Variables...what are they?

[JP50515]

Hey guys...now this one will be hard to explain without pics but try and follow me here.

I have a 1999 Gsx-r 750 front end. In order to run my spoked rim I need to swap wheel bearings...pretty straight forward right...wrong!

The bearings don't exist, they can be made custom but are asking an unearthly amount for them...which I expected to be the case.


Now another member on here and I recently worked together to come up with an adapter that would allow him to run a different caliper with his brake setup. All it was was a spacer with a bolt hole pattern essentially.

What I think I am going to do...is order the stock gixxer wheel bearings, make two more of these spacers, except instead of clearing the middle, I will bore them to fit the gixxer bearings.

So if you're still following, the spacer will bolt to the hub, where to rotor normally does, it will have a bolt hole pattern to space out the new rotor, but it will also house the wheel bearings.

My concern here is staying concentric....which I believe I can achieve by simply bolting one spacer on for boring, and clamping directly to the hub in the lathe chuck. My next concern is using strong enough bolts which shouldn't be too difficult to find.

I just wanted to throw this concept out there to see if anyone could think of any other potential issues?

I've seen this done before so i know it works, but any input is welcome.

Thanks

 

[gggGary]

For best security especially if you do not retain the inner lip that keeps the rotor concentric with the hub, the bolts should have a larger diameter unthreaded shank that extends through the rotor, spacer and a bit into the hub. IIRC the gixxer bolts like "all modern sport bike brake bolts" have that large shank but they won't be long enough because of your added spacer. Finding the correct length of that type bolt should prove "interesting"

In brief the fastener provides two separate functions; the thread creates the tension to hold the rotor tightly to the hub, the shank has the larger diameter and smooth (as compared to thread ridges) bearing surfaces to transfer torque forces from rotor to hub. The spacer makes transferring the torque force even more critical....

No engineer I am, but I have thought about this while working through various hub, brake, fork combos.

 

[gggGary]

Shoulder or stripper bolts can be found several places but note they often have reduced diameters at head and thread/shoulder junctions....

With the extended length do not use stainless bolts, which have a lower tensile strength than say 12.9 grade.

 

[JP50515]

good info there Gary,

That's what I was thinking about too. Last thing I need is to shear the bolts and find myself speeding towards some immovable object lol