1-2 wot slipping shift

**solow172** · 05-18-2008

Hi gents, 98 gtp xp, ssic, ported heads, 2.9 etc. Tranny has a zzp shift kit in it. My car has never really had a very hard 1-2 shift, even when I took out all tm and jacked up the line pressure's and lowered the commanded shift speed. I put a shift kit in it but that really didn't do to much except made a stronger part throttle shift. I'v done the fluid and filter twice in the last year. It didn't smell burnt and there was no material laying in the pan. Now the problem is on a wot 1-2 shift the tranny will start it's shift at 6100 but will not finish till ~6500. Sometimes like last night it seems like it starts the shift but just slips alot making me back off the throttle to shift. 2-3 is good. Thanks for your replies.(trannyman

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**Trannyman95** · 05-18-2008

A lot of things can cause a weak 1-2 shift, but if it was never that great and is gradually getting worse than your problems are likely internal and pcm settings and playing with the accumulator parts ie shift kit is only going to marginally help out and overcome the problem. One of the biggest changes that I have found for making shifts firmer, note that this effects all shifts, are the PCS amperage vs pressure tables. I only work with those tables as a last resort when you just cant get the firmness you need but it honestly sounds like you have more problems than what tuning will overcome since your shaft is taking that long to complete after making various other changes. A stock trans is still just a stock trans until you go inside it to make changes, and I dont just mean in the accumulator body as the shift kits do.