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Old 05-25-2009, 12:51 PM   #1
oldschoolphazer
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Default Speed wobbles? What causes it.

I have an 84 Magna and the other day while passing a slow car on a highway I went to pull back into my lane(by this time i was going about 70mph ) and as I pulled back into my lane my front tire hit a small crack and the bars were shaking violently back and forth but I just held on to them and slowed down and it stopped. What causes this? I noticed it also one day while riding with no hands quickly(stupid I know) and it started to wobble so I grabbed it. Both tires are brand new and balanced.
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Old 05-25-2009, 02:11 PM   #2
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Have you checked to see that your triple clamp bolts are tight?
Or check for play in the steering head bearings.(with the front wheel elevated)


Eric
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Old 05-25-2009, 02:55 PM   #3
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my moped wobled alot because i ran it so hard. my moped was only built to go bout 30-40 and yet somehow my dad when he used it found a way to make it go 50-60. i have no idea how he did it but when i went the full 60 or down a hill it wobles
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Old 05-25-2009, 03:23 PM   #4
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Make sure your suspension is good, and check to make sure your tires isn't low, or misaligned.
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Old 05-25-2009, 03:40 PM   #5
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I'll second the steering head suspicion. Make sure the bearing is tight and check for the proper fall-off.
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Old 05-25-2009, 04:16 PM   #6
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Forgot to add that if you find play in the steering head, pull it all of the way out. Clean and inspect the bearings and races. If any doubt, replace them all.
BTW, I also used to own an '84 V-65 Sabre.(Same bike, taller saddle)

Eric

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Old 05-26-2009, 11:14 AM   #7
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If youre reffering to what they call a "tank slapper", Ive heard a lot of ideas as to why it happens. But one possibility that makes sense to me is when the front tire gets airborne then comes back down out of line with the rear. The front trys to correct itself and ends up overcorrecting.
Think of those videos of racers on sportbikes where they are doing a wheelie, then the bike comes back down and goes into a violent shake/wobble. Same idea when you hit something like a crack or pothole and the front is momentarily lifted off the ground.
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Old 05-26-2009, 05:03 PM   #8
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I had a similar problem - from around 65 up thru 75 - the front tire "dribbled" like a basketball. Last week I bit the bullet and bought new tires and had them spin-balanced.

No more dribbles, no more wobbles...

I'd check to make sure you haven't lost one of your wheel weights.
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Old 05-26-2009, 05:05 PM   #9
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Quote:
Originally Posted by retro View Post
I had a similar problem - from around 65 up thru 75 - the front tire "dribbled" like a basketball. Last week I bit the bullet and bought new tires and had them spin-balanced.

No more dribbles, no more wobbles...

I'd check to make sure you haven't lost one of your wheel weights.
Or that.
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Old 05-26-2009, 06:55 PM   #10
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Possible steering head bearing. But a dangerous situation. Get that fixed asap.
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Old 05-27-2009, 01:38 PM   #11
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My front wheel used to do this as well... it needed to be replaced anyways so i did it.. solved the problem! now i can ride at 70 with no hands!..haha jk
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