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wobbles....

Discussion in 'XJ Technical Chat' started by fintip, May 30, 2012.

  1. fintip

    fintip Member

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    Not good.

    I think they didn't start until after I changed the steering head bearings; I thought it was just because I was very gentle on them, tightened only until the play disappeared... But I went back and tightened them and had a wobble that possibly worse than any other I experienced last night on a nice stretch of highway at 80 that has a sharper lean than most places. I had to ease back off the throttle and straighten up, and it was a bit scary--it didn't immediately go away, not until I backed it off to 60 or 55 or so.

    What could be wrong?

    It could be anything on the entire front end, since I completely disassembled everything to get to it--forks off, wheel off forks, everything. The forks are firmly in place, the wheel's nut was torqued to something in the 70's and I am fairly certain the play isn't there.

    What should I check?
     
  2. bigfitz52

    bigfitz52 Well-Known Member Premium Member

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    Start with your steering head bearings; they might be too tight now.
     
  3. fintip

    fintip Member

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    Too tight will cause a wobble? It's hard to get torque numbers for it, too--who has that weird (C?) socket anyways! I am just having to use vice-grips, as gently as possible. No toque numbers though. Kind of a pain to get to those, as well, lots of things to undo and have to prop the front end first, and leave the front end hanging somewhere...

    Anyways, how does one know if it's too tight?
     
  4. MercuryMan

    MercuryMan Active Member

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    Yes too tight can do it. You should always check the easiest things first because lots can cause it. If the wheel is balanced and the tire is not old or otherwise damaged-these two are common causes but usually show up around 40-55mph-then something else is fighting their balance and harmony-like your bearings or your brake. Also double check all your geometry and fasteners. Jack up the front tire and spin it both directions and observe for any irregularities.

    Something is consistently working it out of round for it to happen at that speed.

    Practice torquing with a wrench on another thing with a similar set up and you can guess at the torque your applying pretty accurately. I usually know within a notch or two of when my torque wrench will click from practice.
     
  5. fintip

    fintip Member

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    What could be the possible problem with the brake?

    And what do you mean when you say 'double check your geometry'? Forks equal positioning is all I can think you might be referring to... and which 'fasteners' are you referring to? does that mean bolts?

    I should note I adjusted the pressure in my forks for the first time. They were at 0psi. As in, no noise of air escaping when I connected a gauge to it. I hand pumped them with a bicycle foot pump, about 10/11 each. I guess I should check those as well and make sure they're spot-on equal?
     
  6. BluesBass

    BluesBass Member

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    I ran into a very similar phenomenon with my XJ. I installed new bearings, rode on them for a few months (and nearly 1000 miles) with no problems, then recently opened up the bike in the turns and instantly felt instability.

    I took the bike home (VERY gingerly, I might add) and tightened the bearings, added loctite for good measure, and rode her the next day. Much to my surprise I got the wobble AGAIN, especially when braking / turning.

    It turned out my steering column bearings hadn't seated completely yet, and a second (or more accurately THIRD including the initial setting) tightening of the bearings seems to have resolved the problem.

    I remember reading a thread on here that gave the directions to torque the steering column, ride for a few hundred miles (though I don't recall the exact amount, maybe between 200 and 500?), then re-torque the bearings. Someone please correct me if I have made any mistakes.
     
  7. mtnbikecrazy55

    mtnbikecrazy55 Active Member

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    did you use a pressure gauge on the fork pressure??

    i use a shock pump that i use on my mountain bike forks, it has very accurate readings, as well as a relief switch to drop down the pressure to exactly where you want it so they are both equal and perfect. 10/11 pumps on a full size floor pump seems like it would be ALOT.
     
  8. fintip

    fintip Member

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    not 10/11 pumps, 10/11psi. The gauge on the bike doesn't show anything below 10, but I have a tire gauge that shows 5 notches between 0 and 10, and I used that to check; I just tilted it sideways to lower the pressure a bit to the desired level.

    I guess I'll keep playing with the steering bearings.
     
  9. a340driver

    a340driver Member

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    I have a fresh "wobble" feel at low speeds - 10mph , weird, also, my brake light came on. I checked fluid, and brake pads, both are OK .. what the heck??
    Oh, I should add, it's on my XJ750 (83)
     
  10. ManBot13

    ManBot13 Well-Known Member

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    Check your tire pressure? It's something simple but can easily affect handling, especially at low speeds, even if you can't "see" it going flat.

    Brake warning light is the fluid switch, a connector could have come loose or the switch could be stuck or failed.
     
  11. fintip

    fintip Member

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    I haven't gotten to test it yet, but I feel like it's worth noting that my problem was very likely caused by my fork lengths being off by a half-milimeter or so. I had changed the headset bearings, and so when putting the forks back in, didn't get them quite level.

    I picked the more sunken-in one, loosened the three clamp screws on the two triple-trees, pushed down on the bikes and got it level with the other, re-tightened... I feel pretty confident that was it. If it wasn't, I'll be sure to bring it back up, but next time I hit that stretch of highway I'll be sure to test it--don't want it to catch at some point unaware.

    Probably unrelated, but... since it's related componentry... my axel-clamp screw popped off today. Not sure why. I was riding two up all day, taking some very sharp turns--small chance I may have grazed it against the pavement on one peg-grinder?--and on the next turn I heard something bounce off. Stopped, walked back, found the screw, and took me a minute but I found where it came off of. Odd.
     
  12. a340driver

    a340driver Member

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    Thanks for your reply, I'll check those items asap
     

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