rear disk brake mount?

[sluginxlt]

i mounted the rear caliper "bar" and was wondering if you guys think this will work right. i cut the factory bar way down and welded it back together with a slug inside. i bent the ends to make it meet up with the frame tubes and cut the mount off the swing arm to use on my frame. i couldnt really find any info on they way people usually mount them and wanted to make sure this looks and sounds like it should work right and be strong enough.

 

[XSLeo]

Looks like it should work. As long as it keeps the caliper and bracket from moving with the rotor then your golden.

 

[sluginxlt]

thats what i figured too. just didnt know how much force is put on it during breaking and wasnt sure if the bent bar would be strong enough.

 

[gggGary]

Just kibbitzing here. The only brake?
Zero nada zip experience with what you have done but for sure some torque and compression forces will be applied to the arm. Now that it's all done I wonder why you didn't use an inside the rear upper tube mount (straighter line of force) instead of on the top mount?
PS like the looks of your frame work, there are there more complete pics somewhere?
As far as that goes why not just rotate the whole caliper mount forward and use a through bolt to a welded mount on the frame skipping the rod entirely?

 

[sluginxlt]

gggGary^ It will not be the only brake im gonna run the front factory disk also. not sure why i didnt just run a through bolt to a mount and get rid of the bar, i thought there was a reason but ive been messing with alot of stuff so i dont really remember, maybe ill go check and see if there was a reason. also if you wanna check the bike out i have a build thread here http://www.xs650.com/forum/showthread.php?t=557

 

[Tech7]

You need that link, so you can have an extra pivot, so the chain can be adjusted.

 

[sluginxlt]

You need that link, so you can have an extra pivot, so the chain can be adjusted.

I was just gonna post that, as soon as i looked at my bike i remembered that is why i needed the link

 

[DLD1]

The amount of force applied to the frame with that short of a link is very high. By using a longer link the the forces will be reduced at the point of attachment. The previous poster makes an important point also, you need it for chain adjustments. Although I've never built a motorcycle frame, I have designed and built 7 SCCA formula cars and raced them, so I can tell you with some experience that a short arm like yours may not cause a problem, since you have a front brake and most of the braking will be done by it, it could cause a problem. By the way, I like the looks of your framework.

Good luck,

DLD

 

[Tech7]

I would think that the tire would lock up well before there was enough force applied to that arm to hurt it, being on the rear. Of course that is just a guess.

 

[gggGary]

Duh oh!

yeah chain drive huh!

 

[TwoJugs]

With the bends you have in the link you also give the rod points of stress that fall directly on the bends. With the stock rod the load is more of a compression, inline force. My concern would be the jog bends? It will probably be fine but you can find a heavier piece of tube then the stock one to make one stronger.

 

[DLD1]

I would think that the tire would lock up well before there was enough force applied to that arm to hurt it, being on the rear. Of course that is just a guess.

My concern wouldn't be hurting the frame. You are right that the tire would undoubtedly lock up and slide before any damage is done. The concern would be the geometric forces it applies to the frame and how it might effect the handling/attitude of the bike. Closely coupled like the photo shows puts a tremendous amount of rotational force on the frame, which could have an adverse effect on the handling under braking.

Gary,

If you are an easy rider (no pun intended), chances are it would never be a problem. I tend to think in terms of racing forces and handling, so that's where my concern comes from.
good luck with your project, and show us some photos of the whole thing.

DLD

 

[Tech7]

My concern wouldn't be hurting the frame. You are right that the tire would undoubtedly lock up and slide before any damage is done. The concern would be the geometric forces it applies to the frame and how it might effect the handling/attitude of the bike. Closely coupled like the photo shows puts a tremendous amount of rotational force on the frame, which could have an adverse effect on the handling under braking.

Gary,

If you are an easy rider (no pun intended), chances are it would never be a problem. I tend to think in terms of racing forces and handling, so that's where my concern comes from.
good luck with your project, and show us some photos of the whole thing.

DLD

Excellent point. Hadn't thought of the effects on the frame. Glad to have someone here with racing knowledge. Gives another perspective to think about. Thanks. You're right though, doubtful this hardtail chop will ever see racing forces applied to it!

 

[sluginxlt]

i ended up not liking the look of it anyways, posted pictures of the new setup in my build thread here http://www.xs650.com/forum/showthread.php?t=557