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Wobble!

  • Thread starter Thread starter Im Faster
  • Start date Start date
Im Faster said:
what exactly should i replace
-wheel bearings
-swing arm bearing
- steering head bearing
anything else?
Click to expand...

To trouble shoot the front end wobble, I would suggest you start with the steering head bearings, they may just be loose.
Put the bike on the center stand and put a jack under the engine (or piece of wood) to get the front end off the ground, check if the front end just flops from side to side.
The front end should have a small amount of resistance and should be free moving from side to side but not just banging into the steering stop when you let it go from either 11 or 1 o'clock.
This test is best done with all the cables disconnected from the handle bars but if you are careful you can simulate it without removing everything.
The correct torque for the steering stem nut that tightens it down is 26-37.5 Ft lbs.

Once you get it setup as per the manual, if it feels notchy as you turn it from side to side you will need to replace the bearings. Loose steering head bearings will wear out faster than correctly tightened ones and usually result in high speed wobbles and instability over uneven surfaces.
 
now that you say that, i did have Cafe kid check out the steering head bearing (he mentoined thet get like notched) and that did not appear to be the case it was smoothe turning.
 
He may have set them a bit loose. Did he actually take it apart, clean, grease and adjust it or just check out the movement on the centerstand? They can also appear smooth on the centerstand but act notchy on the road. Probably not but it's super easy to check.
 
To check for notchy steering bearings, I put the bike on the centerstand and weight the rear end down to lift the front wheel off the ground. Slowly push the bars toward center. If there's a notch, you will feel it with your finger, or it may fall into the notch before you push it to center.

I agree with tkent, they sound loose. There should be some drag in the bearings, but not so much you notice the bike wandering at around 30-40 mph. Trial and error is the only procedure I can recommend (until you get a feel for how much drag there should be), and it's safer to be on the tight side. If the bearings are too loose, you'll also get a shake in the steering if you let go of the bars around 30-40 mph (because your arms provided the damping the bearings should have).
 
My 750 has never been very steady on the highway since it was brand new in 83, it was always alittle darty. I always blamed the rake angle of the front end with the 16"wheel. Put it in the twisties though and it loves it. eats them up turns in fast .
 
Also, a bike that wobbles at speed may not be safe at lower speeds on poor roads or if evasive handling is needed. Getting this fixed is more important than riding.
 
Dogma said:
To check for notchy steering bearings, I put the bike on the centerstand and weight the rear end down to lift the front wheel off the ground. Slowly push the bars toward center. If there's a notch, you will feel it with your finger, or it may fall into the notch before you push it to center.

I agree with tkent, they sound loose. There should be some drag in the bearings, but not so much you notice the bike wandering at around 30-40 mph. Trial and error is the only procedure I can recommend (until you get a feel for how much drag there should be), and it's safer to be on the tight side. If the bearings are too loose, you'll also get a shake in the steering if you let go of the bars around 30-40 mph (because your arms provided the damping the bearings should have).
Click to expand...


what if you get a real bad shake like the bars are trying to beat the tank to death around 30-40 and lesser at say 60-70 if you let go of the bars or just get real lite on them ? like the OP I just put new tires on it had them balanced and checked to see they seated all the way around checked the weal bearings were good bike only has 8,000 miles on it but sat out side a lot
 
GSEScraze said:
what if you get a real bad shake like the bars are trying to beat the tank to death around 30-40 and lesser at say 60-70 if you let go of the bars or just get real lite on them ? like the OP I just put new tires on it had them balanced and checked to see they seated all the way around checked the weal bearings were good bike only has 8,000 miles on it but sat out side a lot
Click to expand...

That does sound like when mine were too loose. I didn't try it at higher speed until it was stable at low speed. Assuming everything else is correct, I'd be looking to tighten the steering bearings.
 
Dogma said:
I'd be looking to tighten the steering bearings.
Click to expand...

Yep. Try that first. Understand, as you tighten the big nut you are drawing the top and bottom fork trees closer together. In order to do that one set of fork tree bolts must be loose. loosen the bottom set as the top set is what sets the fork height.

100_4204.jpg


Of coarse, I may be talkin out my arse :o. My Bike has a High speed weave (100+) and gets loose in fast (80+) corners. Not a head shake but more like a wallow that wants to turn tank slapper. I have tried and changed everything mentioned in this thread and more. Still wobbles !
 
bonanzadave said:
Of coarse, I may be talkin out my arse :o. My Bike has a High speed weave (100+) and gets loose in fast (80+) corners. Not a head shake but more like a wallow that wants to turn tank slapper. I have tried and changed everything mentioned in this thread and more. Still wobbles !
Click to expand...

I have no personal experience with this. However, recalling other threads might provide some ideas.

> Tires, including balance and air pressure. Some magic combinations just don't work.
> Fairing, windshield, if installed
> Equal fluid levels and viscosities in forks. Equal spring pressure and length. Orifices not plugged. Equal air pressure, if air forks.
> Swing arm bearings.
> Frame alignment.
 
Not much to offer on how to correct the problem your having as the previous guys have just about covered it all....

What I would like to mention, is I was out for a ride yesterday, and on a stretch of road that was open, I could see way off into the distance I let her rip, hit 150Kmh and not a twitch to be found, the bike buzzed a bit more than usuall, as I could barely see anything in the mirrors, but she rode as straight an an arrow.....and wobble free.....

.
 
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themess said:
> Tires, including balance and air pressure. Some magic combinations just don't work.
> Fairing, windshield, if installed
> Equal fluid levels and viscosities in forks. Equal spring pressure and length. Orifices not plugged. Equal air pressure, if air forks.
> Swing arm bearings.
> Frame alignment.
Click to expand...
Done, done and done and Head bearings & new shocks and springs & fork bushings.

GateKeeper said:
I let her rip, hit 150Kmh and not a twitch to be found, the bike buzzed a bit more than usuall, as I could barely see anything in the mirrors, but she rode as straight an an arrow.....and wobble free.....
Click to expand...

Yep. I use to do that on mine too. Not any more....
 
Im Faster said:
i dropped into in a parking lot once, on a stupid tar snake going like 3 mph maybe
Click to expand...

We have this in common. My brother tipped mine over when he bumped it with his truck. Hmmmmm ??? :-k
 
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I'm wondering if the bushings in the forks themselves could be worn and cause a problem like that? I have a problem like that but its not real bad. I have a different front end to put on, hoping that solves my problem. I cant think of anything else to change wheel bearing are new, springs new, greased up stem bearings,wheel almost new. Good luck I'm going to keep reading this one just to find out...
 
I had this wobble issue with my GS 1000 ST.
The phenomenon decreased when I took the quarter fairing off but it was still there:eek:
As I had another GS 1000 handy I finally switched the forks around and...bingo the problem disappeared:)
The only difference between the two forks ( both perfectly straight) was the fact that on the defective one, I had renewed the fork tubes with non-OEM ones that don't have a separate lower bushing:rolleyes:
I believe this creates some stiction in the forks that in turn ...generates the wobble as soon as you go over the slightest bump.
It was so bad that I couldn't ride above 120 kph whereas today...:D
In my view anything that hinders the linear action of the suspension front or rear will generate a wobble at high speed.
 
Thanks for ideas my steering stem was adjusted wrong, real dummy that worked on it the first time I shouldn't let me work on it anymore...
I tightened the nut wrong so it was really loose. I'm thinking I am going to check the swing arm bearings again. It rides alot better now no wobble. :D
 
With my bike I jacked the front up took the brakes off spun the tire and could see it go side to side just enof so I took it back to the shop I got it from and they checked it out and replaced it for free Ride on and all. Seems to ride a lot nicer I could not see in the mirrors at hi speed be for (I blamed it on them being cheap aftermarkets) but now I almost like them LOL still has a little bit but nothing like it did so I will keep looking at other things brought up in this post
 
I ran it by Brian at Vintage Superbike. http://vintagesuperbike.com/history.html


Hi Dave,
I just went thru all the GS forum notes and video, many of the people who wrote in were thinking just like me, I would say head bearings and swingarm bearing's, remove and repack, re torque.

When I first started road racing in 83 I crashed the **** out of my bikes, when the fork tubes were tweaked I brought them to a guy who would put the in a press and make them straight again,,,,,,,,but were they really straight or weak now? They worked fin at Loudon which was a slow track but when I would go to Daytona or Pocono I would get up over triple digits and the bike would go into a slow weave/wobble, I didn't want to go any faster so I would just hold it there. Im sure one of the fork legs was tweaked, or maybe my lower triple clamp. If you took your forks off and brought them to a machinist he would put them in V blocks on a surface plate and run an indicator over your fork legs and tell you if one is tweaked/bent.

When ever you have your forks out and your putting them back together in the clamps, don't sock down the lower bolts real tight then do the uppers, tighten the lowers and bit, then the uppers, then the lowers again, do it in series a little at a time. And make sure they are at the same level in oil and at the same level in the upper clamp when you look at them, if one is higher or a bit lower then the other could cause a weave or wobble.

Im a big fan of steering dampeners, all production racebikes came with them stock and allows you to adjust them to the feel you like, if you had a big with big power and it lifted the front end or wiggled under acceleration and you firm up the dampener to take that feeling out.

Fork braces help on an old bike with little forks to increase rigidity, I don't think that your problem though.

I think a tweaked tube, or swingarm bearings myself. Wouldn't hurt to have the boys check you wheels for balance again if you take them off. You never know.

Good luck, If you do find the culprit ping me with the results!

Brian
 
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