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Question about stripped thread on fork

Discussion in 'Norton Commando Motorcycles (Classic)' started by Jpvegas333, May 16, 2018.

  1. Jpvegas333


    Sep 21, 2017
    This is a 1974 Commando that we took and rebuilt the front forks. We put them back on and one of them had a drip from the bottom bolt . The drip seemed to get worse after each ride so I took out the front axle and tried to tighten it more which was a mistake because it stripped and i can't get it out it just spins. I opened up the top and tried to take out the spring but it won't come out. I thought, well a drip isn't so bad so I put it all back together and went for a ride and the next day there was a huge puddle of fork oil. what should I do to fix this stripped bolt? Thanks
  2. franko

    franko VIP MEMBER

    Dec 29, 2013
    Can the screw head be grabbed with a needle nose vise-gripe and pulled on while being turned out? Maybe try to get a small screwdriver under the head of the screw and pry up as you try to twist the screw out.
    Once you have it out, find out what size screw will work and drill/tap to that size
  3. Bob Z.

    Bob Z.

    Mar 30, 2012
    Sounds like you are describing the 5/16 x 24 bolt that attaches to the damper tube inside the slider.
    Perhaps the damper tube thread is damaged.
    There is a fiber washer located on the bottom of the damper tube that seals in the fork oil.
    Check the parts diagram. You will need to disassemble that fork leg again.
  4. RoadScholar

    RoadScholar VIP MEMBER

    Dec 28, 2008
    If it is the bolt that holds the damper body to the slider I'd strip the assembly as much as possible, use a pine wood dowel to jam the damper body then hit the bolt with an air wrench. If the bolt still refuses to unfasten you will have to center drill the head off the bolt. In any case be very aware of possible damage to the sealing surface on the slider.
    Nater_Potater likes this.
  5. Deets55

    Deets55 VIP MEMBER

    Oct 3, 2013
    I think the damper tube is turning with the bolt. I had something similar to that happen. I did not replace the fiber washer with a new one when I took my forks apart. I could not tighten the bolt enough on assembly because (I believe) the old washer was crushed and could not hold the tube in place while tightening the bolt, causing everything to turn. When trying to remove the bolt there was enough friction between the bolt and tube to cause everything to turn as a unit. I think I used an air gun to spin the bolt out. The speed of the air gun allowed the bolt to come out quickly and not cause the tube to spin. I think I also put some upward pressure on the slider to help bind the tube/washer/slider together. I installed a new fiber washer and everything went together fine.
    BrianG likes this.
  6. Nater_Potater

    Nater_Potater VIP MEMBER

    Apr 7, 2013
    You might first try the air ratchet after just pulling the axle out. Remove the seal hold-down nut and fender mounting bolts from that leg so as not to tweek the fender when the slider drops free (hopefully). When using the air ratchet, do so with quick, short blasts on the trigger. Most air tools have incredible acceleration, and you can use that to your advantage against the miniscule inertia of the damper rod. We used to change forks seals this way in the shop. It avoids having to take everything apart first.

    Last edited: May 16, 2018
  7. Jpvegas333


    Sep 21, 2017
    Wow! Lots of great suggestions! I really appreciate it. im Hoping this weekend I'll be able to try a couple of these and I'll report back ASAP.
  8. dave M

    dave M

    Oct 19, 2005
    I concur with others that it is probably the damper rod that is turning rather than a stripped thread. If you remove the fork, turn it upside down and compress the spring and fork tube against a piece of wood on the floor it stops the assembly turning sufficiently to get the bolt out, this also works in reverse when reassembling. I generally put the axle partially through it’s hole, making sure not to cover access to the bolt and use the axle as a convenient handle for holding and compressing while undoing the bolt. This method does not require an impact gun.
  9. Jpvegas333


    Sep 21, 2017
    Happy Memorial Day! God Bless our troops!
    I was able to work on the fork this morning. So the long story is, after I took off the front wheel the Norton very gently fell forward almost crushing me and the forks. Thanks to my dad's after market JC Whitney crash bar it rested happily on it I got a couple guys and picked it up and put it onto a motorcycle jack Was then able to get an electric drill and reverse out the 5/8 bolt fairly easily with the top chrome plated plug firmly screwed in while applying up pressure on the forks. Now I'm going to look for a bolt that is described in the parts list as the parts house is close by. The bolt that was in there is looking pretty stripped. I'll check back and update after.
  10. Danno


    Feb 7, 2010
    First thing that came to my mind. I have used the air wrench technique on all sorts of forks. Some 'require' a tool to hold the damper assembly when hand-wrenching. The air tool eliminates that requirement.