Buggy 4l60e: Shiftingto Early

[farmtruc]

if the trans is shifting correctly and all gears feel like they are engaging correctly, then the trans is probably ok.
The pcm will shift the trans based on mph and tps.
First thing to make sure is; get the tire height and gear ratio correctly calibrated in the pcm. You will not get anywhere unless this is correct.

The mph is coming from the vss, located in the tailshaft housing. I'v seen this: the reluctor ring on the tailshaft doesn't have enough teeth on it, therefore it's reading basically half the pulses or something like that. This has been the case on several 80e conversions.
If the pcm is getting incorrect pulses for whatever reason, the trans will shift early/late.

Another reason, the tps may not be reading it's full sweep, 0-5volts. You can measure this with a dmm. Open is 5v, 0v or so, closed. Volts will probably only hit 4.5v or so.

[88blazerboy]

Had a transmission shop check out my setup today - in their opinion, it's driving pretty good. They did notice that it was shifting gears early, but that at 40+ MPH, it was shifting like it should. They said the loud noise at speeds 70+ MPH was a misaligned drive shaft. They really liked the truck but hated my accelerator pedal position. Me too.

Here is the weird thing, and I have never heard this before, so chime in if you know anything about this - according to this shop, they said that it would be 100 to 120 miles before the transmission really develops a regular shifting pattern. I've only put about 50 miles on it since I got the truck up and running. Is this correct: do these newer transmissions on a GenIV have adaptive smarts?