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Hello,

I'm looking for some assistance from anyone familiar with the assembly of a Monza Junior rear axle. Upon reassembly, I've noticed that the rear wheel does not appear to be centered with the rear fender. It's off by approx. 1/2" to the right.

Is a spacer supposed to be included between the brake housing and the swing arm? The parts manual does not show a spacer in this assembly. However, when I first started this project (which had been partially disassembled for decades), I found a spacer between the left chain tensioner and the axle nut. Since this didn't seem to make sense, I repositioned the spacer between the left brake housing and the swing arm - where it seems to take up the gap. With the spacer in place, the wheel is straight, but off-center. Without a spacer, the lug on the swing arm that engages with the brake housing causes the wheel to angle sideways as the axle bolts are tightened. Am I assembling this correctly?

With the exception of one of the foot peg mounts, the frame appears to be straight. The swing arm and rear fender appear to be unbent, as well.

Please see attached photos.

Thanks for your help,
Jeff

I don't know much about the Monza Jr., cannot refer to a parts list. But, the most important condition to be hold while fitting the rear wheel is:

"Does the chain perfectly line up with the sprockets, i. e. are the sprockets on the same plane?"

Hans

The wheel does look offset in the photo.
Is it in line with the front wheel? A long straight edge, or a helper with a string line could help to check
If the wheel has been re-spoked, was the original offset recorded and set the same? Sometimes they are not central to the hub, as may be assumed.
The spacer doesn't look to be an original feature, but must be used if the brake plate interferes with the swingarm without it. Maybe the casting was shortened for some reason, and the spacer added to compensate? It's hard to be certain with rare old bikes. In any case it's not thick enough to be the cause of the apparent wheel offset in itself.
It would be good to inspect another Monza Jr.

Thank you both for your suggestions. As a follow-up I'll share what I found. After checking and double checking the frame and wheel alignment, I've reached the conclusion that the spacer must have originally been placed where I have it. Nothing else seems to work. Upon closer inspection, careful measurement, and with the aid of some strings, it became apparent that the misalignment between wheel and fender was due to improperly welded or bent fender mounting tabs. I'm not sure of the best way to correct this now that everything is painted. I guess the lesson learned is to assemble everything and check alignment before painting.

I checked the other items mentioned, as well. Although the wheel was rebuilt during restoration, I used a jig that would have properly maintained the wheel offset (if any). Additionally, there is no indication of machining marks on the hub and the sprockets appear to be in the same plane when the spacer is installed. I'm just curious why the spacer in question does not appear in the parts manual assembly diagram. I've analyzed a number of online images from other Monza Jr.s but since this feature is often obscured or ambiguous in the photos I was not able to confirm my findings.

Thanks again for your interest and assistance.
Jeff