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Mount Dual Piston Caliper Behind Fork

Discussion in 'The Garage' started by mrtwowheel, May 15, 2019.

  1. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    This is what I wanted to do on my '74 TX650A. I wanted to swap the forks side to side, put the axle in backwards, change the hardware around so that the caliper can be mounted behind the right fork. DSCN4664.JPG

    I saw no problems with doing this. A banjo bolt would even work to replace the steel line and fittings.

    I swapped the forks and put the wheel on with the axle and all backwards. After doing this the wheel was about 1/4" offset between the forks and the caliper was not aligned with the rotor. Something was definitely different when swapped side to side. I checked the rim to hub difference side to side, no difference there, the rim was centered to the hub. Then I thought about the right spacer and the speedometer drive that actually is a spacer too. Straight edge across speedometer drive and measuring to the hub flange, HEY, the speedometer drive was 3mm lower than the other spacer. Thinking 3mm plus 3mm is damn close to 1/4", that must mean something. DSCN4665.JPG

    I put 3mm of bushings between the left fork and the speedometer drive. I had about 3mm gap between the other fork and spacer before, so, I mounted the wheel with NO gap. This 3mm change put my wheel exactly in the center of the forks, the rotor is centered in the caliper, and the castle nut and cotter pin are just right too. DSCN4668.JPG

    Above, no gap now, or I could take 2-3mm off of that spacer, but I think it's just right now.

    Comments please, pelt me with rocks and garbage.

    Scott
     
    Last edited: May 15, 2019
    gggGary and Jim like this.
  2. Mailman

    Mailman Hardly a Guru Top Contributor

    No rocks and garbage from me Scott. I think you pulled it off really well. I would’ve never thought to do that.
     
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  3. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    giphy.gif

    Nah.... looks good Scott. Nicely done.
     
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  4. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    Thanks Bob and Jim, Maybe there is a flaw in there somewhere. I just can't see one yet.

    Scott
     
  5. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Good work! Watch that the speedo drive doesn't spin, it shouldn't but..........
     
    Jim likes this.
  6. 5twins

    5twins XS650 Guru Top Contributor

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    Have you ridden the bike like this yet? I think there's going to be an issue with the speedo drive. It's spinning in the opposite direction now.
     
  7. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    No, speedometer drive is still on the left side going in the same direction. I've had more than a few Honda's with no positioning dogs on the forks for the speedometer drive, the angle of the cable drive is positioned when assembling, most of those Honda's still had the positioning dogs on the speedometer drive from yesteryears but no matching dogs on the forks.

    Scott
     
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  8. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    This was done with a wheel that was trued and forks that had already been disassembled, cleaned and checked for straightness. To offset the wheel and hub or tweek/bend any other part would have been the WRONG thing to do.

    Scott
     
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  9. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Kinda thinking out loud; is the speedometer drive still CLAMPED into position by the axle nut, or is it it now just filling the space. between wheel and fork? I think it's now the former, if so you WILL need a positive locator for it.
     
    Jim likes this.
  10. Jim

    Jim The thrill of victory and da agony of da feet. Top Contributor XS650.com Supporter

    I've had bikes in the past (don't remember which ones) where the speedo drive housing was free floating. You could grab the cable and rotate it easily. Often wondered what kind of damage the cable would do if it ever locked up....:yikes:.... but, never had one fail.
     
    gggGary likes this.
  11. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I'm not asking the question that you think I'm asking, please read the whole thread.
     
    gggGary likes this.
  12. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    DSCN4670.JPG

    Above, this part of the speedometer drive housing bears against the fork leg in my configuration, or against the shoulder on the axle in stock form. DSCN4669.JPG

    Above, this part which is also part of the speedometer drive housing bears against the inner race of the wheel bearing. A free floating speedometer drive on my bike would be a loose axle, whichever way the axle was inserted.

    Scott
     
    Jim likes this.
  13. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I could disassemble everything and mock up the axle and spacers to show the 3mm difference when the axle is inserted both ways, but I'd rather not. I'm very certain that this is a change that was done right and will work and be safe. I'm a happy guy.

    Scott
     
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  14. 650Skull

    650Skull Dinosaur Lives Top Contributor

    On a 36 spoke hub......
    I measured from the outside of the spaces to the flanges..........then from the face where the rotor sits to the flanges............and from the outside of the spacers to the Hub rotor face

    Rather than post a whole series of pics showing all the differences in the first 2 above.....................This is where the 3mm difference is...............
    IMG_0436 copy.jpg IMG_0438 copy.jpg
    Set up to show how i measured...........couldn't take pics of the actual act IMG_0436 copy.jpg IMG_0438 copy.jpg
     
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  15. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    My same discovery, and that was the answer to my puzzle. Thanks Skull.
     
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  16. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    3mm, it is what it is. I really wish I could make it disappear so you would feel better, But I can't do that and stay here in the real world at the same time.
     
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  17. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    My bad! Finished thinking this through; and of course, the axle nut still pulls everything from spacer to speedo drive together into a non-turning unit.
    front axle wheel reversed.jpg
     
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  18. solo2racr

    solo2racr Suck, Squeeze, Bang, Blow

    Which is exactly why if a fork tube is bent even a slight amount, a caliper on the clamp side will not align with the disc. Which if you look at mrtwowheel's very first picture, is exactly what he was trying to do.
     
    gggGary likes this.
  19. gggGary

    gggGary Stop that! Top Contributor XS650.com Supporter

    Take a look the speedo drive is much thicker than the spacer there's a lot going on on left to right spacing. need to set up some gauges but there appears to be a difference in fork tube centerline to inner axle flat 'tween left and right 34mm forks. The lawnmower re-engine parts fabrication project is taking precedence this morning..
    20190516_164534.jpg
     
    Jim likes this.
  20. mrtwowheel

    mrtwowheel Honda Etched On Brain Top Contributor

    I'm headed out to the shop. Today is a day to deal with parts and tools, not a good day to deal with peeps. Should have read my horoscope.

    Scott
     
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