58 belair help

having problems with it shifting hard...

i replaced transmission vacumm modulator and been trying to lower to idle and it seems to be working better but thats where im at now trying to get rid of that hard shift...


any other ideas on what i can look at?

oh 1958 belair w/ powerglide tranny

Still have the mechanical kick-down linkage hooked up? Try adjusting that, could be hanging up. Also change the fluid. Check and make sure you are getting full manifold vacuum to modulator.

ok ill try that,,,ive been adjusting the carb linkage to pull the idle down...someone said the modulator may be adjustable,,do u know?

ive added atf to it but never changed it,,,do u think that would help?

it was wierd cause the first time in gear was real smooth , i drove it down the street and it died from no gas ,,,cranked it up again and then started shifting hard, noticed a lot of white smoke so figured it was burning atf and it was all in the vacum line, replaced modulator and now this were im at


any help would be appreciated

The vacuum line maybe plugged still somehow. Check to make sure the line is clear with air or brake cleaner. Not sure if modulator can be adjusted, havent messed with an iron powerglide in a while, maybe.

Take a very small screwdriver, put it in the hole where the line goes and see if you feel a screw. You may be able to look in and see. If there is a screw, it is adjustable, back it off a little and try it.