C-4 Transmission is shifting to soon and slips between gears. Performed the band adjustment (while cold). When adjusting, does it make a difference Hot or Cold? Adjusted the old modulation valve both ways with no change in shifting. I replaced the modulation valve. The instructions mentioned a push rod at the modulation valve. When I pulled mine out I did not see a push rod. What does the push rod do? The fluid and filter have been changed. Could the kick down linkage adjustment cause this? The tranny was installed in my show Mav. from a wrecked Grabber, so I cannot say it was working correctly from the beginning. Tranny does not slip out of gear, it just shifts to soon and slips between gears. Questions? Hot or Cold, Push Rod, Kick Down Linkage Thanks for your help.
There should have been a rod between the modulator and the valve inside the tranny. If that rod is missing, it will not shift well, if it shifts at all. Also, slippage between shifts can be adjusted with the modulator screw. There is normally a tiny screw inside the nipple where the vacuum hose attatches, turn it in and shifts will be firmer and later, turn it out and they will be earlier and softer. Stock c4's usually do shift a bit on the "sluggish" side, that's why shift kits are so popular. Also, take into consideration that the trans may have a few miles on it, and the clutches are most likely starting to wear. When they wear, clearances get a little looser and it takes longer for them to engage, another cause of a sluggish shift. If it were me, I'd try to adjust the modulator screw clockwise a few turns and see if that does not help. Good luck!
rod You must have the rod to make the Mod work. If your modulater isn't adjustable you can grind the linkage rod down about .060" at a time to adjust it. Just get another rod and use it. You can actually use a piece of welding rod with the flux cleaned off. Some of that shadetree stuff you don't see any more.
without the rod it will cause it to stack shift( shift at low rpm and low mph) not sure if you have one or not but I would start there just my 2 cents.........
Thanks everyone for your responses. I got ahold of a used push pin from a tranny salvage yard and installed it with a new modulation valve. The thing shifts like a dream! I'm so happy I did'nt have to look at a rebuild.
