NX650 fork alignment question

[Funkster]

Hello all! First post here, hope this is the right place for it )

I have a 1994 NX650 and the front wheel is wonky. I first noticed that it was wrong after having some new tyres fitted, so at the time simply assumed that they'd fitted the front wheel back incorrectly, but now having taken the covers off and had a closer look at it I'm struggling to see how they could have got it wrong unless they managed to bend one of the forks somehow. I may simply have been ignoring the error until this point!

The right hand fork seems to have less angle on it, so that the bottom is too far back and the wheel points to the right when the handlebars / fork bridges are in the dead-ahead position. If I were to loosen the big nut at the top and the pinch bolts of both bridges, will I be able to straighten this out or will it just line itself back up how it is when I tighten it all back up again?

Thanks in advance for any hints!

Cheers,
--
Olly

[sbikerbud]

I'm guessing you haven't had it since 94 and this may be the first new front tyre you've had.

It's possible the previous owner had an off and bent a fork tube, an easy way to hide this is to rotate the fork so the bend points either inward or outward. Then when the wheel is clamped in it looks straight.

The only way to check for sure is to disassemble the forks and roll the tube on a flat surface to look for run-out.

The less scientific way is to loosen the pinch bolts on the yokes and rotate the top tube. If the bottom of the fork wiggles in a circular fashion then the tube is bent.

Alternatively they may just have twisted the forks in the yokes slightly, in that case, loosen all the bolts holding the forks into the bike, twist until straight by clamping wheel between knees and pushing or pulling on the bars, then tighten them all up again

[Rubberchicken]

What he said, and it always helps to push down on the suspension a bit before tightening it all up again properly.

And a quick check if your forks are straight: Get the gaiters off (or push them down) and put a mirror pane across the fork sliders. If you can rock it back and forth it's out of alignment.

[Funkster]

Top tips, thank you both very much!

You're right, I bought it a couple of years ago and this is indeed my first new front tyre. Previous owner would have told me if he'd bent it (bought from a friend), but if the guy before him had had an off he may never have known...

Will take the gaiters off this evening and see what I can see!

Ahh the joy of cheap bikes...

Cheers,
--
Olly

[Rubberchicken]

Oh, do make sure first if it's actually the fork and not just the bars.

The bars are rubber mounted, and it's quite usual for them to be out of center after a light tumble. Has been the case in all my offs, just loosen the 4 bolts and twist it back.

[Funkster]

Hehe, yes I did wonder about that first :o)

Visibly, the bars and the top bridge line up straight.

Just had a thought that's made me wonder if it could be either the aluminium slider or the front axle that's bent... the wheel doesn't line up with the mudguard! If you hold the bars in the dead-ahead, the mudguard points forward (as far as it's possible to tell) but the wheel points right.

Of course the mudguard is far more likely to be bent than anything else so I'm not using it as a datum, but just thought I'd mention it!

No doubt more later when I have another look at it (assuming it survives the ride home from work...)

Cheers,
--
Olly

[Funkster]

Hallo again!

Sorry for the pause, had some non-bike stuff to do the last couple of evenings, but have now done the following:

Tried glass-on-fork-tubes test, and it failed - right fork indeed more vertical than the left.

Slackened all pinch bolts and turned each fork tube in turn. Retried glass test with each fork 180° round from where it was, still failed in the same way.

Conclusion: the fork tubes themselves are (broadly) straight, and the top and bottom bridges are misaligned. Does that sound right to you?

Next step is to undo the big nut at the top and try to straighten it out, however I don't have a big enough lever at hand and will have to wait until tomorrow to borrow the wrecking bar from my dad :o)

Thanks for the help!
--
Olly

[sbikerbud]

you may be able to do it without undoing the big nut

[Funkster]

Did have a go without undoing it, but in the end figured I might as well slacken it all off... which I did today, and am happy to report that when all tightened back up again it seems to be pretty much straight!

Took it out for a blast around the lanes, appears to be tracking straight and the tendency to bump-steer seems to be less. Tyres still follow white lines a bit but I guess that's unavoidable.

Thanks for the help! I think that was the last thing bugging me about the bike so can now just get on with riding it :o)

Cheers,
--
Olly