just had my powerglide tranny rebuilt for my 67 chevelle and now it shifts at about 10 mph. carried it back and the shop is puzzled and thinks it may be related to the kickdown rod lenth. They suggest the original geometry of the rod with original gm intake and rochester (i am now using edelbrock performer and holley 600) are the problem. they are being nice, but it is obvious they don't have much experience with powerglides. it does shift smooth, but way too early for my liking!! any help is much appreciated!

just had my powerglide tranny rebuilt for my 67 chevelle and now it shifts at about 10 mph. carried it back and the shop is puzzled and thinks it may be related to the kickdown rod lenth. They suggest the original geometry of the rod with original gm intake and rochester (i am now using edelbrock performer and holley 600) are the problem. they are being nice, but it is obvious they don't have much experience with powerglides. it does shift smooth, but way too early for my liking!! any help is much appreciated!


that rod is not a kick down rod.... it is a throttle link to the tranny for shift timing.

The vacuum modulator controls only the pressure in the tranny

It's technically called the throttle valve in a Glide. The rod needs to be correctly adjusted, as the throttle valve pressure controls shift points in conjunction with line pressure/modulator pressure/governor pressure/shift valve spring rate, and when throttle pressure overcomes governor pressure it will cause a downshift. This is a bit different than a trans like the TH400 which has a dedicated solenoid for downshifts. The modulator will not usually make much of a change in shift points, but it is more of a part used to fine tune part throttle shift quality once the throttle valve is properly adjusted. However it can move the shift points a tad. The governor is very different in a Glide than any other trans, but if you know what you're doing they can be tweaked to vary shift points. To set the throttle valve rod, you need to have someone hold the carb at wide open throttle, and then loosen the locking bolt on the rod linkage. Then push the rod to fully extend it so it bottoms out the throttle valve inside the trans in the valve body. Snug the bolt down, and away you go.