c4 tranny

Not a trans expert, But sounds like the modulator was getting enough vacuum to go directly to 3rd gear, Might have something to do with it?

when the vacuum hose is off of the modulator a c-4 won't shift until the governor overrides it at high rpms, but a manual shift valve body should be eliminating those aspects of the shifting. i would guess that a gasket or hole drilled in the wrong spot or improper placement of a check ball or an incorrect spool valve placement? check your 2-3 fluid circuit, it sounds like it's somewhere along that, but i'm not really a tranny expert, just my 2 cents! hope this helps

Were some modulators adjustable like dist vacuum advances? Using a hex tool in the vacuum port or something like that? Thought I read that somewhere but never looked or tried it.

californiajohnny wrote: I would guess that an incorrect spool valve placement? check your 2-3 fluid circuit, it sounds like it's somewhere along that, but i'm not really a tranny expert, just my 2 cents! hope this helps

Edited by dave302 - 14-April-2014 at 12:56AM

antlerfiend wrote: Last year my car started to shift on it's own at about 5800 rpm.

alex, so you're saying that you had it in 1st gear, then manually shifted to second and it went straight to 3rd gear?

Yeah Johnny. It went straight to third. Last year it started to shift on it's own without me moving the shifter. It would shift into second before I moved the shifter. Then I would go ahead and move the shifter into second and try and hold second out and it would shift again at about 5800 rpm into third. If I did not move the shifter into third detent, it would shift back into second hen I let off of it at the finish line. My dad built a different valve body with a full manual kit, it will let me hold first now to 7000 but goes straight to third when I shift into second.

Alex, a good rebuild kit from a reputable source would not be all that expensive. A fresh rebuild, good, clean valve body with proper mods, check your converter while it's out and you should be golden. An automatic transmission, more so than any other vehicle component, must be surgically clean inside to function properly. When opening it up, the surroundings, bench, everything, must be as spotless as well. One tiny piece of foreign matter can cause issues. Unlike a manual transmission, automatics have so many passages, valves, and work under pressure, so it must all be exactly right to work correctly. Add in the TV cables, solenoids, computers, sensors from later versions and it really gets complicated! At least a C4/C5/C6/FMX does not have that to contend with.

Oh, the tranny was rebuilt three years ago. I will keep everyone up on the progress. Thanks again.

I will give you the the instructions for adjusting your second gear band. First, you will need a new replacement (Lock nut with seal) for your second gear band adjustment screw. Since the seal on the locknut will probably become distorted, when you remove the locknut to adjust the second gear band adjustment screw.

Edited by dave302 - 18-April-2014 at 11:54PM

Edited by dave302 - 19-April-2014 at 12:35AM

Well I got the new valve body installed with a little help from my dad and it works great. The problem most likely was that I did not get the kickdown lever right. I have learned alot by this experience.