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Wheel judder fazer 600? |
Hi all i have a problem with my bike,its intermitent its judders when i brake but not all the time and it seems to to do this if i dont brake hard.I have had the head race bearing replaced but it still does it.I have taken it back to the shop where i bought it from and they suggested that it needs to be re-tightened they did this but i`m still getting the same problem!!! I am also getting wheel/fork shaking when i do around a ton,this bike is more than capable of riding around the ton mark. I let one of the testers test my bike,he come back and said that there was shaking/movement in the lower forks at the 100 mph speed but he did not find anything wrong with the braking.They are going to balance the front wheel and see where we go from there.I am not totally happy with this but i will see how it goes. There was a mention of a floating disc or something,i think this was some kind of bullshit because i have had 5 bikes before and none of them had problem, I'm wondering if there's more than one thing going on here. I first suspected a warped disc also, but once warped, they stay that way and will shudder every time you apply the brakes. With the high speed vibration I'd suspect the wheel being out of balance but again, this will be constant and the faster you go, the worse it will be. If the steering head bearings are loose, when you apply the front brake firmly at very low speeds, chances are you'll hear a slight clunk or feel a slight thump. This could also affect the handling at high speeds. Have you dumped the bike recently or struck a curb or pothole recently? Has either fork leg lost any oil or if air assisted, lost air pressure? If you release the handlebars at speed, does the bike veer to one side? To check for looseness of the steering head bearings, put the bike on the centerstand on a hard, smooth surface. If you have a jack, put it under the engine and take some, but not all the weight off the front wheel. Grab the top of the front wheel and try to roll it back and forth and if there's play, you'll be able to feel the slight movement at the steering head. While you're at it, jack the front wheel all the way off the ground and move the handlebars from side to side and check for any binding or roughness. Any compentant shop should be able to check for warpage of the discs. You don't say how old the bike is or if it's been stored outdoors, but you may want to check to make sure the brakes are releasing completely. With the engine off and on a smooth surface, apply the front brake as hard as you can and after releasing, see if the bike rolls back or forth easily. It should and if it doesn't, it sounds like the brake system needs to be gone through for an internal cleaning. Last but not least, badly worn or unevenly worn front tires can make high speed handling quirky. One of your rotors maybe warped. It sounds like a balancing problem, failing that you could have a buckled wheel. Increase the front tire pressure to 32psi Try installing a new tire. The treads can get "cupped" due to under inflation. And sometimes the tire bead will not seat properly on the rim. Dunlop tires had a recall from that same problem. It sounds like you've covered most bases already and head race bearings being worn or loose are the first place to visit. They will clonk when you brake hard from about 10mph, but as they've been changed and retightened then they're OK. Next thing is brakes and discs. Disc warpage can be felt at the lever when applied gently as the lever will appear to pulsate. Sticking brake pistons, ie sticking on, will have an effect but it will happen all the time, not just at speed. Lastly, check your front tyre. About 32psi is correct, but if it is worn to the limit then it will judder. My BMW does at about 85 when it's got less than 1000 miles of tread left. It's because the tread wears unevenly and exaserbates the fact that the fork bushes are tired and old. One way to check fork bushes is to put it on the centre stand, get a friend to hold down the back while you grab the bottom of the forks and try to pull and push backwards and forwards. You may well notice a bit of play and this is the bronze bushes inside the forks worn. Advice, get them changed next time the fork seals need changing. They only cost about 拢15 each and there are 2 in each leg. HTH Alan Personal experience and over 25 years of home mechanic maintenance Flat spot on tyre, warped rotors, worn fork metals, excessive sideplay in the disc bobbins, front wheel out of balance. |
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