PDA

View Full Version : Twisted or bent fork? How can you tell?


maxinc
23-10-10, 05:24 PM
My brother-in-law had an off this morning on his 01 ZX6R. He failed to notice a manhole cover on a very wet road while pulling into a petrol station. Speed must have been 10-15mph from what he tells. Bike felt on the left side and did a 90 degree rotation while scraping the road, pivoting around the left clip-on.

Apart from the obvious damage, the fork seem to be out of alignment. When keeping the handlebars straight, wheel seem to point slightly to the left. I was just wondering if there is an easy way to tell if the fork is bent or just twisted. And if the later, can it be adjusted easily or needs special tools only a service might have.

Thanks,
Andy

mjc
23-10-10, 05:54 PM
The forks are very unlikely to be bent in a low speed off. Just slacken off the pinch bolts a little on both yokes and straighten the forks holding the wheel between your legs. Easy.

:smt023

Edit: Problem could be a bent handlebar, so check straightness of the bar as well

maxinc
23-10-10, 06:07 PM
Thanks for the quick reply. It has clip-ons and they look straight enough to my eye plus they can be adjusted individually. I'll give it a go tomorrow, hope the rain stops.

AndyBrad
24-10-10, 08:28 PM
loosen the yokeclamps and rotate the top of the fork. if it "sticks" its bent.

Sid Squid
24-10-10, 09:29 PM
Written in response to a similar problem some time ago:

Loosen everything on the forks and yokes, except the top yoke clamps.
Bounce the front end without using the brakes, this will mean holding the front wheel against a wall or similar restraint. If necessary hold the front wheel twixt knees and tweak the 'bars. Tighten everything from the bottom upwards, so spindle first, then spindle clamps, then bottom yoke, then steering stem top nut/bolt.
If it's off after that something's pi55ed - remove front wheel and mudguard and loosen clamps on one fork, rotate fork, does the bottom end wander? If yes it's bent, check the other one too.
Even if straight check the surfaces of the fork where they're clamped, is it distorted? USDs clamp on aluminium which is soft, if the surface is damaged they won't clamp straight, if yes to this then move them up until the lower yoke is on an undamaged section and go on the the next step.
Remove top yoke, tighten up bottom yoke clamps evenly and try to refit top yoke, do the three holes align perfectly over stem and forks? If no then bottom yoke bent.
Bent top yoke extremely rare, usually if you can sight across either top or bottom surface flat it's fine. If necessary remove forks and fit into top yoke on a checked undistorted section of fork, tighten clamps, check across forks parallel by eye, and measure between them on a machined section next to and as far from yoke as possible.
Check spindle by eye, although a bent spindle is usually a bitch to fit so you'll probably be sure of that already.
Wheel is unlikely to be the cause - a bent rim won't stop you aligning the front end, although it may handle and steer a bit odd.

HTH

SUPERSTARDJ01
24-10-10, 09:51 PM
Mine r the same on the same bike just an 04 instead of 01 but my off was about 2mph and the front points slightly left and feels odd to ride do will try the above suggestions cheers.