I Might Have a Problem

[YB in IN]

When I was riding around town yesterday, I noticed a quirky thing that my 90 K75S was doing. I was preloading the shift lever to make an upshift and rolled off the throttle when it shifted without pulling in the clutch lever. I haven't had it do this before. I did a little experimentation on my street and was able to go both up and down through the gears just by letting off the gas and popping the shift lever. Am I just being paraniod, or is there something funky going on? FWIW I just had the splines rebuilt by Bruno's in Canada last winter, and lubed them all (Final and Transmission) up about 15000 miles ago.

 

[deilenberger]

When I was riding around town yesterday, I noticed a quirky thing that my 90 K75S was doing. I was preloading the shift lever to make an upshift and rolled off the throttle when it shifted without pulling in the clutch lever. I haven't had it do this before. I did a little experimentation on my street and was able to go both up and down through the gears just by letting off the gas and popping the shift lever. Am I just being paraniod, or is there something funky going on? FWIW I just had the splines rebuilt by Bruno's in Canada last winter, and lubed them all (Final and Transmission) up about 15000 miles ago.

Not to worry.. it's normal. It is a technique some racers use. The only risk is not matching speeds carefully. Motorcycle transmissions are what is called "constant mesh" - meaning the gears are all engaging each other at all times, and there is a pair of gears for each speed. Power transmission through the tranny is achieved by one of two methods:

1. Moving the gear so it locks on the shaft it rides on - turning the shaft

or

2. Shift "dogs" - lumps on the ends of the gears that mate one gear to another transferring power. The engagement is also achieved by moving the gear on the shaft.

If the transmission gear speeds are well matched - either type of engagement can be done without using the clutch. The risk of doing this on a regular basis is if you don't match the speeds well - you risk damaging the engaging mechanism, or the shift forks and/or shift drum.

What you described doing - feathering the clutch - is basically what I always do for shifting above 2nd gear - I partly release the clutch and make the shift with a firm motion. It typically results in a "snick" noise instead of the usual BMW "klunk" noise.

I don't do it for the 1:2 or 2:1 shift since the ratios are considerably different (making speed matching difficult) plus neutral is in there to add to the risk.

Not to worry..

Best,

 

[YB in IN]

Thanks, I will procede to not freak out now.

 

[roadcrave]

What you described doing - feathering the clutch - is basically what I always do for shifting above 2nd gear - I partly release the clutch and make the shift with a firm motion. It typically results in a "snick" noise instead of the usual BMW "klunk" noise




Thanks for the tip deilenberger, new to bmw, I ride a 2003 k1200lt and do not like the clunk when shifting, ill give it a try...matthew