Swingarm pivot bolt upgrade, 16M?

Norton7d

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I read some posts that suggest a pivot bolt with a16 mm head is available vs original 14 mm, for strength, is this correct? If so, is it sold new?
 
Perhaps I'm missing the point but whilst the head of the shaft may be bigger the shaft diameter will be the same as OE.
You would need to be two separate gorillas to shear a 14mm head so does the extra size make any difference?
 
There's also a Suzuki swing arm bolt with full sized thread, part swap.
The bolt cracking at the "neck" where the threads end is a "thing". Guess I'm an outlier but have never cracked or seen a cracked one. I gotta be up in the 40-50 XS650s territory, prolly 8-to 10 bushing installs and 20ish swing arms removed.over the years.
 
This one: https://www.mikesxs.net/yamaha-xs650-pivot-shaft-swing-arm-bolt-with-nut-oem-447-22141-00.html
Ideally, they should have skipped the grease bores, since fitting a zerk on the top of the swing arm pivot area is a better solution. I had to blank off both ends, with one M6 grub screw, and one M6 countersunk screw, combined with a cupped washer I made, that covers the protruding thread, and also secures the M16 nut.

Thanks Arctic, any pics of your finished mod?
 
Could get some tomorrow. Basically drilled&tapped for a central grease zerk on top of the swing arm. Then blanked off the LH end with a short stainless steel M6 grub screw. And turned an alloy cupped washer, just deep enough for the protruding M16 thread, and secured it with a countersunk M6 allen head screw, 12 mm long. That way I accomplished 3 things: Securing the M16 nut, blanking off the grease bore, and covered up the end of the thread. Pretty good for a tiny washer :)
 
There's also a Suzuki swing arm bolt with full sized thread, part swap.
The bolt cracking at the "neck" where the threads end is a "thing". Guess I'm an outlier but have never cracked or seen a cracked one. I gotta be up in the 40-50 XS650s territory, prolly 8-to 10 bushing installs and 20ish swing arms removed.over the years.
Gary,
Could it be that on some oem bolts, the shoulder is machined with no or too small a radius, creating a stress raiser. Shit like that happens, like when H###a screwed up the machining on the VF500 Interceptor cranks in the 80s. The cranks broke due to insufficient fillet radius at the crankpin. So it can happen...
 
So I also read the 2 year only TX750 swingarm is a direct swap which is bigger / better, but not XS750 swingarm?
 
There's also a Suzuki swing arm bolt with full sized thread, part swap.
The bolt cracking at the "neck" where the threads end is a "thing". Guess I'm an outlier but have never cracked or seen a cracked one. I gotta be up in the 40-50 XS650s territory, prolly 8-to 10 bushing installs and 20ish swing arms removed.over the years.
I did the Suzuki swingarm bolt upgrade a REALLY long time ago, so long that I don't remember much about it. The Suzuki bolt is SOLID, not hollow like the XS650, no grease fittings on the ends, that's why it's better. You add a zerk fitting to the frame that lubes the bolt at the midway point -- 5twins just illustrated adding this fitting in his "$200 Special" thread. And yes, the end threads of the Suzuki bolt are full size, not stepped down.
I did a little searching, but I can't for the life of me figure out where I got the info on this mod. Maybe from the XS650 forum that closed a few years back? Anyways, the info told you what Suzuki swing arm bolt to order -- that part # is all you really need to know to do the swap. It was an off-the-shelf exact fit, and a very simple mod.
 
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It sure would be nice if you could track this info down. The bolt from the GS450/550/750 seems like a pretty common one but costs around $60 new. However, nice used ones can be had off eBay for about $10.
 
I wish I could track the info down, but I'm out of ideas. Someone else out there has to have done it, maybe they can help. arctic XS seems pretty sure it is the GS750/1000, maybe someone can verify.
I paid about $40 a long time ago (which was extravagant for me), so $60 new today sounds about right.
 
Checking parts listings on Partzilla, the GS450/550/750 bolt is different than the GS1000 bolt. So, there's no such thing as a 750/1000 bolt. The 1000 bolt also fits the GS1100, so it would be a 1000/1100 bolt. I suppose it could be either one of them. The 1000/1100 bolt is cheaper new, only about $40.
 
Okay, one more thing about the Suzuki bolt: the head end (opposite the threaded end) is a full hex head, so you have to shave one of the facets down to make it fit the stopper on the frame.
 
There's also a Suzuki swing arm bolt with full sized thread, part swap.
The bolt cracking at the "neck" where the threads end is a "thing". Guess I'm an outlier but have never cracked or seen a cracked one. I gotta be up in the 40-50 XS650s territory, prolly 8-to 10 bushing installs and 20ish swing arms removed.over the years.
Agreed. Though not near as many as Gary.:rolleyes:
If you shim the inner steel bushing so it's an interference fit in the frame, then the bolt would work just fine being little more than finger tight. I think the problem arises when there's a gap and instead of shimming, people just crank on the nut to try and suck the frame in tight against the bushing.... over torquing it. Properly assembled.... the original bolt is more than adequate. Here's my swingarm install.

swingarm shim.jpg


swingarm shim 2.jpg
 
Agreed. Though not near as many as Gary.:rolleyes:
If you shim the inner steel bushing so it's an interference fit in the frame, then the bolt would work just fine being little more than finger tight. I think the problem arises when there's a gap and instead of shimming, people just crank on the nut to try and suck the frame in tight against the bushing.... over torquing it. Properly assembled.... the original bolt is more than adequate. Here's my swingarm install.

View attachment 149028

View attachment 149029
:bow:JIM :bow2:
Wow someone else sees what I do. That in addition to the sleeve to bushing clearance shims, if the frame gap is too wide for the assembly a shim/washer to take up the gap BEFORE torquing down the pivot bolt nut is the answer. The good news is that about every hardware store in the land has 3/4" machine bushings, so getting a correct fit is easy peasy.
:pimp:
Sorry I missed the swing arm install where you did this.
FWIW it think this is more of an issue with the later specials.

I've always felt like a voice in the wilderness advocating for shims if there is a gap.
Also reefing that fame together forces the bushings out of alignment because there is ONE cross bar just ahead of the swing arm, so the big squeeze bends the bushings inward at an angle.
 
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Good comments Jim on the shim approach :thumbsup:
I currently have two swingarms and pivots apart. Neither warrant any part replacement. Even the original plastic bushings, which I was just so sure were awful, are in very nice condition ?
And they are quite difficult to remove btw. The original pivots are showing such little wear that it’s surprising. The threaded ends have ample radius in the corner. There is no worry about strength here. I was looking for opportunity for improvements here but am likely to just add a zerk on the swingarm and grease it and shove it all back together , With Proper Shims !
I also did see and like the grease groove lathe mod, but I cut just a shallow radius channel.
 

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