Low speed wobble

[rednutt]

Can anyone help me with a low speed wobble on my 1985 GSX1100ef notice mainly around town & roundabouts.If your going one handed and hit a bump it starts aswell,But If ya pulln 180k all good. I've done new tyre,fork oil,front wheel bgs checked the balance on wheel,fork oils even,forks look to be in the forward position again after removal.Checked the rear swing arm bgs.I've even measured the fork level make shore there even by ruler and in mils.Ive got the new steering head bgs adjusted up with a punch so that the steering just falls with it own weight.Should I adjust it tighter?

 

[TheCafeKid]

This may sound a little silly cos you've prolly already checked it, but i had a similar problem on my little Kz, ended up being REAR wheel alignment...but i could swear it was coming from the front. Just a thought..

 

[spyug]

CafeKid has a good point. One of the guys on the XS forum had a similar symptom until he checked the rear wheel tracking. I did a swingarm conversion on my XS and had something the same. when I first rode it, I noticed the bike would do a shake if I down shifted from speed. Almost like a dog flicking off fleas.On checking, I found the rear wheel was tracking off about 1/8" to the right. Straightened it out and fixed the shimmy. Obviously the wheel should be parallel to the front. Have someone hold the bike upright on a flat surface with the front wheel centered and run a straight edge from the rear tire to the front on both sides. You can do the same with laser pointers or laser levels.

The other thing I have heard is if the front tire is of a different tread pattern or size from the previous. Some bikes just don't like some tires. You mention having the wheel balanced but are you sure the wheel is true? You could pull the wheel and insert the axle. Have some one hold the axle either side and slowly rotate the wheel. Also is there any play between the axle and the bearings.There should be a small amount of movement if you jiggle the axle back and forth. More than 1/32" of lateral might indicate a problem bearing.

For a bit more info at what speed does the wobble occur and in what speed range is it present?

I'm sure you have checked this but are the brake disks and calipers properly seated and tight? Is there any extra weight on the front fork like tool bag, new fairing or new windscreen?

Tighteneing the steering stem might help but the forks should move side to side with little stichion so don't over tighten.

These sorts of problems can be tricky to sort out but if we keep at it something will come to light.

Good luck.
Spyug.

 

[ErnieGS1100EZ]

Hey Rednut,
I had the same problem on my Goldwing. It turned out to be the head bearings. I replaced the bearings and torqued them to specs. About a week later I had to retorque. It's been about 4 years now and still tight. There really is no rule of thumb when it comes to bearing torque. Your best bet is to do it with a manual & torque wrench.
If you feel the wobble in your hands it's in the front end. If you feel it in your bum, it's in the rear end.
Also you might want to check the axel nut.
Ernie

 

[trippivot]

do you align the fork tubes on to the front axle?
it is done after you tighten the axle bolt and before you tighten the fork tube lower pinch bolts.

with the axle tight and the fork lower pinch bolts loose one grabs the front brake and compresses the front suspension a couple of times. then tighten up the lowers. this step is almost never done by mechanics who think they know how to work on bikes. it is a near forgotten detail to proper alighment of the front tyre and forks.

the issue of how loose your steering bearings are. they need to be tighter than you described-- front end folds over under it's own weight TOO LOOSE

there is a spec that a weight scale like a fish weight scale is used to determine proper tension on steering bearings. handle bar resistance 2~4 lbs of pressure is needed to move them. not too tight where the bearings feel notchy and not too loose where the head assy. is sloppy I'd call it gently snug

 

[Steveb64]

I'd have to agree with trippivot and Ernie - had a similar problem with one of my GSX's - tracked fine at speed, but when slowing down (esp if hands OFF the bars), the bars would get into a really nasty shake at low (< 30 mph) speeds. The thought was that the frame was tweaked or similar, and as I wanted the engine (had a nice straight frame for it), I just swapped over - and discovered loose head bearings...

Conversely, high speed (180 kph+) wobbles and weaves were due to the rear wheel being slightly misaligned in the swingarm.

Weaves and head-shakes when cornering (usually after hitting a sudden dip in middle of fast sweeper) were cured by changing to radial tyres!

 

[t3rmin]

I tighten my steering bearings so the bars don't just flop to the side. They fall, but with a little resistance. Get the front off the ground and move the bars back and forth and see if it's 100% smooth lock to lock.

Does the wobble happen when you're leaned over or straight up? I had a rim bent slightly on one side and when cornering on that side it would weave a bit.

 

[rednutt]

Thanks for the info. The wobble will happen with the bike up or down. Im gona adjust the headset more and check the wheel alignment.I should b able to do the wheel alignment with a string on either edge of the tyre from front to rear?

 

[t3rmin]

String works. Long 1x1 wood or anything else long and straight is easier if it'll fit through the centerstand area.

 

[Big T]

I should b able to do the wheel alignment with a string on either edge of the tyre from front to rear?

String and a few bits of duct tape to hold it onto the wheel. Try to do it about 1/3 the way up the wheel from the ground, so you don't have any obstructions in your way

It's not uncommon for the rear wheel alignment marks to be off