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Newbie with a tranny question

Nohbdy

New member
Hey everybody. First i'll apologize for re-asking questions. I've read through several of the threads, but i'd like some opinions, since none of the issues seemed to match mine perfectly.

NEWBIE QUESTIONS: I've been led to believe at other forums that the 4T65E and 4T65E-HD are less prone to 4th gear damage than the 4T60E predecessor. The impression i got is that the 4th gear stripping was mostly not a problem in the T65 and beyond. First, which of the two would the 98 GTP have? 65E or 65E-HD? Second, i see a lot of posts in here about the 4th gear stripping. Is that still a major issue with these?

THE CAR: 1998 Grand Prix GTP, 147,1xx stock miles for both tranny and engine.

THE PROBLEM: Sometimes the transmission decides it doesn't like 4th gear much. When that happens, the RPMs jump about 500. Manually selecting third at these times no longer changes RPMs, but manually selecting 2nd does. This convinces me that i've lost 4th gear. The problem has (thus far) always happened at least 15minutes into a drive.

Turning the car on and off again briefly solves the problem. I found that out when I got gas.

The drop out of 4th generally happens on an incline, though not enough of one to force the engine out of 4th. I can make it up those hills in 4th if it is willing to use it.

THE ABNORMALITIES: This never happens on the highway I have yet to be in a position to try it, but i believe that if I were to go 65+ when this was happening i would still get into 4th gear. I haven't confirmed that yet though. Also, it will reset mid-drive to get into 4th again at lower speeds (45+ if maintaining speed). By this i mean it will sit in third for a while, with nothing i can do about it, and then it will drop into 4th like nothings wrong all the sudden. This can happen on a decline, flat plane, or incline.

I actually came to this forum thinking it was a malfunctioning relay for the performance shift causing the transmission to randomly select in and out of the performance shift option - the shifts come later all the way up while this is happening, which is the description of the performance shift. However, what i've read here says that performance shifting should be less noticeable, since i'm being transferred up ~500rpms on my shifts, rather than 100-200rpms. Could i still be correct in my assumption? Is it a larger problem?

I bought the car two days ago and noticed this before i got home, but thought maybe i didn't know the car well enough to be sure. By yesterday i was positive, and having looked into it today i'm worried i bought a car with a faulty transmission. I don't know how long it's been happening - the seller didn't bother to mention it or i wouldn't have bought. I'm about ready to call him and ask for my money back.
 


4t65 are all noted for blowing 4th except the 03 which had the hardened 4th hub. The 4t60 was limited in other areas but my 4th held up to being top swapped no problem in my 97 GP GT before going full retard 5 speed mod. On the plus side, those transmissions are out there and relatively cheap...on the negative side, it's probably not going to happen that you get your money back. How does the fluid level and condition look on the car? Any service history?
 
03 and up has the hardened 4th splines he means ^

You have the 4t65e-hd since you have a GTP. If it's supercharged then it's a hd trans.

If the 4th clutch hub splines strip, you will never go back into overdrive until it's replaced. Also the earliest 4th gear will ever apply is at 45+ so anything below it will be third unless you go past and slowly decel it will stay a bit below 45.
 
thanks for the clarification on transmissions and the like you two

i realize it wont hit 4th at lower than 45mph, the problem is sometimes it still wont hit 4th at 60

From what you're saying it can't be the splines stripping. unless i'm mistaken that leaves the solenoids or the performance shifting setting, but i saw something about coils in a few threads as well. can anyone weigh in on those possibilities?
 
When its stripped out from being the non hardened part when it goes to shift into 4th it's more like a second neutral. It drops to idle then kinda kicks back up then acts like you're riding the clutch until 3rd comes in.
4thStripped.jpg
Then you made 4th gear look like this!
 


Like the other guys have mentioned, 4th is an issue in the T65's. No doubt about it. It's not bad to replace it. Holler if you'd like the write up. (In How To Section)

The rpm fluctuating that you mention, sounds to be like the TCC kicking on and off. Aka oscillation. This can sometimes be caused by a dirty MAF, failing TPS, ignition related issue, MAP sensor and of course a TCC issue itself. I like to rule out the others first though.
 
03 and up has the hardened 4th splines he means ^

You have the 4t65e-hd since you have a GTP. If it's supercharged then it's a hd trans.

If the 4th clutch hub splines strip, you will never go back into overdrive until it's replaced. Also the earliest 4th gear will ever apply is at 45+ so anything below it will be third unless you go past and slowly decel it will stay a bit below 45.
2004 and up have the hardened 4th. Just confirmed this with Scottydoggs.

Sent from my Tab3
 


Here's my noob question about the tranny's, is it possible to upgrade to a 4t80 out of a caddy or is there a different tranny that holds up better with these engines and torgue? Any help appreciated.

Sent from 1BadGT's Rooted Galaxy S5!
 


Yeah I've read through several threads about it now. I have a 02 GP GT model and plan on a top swap and some other mods so I'm also thinking...while I'm making mods, may as well do a tranny swap. Just waiting for the next Pontiac Nationals so I can go as I live in the Akron, OH area. Norwalk is an hour away luckily.

Sent from 1BadGT's Rooted Galaxy S5!
 
I'll have to share the thread in the GPONA forums if it's not there as well. I'm sure there's probably something about it though. You guys here in these forums are a great help and it's great to learn from guys with so much experience in it already. Seriously...this is a great community to be a part of right here. Thanks for everybody's help!!

Sent from 1BadGT's Rooted Galaxy S5!
 
Just do a mild build 4t65. Not worth the uber work and custom stuff unless your planning 400+whp.. which is not really all that doable on a m90. 7/8" chain, 300m input shaft shift kit and clutches and your good to go. oh and hardened 4th.
 
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