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Calling All The 4T65E Experts Please!!!!


New member
Buick Ownership
2004 Buick Regal LS
Hey Guys and Girls, need some help and info on the 4T65E and 4T65E HD

Just recently my car (04 Regal LS) has developed an trans issue. When taking off from a set of lights or a dead stop it feels like the car was on ice and then a bit of a bang and off she goes, although this doesn't happen if I'm taking off very very lightly (barley any gas). My first guess is a bad (or going bad) torque converter. Currently no check engine light on for this issue.

I have a few questions to the ladies and gents that have either rebuilt a 4T65E or have swapped the gearing in one.

1. I have access to be able to pull a HD out of an 04 GS at a fairly local yard and rebuild it. Is this a better option to start with? Just thinking the car will be down for less time
2. Are there any wiring or other differences (or parts needed to swap over) to go from the 4t65e to the HD?
3. what are the better options for rebuild kits or parts needed for rebuild (looking for good quality parts, NO junk please)? links would be AWESOME!!!
4a. what controls the final drive ratios? is it the ring and pinion or the tooth count on the gears and chain
4b. Has anyone swapped in a longer gear? ex. going from a 3.05 to a 2.86
4c. If the gearing is swapped to a longer gear, will the pcm need to be reprogrammed? pretty sure this is a yes
5. What specialty tools are needed to rebuild the trans?
6. what upgrades would be best for longevity? Transgo shift kit will be 1 for sure
7. what are the "weak links" in the 4t65e/hd, are there any ways to corret them?

I apologize for all the questions, found some answers in searching. But I'd like to know more in depth from guys that have experience in this section. I'm good with general mechanics, just never rebuilt a transmission before. Before I'm asked, yes I do have the correct manuals for an 04 Bucik regal/century.
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