tend to round off (especially the ones reference in the video). Use lock-tight on everything putting it back together and use ample assembly lube and fluid where needed.

You will want to flush your transmission cooler portion of your radiator, and get a new torque converter (which is why it ended up costing me $500 total)

One thing the video didn't go over at all is what to do when starting up the new transmission. You'll want to fill the new torque converter with about a quart or two of fluid (till it's full), install everything, pour about half of what you need in, start the car and let it idle and immediately dump the rest in like mad! Slow when you're about done and periodically check levels as it warms up. Take for a short drive, re-check levels, and done!

I recommend DEX6. Makes a world of difference. Feel free to PM me with any questions!

Originally Posted by wstefan20

If you're pondering whether or not to dig into things, check this video out (note, he makes this look easy) https://www.youtube.com/watch?v=31Q8qJvBn-M

Forgot to mention to be careful with that tool I mentioned, I usually improvise with parts of "modified" steels. Basically, one the second clutch piston spring, you'll usually bend it with this tool unless you "extend" it with some metal ring (you'll see what I'm talking about on the rebuild dvd).

The biggest advice I can give though is to be EXTREMELY organized and take pictures of EVERY step. Pay special attention to the spring colors and such when removing. I wasted hours on my first rebuild because I didn't do this (so learn from my mistakes!). Clean everything as you go (a parts cleaner helps a lot, pick up the cheap desktop one at harbor freight, some brushes, and tack cloths) and label/bag it as you go too. Organization is key.

It's not a necessity, but I'd have a good set of six sided sockets because some of the bolts tend to round off (especially the ones reference in the video). Use lock-tight on everything putting it back together and use ample assembly lube and fluid where needed.

You will want to flush your transmission cooler portion of your radiator, and get a new torque converter (which is why it ended up costing me $500 total)

One thing the video didn't go over at all is what to do when starting up the new transmission. You'll want to fill the new torque converter with about a quart or two of fluid (till it's full), install everything, pour about half of what you need in, start the car and let it idle and immediately dump the rest in like mad! Slow when you're about done and periodically check levels as it warms up. Take for a short drive, re-check levels, and done!

I recommend DEX6. Makes a world of difference. Feel free to PM me with any questions!

I'm not new to the transmission as I'm a GM trans tech, have been in a few of them just never ran across this issue. I'm more familiar with all of the newer 6 speeds. I will be putting a new torque converter in. Any ideas where to get a good one And also rebuild kits avasilable for these?

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Originally Posted by mao1848

I'm not new to the transmission as I'm a GM trans tech

Haha well you probably know more than I do! lol So used to people on here never having touched these transmissions!

I've had good luck with ProKing, but unless you're going for performance, I doubt it matters much. I know I'm going to get a lot of flack from recommending this, but I bought all of my parts on Ebay. I went with Borg Warner solenoids and frictions. I'd recommend Sonnax Lube tube retainer, transgo shift kit, superior solutions AFL valve (because it works and you don't have to get the valve overbored and sleeved by a machine shop), and sonnax boost valve. I can't remember where I got it, but there's a company that makes an "extender" pin for the forward servo pin that reduces the risk of it breaking the forward band (you do need to file this down though because it comes way too long). I'll see if I can find it again. I also replaced all friction bands, hardened 4th, needle bearings, bushings, etc. Look on Sonnax's website under their "vacuum test" section. It will highlight troublesome valves that should be thoroughly inspected and cleaned for binding. (wish I had one of these vacuum test kits)

Originally Posted by wstefan20

Haha well you probably know more than I do! lol So used to people on here never having touched these transmissions!

I've had good luck with ProKing, but unless you're going for performance, I doubt it matters much. I know I'm going to get a lot of flack from recommending this, but I bought all of my parts on Ebay. I went with Borg Warner solenoids and frictions. I'd recommend Sonnax Lube tube retainer, transgo shift kit, superior solutions AFL valve (because it works and you don't have to get the valve overbored and sleeved by a machine shop), and sonnax boost valve. I can't remember where I got it, but there's a company that makes an "extender" pin for the forward servo pin that reduces the risk of it breaking the forward band (you do need to file this down though because it comes way too long). I'll see if I can find it again. I also replaced all friction bands, hardened 4th, needle bearings, bushings, etc. Look on Sonnax's website under their "vacuum test" section. It will highlight troublesome valves that should be thoroughly inspected and cleaned for binding. (wish I had one of these vacuum test kits)

Alright I'll have to look into that. Not planning on doing many mods, it's my daily so maybe a few little things but I'm not going to go crazy with it. Want it to still be reliable and fun. I'm used to these trans in impala and other things that dont have as much power. So I'm never worried about it. But these supercharged are a little different story.

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I hear you on that.

The main reason I always choose to replace all this whenever rebuilding these trasmissions is the cost difference between leaving out all but the master rebuild kit and whatever's broken is only usually $100-200 savings, which to me is worth my time and money to just replace it rather than worry about it going bad down the road.

If you need any hard parts, let me know as I have a "parts transmission" just lying around waiting to be torn apart!

Originally Posted by wstefan20

I hear you on that.

The main reason I always choose to replace all this whenever rebuilding these trasmissions is the cost difference between leaving out all but the master rebuild kit and whatever's broken is only usually $100-200 savings, which to me is worth my time and money to just replace it rather than worry about it going bad down the road.

If you need any hard parts, let me know as I have a "parts transmission" just lying around waiting to be torn apart!

Alright thanks, yea I agree. Might as well take a little extra time and replace things that need to be done so I don't have to waste time and money again. If I need something I'll let you know!

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Originally Posted by Mitch R

So I'm kinda hijacking this thread, but I have a 67k mile trans that currently shifts great with no modifications. Since it's going to be a turbo car I know I need some hard parts and will definitely be installing a shift kit, but is there any real advantage to replacing all the clutch packs other than them being new then? Since I have to remove the valve body I figure I'll replace/upgrade the parts in there since I'm already in there, but I'm kinda hoping to limit the amount of stuff I remove since this will be my first time inside a tranny that I actually intend to put back together.

I just ordered all of my stuff last night. I'm going through it all, new seals, steels and fibers, new bands. I've seen the reverse band break on newer trans. Figured I'd might as well do it all, I don't want to have to take it back out. I don't know if there is any advantage but I'm doing it for piece of mind.

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Originally Posted by mao1848

I just ordered all of my stuff last night. I'm going through it all, new seals, steels and fibers, new bands. I've seen the reverse band break on newer trans. Figured I'd might as well do it all, I don't want to have to take it back out. I don't know if there is any advantage but I'm doing it for piece of mind.

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You and I think alike my friend! That's exactly what I did. Good luck!

Originally Posted by Mitch R

So I'm kinda hijacking this thread, but I have a 67k mile trans that currently shifts great with no modifications. Since it's going to be a turbo car I know I need some hard parts and will definitely be installing a shift kit, but is there any real advantage to replacing all the clutch packs other than them being new then? Since I have to remove the valve body I figure I'll replace/upgrade the parts in there since I'm already in there, but I'm kinda hoping to limit the amount of stuff I remove since this will be my first time inside a tranny that I actually intend to put back together.

As long as you don't have any issues now, you'll be ok to use old clutches unless your over 200,000.

For performance, a great resource is the performance rebuild dvd from ebay, had some great advice.

For turbo, personally I agree with triple edge on their approach of upgrading input shaft, pump shaft, output shaft, hd differential if you don't have one, 7/8" chain, custom torque converter, and billet flex plate. Too many people try to skimp on the flex plate and torque converter and end up kicking themselves later.

Basically, for performance, you're easily looking at $2000 just in parts, which is the only reasonI haven't gone for it yet.

This is not saying that you can't run turbo with no mods, it depends how you drive, what your performance expectations are, and how long you want it to last.