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My solution to the GSXR rear caliper brake stay.

Started by TheRadBaron, March 25, 2012, 04:20:13 PM

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TheRadBaron

I just finished up with swapping a 17x5.5 rear wheel from a '90 GSXR-1100 onto my '84 FJ.  There's been a lot of discussion about how to get the brake stay rod hooked up.  The most common solution seems to be to hook it up to the mounting point for the center stand.  I tried this at first but I was unsatisfied with it for a few reasons.  One reason was that I simply didn't like the way it looked.  I'm definitely a function-over-form guy, but the long, low slung rod just looked crude to me.  I also didn't like the way the rod needed to be mounted in such a way that it could move (rotate slightly at both mounting points) with the suspension travel.  Not having the proper shoulder bolts or bearing-type mounts for the non-factory modification, there was an unacceptable amount of slop in the linkage when it was mounted loosely enough to move freely.
Here's what I came up with: 


It's a piece of 1/2' OD steel tubing, 1/16" wall thickness, with 3/8" male spherical rod ends plug welded into it.  I made the front mounting point out of 1/4" steel plate.  It bolts under the bolt for the rear suspension linkage through the swingarm.  The shape of the front mount is somewhat crude since I was using basic hand tools and a bench grinder to shape it, but it works well.  The whole assembly mounts to the swingarm, so suspension travel won't effect it.  The rod ends allow for a system that has no slop but can still allow the caliper to move for chain adjustments.  It lines up so that the mounting points are almost perfectly in line, and there's plenty of tire clearance.
I ordered the rod ends and the neat little seals from McMaster-Carr.  The seals will be nice for keeping grit and water out of the rod ends and wearing them out.  The total bill for the materials was maybe $40.  It's a bit expensive for a simple brake stay, but I'm really happy with the results.  I'm not sure if there could be a problem with the way the stay is mounted to the caliper (offset to one side of the mount) causing it to transmit the braking force in a "non-linear" way to the caliper.  I guess that might cause a bit of twisting action and possible wearing the pads unevenly.  Or maybe I'm being paranoid and everything will be rigid enough to avoid that.
The desire for safety stands against every great and noble enterprise.  -Tacitus

Arnie

Well, that will certainly work.  I think you've over thought and over engineered this, but that's your choice.
I'm curious why you didn't just put a clevis on the caliper end of the rod and let the forward end take care of your angular changes.

Arnie

moonrunnah

it looks good to, no bulky shit, i hate when things look over  crowded
When in doubt throttle out

DB Cooper

I remember when sex was safe and skydiving was dangerous.

TheRadBaron

Quote from: Arnie on March 25, 2012, 08:08:39 PM
Well, that will certainly work.  I think you've over thought and over engineered this, but that's your choice.
I'm curious why you didn't just put a clevis on the caliper end of the rod and let the forward end take care of your angular changes.

Arnie

You're correct that I put a lot of thought into this setup, but I don't think I necessarily over thought it.  I might tend to over-engineer things, though.  I'm not an engineer, but my dad is so maybe it's genetic. 
I thought about the rigidly mounted clevis on the caliper end, but I wanted both ends to be able to move freely since there would be slight angular movement at both ends any time the chain was adjusted.  I didn't want to have to fool with loosening the brake stay mounts when I adjusted my chain.  
I also just REALLY like spherical rod ends.  I think that they're brilliant and I like to fabricate things with them.
The desire for safety stands against every great and noble enterprise.  -Tacitus

Dads_FJ

I'd say you followed the KISS theory quite well.  Nicely done!
John S.

'84 Yamaha FJ1100
'89 Yamaha FJ1200
'94 Yamaha WR250
'80 BMW R100S/Sidecar
'39 BSA WM20