I have a 1990 GXE with about 100,000 miles. Car runs very well and the auto transmission was working fine.

However, the other day, accelerating from a stop, the transmission started making a soft mechanical grinding sound - almost like a noisy brake rotor and pad.

I almost thought it was a brake pad that needed changing, but after putting the car up - I was sad to find that the sound is coming from the transmission.

It only makes the mechanical grinding sound in 1st gear and goes away immediately once the tranmission shifts to 2nd or higher gears. There is no sound in reverse. The tranmission still works perfectly fine, except for the soft grinding sounds in 1st gear.

Questions:

1) anyone have any idea on what the problem could be?
2) do you think my transmission will deteriorate quickly if I keep on driving my car?