Originally Posted by Tommyp
How bad is it for the car if I over-rev when I rev-match or up-shift
DaBiggs is right, once you've slotted the gear in then the only wear your are going to have if you mess up is on the clutch.
Examples that might wear your syncros:
- Quickly skipping gears up or down (out of 5th and straight into 2nd; out of 1st and straight to 4th)
- Over reving when double clutching (rev too much when in neutral)
- When at a stop in neutral, quickly pressing in the clutch and ramming into first before the gearbox spins down.
- Shifting into 1st while moving without double clutching
Not all of these are going to be lethal to your trans, but if you want it to still feel brand new at 100k, then take gentle care of your syncros.