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Buell Motorcycle Forum » XBoard » Buell XBoard Archives » Archive through December 20, 2004 » Troubleshooting 90MPH+ Front Wobble - XB9SX « Previous Next »

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Joele
Posted on Sunday, December 05, 2004 - 01:33 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I observed this wobble and adjusted the suspension per the owner's manual - now that the suspension is set for my weight and I have double check the tire pressure in both tires - I'm out of ideas. Ideas?
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Xb9er


Posted on Sunday, December 05, 2004 - 01:37 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Follow the procedure in the Service Manual for tightening the Steering Stem Cap Nut.
Mike.
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Barkandbite


Posted on Sunday, December 05, 2004 - 01:46 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The following recommendations include some basics, so please don't think I'm being condescending if you already know/practice some of them:

1) How tight are you holding onto the bars -- on a naked bike without a lot of wind protection, it's easy to clench the handlebars just hanging on...this will affect handling and introduce the potential for wobble.

2) Are you sure the tires are properly balanced? Just because there are wheel weights on them does not mean they are balanced. Perhaps a weight fell off...

3) You could always have the dealer check your head bearings just for grins -- I know it's a new bike, but it always helps to check the obvious.

4) Check the torque (as part of #3) of the triples and steerint stem cap nut to make sure nothings loose there.

5) When you feel the wobble are you laying down on the tank or are you sitting upright. I notice that when I lay over (I have Heli's however) that I actually take weight off the front steering assembly and the vibrations/wobbles (if you call it that) increase. Can you even lay on the tank on the Lightning/CityX models due to the way the handlebars are?

At any rate, try experimenting with different body positions to see if it affects te perception of the wobble.

6) What kind of jacket/clothing are you wearing. Believe it or not, if you have loose clothing on that flaps/catches in the wind, the pulsing will transmit and cause vibration and/or pulsing...at least it does on my bike.

If I wear my leathers the oscillations are non-existent. If I wear my summer ballistic jacket, they are (small) present. Just something to consider.

7) Are you wearing a backpack? If so, did you include the weight of what you carry (as well as the rest of your gear) in the weight you used to setup the bikes suspension?

...and finally...

8) If none of that works, to avoid a 90 MPH wobble, ride @ 89 MPH ; ) or order the LSL steering dampener from Trojan like I did...


Chris

(Message edited by Barkandbite on December 05, 2004)
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Joele
Posted on Sunday, December 05, 2004 - 02:07 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

1) How tight are you holding onto the bars -- on a naked bike without a lot of wind protection, it's easy to clench the handlebars just hanging on...this will affect handling and introduce the potential for wobble.

I've actually tried variations on my posture and degree of grip - results are the same really. My other bike is a Honda 919 (also naked) so I'm use to riding naked ; )

2) Are you sure the tires are properly balanced? Just because there are wheel weights on them does not mean they are balanced. Perhaps a weight fell off...

Not sure if they are balanced but I only have 800 miles on the bike and the weights are visually accounted for. How often has it been discovered that the wheels came from the factory out of balance?

3) You could always have the dealer check your head bearings just for grins -- I know it's a new bike, but it always helps to check the obvious.

I want to believe this is the cause because nothing else makes sense - but I will exhaust all other possibilities to get to the bottom of this because it's annoying.

4) Check the torque (as part of #3) of the triples and steering stem cap nut to make sure nothings loose there.

Dealer seems pretty competent - I think I will ask them to check these for me.

5) When you feel the wobble are you laying down on the tank or are you sitting upright. I notice that when I lay over (I have Heli's however) that I actually take weight off the front steering assembly and the vibrations/wobbles (if you call it that) increase. Can you even lay on the tank on the Lightning/CityX models due to the way the handlebars are?

Laying down, sitting up - either way, I feel it.

At any rate, try experimenting with different body positions to see if it affects the perception of the wobble.

6) What kind of jacket/clothing are you wearing. Believe it or not, if you have loose clothing on that flaps/catches in the wind, the pulsing will transmit and cause vibration and/or pulsing...at least it does on my bike.

Vanson Cobra 2 Jacket with gauntlet gloves over sleeve ends. No backpack - Schuberth Concept helmet - Jeans.

If I wear my leathers the oscillations are non-existent. If I wear my summer ballistic jacket, they are (small) present. Just something to consider.

7) Are you wearing a backpack? If so, did you include the weight of what you carry (as well as the rest of your gear) in the weight you used to setup the bikes suspension?

Nope.

...and finally...

8) If none of that works, to avoid a 90 MPH wobble, ride @ 89 MPH or order the LSL steering dampener from Trojan like I did...

I'd be miserable :-(

(Message edited by joele on December 05, 2004)
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Shred


Posted on Sunday, December 05, 2004 - 07:27 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

There are a lot off good ideas but to make it easy check two things Steering Stem bearings/bolt could be loose have someone sit on the bike and then put your finger just below the neck of the frame and do a wiggle test from back to front not side to side. Steering cap should be tighten to 38-42ft-lbs. The other easy thing to check is front wheel bearings, jack the front end up and wiggle test the tire. I had a wabble last march at the demo rides in north G.A was helping with leading and sweeping rides and at the end off the day the 3%ers' took a ride and as we hit 75mph+ I had a wabble the next day I check the front tire by jacking the front end off the ground. It was the bearing! If you find nothings wrong it could be wind or the road surface. Hope you find your problem.
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Dasbuell


Posted on Sunday, December 05, 2004 - 10:42 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

This does not help you... but I thought you and/or others might find this humorous.

My father who passed away several years ago was an old school "body & fender" man. I remember his work... you could never tell by looking or driving that a car he repaired had ever been wrecked. It looked better than when it came out of the showroom! (That is just not my opinion... he had an outstanding reputation.) He hated bondo... and was a master at leading body seams. He literally cut a car in half and put it back together because of extensive damage... and when he was finished... no clue it had been wrecked. This was about 35 years ago... long before fancy alignment machines and frame machines. All old school.

Anyway... A customer came to him about a car repaired by others in the shop about a high speed shimmy in the front. My dad had checked everything out... and could not find any problems. He spent a considerable amount of time under the car checking everything. The customer said that he needed to check everything while it was shaking. My dad responded... "My creeper can't go 90 mph!"

Sorry... this brought back some good memories.

back to regularly scheduled programming!!
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Tpoppa
Posted on Sunday, December 05, 2004 - 10:58 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Joele,

A high speed wobble is likely not due to the steering cap nut, unless it is really, really loose.

If you have a wobble at high speed, or during hard acceleration (when shifting), your suspension settings are making the steering too sensitive.
Reduce the rear preload 1 setting. This should slow the steering slightly and reduce or eliminate the wobble.

(Message edited by tpoppa on December 05, 2004)
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Joele
Posted on Thursday, December 09, 2004 - 10:34 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Ok, changed the rear preload from the 7th position (highest) to 4th position - high speed wobble almost completely gone. I'm thinking about going to the 3rd position but don't know what the negative side would be from that extra static sag. So much for following the owner's manual on suspension set up ; )
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Svo1023
Posted on Thursday, December 09, 2004 - 11:28 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

i have mine set on 2 no problems and i weigh about 200lbs...works for me
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Tpoppa
Posted on Friday, December 10, 2004 - 03:06 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The recommended suspension settings are a good starting point, but YOUR ideal suspension setup will likely vary due to riding style, riding position, and road conditions. For me, the stock setup just didn't work.

Something to Consider
(Last I saw) The recommended suspension setting are the same on the XBr as on the XBs (& XBsx). This can't be correct. Think about the riding positions. On the 'R', more of the riders weight is over the front wheel as compared to the 'S' or 'SX.' Not having enough weight on the front wheel can create the wobble that Joele described. This can easily be fixed by reducing the rear preload (increasing the front preload will have the same effect). Either of these adjustments will increase the rake angle, which will slow the steering, which is a GOOD thing if you don't have enough weight over the front wheel.


Due to the shortish wheelbase on the XB, it is a little harder to get the suspension 'dialed in' than for some other sportbikes. But, when setup correctly the XB will outhandle many (most) sportbikes.
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Tpoppa
Posted on Friday, December 10, 2004 - 03:26 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Here is some more detail that I posted on an older thread that addressed a similar suspension issue. Suspension settings are a hobby of mine.

...are you sure you made the right adjustment? The condition you describe sounds like you had the suspension set in a way that the steering was too sensitive.

Any adjustment that DECREASES rake angle, will make the steering more sensitive (the reverse is also true). Too much sensitivity can result in a wobble at high speed or under acceleration. INCREASING rear preload or DECREASING front preload will effectively DECREASE rake angle and make your steering more sensitive (check your owners manual). If the rest of your suspension is setup correctly, 1 click or 1 line should make a noticeable difference.

When I switched from the stock 207's to Metzeler Z6's, I had the same problem that Brady described. Under hard acceleration, the front end had a tendency to wobble. This was because the Z6's have a different profile then the 207's, and effectively REDUCED the rake angle. To fix it, I REDUCED the rear preload by 1 click, which INCREASED the rake angle and made the steering less sensitive and the wobble went away. INCREASING the front preload would have also fixed the wobble.

The factory recommended setting are a good starting point, but your suspension is fully adjustable for a reason. Proper suspension setup has as much to do with road conditions & riding style as it does with the weight of rider w/gear. For me, the recommended settings were OK as long as the road was super smooth, but Ohio has bumpy roads and the rear tire felt like it was going to hop off the road for every bump. Now, my setup is nowhere close to the recommended settings, and the bike handles 100% better.

Before making suspension changes, it's important to understand what each adjustment will do.

Here is a great article: http://sportrider.com/tech/146_0006_susp/
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