West Coast Chopper rear sprocket spacer

[el Diablo Guapo]

West Coast Choppers sport 20" x 3.0 tires. One of the WCCs i have seems to have even wider tires (with flames for treads!)

this typically causes the tire to rub the drive chain using a "stock" drive chainwheel install kit and engine position. (this appears to be an issue for some using any "fat" tire on their install)

to get a nice clearance i created a spacer. i used 1/2" thick HDPE (high density poly ethelene platic sheet), but you could use any hard drillable material.

2" ID 4" OD 3" bolt circle of (6) .25" holes
(i think the thing is really metric so the bolt circle should be 76mm or 2.9" and the holes should be clearanced at say .28")

the way i came up with six bolts is: the spokes only accepted 3 bolts easily, so put those in a equalateral triangle in the existing holes in the sprocket. then i used the metal backing plate to line up an opposing triangle (think star of david)

stacked everything up- aligned with three bolts- drilled the stack and mounted with (6) grade 8 hardened 1/4" bolts

this went on flat, centered easily, and has just the right clearance

(there is plenty of space in the frame so next time i may try a 3/4" spacer, though this will create and solve it's own issues... pro: extra clearance for drive chain, clearance between engine case and pedal chain -con: requires further engine offset, requires deeper coaster brake extention)

this has been functioning since its original installation as of 2/7/2015 so 12/19/2013 - at least a year later, with some fairy heavy use

to see the front brake i added to the cho-ped forks:
http://motorbicycling.com/showthread.php?t=52425

to see the coaster brake mod (and series of failures) to accomodate the drive chain wheel:
http://motorbicycling.com/showthread.php?t=52513

 

[Toothy]

Ok...looks great. I think I may need to do something similar to my back end. My chain hits the tire. I have an extra mounting rubber ring which may create enough clearance
. What was your problem...Same thing?

 

[maniac57]

I used three rubbers. Two under the sprocket and one behind spokes like normal. It works on my bike but I have a fairly unusual engine mounting position and don't offset the motor at all.
Three rubbers, or a spacer like the OP's, would have been better as my chain tends to mark up the tire right now.w
The biggest single issue I had with the WCC chopper was trying to get the brake arm to fit without bending or breaking in a panic stomp stop.
Whatever mod you do to the brake arm, go back and triple reinforce it before you ride or simply add better rim brakes and ditch the coaster entirely.