Transmission swap

Hey guys, I found a 98 SC Riv in a junkyard close to me with a good transmission. Although my transmission is perfectly fine, I was contemplating the idea of a swap. However, I wanted to know if you think it would be worth it. I'll probably grab the spindles from the car too, so I can upgrade to better brakes. As for the tranny, what would the swap require? Could I just grab the PCM from the car too? How would that work though with a different VIN? I doubt my 96 PCM would work with the electronic 4T65-HD.

You would need the PCM from the 98 and the transmission wiring harness (assuming I am understanding correctly from what I've read). It should just be plug and play, but this is still sort of a grey area. Personally I would grab it and build it up, so then you can throw in a crazy awesome tranny when yours goes.

Yeah I searched through many threads but I could never get a definite answer. Has it ever been done before?

Once or twice that I know of. I would also assume that you would have to do some vacuum tube re-routing due to the fact that the 4T65E-HD is electronically controlled vs the 4T60E's vacuum control.

Im almost positive that the 4T60E does not rely on vacuum for anything except shift pressure. If you unplug the vacuum line from the modulator, the car will drive just fine. You'll just have higher line pressure and firmer shifts in daily driving. I dont think it would present a problem if you were to swap. The 4T60-E is an electronically controlled transmission, same as the 4T65-E. I prefer the way the 4T60-E shifts over the 4T65-E. Things like shift points and rev limiters can be changed with a tune in the 4T60-E, just the same.

th3fr4nchi5e wrote:

Im almost positive that the 4T60E does not rely on vacuum for anything except shift pressure. If you unplug the vacuum line from the modulator, the car will drive just fine. You'll just have higher line pressure and firmer shifts in daily driving. I dont think it would present a problem if you were to swap. The 4T60-E is an electronically controlled transmission, same as the 4T65-E. I prefer the way the 4T60-E shifts over the 4T65-E. Things like shift points and rev limiters can be changed with a tune in the 4T60-E, just the same.

Unless the 4T60E is different from earlier modulator transmissions, removing the vacuum line will produce a no shift condition. If you remove the vacuum line on a THM350/400, it will not upshift.

The 4T60 relied on vacuum for shift points as well, but the 4T60E only for shift pressures. I've had mine unhooked when I was testing the modulator and it shifted fine with the vacuum line just hanging there.