Thread: 99 GTP Trans slippage after fluid change, what's next?

I have a 99 GTP with 240K on the clock. Tranny was rebuilt 80K ago and was shifting fine. Last week I replaced the rack and pinion and while I had the car on jacks, I changed the tranny fluid. Used about 5 quarts DEXTRON III, and 2 quarts DEXTRON, and changed out the filter with a Hastings filter I had bought awhile back. Now the car has a developed a slipping problem when accelerating to highway speeds and also on uphill climbs around 35 mph. The slippage seems to be torque converter lock up issues to me.

What should I do next? I've read that these things can work themselves out as the tranny adjusts to the new fluid. I also was thinking of doing another change and going with an A/C Delco filter instead. And as a last resort was gonna try Lubegard or some sort of additive. Any advice would be appreciated.

-Thanks!

Have you verified that the fluid is full? Fully hot trans, in park, running and on level ground.

Is it the rpms bouncing up and down when you try to accelerate w/o downshifting?

Beyond that if you're going in again I'd add a trans-go shift improvement kit to it. It won't make it bang the gears just quickens the shifts to minimize clutch wear. I have one in my GT with around 280K on it and it shifts just fine.

Yes she's full. The RPM's do bounce up and down. If move the shifter from D to 3 it stops bouncing.

The tranny was rebuilt in 2013. Ive put around 75K on it. It is the first time I've changed the fluid since the rebuild.

Originally Posted by Scottydoggs

sadly at most shops a rebuild is not a full rebuild. they take it apart and replace what was broken and re use all your old crap. like say first gear was slipping, they will replace the 1 st gear clutch packs and nothing more.

Back in 2013 I lost the 3rd/4th band I believe its called. The shop hit me for $650 in parts and $900 in labor. Its been perfect since then.