How to shim the cush drive: Difference between revisions

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[[Category:Final Drive]]

The sprocket carrier is not rigidly coupled to the rear wheel; it "floats" with a piece of hard rubber taking up the slack. If there is too much slack, you'll feel excessive drive lash when applying and releasing throttle. Adding shims takes up some free play and reduces the lash.

The rear sprocket carrier is not rigidly coupled to the rear wheel; it "floats", with a piece of hard rubber taking up the slack. If there is too much slack, you'll feel excessive drive lash when applying and releasing throttle. Adding shims takes up some free play and reduces the lash.

A new cush drive is $42 plus S&H at Ron Ayers, but reports state that even a new one can have more play than desired.

With the rear wheel [[Removing/replacing the rear wheel|off the bike]] and ~~[[Supporting Your Bike While Servicing|~~properly supported]] (~~be mindful of~~ the brake rotor on the other side) wiggle the sprocket carrier off. If you've never taken it off, gunk may be holding it on. Just twist and wiggle, and it'll come off.

With the rear wheel [[Removing/replacing the rear wheel|off the bike]] and properly supported (put it up on some 2x4s or an old 13" auto tire to avoid damaging the brake rotor on the other side) wiggle the sprocket carrier off. If you've never taken it off, gunk may be holding it on. Just twist and wiggle, and it'll come off.

[[Image:Cush drive 1.jpg|150px]]

Now, find a suitable material for the shims. Margarine tub lids, milk bottles, or anything similar should work pretty well. Cut out 12 rectangles, each roughly 5/8" x 1 1/8". Depending on how much slack you have, start out with one or (usually) two shims in each crevice, for a total of 24. Some slack may come back later; then you can add 12 more~~, for a total of 36, or 3 at each crevice~~.

Now, find a suitable material for the shims. Margarine tub lids, milk bottles, or anything similar should work pretty well. Cut out 12 rectangles, each roughly 5/8" x 1 1/8". Depending on how much slack you have, start out with one or (usually) two shims in each crevice, for a total of 24. Some slack may come back later; then you can add 12 more.

Another material that works great is silicone cutting board. Get it at [http://www.bedbathandbeyond.com/product.asp?order_num=-1&SKU=11289967&RN=108 Bed Bath and Beyond]; $4 for two boards. It's quite a bit thicker than milk jug material, but still thin enough to cut with scissors.

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 [[Category:Final Drive]]
-The sprocket carrier is not rigidly coupled to the rear wheel; it "floats" with a piece of hard rubber taking up the slack. If there is too much slack, you'll feel excessive drive lash when applying and releasing throttle. Adding shims takes up some free play and reduces the lash.
+The rear sprocket carrier is not rigidly coupled to the rear wheel; it "floats", with a piece of hard rubber taking up the slack. If there is too much slack, you'll feel excessive drive lash when applying and releasing throttle. Adding shims takes up some free play and reduces the lash.
 A new cush drive is $42 plus S&H at Ron Ayers, but reports state that even a new one can have more play than desired.
-With the rear wheel [[Removing/replacing the rear wheel|off the bike]] and [[Supporting Your Bike While Servicing|properly supported]] (be mindful of the brake rotor on the other side) wiggle the sprocket carrier off. If you've never taken it off, gunk may be holding it on. Just twist and wiggle, and it'll come off.
+With the rear wheel [[Removing/replacing the rear wheel|off the bike]] and properly supported (put it up on some 2x4s or an old 13" auto tire to avoid damaging  the brake rotor on the other side) wiggle the sprocket carrier off. If you've never taken it off, gunk may be holding it on. Just twist and wiggle, and it'll come off.
 [[Image:Cush drive 1.jpg|150px]]
-Now, find a suitable material for the shims. Margarine tub lids, milk bottles, or anything similar should work pretty well. Cut out 12 rectangles, each roughly 5/8" x 1 1/8". Depending on how much slack you have, start out with one or (usually) two shims in each crevice, for a total of 24. Some slack may come back later; then you can add 12 more, for a total of 36, or 3 at each crevice.
+Now, find a suitable material for the shims. Margarine tub lids, milk bottles, or anything similar should work pretty well. Cut out 12 rectangles, each roughly 5/8" x 1 1/8". Depending on how much slack you have, start out with one or (usually) two shims in each crevice, for a total of 24. Some slack may come back later; then you can add 12 more.
 Another material that works great is silicone cutting board. Get it at [http://www.bedbathandbeyond.com/product.asp?order_num=-1&SKU=11289967&RN=108 Bed Bath and Beyond]; $4 for two boards. It's quite a bit thicker than milk jug material, but still thin enough to cut with scissors.