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Bent Forks

Discussion in 'Bling and Appearance' started by CharlieBrown, Jan 27, 2008.

  1. Hey there, Ive got what I think are bent forks on my zzr250.

    When driving straight down the road no hands on the handle bars they sit about thirty degrees to the left. It seems to tack a little heavier to the left than when turning to the right but nothing significant.

    So what I'm asking I guess is how do I go about finding out which part is actually bent? I it likely to be just one part or am I looking at replacing the entire set?

    The impact was a pretty low speed slide under the back of a car. Bike would have aqua planed in as it was a deep puddle and theres hardly a scratch on the underside fairing and I was only doing about 30 at the time.

  2. they have places that do nothing but straighten this sort stuff.
    Just check ur forks are lvl with each other first by having a look at them under/near the clip-ons
  3. Yeah it is possible that they are just misaligned in the clamps now. If you jack under the bike so the front wheel is just off the ground a hairsbreadth, then loosen the clamp bolts, they might just spring back to straight. If it takes more than a slight nudge to line up, you probably have bent something. Could be yokes, fork upper, axle, who knows. In that case take it to a repairer.

    Don't forget
    to tighten the clamps again first, though!
  4. +1 to hotcam.

    From top to bottom, it could be the bars twisted on the mounts if you've got those crappy rubber mounted jobbies. It could be the forks twisted in the triples. Or it could be your fork leg bottoms misaligned on the axle.

    Are the bars straight with the triple clamps? Is the wheel perpendicular tp your triple clamps? Work out where the twist is, or whether something is actually bent.

    For the triples, back the bolts off, then a tap with a rubber mallet can help relieve the tension and pop it back. For the fork leg bottoms, undo the pinch bolts that clamp the axle, then roll the bike forward and hit the front brakes sharply a few times, torque them back up again. For bar mounts, just loosen em up and straighten them.

    Or if you're in a rush, hold the bars tight and kick shit out of your wheel till everything is pretty much heading in the right direction. Fix properly at your convenience. :LOL:
  5. Post some pics to show people what you are talking about.
    30 deg. sounds pretty bad. I know on my bike, the top triple clamp sits a few degrees off to the right, but it doesn't affect my bike ... not that I have noticed anyways.
  6. I know what's he's talking about, and Hotam and Devotard are on the money.. I've done this exact fix myself a couple of times and it always works.

    What I want to know, is how did the forks get like this in the first place??? Have they been like this all the time, and you've just noticed, or have you, perhaps, had an altercation witha solid object, like a kerb or something? Some enlightenment as to HOW this has happened would help with fixing it.......
  7. Hey Paul...

  8. :oops:

    Just got back from a ride and the brain is still out there, sorry about that :oops:

    Ok, stand over the top of the forks, and look down the front of them, from the handlebars towards the wheel. If there are straight "front-to-rear", you may have saved some cash and the above fix should work, as it's most likely they that 'twisted' in the triple clamps.
  9. The forks probably aren't bend, but just twisted. Put the front wheel agains a post ...and push the bars the other way. Failing that, loosen the triple clamps a litlle and do it again.
  10. If all else fails Bob martin engineering specialise in this sort of straightening type stuff, their in FTG.
  11. It's a ZZR250, if the forks end up being bent, buy some second hand ones. It will be cheaper than getting them straightened, and the bike won't be out of service for days.
    TO PROPERLY check for bent forks(short of disassembly and rolling on a surface plate), remove front wheel, loosen triple clamps just enough to allow you to rotate the fork tubes, then measure the distance between the bottom of teh forks. Rotate one fork 90 degrees and re measure, rotate another 90 degresss, measure again. Do same for other side. If the measurement changes radically, well, bent fork stanchion.

    Regards, Andrew.
  12. :shock: Genius. I never thought of that.

    There should be a thread with concise stuff like that.
  13. [​IMG]


    Dunno why but the Image Poster has rotated my images on the upload, but I think you get the idea!

    I tried loosening the tripleclamps and kicking the crap out of the wheel in the absence of a jack and rubber mallet, I had to get my girlfried to lean back on the bike whilst I did it. Looked pretty hot but she didnt appreciate the remark! Still bent though as you can see..

    Will take the wheel off and test out typhoons suggetion, but I'm fearing the worst at this stage. Looking at them to me it seems that the triple clamps are lined up with the bars but the wheel is not perpendicular to the clamps.

    With the pinch bolts for the front wheel do they need to be tightend to a specific torque when replacing the wheel or just a half turn to be sure?
  14. Strictly speaking yes, but it might well be below the range of any torque wrench you're likely to own. Then it comes down to feel and that's not something you can accquire from an internet forum. Well, not this one anyway :grin: .
  15. Bob Martin Engineering are no longer in business, regrettably.
  16. Rog, that's a loss for certain! Any idea who bought his engineering gear?

    If desperate, Bike Magic in moorrabbin have a frame straightening jig... I'm about to get their handy work rechecked... will let you know.

    Great post Typhoon.
  17. Yeah Rob. Bob died a few years back, and his son Steve still has it all. Tell you more when next we meet.
  18. no one bought the gear he didnt sell it, just closed the doors and went back to working on off shore rigs.

    and bike magic wont be straightening any frames either (unless they are steel)

    prick toads in their infinate wisdom have decided that no ally frame (or any other ally part) is allowed to be repaired, and all bikes with minor frame damage (that wouldnt have been a problem to repair) are now instant stat write offs

    so if your top tube is ally (as it no doubt will be) and it is damaged in any way then its a new set of fork legs for you

    you cant even get rims with minor dings re rolled
  19. From the pic it looks to me that the headstem is twisted/bent.
  20. So they sell the stat write offs at auction to recoup money... and whom ever buys them needs to repair them right?? How do they repair them???

    Speaking of Bike Magic, I saw their jig. I can't confirm what material it's capable of straightening, but they used it to straighten my bent forks.