4L60E Blues

Need some help. I have been helping my son to become more self relient, and may have gone in too deep. He has a 95 Firebird that blew out all of its trans fluid. He and I attempted a rebuild with a Transtar deluxe kit, and things went together reasonably well. Put the trans back into the car, filled it up with Dexron and it rolled forward....but no reverse! No fluid leakage, pulls really strong all 4 gears, and has trans braking in 1st. One fella suggested a check ball, didn't say which one though. I thought I would ask politely for help before we start taking it back out. We did the ohm check on the pressure switches, an we gapped the clutch packs to .070 (spec was.06 to .08). Of course when it rains it pours, my other boys 1995 pickup lost 4th earlier this week, Is this a 1995 issue, or my boys tough on their cars? They are 17 and 18 (I think the latter.) On the pick-up, we unplugged the harness, truck pulled in 1st, not 3rd. Any advise would be a huge help to an overworked dad.

1995 did not have any really model-year specific deficiencies in the transmission. The core design of that transmission was about 15 years old by then, and the "bugs" had been just about eliminated. While it's possible that your novice drivers are harder than normal on their equipment, outside of constant abuse, the transmissions should be able to tolerate it. If the transmissions were drained and refilled at proper intervals, they should outlast the vehicles.

#1 - No Reverse

Since the transmission evidently operates in LOW range, we can presume the low/reverse clutch is applying properly.

It's possible that the transmission is not providing oil pressure to the reverse input clutch pack. That could be due to valving (including a solenoid, checks, or spools), the reverse apply piston or seal, or the sealing rings on the main shaft. It's also possible that the reverse input clutch is applying, but the forward clutch or the 3-4 clutch is not completely releasing. The forward sprag clutch also needs to hold and release properly - Did you test that under considerable force before assembly? If the driving wheel are raised, does the transmission even attempt to turn the driveshaft in reverse?

#2 - No OD

If the transmission operates in 2nd range, the band is likely still intact. However, the 4th apply piston might be a problem. Before going that far, however, it would be prudent to scan the vehicle for transmission error codes. The PCM might be sensing a sticking TCC solenoid,or have a faulty brake pedal switch input. The line fluid pressure sensor could also be a problem.

If the electronics are checking out, the 2-4 servo would be the next easiest item to check. A broken/bound 4th apply piston spring can prevent band engagement in 4th, as can a worn 4th servo piston of damaged piston seal. A sticking 2nd apply piston can do the same. Moreover, a blocked exhaust port for the 4th apply piston can prevent 4th gear upshift. This port is in the RH oil pan mounting flange, and improper installation of the oil pan gasket or overuse of RTV sealant can block the port, preventing application of the band in OD.