EvenmoreXS
1981 XS650
Great advice Leo. Thanks for going into detail.
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Swing arm Pivot bolt push
- Thread starter EvenmoreXS
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Voice in the wilderness here, but on at least one bike (83 Heritage special) the frame pivots were so wide compared to the swing arm that I placed a 3/4" machine bushing between the frame and swing arm to reduce the gap before tightening the bolt. I thought this to be a better solution than racking the frame to remove the gap. Sucking in the the frame sides against the nearby cross brace would create bending distortions to the bolt and pivots that can't be good for either. It's my theory that excessive torque and frame bending is what causes some bolts to break at the threads, my two cents.
This is entirely separate from the (sometimes needed) bushings behind the swing arm pivot caps to set the pivot sideplay.
This is entirely separate from the (sometimes needed) bushings behind the swing arm pivot caps to set the pivot sideplay.
EvenmoreXS
1981 XS650
My frame is an 81 and I didnt notice any excessive gaps, I will double check though.
The odd frame, swing arm combo may have excess space as you describe. Most aren't that far out. Perhaps that frame was damaged by some who couldn't get the bolt out and wasnt carefull cutting it out with a sawzall. Cut through the end of the tube welded in the frame instead of the end of the swing arm bushing.
Leo
Leo
Agreed.
This bike was a low miles decent shape bike. Just a heads up the frame can be wide, put the bolt through, check swing arm side to side movement before tightening, if there's enough gap to use a spacer, it's worth considering.
Adjusting the torque to achieve no play is the important thing. On mine the pivot shaft was a very snug fit it the bushings, even well greased it took a very firm push to insert it. If your fit is a bit looser then it might fall slowly.
Checking the fit of the pivot shaft in the bushes and in the frame is a good idea, especially if you find excess play.
On the 81 I thought the bushings were bad but when I started to take it apart I found the bolt thread broke off and a po drilled and threaded the bolt and put a 5/16's bolt in to hold it.
After I got it apart the stock fiber bushings were a very snug fit on the pivot tube. So I set the torque the way I did with the 75, tighten till the swingarm stayed were I put it. No play.
So checking the bolt torque may fix some stock bushing play without replacing with bronze bushings.
Also keep them well greased. I put a shot or two every couple oil changes. The grease fills the bushings and minimizes the play as well as the wear.
Leo
Checking the fit of the pivot shaft in the bushes and in the frame is a good idea, especially if you find excess play.
On the 81 I thought the bushings were bad but when I started to take it apart I found the bolt thread broke off and a po drilled and threaded the bolt and put a 5/16's bolt in to hold it.
After I got it apart the stock fiber bushings were a very snug fit on the pivot tube. So I set the torque the way I did with the 75, tighten till the swingarm stayed were I put it. No play.
So checking the bolt torque may fix some stock bushing play without replacing with bronze bushings.
Also keep them well greased. I put a shot or two every couple oil changes. The grease fills the bushings and minimizes the play as well as the wear.
Leo
glennpm
Another Old Biker Nut!
Hi 5Twins,
Just wondering if you have also drilled holes in the swingarm pivot bolt shaft so that the grease would be supplied directly to the new holes you drilled in the sleeve? Good mod and I can do it easily now and will.
thanks,
Just wondering if you have also drilled holes in the swingarm pivot bolt shaft so that the grease would be supplied directly to the new holes you drilled in the sleeve? Good mod and I can do it easily now and will.
thanks,
No, the grease will travel down the inside of the sleeve and go out the middle holes as well. Besides, the pivot bolt already has an inherent weakness - the threaded end is prone to breaking off since it's under-cut into the shaft. The last thing you want to do is weaken the bolt further by counter-boring the grease flow holes through the center of the bolt deeper. As I said, I like to do both mods - the added center grease nipple and the extra holes in the pivot sleeve. Grease is a wonderful thing once you take it out of the can and apply it, lol. It does nothing sitting in it's factory container. You need and want it applied at least yearly to your swingarm pivots. I can pretty much guarantee those poor things have been starved of it since they left the factory.
Had the swing-arm bolt break at the thread taper on my 83 Heritage. Don't know if it had anything to do with the frame. I found out that this was a common problem for the XS650.
glennpm
Another Old Biker Nut!
Thanks 5twins!
A few things to note, people.
1. A properly installed swingarm should fall under its own weight when released.
2. If insufficient torque is applied to the pivot bolt flex at the pivot will be aggravated and the bolt will break at the threaded section where its diameter is stepped down. This is why I no longer use needle bearings; the thrust bearings used in those kits tend to lock up when more than 30 ftlbs. is applied.
3. If the swingarm locks up with less than 47 ftlbs. of torque applied, it's either because the pivot tube is locked up in the bushings or because the pivot tube isn't long enough to clear the bushings and keep the bushings from contacting the thrust plates in the seals.
4. Bronze bushings usually have thicker flanges than OE nylon bushings and often cause inadequate relief. The cure is to knock a few thousandths off the ends of the swingarm with a flat file. Measure side play and flange thickness first, use a thickness gauge to scribe lines before filing, install bushings, check fit, and if you have to, pop out the bushings and file again. Bind between pivot tube and bushings can be corrected with a fine paper roll on a rotary tool. Max. side play is 0.5 mm.=0.020". Correct with shims if necessary.
1. A properly installed swingarm should fall under its own weight when released.
2. If insufficient torque is applied to the pivot bolt flex at the pivot will be aggravated and the bolt will break at the threaded section where its diameter is stepped down. This is why I no longer use needle bearings; the thrust bearings used in those kits tend to lock up when more than 30 ftlbs. is applied.
3. If the swingarm locks up with less than 47 ftlbs. of torque applied, it's either because the pivot tube is locked up in the bushings or because the pivot tube isn't long enough to clear the bushings and keep the bushings from contacting the thrust plates in the seals.
4. Bronze bushings usually have thicker flanges than OE nylon bushings and often cause inadequate relief. The cure is to knock a few thousandths off the ends of the swingarm with a flat file. Measure side play and flange thickness first, use a thickness gauge to scribe lines before filing, install bushings, check fit, and if you have to, pop out the bushings and file again. Bind between pivot tube and bushings can be corrected with a fine paper roll on a rotary tool. Max. side play is 0.5 mm.=0.020". Correct with shims if necessary.
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