My Transmission questions???

**JDCMoney** · 10-24-2009

O.k. I have done alot of reading and I have some questions....

Last week I asked about my transmission at highway speeds...

I got a 98 GTP, now my tranny shifts smooth and quiet and I dont think there is any problems but I noticed at highway speeds if I let up on the gas the tach will drop to 900rpms or so and then when I step on the gas again it is almost like the tranny is slipping until it gets up to the RPMs the car was doing before I let up...

You guys said the Overdrive isnt working, that the 4th gear is possibly sheared and it makes perfect sense... now my questions...

The transmission works perfectly otherwise, is it possible there is a solenoid or a relay for the overdrive? only cuz its hard to believe that gear is blown out and its not making any wearing noises or grinding or such.

If it def needs replacing what tranny should I go with... a 2003 GTP tranny cuz I read GM upgraded that 4th gear.. or go with a non-hd tranny for the higher gears? Is the non-HD justbolt up or do you have to modify anything first?

What would be my best bet here?

**Trannyman95** · 10-25-2009

It definately sounds like your 4th clutch shaft is stripped. This is pretty common on 97-02 model years. It will often make no noise nor will it set a code and will exhibit the exact conditions you have. A bad shift solenoid is not the cause and this is verified by the fact that your other ranges work ok. There are only 2 shift solenoids in these transmissions and they work in different ON/OFF combinations to cause the transmission to be in specific ranges and because of these there is no combination of no 4th gear and everything else working properly. Replacing your trans with a used one leaves you a few options but if you want to use an 03 trans then you MUST use an 03 pcm with your car as the transmissions are electrically different and is not a direct drop in because of this. Physically it will work just fine, but electrically there are changes. If you use a GT trans to have the 3.29 gearing keep in mind you will have to have the pcm reprogrammed to compensate for this and you will also want to swap the HD diff, output shaft, and tail housing from your existing trans over to the new trans.

**JDCMoney** · 10-26-2009

Originally Posted by Trannyman95

If you use a GT trans to have the 3.29 gearing keep in mind you will have to have the pcm reprogrammed to compensate for this and you will also want to swap the HD diff, output shaft, and tail housing from your existing trans over to the new trans.

Now I should be able to take the HD dif, output shaft, and the tail housing from my current tranny or with the 4th gear sheared not a good idea?

**Trannyman95** · 10-26-2009

Swapping the part will be just fine as long as they are in good condition, so make sure you inspect the differential good before installing it into another trans. It would also be a good idea to clean the parts off to get the debris off of them as there will likely be a small amount of normal debris attracted to the parts.