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Help needed: Rotor bolts for spider and hub

Discussion in 'The Garage' started by QWERTYMage, Apr 19, 2016.

  1. QWERTYMage

    QWERTYMage XS650 Addict

    I need to find a replacement for a single missing rotor bolt (small bolt, attached the rotor to the spider) and 3 bolts for the spider (large, attaches the spider to the hub)...

    What sizes are the two types of bolts (thread, pitch, length)? I will be buying a complete set of each size to ensure they are balanced.

    It's for a '75.

  2. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

  3. QWERTYMage

    QWERTYMage XS650 Addict

    Wow. That's great stuff. Thanks!
  4. QWERTYMage

    QWERTYMage XS650 Addict

    The Smaller "spider bolt" is M6 18mm length. Part number 90109-06018-00. Ordered from Boats.net

    The bigger "Hub bolt" is M8. Unknown length. Part number 90109-08367-00. Not in Boats.net inventory.

    This helped a lot, TooMany XS1Bs. Thanks again.
  5. TwoManyXS1Bs

    TwoManyXS1Bs BBQ Hunter Top Contributor

    Good. That '06018' is easily decoded.

    Bit more of a challenge. That '08367' *might* be decipherable, research that 2nd link.
    The middle '3' may mean a special head or treatment, with possible length of 67mm.

    You're welcome. Often not sure if helping, or making it worse...
  6. fredintoon

    fredintoon Fred Hill, S'toon. Top Contributor

    Hi 2Many,
    FWIW, I just swapped my front disks from one wheel to another so I still vaguely remember the disk attachment bolt sizes.
    8 has to be the M8 thread size.
    The final 67 translates to 2-5/8" which seems a bit too long for the bolts I took out but admittedly I didn't measure them.
    The 3 might indicate a reduced head size because the stock bolts on one side have smaller heads than the Bolt Supply House sourced Gr 8.8 bolts on the other.
  7. 5twins

    5twins XS650 Guru Top Contributor

    Why not just measure one of the three remaining bolts you have?

    The disc mounting bolts are M8 and have the standard thread pitch (1.25) but if your hub has blind mounting holes, you must be sure what you use isn't too long. If it is, it could break the back out of the hub.

    On the later hubs, starting around '76 or '77, the holes were open on the back and the bolt part number changed. That may indicate a longer bolt. The later bolts are 30mm long but like I said, that may be too long for an early blind hole hub. If you have one, best you measure the hole depths, add 7mm for the disc thickness, then knock a couple MM off for clearance and just to be safe. On a blind hole hub I have, I'm using 22mm long bolts. That just happened to be what I had on hand in stainless. I'm thinking the originals may have been 25s, but don't hold me to that.
  8. 5twins

    5twins XS650 Guru Top Contributor

    My blind hole hub. It's from a '73 or '74 TX750 .....

  9. QWERTYMage

    QWERTYMage XS650 Addict

    I was gonna measure as a last resort. I want to make sure I get as close to factory spec as possible, since my life rests on the brakes working properly.

    Thanks for the help, guys!

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