17” on a special

[mm1ut1]

I recently bought a 79 special that had the 16” rear replaced with a 17”. I rode the bike once, about thirty miles with no problems noticed. I then put new tires on the bike (that’s when I found out it originally had a 16”). When I put the rear axle in it went in about 1/8” further than it was when I took it off. When it’s fully in the rear caliper binds. Backing off the axle allows the rear wheel that 1/8” side to side play, which I don’t think is correct/safe .It has what looks like a homemade spacer between caliper and torque arm.
I am buying a 78 axle with spacers and am hoping this solves the problem. My question is if I add a 1/8” washer next to the homemade spacer would this solve the problem? Any difference between a special and standard axle ? I would love to see a photo of the two side by side.
What is allowable side to side play for rear wheel? Also what do you use on rear drive gear ? Lithium grease ok ?
I am also not able to post questions under the maintenance forum . Is that because I am a new member?
ok that’s all for today. TIA !

[mm1ut1]

Well I tried putting in a washer and thought I had the axle seated but as I tightened up the axle nut the axle kept sucking in past where it was originally. I must be missing something here. Weather getting nice and I want to ride!

[mm1ut1]

How axle looked when I got the bike

[DiverRay]

With the Standard rear axle and spacers, you should have no problems. I did the conversion for Special Ed, a member who no longer owns an XS, years ago. Pay attention to the shield for the right side seal and spacer, as they are the different parts. On Ed's bike, we just put spacers between the rim and rotor to space it closer to the correct position.

[mm1ut1]

Well after much wailing and gnashing of teeth I pretty much got it the wheel to spin freely, or so I thought. I rode it two miles then stopped and checked everything. Only issue was rear disc uncomfortably warm to the touch. I didn’t use the rear brake so it must be dragging slightly. I think the homemade spacer is over or undersized causing the rear caliper to bind slightly. I have a 78 axle with all the spacers on the way from mr eBay. In the photo below you can see the difference in spacing as it is now compared to the one above asI got it.
This bike has been refurbished several times over the years. Should last a long time.

[mm1ut1]

Spent another frustrated day working on it. Had the wheel on and off so many times my arms cramped up. If I hadn’t just bought a new tire I would get a 16” rim off eBay and be done with it .

[Bonz]

You may be able to tell which rear pad is rubbing, if one is noticeably hotter than the other. Not sure if an infrared heat gun (that shoots out the red dot and reads the temperature) allows you to do that but the dragging side is going to be hotter than the other. Uncomfortably warm is much better than burn your skin hot. Doesn't take much to make things warm on a disk. As well, if it's wheel position related and not caliper position related, check everything is aligned on the drive side so there won't be accelerated wear on the final drive and wheel splines.

You are spot-on, should be no side to side play in the rear end, that's bad juju anyway you look at it.

As I recall, make sure both pinch bolts are loose, tighten the axle nut down to the torque spec and wherever it lands, tighten the pinch bolts. Of course, up on the center stand and then you know the axle is centered as well as it can be with your existing hardware, and see if it makes a difference in the brake rub.

[mm1ut1]

Tried it again and saw that the caliper is slightly cocked. Shim inboard of the caliper should work. I am going to order a round shim set. Couldn’t find a metric set so instead of 20mm id I will use 1”. Going to use a feeler gage to determine shim thickness. I used to have a buddy who was a machinist, sure miss him now ! I’ll get this sucker right yet !

[DiverRay]

Mount bracket is probably bent a little. Shim is the easy fix, finding a "good" mount would be best, if you can.

[Bonz]

Good work examining things more closely and finding the culprit. Once you get that dialed in you're gonna be riding high, wide and pretty!

[mm1ut1]

Caliper is definitely binding. I couldn’t get close to proper torque on the axle before rear locked up. Tried several different spacer combinations and no luck. I think the homemade outer spacer is too narrow. I ordered some shims so hopefully I will have it running soon. The “Good” news is that the weather will be lousy the next week.