All,

I just had my transmission rebuilt (sun shell broke, Beast sun shell installed and 5 gear planetary installed instead of 4 gear along with all gear packs) and we installed it with no issues at all. Only things I'm noticing that seem off to me are the following. When I got to take off, it seems as if I have to reach about 1300 RPM before the full power actually kicks in. Everything is fine after that until I get to OD. Once I hit around 45 and up on the highway, I see a 200-300 RPM fluctuation up and down. Doesn't feel like a downshift at all. Just a fluctuation of some kind. I don't know what it could be. I have been all over some forums and do not see this exact list of issues. It could be two separate things that I need to look at. Just need some help to push me in the right direction.

 

Welcome to the forum.

 

Moving to the Corvette section of the Forum where you will get more views.

 

Ever get the fluctuation problem figured out?...same problem on a silverado after transmission rebuild.

 

The delayed power at takeoff and RPM fluctuation in OD could be a tuning issue, torque converter not locking up properly, or a slight fluid level problem. Check the trans fluid level first, then consider getting a tune to adjust shift points and TCC lockup. If that doesn’t fix it, have the shop recheck the rebuild especially the valve body or solenoids.

 

We finally figured out the 300-400 RPM fluctuation we saw at highway speeds after the 4l60e rebuild on a 1999 Silverado. We had installed a sonnax 4th gear super hold dual servo as part of the rebuild. We put the oem stock servo back in and problem solved! The transmission worked flawlessly and the 300 rpm surges were gone! We suspect we might have had the servo pin a little too long...or there was something wrong with the sonnax super hold part. We spent a lot of time adjusting things with HP tuner thinking the problem was elsewhere (TCC lockup) and installing a lot of other unnecessary parts!...lol Appreciate all help and hope this also helps someone else out down the line.