Okay ive got a c6 in my fox behind a turbod 302. its a stock c6 with a b&m converter. the problem: wont shift under full throttle, flares between shifts, and sometimes has a problem going into gear.

i know the trans uses a modulator valve which is operateed from vacume, could this be the prob. how does it work when the car is under boost? i check the linkage and it seems to be good. fluid level is good. i just dont know much about transmissions to diagnose the problem. please help!!

The boost is upsetting the modulator.Read the link,there is a valve made by transgo that is for boost when using a modulator. The boost on the modualtor is causing the no shift and possibly upsetting the modulator enough to affect pressures to cause a flare. Other alternative is to go to manual VB that runs a constant line pressure and does away with the modulator.

http://www.turbobuick.com/forums/transmission-talk/255286-th400-build-pictures-5.html

Any idea where i could find one for a c6 or any ford tranny? all i could find is one's for GM.

Or do you think a the valve will work on a ford mod? how many would you suggest?

My understanding is only one required and same valve will work for any vacuum modulator ,worth a try

ok thanks. i was thinkin... couldnt i just run a tee in the vacuum line running to the trans and run a check valve on the tee?

how much vacuum is needed for the modulator valve to operate?

The vacuum modulator will operate from 0 to whatever vacuum the engine can produce.

Low vacuum = late shifts.
High vacuum = early shifts.


There is no magic number.
Simple as that.