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Can I exchange '75 fork lowers with '77 fork lowers?

Discussion in 'The Garage' started by JMcNinch, Jun 5, 2015.

  1. JMcNinch

    JMcNinch JMcNinch

    Hey guys, I have a set of fork lowers that will not hold back oil, even with new fork seals. Apparently when the last guy changed the seals, they just pried against the weak aluminum cracking them / changed the shape of the cup that holds the seal.:doh:

    My bike is a 1975 and I have a local junk yard that has a pair of forks off a '77. Does anybody know if I can do a direct swap of the fork lowers? Are the tubes the same from '75 to '77? My main concern is the location of the brake brackets etc.

    While we're on the topic, how do you guys get stubborn stuck fork seals out? What techniques etc have you had success with?:banghead:

    Attached Files:

  2. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi JMcNinch,
    '77 is dodgy because it's the first year for 35mm fork tubes so take your caliper to the junk yard to be sure.
    If the donor forks are 34mm you are golden.
    If they are 35mm you'll need the complete fork from triple trees down to brake caliper plus the one piece brake disk that fits it.
    I've gotten away with prying fork seals out with a big screwdriver but there is a tool for that.
    It's been shown here a while back, perhaps the search button can find it?
  3. weekendrider

    weekendrider Iron Horse cowboy Top Contributor

    S.W. MO
  4. JMcNinch

    JMcNinch JMcNinch

    WTF? I cannot even comprehend that method of getting the fork seals out, but I imagine it would create the amount of force necessary to get the job done.
  5. JMcNinch

    JMcNinch JMcNinch

    Thanks for the info. I know for a fact the tubes on this particular '77 are 35mm because I had the guy measure them for me over the phone. Looks like I'm gonna have to hit ebay.
  6. 650Skull

    650Skull SSSSSSSSSlither Top Contributor

    Put a wanted add on here. Often forks sets for sale as well
  7. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi JMcNinch,
    what Skull said. Lots of good XS650 stuff bought and sold via the site want ads.
    Think about upgrading to 35mm forks. You might find a set in the want ads.
    Or how much of the 77 front end is there at the junkyard?
  8. buzzword

    buzzword XS650 Addict

    I'll have a clean and functional set of 34mm forks/triples/caliper/rotor for sale here shortly as I'm doing a GSX-R USD swap on my 75. If you're interested, shoot me a PM and we can work something out.
  9. JMcNinch

    JMcNinch JMcNinch

    Thanks for the tip. I ended up finding a nice set of forks on ebay. I believe they were a couple years older than 75 but not sure exactly what year they are from. I just dropped the whole fork assembly out of the triple clamps and put these up in.

    I am interested to see your fork swap because I have thought seriously about modernizing the front end of my bike too. Let us all know how it works out!

    - Joe
  10. XSLeo

    XSLeo XS650 Guru Top Contributor

    Ok, the first two years had drum brakes up front. 72 had a one year only floating rotor set up. These won't work with the 73 up solid mount rotors. A set of 73 to 76 forks will work with your calipers. The 76 just moved the caliper to the rear of the fork.
  11. JMcNinch

    JMcNinch JMcNinch

    That basically sums up what I found out. The forks I ended up with must have been 73's then. I believe them to be older than the stock forks I had. The fork lowers were subtly different. I rode the whole season last year with the new set and had no issue whatsoever. I think this year I may try to shave the excess tabs off the left leg.

  12. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Joe,
    the tabs ain't "excess" it's just that you are not currently using them, what if you change your mind about that and decide to install the second front disk?
    It's way more difficult to put the tabs back on, eh?
  13. JMcNinch

    JMcNinch JMcNinch

    If I ever were to go dual disks in the front it would be through a front end swap for a sport bike. I'm fairly content with the stock lackluster braking at the moment, but appreciate forethought! :thumbsup:
  14. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi Joe,
    yeah, forethought is good.
    Should you decide to do that upgrade you will be selling the existing forks to defray expenses.
    The current forks will sell more readily if they ain't been molested.

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