Fork axle lug removal

Discussion in 'Japanese polycylindered adventure bikes' started by Motociclo, Jul 15, 2018.

  1. Motociclo

    Motociclo Long timer Supporter

    May 18, 2017
    Not often you will ever have the need to remove axle lug, I never have had too.
    Had a beaten up lower fork leg off a 96 CR250, it is a KYB fork, so I thought I would take it apart.
    In the case of this leg, I Wasn't concerned If it was damaged, but I still tried to be careful. Not reusing any of these parts. More of a learning curve.
    Let's get started.
    View attachment 1280016
    This is the hex head grub screws that needs to come out first. KYB were kind enough to stake it also.
    I ended up just drilling the screw out. I ground down the stake flats, but couldn't get enough bite with hex key, so it just chewed it out.

    There is a technique that involves drilling out the flats of the stakes with a very small drill bit. Only just enough to remove stake. This should enable grub screw to come out.
    I have heard of people using EZ outs also to extract screw. Need to be careful not to drill to deep.
    Be warned, grub screw may likely be a pain to get out.

    After the screw is out. Get a Dremel tool and grind down the damaged threads.
    Shouldn't take much, but if you don't, damage to axle lugs is almost certain.
    Like I said, i drill screw out. I made a make shift end mill drill bit to remove remaining screw and to help clean up threads. Then tidied up with dremel bit.
    View attachment 1280067

    Now time for heat. I used a blow torch and kept it moving around lug. Got it pretty hot.
    I then got a piece of wood, placed on top of leg a gave a couple of good hits with hammer. Helps loosen stuff up.
    Applied a bit more heat, then started to twist off the leg. It started to screw off pretty easily. Go a bit forward, and a bit back. Then it stopped. If it does this, don't force it.
    I got Dremel out again a ground out burred threads. I reheated then put a bit of oil in hole also, then started the unscrewing of tube again. This time it came free. Still going bit forward, bit back. I add more oil down fork leg and in hole. It does help.
    Finally free. Not pretty, with 20 years of built up crud.
    View attachment 1280083

    This pic paints a good on the need to get screw out and clean threads.
    This damage is mostly caused by the remaining grub screw. After I got that out, and ground damaged threads It came free. On the left side of damage mark, it can be seen where grub screw lives. Only leaves a small mark.
    View attachment 1280092

    This Wasn't a real successful attempt to remove lug. Was hoping to do a better job.
    KYB forks have rep for being a bitch to get lugs off. No excuses though.
    The damaged caused to thread on tube isn't real good. Fork tube could be reused, still plenty of good thread and loctite would hold it very well. The threads in the lug are in good shape.
    If these parts were to be reused, i would be cleaning up threads on both parts and replacing o ring that lives inside lug.
    I believe WP and Ohlins don't use grub screws in lugs to hold tubes. Clearly they don't need it.

    A couple of points,
    Grub screw is a pest to get out. At least on this fork.
    The need to grind down damaged threads is also a must.
    Plenty of heat and a bit of patience.
    The only hard part is getting grub screw out and not damaging threads. Get that right and it is an easy task.

    Here is a link that has some good info on how to remove lug with some success.
    Lost Cartographer and RallyX like this.
  2. Motociclo

    Motociclo Long timer Supporter

    May 18, 2017
    Have had another crack on getting axle lug off inner tube.
    This time a good success.
    Plenty of heat, and got grub screw out first.
    Very gently. Screw out a little, then in a little. Repeat until it is out. Note the peened end of grub screw.

    Inspected hole grub screw came out of. Not much burring on thread on inner tube. Decided not to try and clean up threads.
    Reheated lug and then put a little cutting lube on to run down between inner leg and lug. Commenced the unscrewing dance. A little out, a little in. Keep adding lube and keep unscrewing until it comes out.
    Success. Threads are good. Could reuse this if required. Note the tiniest blemish on thread where grub screw once lived.
  3. Motociclo

    Motociclo Long timer Supporter

    May 18, 2017
    Have a few sets of AT forks laying around.
    Thought i would remive an axle lug.
    These tubes are tight.
    Getting grub screw out easy enough.
    T7 torx bit. Heat grub first, then undo gently.
    I found that the grub only just grabs the very top portion of thread. Didn't seem to leave a mark either.
    I use a temp gun for curiosity, had to heat lugs to 120c to help break down locking agent.

    You won't undo tube with out a similar tool.
    Very tight.


    Once you break to locking agent, need to go forward and back. Don't just try to screw out in one hit. Doesn't hurt to put some lube, grease, oil etc, in grub hole to help lube threads. Heat and lube, always your friend. Remember, be patient.
    These forks i aquired. Had leaky fork seals.
    Oil, dirt etc collect between tube and lug, also add to effort required to extract.
    Pics below show how much crap has been collected.
    No thread damage either.
    Bottim pic shows seal location.