79 F250, C-6 downshifts wierd

[surewhynot]

A buddy of mine has a 79 f250. 351/c-6. It up shifts nice, but when he lets off the gas at 35mph or less, it down shifts to 2nd. Hit the gas again and it goes right back into 3rd.

I'm stumped. The tranny was rebuilt about 1000 miles ago, but that doesn't mean much. I was thinking a piece of trash in the governor, but I'm not a tranny guy. Could the vac. mod cause this? Any other suggestions? Thanks in advance.

 

[blacksnapon]

I cant remember if the modulater valve has the adjustment screw in the center or not. Pull the vacuum line off and see. If it does, start adjusting.

 

[surewhynot]

Ahh crap. I should have thought about that! Help me remember. Tightening raises the shift points slightly?

 

[blacksnapon]

Ahh crap. I should have thought about that! Help me remember. Tightening raises the shift points slightly?

I think so, remember, I dont see many 70's vehicles anymore!

 

[surewhynot]

Or remember the 70's, but thats a whole different thread. Thanks for the help Vince. When I see him tomorrow, I'll give it a shot.

 

[blacksnapon]

Or remember the 70's, but thats a whole different thread. Thanks for the help Vince. When I see him tomorrow, I'll give it a shot.

There's that speechless thing again!

 

[d-kuzmen]

Had a bronco that shifted the same way. Adjust the mod valve...