Need swing arm pivot tube measurement

[Sci85]

Hello,

Can someone measure their stock swingarm inner bushing/pivot tube length? I bought this bike as a work in progress and so far, I am finding lots of effed up stuff by the PO. Anyway, upon inspection of the swingarm, the pivot tube is sitting below the out brass bushings by at least an 1/8". Mine measures 197mm or 7 3/4" while the inner swingarm measurement on the frame is just shy of 8". I know there should be a little clearance but this seems excessive. I'm thinking this inner tube may have been cut down for some reason looking at the end markings.

Anyway, if someone could get me their inner bushing/pivot tube length and possibly the frame to frame inner measurement that would be very helpful.

Thanks!

 

[80brat]

7-3/4 is right but also dust caps or seals

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[Sci85]

Really? That leaves me just under 1/4" between the frame rails and the pivot tube. That seems way too much to pull together. At 7 3/4, with the brass bushings installed, the pivot tube does not extend beyond the swingarm bushings. In fact, it's below them by about the thickness of a brass bushing flange. Is it common to have to shave down the brass bushing flanges by over half their thickness?

Thanks.

 

[gggGary]

There are some brass bushings around with "too thick" flanges. Was the swing arm powder coated? that can add some width.

I had an 83 that was really wide between the rails, I ended up adding a machine bushing, or two to make up the distance. Here's a good thread on the swingarm set up

 

[Sci85]

Hey thanks for the reply. Im shocked the PO doing this build before was thinking this setup was ok.

I read that thread and yeah, the swingarm was powder coated. So, I will remove the existing brash bushings and remove any paint that is covering the swingam ends. But, it will still leave too much xlearance between the frame rails so i'm interested in your bushing setup. I'm assuming it fits against the pivot tube yes? How much space did you need to take up? Is there a factory side clearance spec for this fitment?

If you wouldn't mind sharing your OD, and ID of the bushing you made that would be helpful.

thanks again.

 

[gggGary]

It's been several years I think I went down the to local hardware and picked a machine bushing or 2 with an ID that fit, 3/4" maybe? the OD was plenty big no clearance issues.

Heres a pic of that swing arm. You might eyeball the thickness of these flanges with yours.


Seems to me the spec is that the shaft should be about .0004" proud of the flange.

 

[Sci85]

Yours do look thinner. I'm not too worried about getting the pivot tube proud of the bushings as I can remove material from the flange and the swing arm. Im more worried about the frame clearance.

so, just so I'm clear, any washer or bushing needed to take up the clearance, it needs to press against the pivot tube correct?

 

[gggGary]

Once you have the pivot tube, flange clearance set; the grease seals go on, then the spacer would go between that and the frame. One or both sides as needed so you don't have to bend the snot out of the frame to compress it so the pivot tube does not rotate on the bolt. The ID of the spacers should be the bolt size the OD is really not critical.

Please let us know what works for you and if you could get a pic it would be great!
I had a bunch of shots of this project but not one showing the spacer(s) in place.

 

[TwoManyXS1Bs]

Maybe some help in here: http://www.xs650.com/forum/showthread.php?t=28637

 

[gggGary]

My pet theory on this is that by 1982 the tooling and jigs were getting worn out and tolerances were getting sloppy. This a typical sell a product till the tooling is worn out manufacturing practice. After the first couple of years the XS650 was a "loss leader" get em' in the door then upsell type of bike.

 

[Sci85]

Well, after looking more closely at the swingarm, I noticed that the right side bushing was not fully seated. It looks like he also had them in during the powder coat so I had to pull them and sand the ends of the swing arm. But, it was still not enough. So I ended up having to remove about 20 thousandths from each bushing flange. I do not know where he got these so i can't speak to that. I am sitting on about 40 thousandths proud now. That's what it should be correct?

oh, and I did have to get a cylinder hone to get the shaft to actually rotate within the bushings. I should know better than to buysomeone elses project mistakes haha.

 

[5twins]

You'll need to consult your factory shop manual for that dimension. Although I'm not sure it was ever even listed. This is something that was assembled at the factory and we, the end users, were never supposed to fuck with. Flash forward to 30+ years later and guess what - we need to throw a few humps into them, lol.

 

[gggGary]

Pregrid claims he found .040" as book spec MAX freeplay, but that seems like a bit much....

Quote Pregrid "OK, the only spec I see in the book is for swingarm f(r)eeplay which is .040" max. So am I right in assuming that if the pivot rod sticks out .020 or less from the bushings I'll be golden?"

OK that IS what the book says. freeplay .040" or 1.0 mm To get that figure shocks and wheel removed grasp end of the arm moveleft, right. So if the freeplay is .040", is that back there????? Who knows and they don't even mention the assembly shims found on some bikes. I guess though you are in line with the spec and "should be good" You obviously did a lot of reading about this, good on you. Did you notice I got caught out early on about the placement and function of the OEM shims vs. the spacers we talked about above? I still think some frames, yours maybe, need some added shims rather than the big crush to take up the wide gap.

 

[Sci85]

Thanks guys. I will mock it up and get a "feel" for what it looks like and how it performs. I'm sure the freeplay should be minimal, whatever that is haha.

 

[xsdogstar]

I measured the frame (447-106555) 1975 and the inside dimension is 7.5".

Will a 1977 swing arm work on the 1975 frame?

What are the differences.

 

[gggGary]

Yes 75-77 are the same. All swing arms 74 up will fit, the 78-80 specials had disc brake mounts not drum.
The 74-79 standard model swingarms have a provision to remove the axle out the back, the 78-83 special swingarms have a closed rear section so the axle has to be pushed out the right side. The special pipes are upswept, the straight back standard pipes won't allow axle removal to the side without also removing the shocks. But the arms can be used on either frame.

 

[gggGary]

Yes 75-77 are the same. All swing arms 74 up will fit, the 78-80 specials had disc brake mounts not drum.
The 74-79 standard model swingarms have a provision to remove the axle out the back, the 78-83 special swingarms have a closed rear section so the axle has to be pushed out the right side. The special pipes are upswept, the straight back standard pipes won't allow axle removal to the side without also removing the shocks. But the arms can be used on either frame.

 

[xsdogstar]

thanks gggGary

Great answer. Awesome.

While we are at it...

will the rear motor mount for a 77 work with a 76 engine on a 75 frame...

Anthony

PS Great quote... I'm writing it down and bringing it to work tomorrow. And will have a quote from Joe here tomorrow as well...

 

[gggGary]

yupper all motor mounts 74 up interchange. Some of the specials had chrome front mounts. 72-73 engines will fit in the later frames if you use the later mounts also. 70-71 engines and at least the front mounts are a bit different from any other years.

 

[Sci85]

gggGary, no expert my arse..Good stuff dude. Anyway, I put it all together and torqued it to 47 ft lbs. Swingarm doesn't move on its own. Seems to me if the pivot tube is supposed to be proud of the bushings and clamped between the frame rails, then the swingarm should move freely correct? Or do you need to wait for the new bushings to wear some?

Also, how are you getting the seals over the bushings? Mine seem to be too small to want to fit over the ends of the bushings.

thanks.