2000 Grand Am - Trans Band Adjustment

Does anyone know where I can get instructions for a transmission band adjustment for a 2000 Grand Am, Quad 4? I have already looked in my cheap Haynes manual and there is nothing there.

Band adjustment can only be accomplished by changing the actuating pin length under the servo piston (technically, through the piston). The anchor pins are in a fixed position, so there are no external adjustments like the older PowerGlides, Super-Turbines, and 350-400 Hydramatics had.

Which band(s) do you want to adjust? There are three. Most often there is more than enough travel in the servoes to actuate the bands fully and release them fully with plenty of overtravel in both directions. Adjustment is almost never necessary unless something really bad has happened. If you feel you have a band slipping I'd advise first looking at fluid condition, then performing a line pressure test. If a band is slipping, you'd better act soon or risk burning a band, drum, or clutch by continued operation.

From left to right, there is a reverse band (removed), a 1-2 manual band, and a forward band.

http://www.wwdsltd.com/files/4T60PowerDrumAssembly.jpg


You can remove the servoes with the transmission in the vehicle. The forward band is a bit more difficult location since it is on the rear of the trans but is a little easier to remove since it is bolted on rather than retained by a spring clip.

http://www.wwdsltd.com/files/4T60ForwardBandServo.jpg


The reverse band servo is on the top of the trans.

http://www.wwdsltd.com/files/4T60ReverseBandServo.jpg


The 1-2 band servo is accessible by removing the pan.

http://www.wwdsltd.com/files/4T601-2BandServo.jpg


The 1-2 and forward bands are fed by pipes in the oil pan and these are easy to check for obstructions and leakage. The accumulators for these are also in the pan and are therefore fairly easy to check. Leakage past an accumulator seal can result in poor band clamping as well. A leaking or loose cover on the 1-2 manual band servo will also affect the forward servo application since the oil for the forward servo is ported through the cover for the 1-2 band servo, so it may be worth a look just to check the servo cover bolts, pipes, and accumulators. Once the pan is off to drain the nasty old oil and remove the filter, you might as well look at those suspects.

I do not have any real reasons to suspect the bands are out of adjustment. I was going to look in this direction because I have read in a manual for a different car the instructions for a band adjustment, and it seemed pretty simple. I guess that is not the case with this car.

It is actually my son's car, and he has recently mentioned that his transmission shifts hard into top gear. Not knowing much about transmissions, I was going to look at some of the cheap, easy stuff first- speed sensors and that sort of thing. After reading your very detailed reply, I will probably not mess with the bands.

Thanks for your help.

A hard shift can be the result of high line pressure and/or a problem with an accumulator/spring. It could also be a solenoid, but that's not as likely. Checking line pressure would be a good start.