Shifting points

[john Harlow]

Rebuilt th350 with shift kit out of c10 pickup. First installed shifted hard at high shift points, then i got the bright idea of changing modulator to get it to shift even higher points raised car up in rear remove modulator lost about a quart of fluid. Changed moduator adjusted a turn. and it shifted softer and a lot sooner. no matter what i do still shifts quick and soft. Even put old moduator back in in trans still shifts soft and very soon. What did I do?

 

[camaro71/holland]

Have you added new ATF to make up for the loss? Good point to start with...

 

[berg2695]

Maybe the valve that the modulator operates was stuck. Changing modulators may have 'unstuck' it.

 

[john Harlow]

fluid was added

 

[CorkyE]

What stall/rpm is the torque converter? Does it shift soft and quick if you accelerate rapidly?

 

[john Harlow]

Stock converter, yes shifts soft and quick on rapid acceleration also. Shifted hard and later before I started messing with it.

 

[CorkyE]

Check for leak in vacuum line to modulator, modulator connected to transmission correctly? Has to be something simple if you changed the modulator and instantly start having issues.

 

[john Harlow]

Modulator connected correctly, most of vaccum line is metal brake line, I'll check the short rubber lines. Also have to almost come to a stop before it will downshift.

 

[camaro71/holland]

Defective modulator (leaks)usually has the opposite effect: late and harsh shifts.

I would start with some easy checks before moving on to internals like the VB: unplug the VM and see what happens. If it returns to shifts you accidentally closed an existing leak when changing the modulators.

Then I would pull the GOV and check the operation of the primary and secondary weights and the valve itself.

Shifting points while in D are the effect of GOV (oil) pressure operating against the VM pressure.

 

[john Harlow]

Since my th350 is a long tailshaft out of a truck would a th350 govenor out of a car have higher shift points?