FarmerFrank
Full Access Member
i mean the modulator on the trans itself, doent it controll that?
C6 valve body swap?
- Thread starter FarmerFrank
- Start date
Wyreth
Certifiable Noob
On a gasser you have to adjust the modulator, because it see's manifold vacuum, which isn't "adjustable." However on our trucks the VRV controls the vacuum the modulator sees, effectively controlling the shift points. So adjusting the VRV moves where your shift points occur, only without crawling under the truck.... in the snow..
If you're set on adjusting it at the modulator, backing it out makes for lower softer shift points, and screwing it in is higher and harder.
If you're set on adjusting it at the modulator, backing it out makes for lower softer shift points, and screwing it in is higher and harder.
FarmerFrank
Full Access Member
Im picking up what your putting down
Garbage_Mechan
Garbage Mechanic
This whole story sounds EXACTLY like what I went through with the 86. After all the checking, pressure testing, R&R of the valve body and complete tear down and inspection of the valve body it came down to forget the book, adjust the VRV until it shifts. I have the shift kit that allows manual 2-1 shifts and firms things up a bit. What I learned from all of this after verifying pressures etc, was to tap a vacuum gauge into the line going to modulator. Run it into cab in easy view. Be sure changing throttle settings changes vacuum linearly. If so the system is good, the adjustment just needs to be moved far enough. I used the vacuum gauge as a baseline to set the VRV. If it was still to low, I moved VRV to reduce vacuum 1/2 inch. Then test drove. Made the dial in much quicker. I would suggest this to anyone. I can tune the shift point now from early and soft to late and hard. And moving the VRV with the gauge to watch under the hood allows you to know how much you moved it each time.
Last edited:
