View Full Version : Damage from Downshifting?

09-24-2007, 07:04 PM
I was racing my buddys bike this weekend and i went from a 60 roll and i downshifted to second. When i did it my tires chirped from not matching the gear speed. I dont know if its me or that i just havent noticed it before really, but when i put the car in 1st or rev. i can hear some slight chatter/clicking sometimes when i let off the clutch. it doesnt do it all the time. but i can get it to do it by surgin the throttle a lil. any ideas?

09-24-2007, 08:52 PM
You will probably hurt something by downshifting because of your IRS car.. .. eventually something will give. It sounds like something internally has already done that by the description you are giving about your clutch. Could be any of the following, clutch, pressure plate, pilot bushing, or something inside of your transmission like a synchro...

SCMC has track events and we just had on in SW MI where you could have come out and met many of us. (Keep speed off the street, put it on the track.) ;)

09-24-2007, 10:39 PM
i took the car out tonight with the top off tryin to listen more closely. It only will make the click sound like once it when lettin up the clutch in first will giving it some gas, if at all, and it is really faint (almost sounds like a click when the A/C compressor kicks on). But you can cause the noise to happen again in first if you play around with the throttle and surge it a lil. But im still not sure if it is normal or not. I havent downshifted very much like that. 2 or 3 times tops, so i doubt it would have done anything. What exactly does clutch chatter sound like and what is it?

The thing that doesnt make sense is that i only did a down shift from 5th to 2nd at 60mph. and the noise is only noticable in 1st/rev. really. So that leads me to think that i wouldnt be the syncros. because there is one for every gear right?

09-24-2007, 11:42 PM
could be the TOB going bad.

09-26-2007, 06:30 PM
I think im prolly just being stupid paranoid. I wont do any more harsh DS without matchin the gears..Trans issues shouldnt be as bad as automatics..

10-02-2007, 08:33 AM
I did the same thing at the track but my speed was much higher than 60mph. Accidentially shifted into 2nd gear at 110mph (shift knob became loose which caused me to miss 4th gear) that resulting in a trap speed around 80 mph but sill had an ET of 13.5s. Once I realized my mistake I got it out of gear as fast as possible. The transmission gears are really strong and will take most abuse. However, the stock clutch will give way since it has some slip to the clutch disk and mounting hub (has built in mercer or dampening). At least I did not have sticky tires at the time which took most of the shock and saved the rear end and driveline from damage. Most likely the clutch hub may have been damaged or the dampening springs may have been over compressed resulting in loss of damping force which may be the noise you are hearing. It is possible that a rivit that holds the clutch material in place may have been sheered off. Worse case is a crack in the flywheel or damaged flywheel bolt.

Clutch chatter is basically caused by the clutch disk skipping on the surface of the flywheel and pressure plate surface which causes a shudder or vibration throughout the drivetrain. There is probably more to it than what I described but what you are feeling is probably not that.