Rear wheel alignment mystery...

cknight · Post by **cknight** » Tue Jul 14, 2015 7:48 pm

I just checked two later type spare CB77 swingarms for trueness. Both have the same measurements from the outside of the front pivot bushings to the outside of the plates that hold the rear axle. The plates are right at 1.8mm inboard. The spacer dimensions you have are correct. There should be no offset from the center of the rim to the center of the hub. It would appear that your swingarm may be bent to the right. G's plumb bob is also an excellent check. Regards, Chase

rrietman · Post by **rrietman** » Tue Jul 14, 2015 11:40 pm

I have a box of swingarms in my parts room marked "bent". pretty common. don't know why I keep them at all, they are pretty much scrap metal as far as I am concerned.
Randy

R100 · Post by **R100** » Wed Jul 15, 2015 7:55 am

cknight wrote:I just checked two later type spare CB77 swingarms for trueness. Both have the same measurements from the outside of the front pivot bushings to the outside of the plates that hold the rear axle. The plates are right at 1.8mm inboard. The spacer dimensions you have are correct. There should be no offset from the center of the rim to the center of the hub. It would appear that your swingarm may be bent to the right. G's plumb bob is also an excellent check. Regards, Chase

Thanks for taking the time to make those measurements Chase.
My morning is taken up, but I will delve into this again this afternoon and report back.

G-Man · Post by **G-Man** » Wed Jul 15, 2015 10:33 am

Knowing what we know from the measurements people have taken. It shouldn't be a massive job to make up some tooling to straighten those piece out......

G

rrietman wrote:I have a box of swingarms in my parts room marked "bent". pretty common. don't know why I keep them at all, they are pretty much scrap metal as far as I am concerned.
Randy

R100 · Post by **R100** » Wed Jul 15, 2015 5:00 pm

Well still no "eureka" moment. Quite frustrating.
I did determine that my wheel hub is centered with the rim, i.e. no offset.
Re-did the measurements of the s.a. using my tablesaw surface and the discrepancy is about 4 mm side to side.
Then I did a layout on my bench of the s.a. Diagonal measurements were only slightly off (1 mm) and a line centered and at 90 degrees from the centre of the pivot bolt hits the line of the axle only 1 mm off centre.

Still scratching my head about this.

Steverino · Post by **Steverino** » Thu Jul 16, 2015 2:21 am

I have learned the hard way that while these swingarms seem pretty springy, they can be bent to the point of ruin without too much effort.

R100 · Post by **R100** » Fri Jul 17, 2015 9:33 am

CKNIGHT -

Tried sending you a PM but it did not seem to work.
Any chance you might be willing to sell one of those two good CB77 swing arms you mentioned?