Thread: trans swap

Regulat (gtp) trannys don't work in the GTPs (HD trans) if I remember right

If you swap them it would be wise to also swap the differential. The L36 diff won't hold up to the L67's power.
Your gearing will be different so this should be programmed into the PCM.

Edited: Also check to make sure the 97 has the 4T65E-HD transmission. It may be the 4T65E same as the 98 SE.

Hopefully dave from t e p steps in here.

IIRC, Your 1997 gtp is a vacuum controlled transmission.

Also, the 98 se may have a 3.1L

Sent from my DROID RAZR using Tapatalk 2

I know the 97 NA had the 4T60E but what about the 97 GTP?

Originally Posted by copgtp

Hopefully dave from t e p steps in here.

IIRC, Your 1997 gtp is a vacuum controlled transmission.

Also, the 98 se may have a 3.1L

Sent from my DROID RAZR using Tapatalk 2

no, gtps did not use that.

Want to save the SE? I'll personally PP you $20 if it's a headgasket. Meanwhile..please read this thread
http://www.grandprixforums.net/97-03...ure-60667.html

99% of Na issues that are diagnosed as a head gasket etc, are a bad upper and/or LIM gaskets.

Originally Posted by gmpowered

no, gtps did not use that.

So the 97 GTP used the 4T65E-HD or the 4T65E?
Bill? Anyone?

4T65E HD in 97

96 Bonneville SSEi, Park Ave Ultra and SC'd Riviera had the 4t60E

In 4T60's you can't just swap diffs between different years etc. GM was hunting around etc and changed the pitch etc on the pinion often. If you put the wrong pitch diff into a trans..it'll blow the planetaries off in record time.

Originally Posted by BillBoost37

In 4T60's you can't just swap diffs between different years etc. GM was hunting around etc and changed the pitch etc on the pinion often. If you put the wrong pitch diff into a trans..it'll blow the planetaries off in record time.

I thought all 4T65E's were diff swappable. If not then I'm confused.

Originally Posted by STW

1) the se has the 3800
2) the gtp has the hud and sport shift so what ever trans that is.
3) its definitely a blown head gasket, coolant is coming out the exhaust, looks like im driving the batmobile with the smoke screen on.

Did you read the link Bill posted?...and rule out the UIM? The symptoms are exactly the same. If it were a head gasket (almost unheard of on the 3800) it probably would have hydrolocked by now.

Originally Posted by matt5112

And it'll hydrolock from a UIM/LIM as well.

Severe cases, yup.

sir i ran my car hot 20 times in a night. from a cracked radiator... it took me 3. hours for a 30 minute ride... no exaggeration ... no coolent.. baked the lower intake manifold... i sworn the hg was blown... did a compression test and all were good... changed the lim. gaskets. good to go.. soo dont be so sold on a hg after it ran hot...