Fork widths, axle lengths, spacers and the like.

[dirt3rats]

I searched the board and found 1/2 of my answer. Now I need the other half. According to my research (on this site) I have come up with the following info. Please correct me if I got any of this wrong.

1. 72-73 forks are different (34mm) than later 74& up (35mm)

2. The width between forks on later models (74&UP) is around 180MM

What I need to know is the distance between the fork bottoms in relation to the front axle. I was fairly certain the front end I am working with came from a 72 but after scouring this site, I am now completely uncertain about my ability to count correctly. I would have bet money that I came up with 150MM i.D. for the forks but I can't seem to verify that at all and I am currently unable to measure it again anytime soon. I am trying to get some numbers to a guy for axle spacers for a custom rim. Did I mention that I am nowhere near the bike?

All help is appreciated.

Signed,

Stuck at work

ps. If anyone has ever used the old knuckle/pan style axle adusters with a stock XS axle, point me in the direction of a damn parts source already.

 

[littlebill31]

Here's 2 threads on it that might help a little.
http://www.xs650.com/forum/showthread.php?t=12443&highlight=fork+swap
http://www.xs650.com/forum/showthread.php?t=15137&highlight=fork+swap

 

[dirt3rats]

I read them but didn't find what I am looking for. I am trying to find the distance between the fork bottoms. I thought I came up with 150mm from inside to inside but after finding a numerical error with my bearing spacer dimensions, I am second guessing my other dimensions as well. Since I am not near the bike, I was wondering if anyone had these dimensions handy

 

[GreasyC]

We can all throw some measurements at you of our bikes but the only guy who's really matter are the guy you're making the spacers for. Some reason he can't measure the actual forks this will be fitting?

 

[dirt3rats]

I guess I didn't make myself clear. I was looking for the distance between the fork lowers for an older stock XS and I wasn't near the bike to double check my original measurements. No one was able to provide an actual answer so I used some other resources and figured it out. Thank you for your responses.

 

[dirt3rats]

And in case anyone else is looking for the same info, the measurements for these forks were 150MM inside to inside, 35MM tubes w/external top nuts.

 

[XSLeo]

In your first post you have a few errors. 70-76 had 34 mm forks, 77 up had 35 mm forks. The 76 forks were the first year of the caliper being behind the forks.
The set of 75 forks I have leaning on the wall next to me measure 155 mm between the fork lowers at the axle.
From the wheel swapping I have done all years were spaced the same. That's a 75, 81 and 82, both mags and spoked wheels.
If you measure the disc brake caliper mounts the earlier bikes used a center to center on the mount bolts of about 82 mm, the later disc brake, 77 up used a CTC of 110 mm.
Don't have a 70-73 to compare. So they maybe different.
If you go to a parts place like boats.net and look through the parts listings you can compare your forks to the pics and get a pretty good idea of what your forks are.
Leo

 

[dirt3rats]

This front end must be some sort of mutt then. The tubes are definitely 35MM, with caliper setups on both sides, but the distance between the two at the axle is only 150MM. The triple is the longer, late model one.

 

[XSLeo]

That longer caliper mount means It came off some other bike that used 35 mm forks. I have no idea what though.
Maybe some of the people out there with other bikes can tell us what the 150 mm spacing came from.
Early Harley Sportsters and FX's used a 35 mm fork. Don't know the caliper mount spacing though.
Leo