Is transmission normal?

Guys,
I always heard GTP's trannys were easy to break comparing to SE or GT, so I worry about my 97 GTP a little bit.

When I accelerate, engine revs over 3000 RPM, I can feel tranny shifts to next gear, some kind of sudden pushing, not strong.

I am not sure how all other GTPs' trannys work. Are they shifting very smoothly without feeling anything?

the problem with the transmissions in the GTP and Bonneville SSEi is that the transmission is produced for use in the 3800 naturally-aspirated engine. While it works with the supercharged one, all that extra horsepower could very well cause problems. shifting depends a lot on the type of driver you are. if you have a lead foot (like me :p ) then you might not shift to closer to 5K rpm. especially on a cold day, if your just driving real easy, then the trans might feel a little rough shifting in and out of gears, because the transmission fluid hasn't had a chance to warm up quite yet.
I am very much an advocate of babying your transmission (esp. the 3800 supercharged. I have an SSEi, so I know how it is) I have had my car for a year now, and it has about 140K on it. I have changed my trans. fluid twice. that may be a little extreme (it probably is), but i figure spending the $60 once a year is cheaper than a grand-or-more transmission.

the problem with the transmissions in the GTP and Bonneville SSEi is that the transmission is produced for use in the 3800 naturally-aspirated engine. While it works with the supercharged one, all that extra horsepower could very well cause problems. shifting depends a lot on the type of driver you are. if you have a lead foot (like me :p ) then you might not shift to closer to 5K rpm. especially on a cold day, if your just driving real easy, then the trans might feel a little rough shifting in and out of gears, because the transmission fluid hasn't had a chance to warm up quite yet.
I am very much an advocate of babying your transmission (esp. the 3800 supercharged. I have an SSEi, so I know how it is) I have had my car for a year now, and it has about 140K on it. I have changed my trans. fluid twice. that may be a little extreme (it probably is), but i figure spending the $60 once a year is cheaper than a grand-or-more transmission.


The N/A engines have a differant Tranny then the Supercharged engines......where do you get that they are the same?

BTW: at WOT my tranny doesnt shift till over 6000 RPMS and I have no Problems

The N/A engines have a differant Tranny then the Supercharged engines......where do you get that they are the same?

BTW: at WOT my tranny doesnt shift till over 6000 RPMS and I have no Problems


So tell me whats the difference between the 2 trannies? As far as I know both have the 4T65E trans in them. I have seen more failures in the non-super charged version than the super charged ones.

4T65E is in the N/A
4T65E-HD is in the Supercharged Cars

I guess you could say we are both right....they are the same but differant versions of them

The HD tranny is made a little stronger then the regular....

I agree with GTPCatz, the 4T65E-HD is more stronger than the N/A Grand Prix.

Hardywang, my GTP tranny does the same than yours and isn't bad (i think so). Others friends GTP make the same thing at shift to other gear.

I just looked up the difference in the tranny's, and its differnt for Bonnevilles and Grand Prixs.

Bonneville 3.8 N/A
4T65E with the MN3 code, meaning it uses a 258mm torque convertor.

Bonneville 3.8 S/C
4T65E with the MN7 code. Uses the 258mm toque convertor (same as above), but upgrades to a heavey duty gearbox.

Grand Prix 3.8 N/A
4T65E with the M15 code, meaning it uses a 245mm torque convertor.

Grand Prix 3.8 S/C
4T65E with the MN7 code. Uses the 258mm toque convertor, but upgrades to a heavey duty gearbox.


Some other info. if interested:
Hydra-Matic 4T65-E Transaxle (M15/MN3/MN7/M76)

Type: four speed front-wheel-drive, electronically controlled, automatic overdrive transaxle with electronically controlled torque converter clutch
Engine range: 2.5L - 3.8L
Maximum engine torque: 280 lb-ft (380 Nm)
Maximum gearbox torque: 400 lb-ft (542 Nm)
Gear ratios:
First: 2.92
Second: 1.56
Third: 1.00
Fourth: 0.70
Reverse: 2.38
Maximum shift speed: 1-2 6500 rpm
2-3 6250 rpm
3-4 6000 rpm
Maximum validated gross vehicle weight: 2903 kg (6400 lb)

thanks guys for your information

I have a 2002 GT, and I'm considering mods to upgrade the stock 200 HP by 30% to 40%. The car will still be a daily driver, so I want to maintain reliability, but I'm sure that I'll be punching it on occasion.

What precautions do you think that I should take? Do you think that Mobile 1 ATF is a good idea?

(you may have wanted to start a new thread, this one is a month old)


:1: Synthetic Fluid is always a good idea. It won't break down as easily, it lubricates better, and it runs cooler than conventional fluid. When I buy my first brand new car, i will be running almost all synthetic fluids

I wouldnt run synthetic in the GP trans. Many people have reported problems after switching to syn. fluid. It has a tendancy to lubricate too well, and slipping has been noticed.

Well that is true, but, if you still want to use syntec there is a product that converts ATF to high friction ATF(Japanese Spec). I will get the brand for you but the point is that will allow you to have a normal shifting tranny with syntech oil.