MK3 swing arm

If someone has a bare MK3 swingarm could you please measure it at the wheel end and inside measurement at the end. Mine measures 8 3/8". My problem is that I have to move the entire piece, sprocket + wheel flush right to make everything work. This requires a spacer of .210 inch...almost 1/4" and I don't know why. Everything appears to be stock with no alteration. All pieces appear to be there. On the right side if i push it full flush right the caliper will line up just fine so I know from the wheel everything is OK. So the problem is all on the left side and it needs a spacer but I don't believe there was one stock. What gives?

seattle##gs said:

If someone has a bare MK3 swingarm could you please measure it at the wheel end and inside measurement at the end. Mine measures 8 3/8".

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= 8 1/8".

that is very close to the .21 spacer I need. Why the difference? Everything looks in good shape, no damage. I can go ahead and make the spacer but I want to know why.

If memory serves me right, there is a spacer on that side in there somewhere that goes over the dummy axle and butts up against the sprocket bearing.

I guess that's in there, and correct?

seattle##gs said:

that is very close to the .21 spacer I need. Why the difference? Everything looks in good shape, no damage. I can go ahead and make the spacer but I want to know why.

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I don't know, but I seem to remember from previous discussions that 8 1/8" is the correct dimension.

If you fit a spacer it will increase the dimension between the lower shock mounts which could result in the shocks leaning inwards.

I already have the mysterious gap. It ended up .325. I made up a spacer and installed it on the left side between the speedo gearbox and the swingarm. This dimension includes the thin washer it replaced. While was at it I found the speedo gearbox needed a thin washer, perhaps .030, t keep the speedo drive from binding against the sprocket. Now everything turns freely, the wheel APPEARS to be in the center of the motor cycle, the caliper straddles the disc almost in the middle. The raer sprocket appears to be shifted slightly to the right of the gearbox sprocket but after everything else I've solved, I'll live with it. The big question is why my swingarm has extra space. since I have no answer and don't expect one, I just have to deal with it.

FWIW, I just measured the only bare MK3 swinging arm I have, and it is just barely over 8", looks like 8 1/32". For comparison, I measured several other pre-MK3 arms, and they were all between 7 31/32" and 8 1/32". These are all used items, so it's hard to be sure exactly what they were when new.

Ken

Thanks for the measurements. Can anyone explain the extra width in my swing arm?

My extra swingarm is also 8 1/32" wide at the axle slots.

As far as your wider swingarm goes... the obvious thought would be that it's bent. IMO, just being wider can be compensated for by adding a spacer. If there is some twist to the arms of your swingarm then your wheel will be out of plumb. It's easy enough to measure if the axle slots and the swingarm pivot are relatively parallel if the swingarm is not installed on the bike. If it's on the bike, I don't think there's an easy way to measure it for twist.