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2004 GTP 4T65E-HD interchange question

Tony Mendez

Tony Mendez

New member
I have a 04 GTP that is having tranny issues. I think I have an internal problem with the sprag clutch. No forward movement when in DRIVE but when in MANUAL I can drive the car although it shudders on accel from a dead stop. Believe the over-run cutches are getting the car going due to a blown one-way sprag clutch. I am looking for a donor transmission but need some advise on interchange. I found a 06 GTP trans with 4k on it. Anyone have some advise on if this 06 trans will work or am I dealing with a 1 year only application? Any other advise greatly appreciated. I plan on rebuilding the original unit so if anyone has some thoughts on that also, it would be greatly appreciated. Thanks in advance.

Tony
 


If you can only drive the car going into manual mode, then likely you lost the forward band or something else likely broke.


So this car is a just a GTP or is it a COMP G?
 
The guy who has the tranny wasn't 100% certain. The price is right, I just wasn't 100% certain myself and didn't want to buy it and install it just to find out it wouldn't work....lol. Thanks mwinters29
 
you are correct, the comp G has 3.29's.
they also have tap shift which might mess with the trans somehow. not sure on that.
 


ctracer said:
you are correct, the comp G has 3.29's.
they also have tap shift which might mess with the trans somehow. not sure on that.
Click to expand...

The tap shift feature I have was what had us questioning the swap. The tranny he is selling came out of a car w/o tap(manual) shift. He assured me the trans came out of a GTP.
 
From a little research it seems that only the comp g cars got the tapshift, but that may not me 100% true.

The base model GT1 and fancier GT2 have the Series III 3800 V6 engine, putting out 200 hp (150 kW) and 230 ft·lbf (310 Nm) of torque, while both GTPs have the supercharged (Eaton Gen 5 Supercharger) 3800 Series III V6 engine with 260 hp (195 kW) and 280 ft·lbf (380 Nm) of torque.

A Competition Group (Comp-G) package was available for the GTP that included red painted brake calipers (same brakes as the 'standard' GTP), sport tuned suspension, heads-up display (also in GT2 model), 4-speed automatic transmission with paddle-style TAPShift, StabiliTrak dynamic control system, 3.29 axle ratio, performance tires and Magnasteer II. Also, a 10-spoke light weight wheel was standard with the Comp-G package but could be 'upgraded' to the GTP optional wheel.
Click to expand...

So it would seems that you will likely need to find another trans came from a comp g/tapshift?
 
well if u have tapshift now ur going to want to find another 4t65HD from a car with tapshift. you could still use one from a comp g with the higher ratios to get a little more kick but your gas mileage will go down a tad. if you do that you will just have to get your car tuned.
 
After some thought I will just drop the unit I have and rebuild it. Any recommendations on upgrades. I don"t really plan on racing this car but whats the use of having a Super Charged GP and not get heavy foot syndrome occasionally? Throw some thoughts and ideas at me and we'll see what sticks.
 


Triple Edge Performance

Check them out, he does awesome work and sells a crap ton of stuff from rebuild kits to shift kits to whatever you want. Lots and lots of info on the website too and if you have a question, email him and if you leave your number he can help you and is a great guy to deal with.
 
Small world.

This GTP has sparked my interest in the performance aspect of FWD street cars. Like any motorhead, I am looking to make some improvements in performance. I have been into the Firebird/Trans Am scene for many moons and have had my share of earth shakin 400 and 455 machines. Gotta love that V8 sound. But this GTP is something relatively new to me and I have been reading up on tranny performance upgrades seeing as thats the focus with this car at the moment. Going to call Triple Edge Performance on Monday like you suggested. I have the tap shift feature, might as well get the most fun outta that, right...lol. Any engine upgrades you recommend?
 
There is a safely modding your 3800 car thread in the SC section or the general tech section, I forget. It'll give yoyu a basci run down of what mods you can do.

But what most do is the simple 3.4 (3.6) setup. Headers, Intake, spark plugs, 3.4 pulley for gen 3 blower and 3.6 for gen 5 blower and a tune.

And having a way to scan the car via a aeroforce scangauge and or a tuning program like HP tuners. A wideband is great to have for tuning if you don't buy a canned tune from a vendor.
 


ha ha weird i have a trans for sale from a 06 s/c gp with 4k miles on it... anyway if you have a comp G and you used a regular gtp trans at the very least you would need tuned/swap the diff from the old trans, and im not sure if you could just hook it up and loose the tap shift feature or if that would cause issues
 
Was going through the glove box and found the original window sticker. In the list of options and to my surprise I find that my car is actually a GTP Comp G. Also found in with the owners manual sleeve the Comp G trunk label. So now I have to rethink some things but am happy to have the Comp G gear ratio.
 
Well, here is the plan. A complete Triple Edge trans is just not in my budget at the moment but a Triple Edge Stage 1 or Standard complete kit is do-able. I would really like to find another trans to rebuild so when I drop the one in the car on the floor, the fresh rebuilt is ready to go in. Problem is I am not having any luck finding another 4T65E-HD Comp G trans to rebuild:th_shakinghead1:

Anyone have any leads on a trans that will work for my rebuild?
 
for a few days i thought my trans was on its way out, it seams possible to swap out the diff, valve body and maybe the main solenoid pack to a non comp g trans and it should work, doesnt seam people have a straight yes answer on this but found some threads that said i could/should work
 
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