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+--- Thread: ***C4 auto not shifting---need ideas ASAP*** (/thread-754.html)
***C4 auto not shifting---need ideas ASAP*** - chuzie - 06-12-2008
The C4 Auto in my 77 was shifting pretty hard before I placed it in storage 2 years ago. I would have to get the RPM pretty high and then let off the gas to get it into 3rd especially and then it would CLUNK once really hard when it did shift.
I have not installed any mods in the tranny but can't say what the person before me did or did not do.
I have plenty of Type F fluid and yes, I check it correctly.
I tightened both band adjustors as best I could but really couldn't get my torque wrench in there so I had to use my calibrated elbow to wag 120 inLb and then back off accordingly. They are pretty far in there though so that is a thought that maybe I am just worn out.
I have not pulled the valving yet since I wanted to see if there is a external fix first.
I check to make sure the linkage is secure and I do get all my detents on the shifter and I am not running in between a set.
I could tow it to a tranny shop but I will need some recommendations and what fun is that to have a mechanic do the work for you? I am certainly open to doing a C4 rebuild myself if it is necessary.
Ok everyone, give me some troubleshooting ideas to get this thing shifting again. It sat for 2 years and stopped shifting. Sounds weird.
-Mike
***C4 auto not shifting---need ideas ASAP*** - broncomatt - 06-12-2008
It doesnt look good. It sounds like the press had to build to get the band servo all the way. Now it is simply too far to move. It is also possible an obstruction has gotten into the return line or in the vavle body. The bands being adjusted all the way in is an indication the bands are worn out.
The only thing you can try and do your self would be drop the pan and inspect, possibly retry with new fluid.
The c4 is a simple tranny to overhaul, you'll need a clean workbench, and some paitents. It takes some time to get all the depths and clearences right. I had a bench with a hole cut in it to allow the tail shaft to sit threw, made working on trannys easyer.
A good time to upgrade to kevlar clutches, bands and a custom vavlebody.
Broncomatt
***C4 auto not shifting---need ideas ASAP*** - chuzie - 06-12-2008
That is the response I figured I would receive. If I pull the pan I am going to pull the tranny cause I am not paying to refill that thing with fluid only to have it now work; know what I mean?
That is fine though, I was looking for an excuse to learn how to overhaul a C4 anyway. Now I need to get ideas about upgrade options before I run out and spend my $$$ twice, but that will be another thread and a tech write-up.
Thanks bro.