Thread: 1-2 sliping/sloppy shift...

hey been reading around and thought i would post up and see what you guys thought... about 3-4k miles ago i changed the trans fluid and filter and refilled with with valvoline dex 6 full synthetic. at the time think i had about 55,000miles on the clicker... Every thing has ran fine with the exception on when i raced at the track like a few weeks later it would act funny shifting early and sloppy into second with the traction control off... with the tcs on it ran fine... well recently within the last week i noticed that wot in first was solid till it shifted it would "slip into" second. same feeling as if you were to "feather a clutch" every other gear works fine... and it only seems to be at wot. i baby her now to prevent any further damage and ordered a shift kit hopein to get a more aggressive shift but i am now lookin around and it might be this "boost valve" and was wondering how common is it to be bad.. and can it be replaced with the trans in car and what materials/tools would be involved... with my quick poking around haven't had too many hits on the search but going to continue looking... any input would greatly help thanks guys!

Mines doing the same thing.

You easily have a 300+whp list worth of parts on a stock trans, its not going to shift firm and is going to get worse the more WOT runs you make. A shift kit might get you along for a while but you are going to need a built trans to live with your setup. Even if a shift kit helps- cross your fingers your input shaft doesnt let go. I wouldnt worry about a boost valve problem at your mileage. If you car was 100% stock then you could worry about normal repairs, but with much higher power levels than stock there is a lot more to the picture. Also what maf are you using? Is it stock or aftermarket? Low maf input has a direct relation to trans line pressure. If you have made your intake pipe larger recently this can cause the airflow to slow down around the maf sensor element and cause low line pressure. Do you have a way to scan the car and monitor transmission data? It would be good to know the commanded pcs amps during a run to see what the pcm is commanding for pressure.

also if you have a 97-03 tranny... DO NOT use dex 6. it is thinner than dex 3 and makes the tranny slip.