Thread: '04 Trans Swap - What parts should I replace on donor trans before installation?

Lots of great info here. Thanks to BillBoost37, as your "How to remove a transmission" post gave me the 100% confidence to jump in and replace my first FWD transmission. After I read your post, I bought the trans and am awaiting delivery.

Backstory is that my son's 2004 Grand Prix GT1 had a recent trans failure (~99k original miles). While driving, he lost all power with the trans. Had the car towed home and after it sat for a few hours, we were able to drive it into the garage. Decided to see if a trans filter/fluid change would help things. Pulled the pan and there was a ton of grey sludge on the magnet and in the pan. Cleaned everything off, installed new pan and refilled the fluids. With all the sludge, I figure something, somewhere got plugged. After we did the filter/fluid, he was able to drive the car, but we still wanted to have it checked by a local shop. They diagnosed it as having lost 3rd gear. Quoted $2700 to remove, rebuild and reinstall. If I removed and reinstalled, only $1800 to rebuild. Needless to say, that spurred me to decide to pull the trans and find a donor.

I bought an '04 Grand Prix trans from eBay. No idea of mileage, but the case was clean and painted as well as the torque converter. No leaks. Guy from the yard could not give specifics on mileage, but recalled testing the trans in the car and indicated no issues. Only paid $215 for the trans plus shipping, so I am getting off cheap right now. Just looking for something to get through the next few years if possible.

So now to the real purpose of this post: What recommendations are there on some components I should be replacing before I install the donor transmission? I see lots of stuff about the TransGo shift kit, but thought there were also some shift solenoids or something I should also be addressing. Any recommendations?

Looking forward to any feedback you might have.

Regards,
John

Just for personal clarity, are all the 4T65-E HDs interchangeable? (ie '04+ works in 97-03)?

Hmm, maybe I asked the wrong question...

The more I research, the more confused I am about the '03 tranny...

I remember when I replaced my solenoids and broke my wire harness, I had to find a "different" style harness...For some reason mine was a 19 Pin compared to 14 or 16 pin...

Are the bell housings the same?

Are the trans mounts in the same location across the board?

If I wanted to find a "donor" to rebuild or send to TEP, I would need to find an '03, correct?

I see the difference about the diff also (HD)...

I see that the VB, CP, line fittings, and check balls are all a little different, but other than that, what makes the '03 so unique?

Sorry to thread jack!

Well, made a weekend of it and got the trans swapped out. It took me MUCH longer that I ever expected to get the swap done. I think some of that is because this was the first one I was doing and wanted to take my time to ensure everything was done right AND safely. Spent the money to buy the engine support, which gave me more confidence than rigging a 4x4 across the engine bay. Had some issues securing it. Could only find 3 lifting lugs on the engine, but that was fine. We did fully remove the sub-frame, which necessitated removing all the underside front plastic. I thought the subframe was only aluminum, but we were not 100% sure and couldn't confirm the weight. Used alot of caution when removing. Turns out it probbaly only weighed about 80 pounds, so alot of concern for nothing. The engine to trans bracket was a PITA to get out and the one bolt that is buried about 18" back was actually loose when I went to remove it. Had issues removing some front suspension on the driver side. Could not get the tie rod joint to pop out of the knuckle. Ended up unthreading it from the tie rod. The torx bolts for the lower control arm were a little bit of a struggle as well. Overall, it took about 8 hours to get the car jacked up, engine supported, suspension torn down, subframe removed and transmission removed.

Once we had it out, I replaced the Torque converter seal as well as the EPC, TCC, (2) shift solenoids and the manifold pressure switch. Also has to pull the wiring harness from the original trans and put it into the donor trans. Plug on the donor trans was damaged. Replaced the side cover gasket and the inner seal. Probably abou

Took another 12 hours or so to get the trans back in, subframe installed, axles installed, suspension reconnected, fluid/filter change, remove jack & engine support. To my delight, there were no extra nuts or bolts left over. Road test went well so we are considering the transplant was a success! We did notice a rotational noise coming from the front driver side that changed with the speed of the car. Car is not pulling when driving or braking. I suspect it might be related to the drivers side hub.

The only issue is an ABS & Traction light that came on after my son drove it to work on Monday. It came on right before he parked the car. After turning the car off, the warning lights go off and do not return until he has driven the car a bit. I suspect this might be a worn front bearing. Will need to investigate later this week when time allows.

Just broke it down bye talk type and scrapped it. We broke the side cover after removing it because a bolt was stuck. Had to get the side cover off in order to grab the wiring harness.