AJS & Matchless Owners Club

I've just put a half-width (?cast iron) front hub (1953) together, prior to wheelbuilding. Spinning the hub (i.e. minus spokes and rim etc.) for the first time the bearings run well, but the hub is slightly unbalanced at higher revolutions (i.e. I can feel a slight judder in my arms when holding the axle). On slowing the hub returns to the same (heavy) point each time. A 15-20 g weight (0.5-0.7 ounce) balances the hub. Is this something than can be corrected via wheel balacning (once the spokes, rim, and tyre are added), or should I try to balance the hub itself? Any thoughts are most welcome.

I'd balance after building the wheel and with a tube and tyre fitted (that's how you will be riding) as you may find that there may not be as much weight needed to balance the whole assembly than with just the hub.
Either way it's simple enough to add balancing weight(s) to a spoke or two.

SPRIDDLER wrote:I'd balance after building the wheel and with a tube and tyre fitted (that's how you will be riding) as you may find that there may not be as much weight needed to balance the whole assembly than with just the hub.
Either way it's simple enough to add balancing weight(s) to a spoke or two.

That's just how car wheels are always balanced whenever you get a new tyre fitted.

Hi

That's quite a large out of balance for something a small as a hub, are you sure the bearings are free?

If so I'd suggest marking the heavy point of the hub and building the wheel with the valve hole in the rim opposite to this.

As said above - there's little point in balancing a wheel until it's fully assembled with a tyre and inner tube.

Regards Mick

May thanks (Rob, Spriddler, Mick) for your replies, which are welcome and useful.

It's a good idea to mark the heavy point. The static balance on my other bike (M16 1954) shows the valve as the heaviest part (I will get this balanced one day), so that makes perfect sense.

I was hesitant about getting the wheel built, but now I'll go ahead.

The bearings seem pretty good; I've provided the correct endplay (2 thou); the outer bearing cases are square in the hub; the axle is stright (checked on lathe).

Again, many thanks.

Fair advice from mick D , spin the hub,mark the heavy point then build wheel with valve position opposite,balance up when tired and tubed. Years ago we made our balance weights out bits of lead strip cut narrow and wrapped around the spokes, mind you it was a pain
Climbing on church roofs, L O L.