My 1st gear band seems to be slipping.When I manually downshift into 1st,it seems like its in neutral.When I hit the gas,it goes.It seems normal in drive but I have had it downshift into 1st and slips a bit.
Do I need to adjust 1st gear?How do I do that?
fluid level is good,no sign of burned oil.
Had it rebuilt 5 yrs ago.

 

you are checking the fluid with the car running right? i have to ask

 

yes

 

there is a procedure for tightening / adjusting the bands but i'll be damned if ican remember the details

 

Adjusting the bands on a C4 is pretty easy.
On the low/reverse band you use the set screw on the right side of the tranny, just above the vacuum modulator.
Put a wrench on the screw and an box end wrench on the jam nut. Loosen the jam nut without turning the screw.
Now torque the screw down to 10 foot/lbs torque, which is just snug-not tight. Now back off 3 turns. Keep the screw from turning and tighten the jam nut. Thats it.
If you are not confident making the adjustment then just keep track of how many turns it took to tightnen the screw so you can put it back if you are not sure. Don't over torque the screw. Use a sharpie to mark the screw or put a scratch on it to keep track of the turns. Work slow.

 

Acutally, Your trans is working correct. If it was slipping you would be slipping in reverse also. The band is additional holding power in 1st. When downshifted into 1st while moving without any throttle it will apper as if it is in neutral. The one way clutch in the rear is overrunning at this point until you accelerate.