I have a 2013 Ford Mustang with an MT82 6-speed manual transmission. I don't know the history of the car so I figured it would be a good idea to change the transmission fluid. I drained it out and pumped new fluid back in.
I have done many automatic transmission drain and fills but this was my first time owning a manual car. I believe I may have underfilled it a bit. After reading online the car was not completely level and was at a slight incline probably causing the fill hole to falsely let me believe it was full when it was not.
I drove it around for a mile or two and now the car makes a bad noise when in neutral and the shifter shakes. When I put the transmission in neutral and push in the clutch pedal the noise goes away, but as soon as I release the clutch pedal it starts making a bad grinding noise. When I press the accelerator to increase the revs in neutral the noise goes faster.
I jacked the car up and made sure it was level and full, but it still seems to make the same grinding noise. I put a full 3 quarts in until the hole started to leak.
I was looking for some general advice... reading online it seems to suggest that the input shaft bearing may be the problem... not sure if there is anything else I can try.