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Front end shimmy under hard braking
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  (#1)
Knee Draggin!
 
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Front end shimmy under hard braking - May 20, 2007, 10:36 PM

I'm riding a '06 R6 and under hard braking I'm getting what I would describe as a shimmy in the front end. I started to notice it as I have been building up the miles and started riding it harder. I've made minor tweaks to the suspension settings and thought that might have cause it so I put it back to factory and a few other settings with no luck. I can't see anything with the brakes or tires (stock); they have about 1,500 miles on them with no obvious damage. The shimmy happens while cold and also after the brakes and tires have warmed up.

I didn't notice this when the bike was new but I wasn’t pushing it either. It isn't a huge problem but something I'd like to fix none the less. It's taking a little bit of my confidence away while braking for a turn.

Thanks in advance for any suggestions!


Charlie
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May 20, 2007, 11:02 PM

Sounds like your steering head bearings are loose
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Meh
 
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May 20, 2007, 11:06 PM

Steering head bearings would feel like more of a clunk forward and less like a shimmy feedback. If you feel the bike clunk forward when you first grab the brake at low speed...probably a head bearing adjustment issue.

Regardless of your inspection of the tire, that is where I would start (cupping, uneven wear, out of balance). Next I would look at you break rotors to see if they are withing tolerable runout limits. After that, you are looking at wheel bearings and geometry issues which are all highly unlikely.
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May 20, 2007, 11:37 PM

check your tire pressure. it fixed my shimmy.
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May 21, 2007, 12:38 AM

is your suspension properly dialed in?

i had some vibration and shaking when i got on the brakes hard. i thought my rotors were jacked up, but they were straight. i softened my rebound damping by two or three clicks and it got a lot better.


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May 21, 2007, 07:55 AM

Sounds like the rotors might be warped. Bring it down to Fast Lanes and we'll take a look at it.


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May 21, 2007, 07:57 AM

Quote:
Originally Posted by JohnnySpeed954
Sounds like the rotors might be warped. Bring it down to Fast Lanes and we'll take a look at it.
Look, he got the company line already!


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May 21, 2007, 08:01 AM

A few things come to mind....

Head bearings shot or steering stem nuts are loose. Remove top triple to inspect.

Cupped tire? Look for unusual wear.

Rotors... Put it up on stands and spin the wheel... look for the rotor "waving"


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May 21, 2007, 09:14 AM

Steps to check. Since you already checked the tires.

1. Suspension ( is it bottoming out? ) Soften up your rebound and add preload.
2. Steering Head Bearings
3. Fork seals and oil
4. Rotors


You have gotten good advice in this thread thus far. If you cdo not want to pay for a shop to do it. I can take a look at it if you want.


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May 22, 2007, 10:48 AM

Well with all the advice I decided to tear into her yesterday. I took the front end down to the point where I could pull the bearings. I cleaned everything and inspected it and found nothing obvious. I re greased everything thing and reassembled with proper torques. I even removed and reinstalled the rotors and calipers. While they where off I checked the rotors for warping against a straight edge ruler and checked out the pads. I took her out this morning and hit a few roads before works and she ran like champ, no more shimmy. Besides a new tire and the dreaded fork seals and oil I think I tried everybody’s suggestions. If all of that didn't do the trick my next stop was the fork oil which I probably would have needed help on! I 'm not sure which one did the trick but thanks to everybody for the advice and the offers for help.


Charlie
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