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Thread: 00 GTP Tranny issues

  1. #1

    00 GTP Tranny issues

    Lastnight while driving my 00 GTP, i slowed down to pull uphill into a buddies driveway and then boom, no tranny. Car has reverse, 2nd, and 1st. I put the car in 1st to get up the hill and you could feel it shudder. I checked the fluid and the level is full and its not burnt. Has anyone had this incident before? The torque hasnt locked for a few years due to a bad TCC and sometimes in when cold, it shifted hard from 1-2 sometimes "hanging up" in between. Could a bad Pressure Control Solenoid Valve or sticking valve cause this? I havent scanned for DTC's yet as my scantool is at work. Also, I have the alldata online manual for this vehicle. It says in the manual that this car is equipped with a 4T65E Hydromatic Transmission. I thought these cars had the 4T65E-HD's in them? Reason im asking is I have a 2001 Monte Carlo SS with 63K on it thats been totalled do to a rear end collision. I believe that has the 4T65E tranny in it which would be interchangeable. All help is appreciated! Thanks in advance!

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  3. #2
    so i found out today that my gtp has a 4t65e and so does the monte carlo. Only difference is, the gtp has a 2.93 gear ratio and the monte has a 3.29 gear ratio. I was told that the dealer could reprogram the PCM to accept the 3.29 ratio tranny. Does anyone know if there is any truth to this? Im going to call my local Gm Dealer tomorrow and see what they say. Just wondering if anyone has done this???

  4. #3
    Full Throttle Extreme! insaneABOT's Avatar
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    If you have hptuners you can do it yourself. But I think the dealer should be able to reprogram the pcm for you.



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  5. #4
    Constantly Overachieving Merlin's Avatar
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    yea this is possible, you will end up changing your transmission from a heavy duty one to a regular transmission.

    there are threads on swapping the hd equippment over onto the monte tranny.
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  6. #5
    well I called 2 local dealers today and they pretty much told me that i didnt know what i was talking about that there was nothing in the PCM that would change the gear ratio. So i stopped by another chevy dealer thats pretty much a hole in the ground that doesnt have a single new GM on the lot and the service manager seemed to know what i was talking about and is calling GM technical assistance in the morning. As far as having an HD version, both dealers i called told me that i had the plain 4T65E XAB in my GTP and that it wasnt a 4T65E-HD. Considering their attitude about my PCM reprogram question, i wouldnt doubt for a split second that they could be wrong. Im not too worried about it anyways. As it is, the belt has been off the supercharger since the summer. The car has 179K on it and the motor is bone stock. So im not worried about a HP issue whiping out the tranny anytime soon LOL. I just need to get this thing back on the road so that my gf stops driving my silverado. A 1993 Honda civic 1.5 isnt too fun to drive when you're used to driving a fullsize pickup.

  7. #6
    Mud in the hvac box again FlyinGTP's Avatar
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    your car does have a 4t65e hd. it's the only way gtp's came. There were many variations of it. most of which had to do with what version valve body it had in it as gm had a ton of issues with the valve body's causing different issues.

    The main differences that you need to worry about is that the non hd diff has a 3.29 final drive where as the hd has a 2.93 final drive. this is controlled by the drive chain and there sprockets. The pcm will need to be reprogramed to account for this or you will burn up the new tranny. I would not have the dealer do it because they would have to flash it as a GT which would not be good for your supercharged motors fueling and timing changes. they don't have any other option to do that. You will need to locate somebody who has hp tuners or a dhp powertuner. both will have the capabilities to reprogram the pcm to account for the different speedo.

    Also you will need the pass side axle from the monte as well if you don't do the hd upgrade to the transaxle. all you have to do turn the non hd trand into the hd trans is swap the differential which is physically larger in size, this also requires the gtp pass side axle which you already have.

    Its not a rough job to swap the differential out on these cars. and i would be that your differential in the gtp trans is still good. that being said all you need to do is swap it and the cover over to the non hd trans and your set.
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  8. #7
    if I were to swap the differentials, would I still need to have the PCM reprogrammed? Im more than capable enough to change out the diffs as i am a master tech for nissan. Still havent heard anything from the dealer yet anyways. I do want to get this thing going asap as stated before.

  9. #8
    also, would I have to change the torque converter also?

  10. #9
    Mud in the hvac box again FlyinGTP's Avatar
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    Quote Originally Posted by billjoyal View Post
    if I were to swap the differentials, would I still need to have the PCM reprogrammed? Im more than capable enough to change out the diffs as i am a master tech for nissan. Still havent heard anything from the dealer yet anyways. I do want to get this thing going asap as stated before.
    Yep changing the diff is pretty easy on these cars the only think you really need to pay attention to is making sure you have the torrington bearings installed in the right direction. Yes you still need the pcm reflashed because the diff has nothing to do controlling the ratio of the final drive on these cars. that is controlled by the drive chain and sprockets. that being said you need to take apart about 80% of the transaxle to change the sprockets which is what actually gives you the final drive gearing.


    Quote Originally Posted by billjoyal View Post
    also, would I have to change the torque converter also?
    well the n/a converter is a smaller 248mm converter. all the aftermarket high stall converters are based on the smaller 248mm. the stock gtp converter is 260mm. If your gtp has the dual bolt pattern flex plate from the factory you can use either converter. If you decided to use the 248mm and only have the single pattern flex plate you will need to flex plate from the monte carlo as well. I would recomend using the 248mm converter for two reasons. number one its smaller and has less rotating mass which will help increase the life of the transaxle and because its from a n/a car it will stall a bit higher then your stock one did in the gtp. the second reason i wouldn't use the 260mm converter is because it probably has a ton of junk in it from when the orginal trans failed. you could try and have it flushed but in all reality you probably still have issues with it.

    the final thing is your going to need to at least flush the trans cooler in the radiator to try and get the junk out of that. if you can you could probably steal the radiator from the monte as well and just but that in and call it a day if you wanted. Or you could pick up a b&m or something and put it in place.
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  11. #10
    I have the complete 01 monte SS. I bought it used with 40K miles and drove it a year then it got rear ended which totalled it out. I bought the car back for $400 from the insurance company so all of the drivetrain is complete and only has 60K miles. I can buy a used XAB tranny for $675 for the GTP that will bolt right in no questions asked but im trying to do this as cheap as possible (as any mechanic would) so this is why im trying to use the monte tranny. I know the PCM wont work out of the monte because i've tried using it for an issue I had with the GTP before and it wouldnt even start the vehicle. Like i said before, the GTP isnt getting any forced induction right now because the belt is off. Ive located a TSB from GM that says when the vehicle loses Drive and 3rd but has normal operation in R, 2, and 1 to replace the sprag assembly and to also check the PC solenoid valve. By the time i get done rebuilding the tranny with 179K miles on, i could buy the used one and have a warranty and a lot less work. Ive looked into HP tuners before for the price of the program, i could have the used tranny. So i guess im pinned to the board now and have to spend the money or the car wont be fixed lol. Thank you for your help!

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