Hi Guys,

I just had my 289 rebuilt (balanced and RV cam), dropped it into my '65 coupe, added a pair of tri-y headers and dual exhaust. Engine now runs great, more power, etc. All good so far...

While I was "running in" the engine the C4 transmission started giving me some grief. For the first 50 miles it worked fine, changed when it was supposed to and then one night when I was driving home from work, it struggled to shift out of first into second and then remained in second from there on. It won't shift to 3rd gear.

First I thought it must be the fluid level, which I checked again. It was a little low, but I topped it up and the fluid level is fine. Still the same problem exists - it won't shift up to 3rd.

What's got me stumped is that it drove 50 miles with no problem, it's not leaking any fluid, but it won't change up. The weird thing is that I had the trans rebuilt about 1000 miles ago before the engine went in so I don't imagine anything is broken internally.

I checked the kickdown linkage to see if it was jammed but it appears fine too.

Any suggestions as to what might be causing this?

Thanks!

- Jason

 

who rebuilt the trans, talk to them
sometimes a rebuild may consist of a patch, not a full rebuild, and it has worn down somewhere else or it was "patched" wrong

 

Check the line to the vacuum modulator. See if it's off or has a vacuum leak.
Also is it a green dot trans. The linkage might be out of adjustment.

I dont think it would be the governor as it does shift 1-2.
Maybe a sticking valve body...

 

Thanks for your replies so far...

The guy who rebuilt it moved out of state and I don't have his contact info, so that's not an option.

I'm pretty sure there's no vacuum leak. I tightened up the line to the back of the carb and rechecked it again tonight - seems ok. I guess it might have a leak at the other end, so I'll look into that.

Thanks,

Jason

 

And yes (sorry) it is a green dot trans. I'll check the linkage adjustment.

If i start in the regular D position it'll shift from 1st to 2nd by itself.

If I start in the green dot position it'll start in 1st and only shift to 2nd if I push the shifter to D.

 

Ok... problem solved. Thanks for your assistance.

I checked the vacuum line at the tranny and found that where the solid line goes into the small rubber hose before it goes into the vacuum modulator, was broken - hence no vacuum, which is required for the C4 to shift into 3rd.

Thanks again,

Jason

 

Thats what makes this forum great!!!

 

Green dot should start in 2nd and shift to third only... regular drive should go 1st,2,3..