View Full Version : Tranny late shifting...94 auto

06-14-2012, 12:14 AM
Hey guys, im getting my car back on the road (hopefully picking up my license tomorrow) and before i stopped driving it there was a problem with the shifting. First ill start with the usual info!!

1994 auto tbird sc
79,600 miles
Deleted cats, magnaflo res(that blew the seam and needs replacing) and two flowmaster mufflers out the back
Cold air intake
Intercooler Fan
3-5% O/D on supercharger snout

I had the tranny flushed at around 60-65K (perks of working at a shop) I did this as preventative maint. The fluid was still red at this time. Then about 1,000 miles later i dropped the pan and replaed the filter cleaned the magnet and the pan real good and put everything back together. Now heres the problem....The car drives beautifully under normal driving, shifts smooth and flawlessly, never hard or showing any signs of distress. However when i WOT the rpms climb then when its time to shift the tranny lags and something (im assuming the tranny) makes a grinding sound until the tranny shifts and its back to normal again!! I dont remember exactly but im pretty sure this started happening after the overdrive on the s/c. My theory is that with the free flowing exhaust and the od that the engine is revving up faster than the tranny can build pressure in the valve body. So what do you guys think? Am i right, wrong, or crazy lol.

I remember seeing about a jmod i believe its called where you drill holes in the valve body plate? Is this what i need to do? Also i remember about a spring and piston or something that usually goes bad and needs replacing? I can probably find out that but just havent searched yet. I can get any tranny related parts from my boss and do the work myself but p/n's would be awesome. I appreciate the help as always and looking forward to letting the bird fly once again!!

06-14-2012, 01:19 AM
JMod and refill with Mercon V is the usual suggestion.

JMod information is over at TCCoA.COM in the articles.