Thread: tranny swap

You'd need to swap the torque converters and get the passenger side axle from an HD. Cooler line fittings may be different. You will also have to get your PCM reprogrammed for the different final drive ratio.

Not to mention that you might want to try to keep the 3.29's from your GT tranny...

I can't fathom 2.93's on a N/A car...yikes.

Well, for the gearing if you want to keep your 3.29 gears (which would keep you from needing PCM reprogramming) you'll need to disassemble parts of the trans to get to the chains and sprockets. They would need to be swapped from your current trans to the HD. Otherwise you could get new ones.

Originally Posted by crazyGPlover

also, if you can upgrade the steels and clutches to the GTP size so you can use the GTP sprag gear. much stronger and is a performance part already.

Nope, there's no difference at all with the clutches or the sprag. The only difference between the HD and non-HD transmissions is the diff/cover/output shaft, and they put different gearing on the input side. Not only that, I believe the pinion shaft and spider gears that cause most diff failures are the same between the two (someone please correct me if I'm wrong on that), so the differences between the HD and non-HD are negligible. The roll pin most often breaks because one of the spider gears catches on the pinion shaft and rotates it, breaking the pin, and that should only happen if one wheel is moving significantly faster than the other. One wheel peels = death for either trans.

The sprag changed in 03 on all of the transmissions, it has nothing to do with HD vs non-HD. Dave has also said many times that there's no advantage to the diode type vs the pawl type sprag, and it only affected the input clutches.

You could be right on the size of the spider gears, but I still don't see how it would change the problem. The lack of lubrication for them makes them seize to the pinion shaft and rotate it, sheering the roll pin.

Originally Posted by crazyGPlover

well i did use an 04 gtp trans to put into my 02 gt. the sprag is different, and the clutches are too, the teeth are larger in the gtp compaired to the gt. and the spider gears are much larger in the gtp differential also. trust me i had just done the swap a week ago, and i compaired the 2 diferentials, along with other parts to see what i could use and what i couldnt.

I have those parts, and my transmission isn't an HD. It's just changes that came out in 03. They don't really help with anything anyway, as the transmission still fails in the same ways it always did.

The stronger diff only helps when doing burnouts or hard launches. Other than that my non-HD diff has been taking the punishment of the blower just fine. HD transmissions are not anything special. In fact, I'd rather have a non-HD with the HD diff so you get 3.29 gears.