GTP Trans problems?

[LT1GMC]

Is it common for a GTP to go thru 2 transmissions in 80k miles? I just bought one that had third gear clutches burned, the dealer is fixing it before I get it, but when they took it apart, there was a tag saying GM rebuilt. Any ideas on weak points or whatnot that I should look at now? Thanks

 

[Trois Buicks]

Where to start--- weak input shafts (or, in sc3800-speak, "turbine shafts"), not enough clutches in the direct clutch pack, cheap clutches, low torque rating, "wham bam/thank you ma'am" rebuilds...

Morgan
'87 GN (11.19 @ 120)
'99 GS (14.20s @ 98.1, the usual mods)
'67 GS Californa

 

[GTP-1]

I had a '97 GTP that burned 2 NEW GM units before i turned it back in for trade in on a '99. The car had about 28,000 miles on it when i gave it back for good. All depends on how you drive. I drive aggressive but not damaging. No rolling drops into gear, no stupid stuff. They say heat kills tranny's....and it is SSSSSOOOO true. My first tranny actually broke the input shaft into 3 pieces and crushed the needle bearings when doing so. The dealer let me be there when they opened it up. I now have a '99 with a tranny cooler. This won't help the weak parts but will eliminate the clutch pack issues. I would by the biggest cooler you cna stick in front of the grille. I have a 26,000 or 28,000 GVW unit and have flawless perfomance out of this car (50,000 miles so far) and this car has the extras the other didn't, like the pulley, KN, etc.)

 

[LT1GMC]

Hey, you didn't happen to buy that GTP used from a guy in Kokomo did you ? I sold my 97 to a guy from Ft Wayne! Thanks for the info, I will put a big cooler on it, kind made me nervous that this was the second time, as I have had real good luck with GM trans in the past.

 

[KendallF]

My 97 GS trashed a cheesy plastic washer behind the output shaft and chewed up the needle bearings, shaft, and the side cover of the trans at 55,000 miles. After an expensive rebuild that included a bunch of new parts from GM that aren't available from the aftermarket yet (example: new side cover at ~$300 vs. a $5 bushing to repair it that's available for the 4T60Es) it's doing fine at 77k currently.

 

[Scott 97.5 GS]

Sort of off topic, but...I'm beta-testing a LSD unit that should be available mid-December. It should be fun.

I've been lucky that my original tranny is still holding up considering my Hoosier DOT Slicks, 13.0x ET runs with mid-1.8 sec 60' times.

Input shafts breaking in pre-99 4T65e models is supposed to be rare. The input shaft (turbine shaft) design changed for the worse around that time.

Scott
97.5 GS

 

[GTP-1]

They changed the shaft to a weaker design in '99?? OUCH. didn't know that. I thought they were a little beefier than the older units. I knew '97's had problems more so thatn the others in the GT I think. OTher than input shaft, what else do you know??

Oh...and per the question. I bought both my '97 and '99 GTP's new from the dealer in Marion. I just moved to Fort Wanye from there a few months ago.

 

[Scott 97.5 GS]

I am not sure what else breaks in the differential, but the next weakest link seems to be the turbine/input shaft. I am not an expert on this topic, but I have looked into the options for a stronger tranny. It looks like stronger parts have been found for most of the failing components except for the turbine shafts.

I am sure Scott Cook or Mike Dye can shed much more light on this topic if you wish to look them up on the clubgp.com site.

Scott
97.5 GS