[TC]

I have the same short shifting problem as the post by JRHPAH with my TH400.
I have kinda fixed it by using a Corvette Gov., it will drive out normal in first most of the time.
Sometimes at low speed 5-10 mph it will shift into 2nd and then want to wind out alot before it shifts int 2nd.
I also have the modulator screwed in alot as I have a low vacuum motor 7" @ idle.
The tranny will also downshift into 1st. from 2nd at 40-45 mph under med. throttle?
Could this be from a worn or bad governor bore?
T.C.

 

[OLD GANG]

I don't think that is the problem. B&M makes a governor recalibration kit that might help, part #BMM-20248. Do you have a shift kit in the trans? If not, that will help also.

 

[Oldani Motorsports]

You need to tweak the governor to get shift points where you want them. As to governor bore, you can make a go/no-go tool to check the bore size.

 

[TC]

Thanks for the replies:
I actually have it shifting pretty good, if I could get rid of the downshift into 1st. at med.hard throddle problem.
Kinda scary going into 1st at 45-50 mph, goes rite onto the rev. limiter.
I just thought maybe the gov./gov. bore was causing that?
T.C.

 

[Trans1226]

If the governor bore is bad it would be very worn, scored, or cut so would the governor. The governor could also be loose at the base.
The first thing I would try is a low vacuum modulator.

 

[TC]

Thanks for the reply, If ya mean the modulator with the large can, it looked like it was off something from the 1950's ?
I all ready did, Didn't make any difference?
IF that was the wrong part, please let me know and if ya have a part number that would be great.
T.C.