Rebuilding the new edition Whizzer clutch

Discussion in 'Whizzer Motorized Bicycles' started by Quenton Guenther, Feb 3, 2010.

  1. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor


    This article was original published in the Whizzer Newsletter [I think Aug or Sept 2008]. I suggest all Whizzer owners subscribe to the newsletter.

    There are many versions of the automatic clutch from Whizzer USA, and I will try to cover all the problems & fixes when possible. The clutch uses several different types of metal, different contact materials, shoe width, bearings, seals [or not], mounting arms, mounting bolts, spacers, and, and all are not created equal. I will cover the problems & fixes from the early versions to the most recent effort.
    The very early clutch prototypes were made from steel, but were soon changed to cast iron, now part of the clutch is made from aluminum. Almost all of the clutches can be upgraded or repaired, however different versions require different "fixes".
    The very early units only had the shoe mounting pins pressed into the hub a very short depth, and when the pins were stressed [working normally] they pulled out of the hub, and left a lot of parts milling around inside the hub. The fix is to dispose of the pins, drill the holes all the way through the hub, thread holes with ΒΌ" X 20, use 3 shoulder bolts inserted through the hole in the shoe, install a small washer, thread the bolt into the hub, install a nut on the outside to lock the bolt... Fixed.
    The next generation still had a similar problem, loose pins, but this version had the pins go all the way through the hub, but tried to smash the ends to hold in place. This version didn't usually deposit parts inside the hub it just stopped engaging. The same fix applies using the shoulder bolts.
    The next problem and fix will apply to approx. 99% of the clutches. The cast edition of the clutch, also had the bearing ramp made of the same material, however the next edition had a hardened [not] sleeve installed for the bearing to ride on. Each version presented the same problem, needle bearing don't like to ride on rough, & soft surfaces. 90% of all the clutch problems are found at this location. The fix, thanks to Kurt M., Gerd L. & myself is to simply machine the soft bearing ramp down to .0935" and press a polished, Rockwell 58 hardened sleeve onto the hub, grind end flush with the hub.. Fixed.
    The latest generation has presented several new challenges. Instead or using a high quality bearing race, Whizzer changed the bearing arrangement to compensate for the softer bearing race. All earlier versions had a 3-section bearing and 2 grease seals. The 2 outer sections of the bearing rode on the bearing surface, and the center provided the one-way bearing to provide a way to start the motor. Whereas the later version used larger ball bearings on each side, and a single one-way bearing in the middle. Two issues arrived at the same time as the clutch, it appears the grease is leaking through the ball bearings on both sides and managed to coat the shoes with grease on several [all] I have worked on. The second problem is a very easy fix. Either the hole is too big, or aluminum expands faster when hot than does the steel caged one-way bearing, but the bearing moves inside the hub and the motor can't be started until the clutch cools down [approx 20 min.] The fix for the loose bearing is simple, remove one of the larger side bearings, and tap out the one-way bearing. Use a punch and make dents in the surface where the bearing normally resides, coat O.D. of the bearing with a good grade of Loc-tite [red or green], install [watch the direction] bearings back into hub... Fixed.
    I am still working on the issue of the grease leaking on the latest version, and it looks like thinner outer bearings and the use of seals might provide the best answer.

    PS the original article include pictures.

    Have fun,
    Last edited by a moderator: Dec 15, 2015