C4 shifting soft and too quick

[jmhend]

All,

I'm running into a few small issues with my daily driver. I am having a choke issue (I will post a separate thread on that) and a shifting issue. So were talking about a C4 that seems to shift early and soft. I'm not overly concerned with the soft shift but the early shifting is concerning.

The bronco is shifting from 1st to second, to third (high) all before 10 miles per hour.

A few things to note once its in high it runs fine (no issues at all). There is not a kickdown rod installed. Vacuum and fluid (it could use maybe less then 1/2 quart) seem to be good but I can run a vacuum test if that is where the conversation goes.

Thoughts?

 

[chuddy]

I had the same issue with my 75 Denver. The C4 would shift WAY too early like yours. To make a short story long, it was low on fluid because it was draining back into the transfer case. We replaced the seal in the t-case adapter, filled the c4 to the proper level, and now it seems to be shifting properly. Maybe it's a low fluid thing like mine was?

 

[hyghlndr]

The modulator can be adjusted, youtube it, pretty simple? Also check line, recently found a hole in the tube of one which was causing problems, also seen the rubber end portion crimped a few times.

 

[blubuckaroo]

X2. Just adjust the modulator to shift a bit later, and it will be firmer.

 

[Broncobowsher]

Not all modulators are adjustable. Most are.
If you pull the vacuum hose off and fluid runs out, the modulator is shot and needs replacement. And the soft vacuum lines

 

[jmhend]

Thanks guys,

Chubby, I was thinking low fluid level as well. I did check it cold (I had to run out of town) and it does appear to be about 1/2 a quart low. I will check it warm next week when I get back.

Others, yes I am aware of the possibility to adjust the modulator however Im not overly looking to increase the "firmness" of the shift but more the shift points. I will throw a vacuum gauge on it when I get back to ensure there are no leaks. I can't hear so that doesn't help.

 

[tasker]

CHECK for vacuum leak...also good call on the fluid coming out of the modulator

 

[jmhend]

CHECK for vacuum leak...also good call on the fluid coming out of the modulator

will do. Give me a few days. its a little warm down here. I need to spend a little time by the pool cooling off.

 

[Broncobowsher]

Are you running a single hose modulator or a 2-hose?

 

[jmhend]

Are you running a single hose modulator or a 2-hose?

Single hose, it is soft (rubber) line from the carb to a prebent metal, to another soft line at the modulator.

https://www.cjponyparts.com/transmission-modular-lines-bronco/p/TCL7302B/

Rubber hose on each end of that stainless line in the link