C4 Shifting Wrong

[bluebronco72]

Good Morning, my transmission is not wanting to shift right. It is wanting to shift 1 - 2 around 22 mph and 2-3 around 50-55. I had a pink stripe vacuum modulator in it tried adjusting it and the shifts stayed the same. So I read the green stripe was the better option so I purchased a green stripe and still no change. I haven't tried adjusting yet but will start. I just didn't know if there is something else that I might be missing that I can try to get the shifts more around the correct shift speeds. Thanks in advance.

 

[jerrybromley]

Just a quick thought but...........Is it possible that you not getting proper vacuum to the modulator..ie...bent or plugged vacuum line ?

 

[bluebronco72]

Brand new lines but I could check vacuum with a gauge. I had the line on the back of the carburetor but moved it to the intake manifold.

 

[jerrybromley]

What's the history of this tranny ? Rebuilt , shift kit , valve body or just started acting up ?

 

[bluebronco72]

I bought the transmission used in a package deal with an engine and tcase. I bought it to do a auto conversion. I replaced the filter and fluids it looked like it had been rebuilt at some time. fluid was pretty clean and not sediment in the pan so I decided to not get it rebuilt.

 

[jerrybromley]

I'm no" tranny guru" but it would seem to me that the used transmission is a complete unknown.... so it might be worth it to have a rebuild kit put in it ,and have the technician that does it make sure the valve body has not been changed to make it shift harder
GOOD LUCK

 

[needsmoarturbo]

Here's my 2 cents... Is your kickdown linkage or cable working right? I think from how I interpret your description it sounds like it's shifting way later than it should? I would at least check the kickdown and make sure is not stuck in full throttle position, I think this would cause you issues.

 

[Slowleak]

I would pull the modulator and check the length of the pin. It should be 1.62 inches. If the pin is the wrong length it can really throw the modulator adjustment, and shifting, way off.....

 

[WheelHorse]

Make sure you kick down lever is returning to it's resting position. I've seen "rebuilds" not address the kickdown and the lever would not fully return causing later than normal shifts.

 

[Rustytruck]

kick down lever has an internal spring and another light weight extension spring from the kick down lever to the carb base to help pull the kick down rod back towards the radiator when your not forcing a down shift.

 

[sanndmann3]

have you checked the modulator itself?

 

[jmhend]

Good Morning, my transmission is not wanting to shift right. It is wanting to shift 1 - 2 around 22 mph and 2-3 around 50-55. I had a pink stripe vacuum modulator in it tried adjusting it and the shifts stayed the same. So I read the green stripe was the better option so I purchased a green stripe and still no change. I haven't tried adjusting yet but will start. I just didn't know if there is something else that I might be missing that I can try to get the shifts more around the correct shift speeds. Thanks in advance.

Have you tried to shift the transmission manually? How is your fluid? Are you checking it cold or warm?