Just a few comments concerning the Whizzer automatic clutch.
Due to a special request, I will pass on a few changes I made to one version of the automatic clutch.
It is important to note the latest version of the automatic clutch from Whizzer can not be upgraded with my modifications. Due to current design, I can only exchange the hub with a previous version that has been modified. The reason the current version can't be upraded is because replacing the sleeve with the Rockwell 58 hardened sleeve weakens the area where the shaft is affixed to the hub. This problem centers around the use of additional
bearings and the removal of too much metal to support the shaft.
On my 1950 Sportsman it is possible to lift the front wheel off the ground [wheelie], and I have been asked to share the methods used to make the clutch work this well.
It is important to explain how the clutch operates in order to make the changes have merit. Because of bogus information, many think the clutch works better on a stock motor, however the opposite is actually true. The quicker the shoes can be "thrown" against the drum the quicker it "locks", and the better it works. The flaw in the design is centered around the clutch operating at idle, it is at this time the bearings are riding on the soft bearing race. Only when the shoes are engaged does the clutch work as one piece, and shifts the assembly to use the smaller bearings that hold the assembly to the arm.
During testing and high mileage runs it soon became apparent the quicker the clutch was engaged the more reliable it became. The factory was in fact at odds with the known tests and cancelled warranties over these proven theories. The more the clutch was used at low speeds the quicker it failed.
Here are the changes I made to make it work best and last the longest. The soft bearing race was changed to a Rockwell 58 rated bearing sleeve, removing the problem of the bearings "eating" the sleeve. During the replacement of the bearing sleeve I also noticed the hub wasn't always parallel to the bearing surface causing a mis-alignment of the shoes. During the sleeve replacement process I found it necessary to cut the inner hub to match the shoe angle. During the rebuilding process it also became clear the inner surface wasn't always level, but machining the inner surface corrected that. Another change that helped the clutch engage better was to "rough" the inner surface to help make the shoes grab better [sand blasting the inner hub was suggested in a post on this site], and aided in a quicker engagement. Drilling holes in the hub was another change that helped remove any "dust" and also created a better mating surface for the shoes.
I tried many different shoe combinations and springs, but the original springs worked best, but I "stretched" them slightly to reduce the opposition to the centrifugal force to allow quicker movement.
Lots of quick power, better bearing surface, weaker springs, and 20" wheels are the reasons my bike will pull wheelies using the automatic clutch.
Have fun,
Due to a special request, I will pass on a few changes I made to one version of the automatic clutch.
It is important to note the latest version of the automatic clutch from Whizzer can not be upgraded with my modifications. Due to current design, I can only exchange the hub with a previous version that has been modified. The reason the current version can't be upraded is because replacing the sleeve with the Rockwell 58 hardened sleeve weakens the area where the shaft is affixed to the hub. This problem centers around the use of additional
bearings and the removal of too much metal to support the shaft.
On my 1950 Sportsman it is possible to lift the front wheel off the ground [wheelie], and I have been asked to share the methods used to make the clutch work this well.
It is important to explain how the clutch operates in order to make the changes have merit. Because of bogus information, many think the clutch works better on a stock motor, however the opposite is actually true. The quicker the shoes can be "thrown" against the drum the quicker it "locks", and the better it works. The flaw in the design is centered around the clutch operating at idle, it is at this time the bearings are riding on the soft bearing race. Only when the shoes are engaged does the clutch work as one piece, and shifts the assembly to use the smaller bearings that hold the assembly to the arm.
During testing and high mileage runs it soon became apparent the quicker the clutch was engaged the more reliable it became. The factory was in fact at odds with the known tests and cancelled warranties over these proven theories. The more the clutch was used at low speeds the quicker it failed.
Here are the changes I made to make it work best and last the longest. The soft bearing race was changed to a Rockwell 58 rated bearing sleeve, removing the problem of the bearings "eating" the sleeve. During the replacement of the bearing sleeve I also noticed the hub wasn't always parallel to the bearing surface causing a mis-alignment of the shoes. During the sleeve replacement process I found it necessary to cut the inner hub to match the shoe angle. During the rebuilding process it also became clear the inner surface wasn't always level, but machining the inner surface corrected that. Another change that helped the clutch engage better was to "rough" the inner surface to help make the shoes grab better [sand blasting the inner hub was suggested in a post on this site], and aided in a quicker engagement. Drilling holes in the hub was another change that helped remove any "dust" and also created a better mating surface for the shoes.
I tried many different shoe combinations and springs, but the original springs worked best, but I "stretched" them slightly to reduce the opposition to the centrifugal force to allow quicker movement.
Lots of quick power, better bearing surface, weaker springs, and 20" wheels are the reasons my bike will pull wheelies using the automatic clutch.
Have fun,
