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speed wobble

  • Thread starter Thread starter purplemotoman
  • Start date Start date
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purplemotoman

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I have a 79 GS850 and I have a bad speed wobble above 180 KM/H.
I put a set of tomaselli handlebars on it and had the front wheel balanced.
Are there any suggestions on what to try, other then slow down?
Thanks
 
Make sure the the steering stem is tightened accordingly. A loose headset can cause a wobble.
 
wobble

wobble

Let me see. Good and correcty adjusted/tightened tyre pressures, swingarm bearings, tyres, rims, steering head bearings and wheels axles. Oh yeah change up to top gear and see what she can do. 8-[
 
Actually, the REAR tire can cause the bike to wobble also. Is the back tire overly flat in the center? I have seen that cause it too! Ray.
 
sharpy said:
Let me see. Good and correcty adjusted/tightened tyre pressures, swingarm bearings, tyres, rims, steering head bearings and wheels axles. Oh yeah change up to top gear and see what she can do. 8-[
Click to expand...

Plus suspension. Front and rear. That about covers everything I did.
 
All the above plus check the front springs. If you have front end sag as most of these old GS's have that can also be part of the problem. You didn't mention if you had a handlebar fairing or not so I will assume you don't. Generally a high pitch wobble will be caused by problems with the front suspension/steering/tire while a low pitch weave could a symptom of rear suspension/tire or loose swingarm bushings. The old stock GS's are prone to some wobbles at those speeds but shouldn't be bad enough to cause concern. However, some times it doesn't take much to make them down right scary.
 
I had a bad one last year but I held onto her.
By the time I was slowed down I ended up in a loose gravel shoulder.
 
purple; is this a less than 1 cycle/sec wobble or a slower weave? ,a weave is usually related to the swing arm or chassis problem and the higher frequency wobble is fork/headbearings/ frt tire, . hmmm,note to self: read thread then post sorry for the redundancy
 
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I notice it the worst at high speed when I hit a patched crack in the road or, when passing someone, I cross the yellow line.
I would say that it isn't a fast vibration type wobble , it is more like a slow weave.
 
back in 1983 I have had about the same problem with a honda v65 magna. did I look and search for what was apenning? I finally discovered that the frame was cracked in the front end. I took it apart and welded it and way it went.
 
purplemotoman said:
I would say that it isn't a fast vibration type wobble , it is more like a slow weave.
Click to expand...

My $.02 Its in the front. Mine was a slow weave so first thing I did was the swingarm bearings. No results. Next I did the whole front end. New tire... no dif. Fresh oil...no dif. Next I did Shocks, Springs, Fork seals, Steering bearings. Much, much better. For now Im gonna keep it under 100mph. Thats the best advice. :-D
 
purplemotoman said:
I have a 79 GS850 and I have a bad speed wobble above 180 KM/H.
I put a set of tomaselli handlebars on it and had the front wheel balanced.
Are there any suggestions on what to try, other then slow down?
Thanks
Click to expand...

Other than the obvious checking of loose wheel, head and swing arm bearings and things like tire balance (which you've done) one thing that WILL aggravate and amplify a speed wobble is unequal fork oil / air combinations. This is compounded with many add-on windshields which often add downforce or, at particular speeds, bad buffetting.

If the picture is the bike in question, if nothing else is apparent, I'd carefully check the fork oil type/level and air if yours uses it. (Hint I've added a balance tube from one tube to the other to at least balance the air).

Great fun going into a speed wobble at that speed isn't it......especially when it gets worse when you apply the brakes ;)
 
Are your tires stock size. at high speeds bias tire grow in diamiter, just watch a dragster during burn out. those are meant to grow at speed to act as gearing. even diff manufactures, have some diff outer diams than others,allthou not alot. SN.
 
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