[dataway]

Thought there was a "drive train" section, evidently not.

So, couple of questions after my first test drives.

Is an original OEM modulator adjustable for shift point? Mine seems to be shifting a few hundred rpm early. Like almost immediately after you leave from a stop it shifts to 2nd. I have to slow down to a dead stop to get it to start back off in 1st.

Manually it works great, shifts firm but not harsh. I rebuilt the whole trans using a Trans-go kit, nothing outlandish, basically stock. Converter is the Hughs 30SP(?) "Tow" model. 068 cam, Q-jet, engine has outstanding vacuum.

I'd like to use the OEM modulator if it's adjustable. I'll be honest, I don't even know if it's working properly ... sat in a box for 40 years, was a bit sticky till I freed it up.

And .... while checking out the diff I noticed if I rotate the driveshaft one direction the trans makes a quiet whistling sound, like drawing a squeegee across glass, you'd never hear it except in a very quiet shop. Sounds internal to the trans, up front somewhere ... don't think it's the speedo cable or tailshaft seal. Doesn't do it if I turn the driveshaft in the other direction.

Hate to bother folks with this kind of stuff, but it's been 40 years since I drove the car so I long ago forgot how it should behave and sound ... heck 40 years ago I would have jumped in and smoked the tires no matter what sound it was making

[stevep]

Check your governor 1st

[steve25]

I thought the Governor only controls the rpm of where the shifts take place at full throttle and no vacuum?

[FrankieT/A]

Originally Posted by steve25

I thought the Governor only controls the rpm of where the shifts take place at full throttle and no vacuum?

This ^^^

[Half-Inch Stud]

Governor control the early roll shifts (only a little with a selection of Stock
Govs #s 11-33); use stock outer weights with holes in them for a wee later shift from a roll. Inner weights; use stock lighter weights and flimsy springs for higher rpm WOT upshift.

Stock big can Mods might have the adj-screw brazed so it cannot be turned. Try and see if turning screw in can occur, and how the shifts are delayed. If screw locked then get the small single-red strip Modulator and adjust away. Keep the big can modulator on the shelf,as they might have value to some folks.

[Schurkey]

The bigass modulators "can" be adjusted, IF (big IF) you're successful in breaking the spot-weld that secures the screw. I don't remember seeing the screw brazed, but who know how many variations GM had.

Unlike the cheap aftermarket mini-modulators, the bigass ones compensate for altitude.

Trans squeal when turning driveshaft is totally normal. You're hearing the one-way clutch turn opposite to it's lock-up direction. Maybe some band-drag.

[dataway]

Thank you gentlemen, you've both put my mind at ease and provided me with useful information.