Fork Alignment on my 9er - Wrist Twisters
 
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post #1 of 14 Old 09-20-2006, 11:46 AM Thread Starter
 
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Fork Alignment on my 9er

Pardon me if this is a rehash (and it does appear to be a partial rehash), but I have some questions about aligning the forks on my '02 919. I had a moderate get-off at a trackday and am currently in the process of getting things back together. That said, this bike was slightly out of alignment when I bought it.

My current symptoms:

1. Handlebars turned slightly to right when driving straight. - The left handlebar appears to be about an inch "higher" than the right when driving straight.

2. Wheel slightly off in relation to fender. The wheel is just a fraction (1/4"?) off the plane of the fender.

3. Headshake @ 45mph. I get zero headshake at other speeds, but I'm getting some minor headshake at 45mph. Not a lock-to-lock tankslapper, but not a minor vibration either. I'd say the bars move 1.5 inches either way when I take my hands off.

My question is: Can I re-align this simply by supporting the front end, loosening all of the bolts on the triples, axle, and fender, eyeball it straight, and torque it all down again?

If I have a bent triple - can I bend it back by putting the tubes in the lowers and yanking it back into place?

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post #2 of 14 Old 09-20-2006, 12:00 PM
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Quote:
Originally Posted by ajohn505 View Post
Pardon me if this is a rehash (and it does appear to be a partial rehash), but I have some questions about aligning the forks on my '02 919. I had a moderate get-off at a trackday and am currently in the process of getting things back together. That said, this bike was slightly out of alignment when I bought it.

My current symptoms:

1. Handlebars turned slightly to right when driving straight. - The left handlebar appears to be about an inch "higher" than the right when driving straight.
u'r bars could be bent, but whatever the reason...u need to figure it out pronto

Quote:
2. Wheel slightly off in relation to fender. The wheel is just a fraction (1/4"?) off the plane of the fender.
screw the fender...it's not any kind of indicator for alignment...u need basic alignment procedures asap

Quote:
3. Headshake @ 45mph. I get zero headshake at other speeds, but I'm getting some minor headshake at 45mph. Not a lock-to-lock tankslapper, but not a minor vibration either. I'd say the bars move 1.5 inches either way when I take my hands off.
could be tire balance, rim, forks...any damn thing but i'd start w/ the wheel

Quote:
My question is: Can I re-align this simply by supporting the front end, loosening all of the bolts on the triples, axle, and fender, eyeball it straight, and torque it all down again?
not exactly, again u need the fork assembly procedure asap, check adam's site...and get a piece of plexi-glass or glass

Quote:
If I have a bent triple - can I bend it back by putting the tubes in the lowers and yanking it back into place?
dude...

any wrenches live near this needy niner?

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post #3 of 14 Old 09-20-2006, 12:56 PM
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Quote:
Originally Posted by ajohn505 View Post
If I have a bent triple - can I bend it back by putting the tubes in the lowers and yanking it back into place?
No. If you had enough force to bend the triple back 1) you could not get it back into perfect alignment and 2) you would be putting undue stress on the fork and possible bend this. Remove the forks and roll the tubes on a known flat surface to check for straightness. If you can see for sure triple is bent replace it. Note: the forks should slide in and out of the triples with little effort when its all loose and suspend, wheel off etc. If it's binding or jammed.. something is bent or skewed.

Also, I noticed that on the 9er, rear wheel alignment can make a huge difference on triple perpendicularness. When things go wrong and bikes go down anything could have moved. Check the rear wheel for proper alignment. It might be kinda hard to eyeball the straightness of your front end with bent handle bars.

Good luck. Bummer when sh!t is jact! Man.. just start throwing parts at it!

- Rev. CYCHO -

tires.... it's what's for dinner!
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post #4 of 14 Old 09-20-2006, 01:04 PM
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Sounds like you have some serious problems. For starters remove the front wheel, fender, and brake calipers. Remove the handlebar. Loosen the upper and lower triples one side at a time. You should be able to slide each fork tube all the way up while rotating it. If either fork is bent you will not be able to perform this task. The lower triple could also be tweaked but check the forks first. They are the weak link.

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post #5 of 14 Old 09-20-2006, 01:11 PM Thread Starter
 
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The handlebars are not bent, since they are brand new Coerce Hyperbars - this is definately an alignment-related issue.

I'm not completely new to wrenching on my bike - I've done my own sprockets, exhaust, wheel removal, plugs, etc, but I've been fortunate to not have to do much with the forks so far.

I'm hoping nothing's bent. What you all are saying is that there's no way things could have just been tweaked a bit? It's pretty certain that something's bent?

I've put enough money into fixing this thing already to think about replacing much more right now

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post #6 of 14 Old 09-20-2006, 01:35 PM
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I hate to be the bearer of bad news, from your description it's more than a simple tweak. In fact there is no such thing as a simple tweak.
Tweak = Bent!

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post #7 of 14 Old 09-20-2006, 01:44 PM Thread Starter
 
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Well, maybe I'll have an excuse to pop in some f4i forks, though I wasn't looking forward to the expense. Mabye I'll get lucky and it'll just be the triple.

Crashing sucks if you're not rich

I'll support the front end and do the bent tests this weekend - hopefully I'll have some good news to report on Monday.

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post #8 of 14 Old 09-20-2006, 02:25 PM
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It can just be tweaked--happened all the time when I crashed my dual sport & dirt bike. Loosen the triple clamp bolts & axle including pinch bolts & start over.

Then its the straddle the wheel & turn the bars until its straight like your old Huffy. I did this while my bikes were on a stand.

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post #9 of 14 Old 09-20-2006, 02:30 PM
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If the triples got knocked out of line nothing is gonna slide up and down in them, even if the fork pinch bolts are loose. Do what Mike said and loosen the triple clamp nut also. I've seen dirtbikes that I would have bet money the forks were bent, but the triples were misaligned. Can you do this and not bend a fork tube you might ask? I don't know, but they came back in when everything was loosened up and realigned/retorqued. I think the fork tubes were bending from the offset pressure, but not permanently bent. You can't hurt anything trying.

The oscillation at 45 might still be there, even if everything lines back up. If so, check to see if the rim is bent.

"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
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post #10 of 14 Old 09-20-2006, 02:43 PM
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Forget all that stuff you just read. you can spot twisted forks easily by eyeballing from the side. With one eye closed is each fork in plane, ie parallel with the other. If not loosen just a little, upper and lower fork clamps, leave the wheel on and tight, grab wheel between knees and tweek the bars in the appropriate direction. Eyeball again. If it won't straighten then you have a problem.

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post #11 of 14 Old 09-20-2006, 03:21 PM
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Good luck with the calibrated eyeball... It can work by trial and error. Bottom line, pull the forks, set them up one at a time in v-blocks and check the runout. 0.008" max.

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post #12 of 14 Old 09-20-2006, 03:30 PM
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Quote:
Originally Posted by m51142 View Post
Good luck with the calibrated eyeball...
Yeah, and the oscillation really scares me. Usually happens in multiples of wheel speed. Saw a guy one time who had a bike that would do it at 55. Noticable from beside him. Cleared up around 60. Said it was controllable. Unfortunately he later found out it would also do it about 110 and he couldn't control it. A new bike solved his problem.

"Towards the end of the vid, it looks like she may have had a bafflectomy." - MarylandMike
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post #13 of 14 Old 09-20-2006, 03:35 PM Thread Starter
 
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Quote:
Originally Posted by HondaJim View Post
Yeah, and the oscillation really scares me. Usually happens in multiples of wheel speed. Saw a guy one time who had a bike that would do it at 55. Noticable from beside him. Cleared up around 60. Said it was controllable. Unfortunately he later found out it would also do it about 110 and he couldn't control it. A new bike solved his problem.
It didn't happen at any speed other than 45mph for me - I was back out on the track about an hour after my crash, bent bars and all . Other than the offset, she tracked straight and true to 125mph.

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post #14 of 14 Old 09-20-2006, 05:29 PM
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Chances are you might have a damaged tire to cause the wobble, Heat cycles & track time are hard on tires.
Defiantly do a maintenance check on all the hard parts first.
Forks are fragile when not used as designed, like in a crash. If all checks out O.K.,
By a reputable mechanic.
And the shake is still there, try new tires.
Mine is shaking a little and my bike is perfect, but the tires are worn.

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