high speed whoble

[prue1]

High folks, I have put on about 1000 miles since my rebuild and I appreciate all the help along the way. The bike is running quite well ( knock on wood). I have one problem that I cannot figure out. At 60mph plus and also in very windy conditions, my bike has a very troubling whoble. I have checked for play in the front fork yoke and the rear swing arm with none noticed. I have tightned down my steering damper with mixed results (minor help at speed/weird sensation when slow). The previouse owner replaced the steering head ball bearings with tapered and the swing arm shaft and bushings. I am unable to get any grease into the swing arm bushings using a grease gun. Could the dust covers be installed incorrectly or might there be no room for anymore grease (if this was the case, wouldn't the old grease be pushed out by the new grease?

Any assistance is greatly appreciated.

Thank you.

 

[5twins]

So many things can cause a wobble that I don't even know where to start, but I'll list a few ...... mismatched tire tread patterns front and rear, tire balance, tire inflation, incompatible tire sizes, bad rear shocks, too stiff rear shocks, wrong length rear shocks, bad functioning forks (sacked springs, low oil level).

If your swingarm bushings are the usual aftermarket bronze ones, they have grease grooves on the I.D. that swirl out from the bottom to the top. They are designed to get their grease from the rear. The stock set-up delivers the grease from the side, about midway up the bushing. You need to add a grease fitting to the center of the swingarm like so .....

Mount it just onto the gusset plate. You need the added thickness or the threaded portion will stick into the arm too much. Use a 45° angled fitting, aimed to the rear, for easiest access. Something else you can do so the original fittings can be utilized is add a couple more grease outlet holes to the pivot tube. The originals, the ones that grease the side of the bushing (and are no good now), are indicated by the blue lines. Drill a couple more holes where the red arrows are .....

 

[XSLeo]

How did you check the side play of the swing arm? Best to remove the rear wheel, unhook the shocks from the swing arm. now try to move the swing arm sideways.
Another thing I have found is that if the swing arm pivot bolt is loose the swing arm pivots around the bolt instead of the pivot tube. One way to check this is to lift the swing arm up level and let go of it. If it drops then the pivot bolt is loose. If it holds it's position then it's ok.
As you tighten the bolt it squeezes the frame against the ends of the pivot tube. If loose the frame won't hold the pivot tube from turning as the swing arm moves up and down. The bolt fits loosely inside the pivot tube. This leaves to much plat and can lead to handling issues.
On the tapered roller bearings in the steering head, you adjust to get 1 inch of fall away. To find your fall away lift the front wheel off the ground. If it stays straight ahead your good to proceed. If it won't stay straight then unhook what ever cables or such so it will.
Hang a string with a weight off the center of the rear of the fender. Have it hang just off the ground. Draw a line under the weight inline with the bike, Draw a line 1 inch on each side of this line.
Now using just a finger tip push the end of one hand grip so the wheel starts to turn. watch the weight. at some point the wheel well fall to the side under it's own weight, this is the fall away point. This should occur just as the weight is over the line one inch to the side. If it falls away before the 1 inch line the bearings are too loose, if it falls away past the line the bearings are too tight.
On greasing the swing arm try pulling the grease zerk off one side then pumping grease in the other side. Everything could be tight enough your grease gun won't have enough pressure to push grease through.
This way grease travels in one zerk into the bolt, out a hole to the space between the pivot tube and bushings, across the swing arm and does the reverse of the first side to come out the hole the other grease zerk was.
Some drill a hole and thread it for a zerk in the middle of the swing arm so you push grease out both sides from the middle.
You can also loosen the pivot bolt to give a bit more space for grease to come out between the ends of the swing arm and frame.
If you have an adjustable steering damper, does this mean you have an early bike? Like 70-73. These early bikes had less bracing on the frame and was a bit more flexible than the 74 up bikes. This maybe part of your issues. Not much but maybe.
Leo

 

[prue1]

So many things can cause a wobble that I don't even know where to start, but I'll list a few ...... mismatched tire tread patterns front and rear, tire balance, tire inflation, incompatible tire sizes, bad rear shocks, too stiff rear shocks, wrong length rear shocks, bad functioning forks (sacked springs, low oil level).

If your swingarm bushings are the usual aftermarket bronze ones, they have grease grooves on the I.D. that swirl out from the bottom to the top. They are designed to get their grease from the rear. The stock set-up delivers the grease from the side, about midway up the bushing. You need to add a grease fitting to the center of the swingarm like so .....

Mount it just onto the gusset plate. You need the added thickness or the threaded portion will stick into the arm too much. Use a 45° angled fitting, aimed to the rear, for easiest access. Something else you can do so the original fittings can be utilized is add a couple more grease outlet holes to the pivot tube. The originals, the ones that grease the side of the bushing (and are no good now), are indicated by the blue lines. Drill a couple more holes where the red arrows are .....

e
Thank you for the quick response, let me look into the points in your post.

 

[prue1]

How did you check the side play of the swing arm? Best to remove the rear wheel, unhook the shocks from the swing arm. now try to move the swing arm sideways.
Another thing I have found is that if the swing arm pivot bolt is loose the swing arm pivots around the bolt instead of the pivot tube. One way to check this is to lift the swing arm up level and let go of it. If it drops then the pivot bolt is loose. If it holds it's position then it's ok.
As you tighten the bolt it squeezes the frame against the ends of the pivot tube. If loose the frame won't hold the pivot tube from turning as the swing arm moves up and down. The bolt fits loosely inside the pivot tube. This leaves to much plat and can lead to handling issues.
On the tapered roller bearings in the steering head, you adjust to get 1 inch of fall away. To find your fall away lift the front wheel off the ground. If it stays straight ahead your good to proceed. If it won't stay straight then unhook what ever cables or such so it will.
Hang a string with a weight off the center of the rear of the fender. Have it hang just off the ground. Draw a line under the weight inline with the bike, Draw a line 1 inch on each side of this line.
Now using just a finger tip push the end of one hand grip so the wheel starts to turn. watch the weight. at some point the wheel well fall to the side under it's own weight, this is the fall away point. This should occur just as the weight is over the line one inch to the side. If it falls away before the 1 inch line the bearings are too loose, if it falls away past the line the bearings are too tight.
On greasing the swing arm try pulling the grease zerk off one side then pumping grease in the other side. Everything could be tight enough your grease gun won't have enough pressure to push grease through.
This way grease travels in one zerk into the bolt, out a hole to the space between the pivot tube and bushings, across the swing arm and does the reverse of the first side to come out the hole the other grease zerk was.
Some drill a hole and thread it for a zerk in the middle of the swing arm so you push grease out both sides from the middle.
You can also loosen the pivot bolt to give a bit more space for grease to come out between the ends of the swing arm and frame.
If you have an adjustable steering damper, does this mean you have an early bike? Like 70-73. These early bikes had less bracing on the frame and was a bit more flexible than the 74 up bikes. This maybe part of your issues. Not much but maybe.
Leo

you have brought up some good suggestions, let me look into them. thanks.

 

[prue1]

you have brought up some good suggestions, let me look into them. thanks.

Hi Leo,

My bike is a 72 with a steering dampner, how does this effect the fall away test?

Thanks

 

[5twins]

Make sure it's loose and not applying any friction at all.

 

[prue1]

Make sure it's loose and not applying any friction at all.

10-4, thanks

 

[prue1]

Hi Leo,

Took rear wheel and shocks off, my swing arm does not fall and I can detect no horizontal or back-in-forth movement, all seems to be in order.

When I took the zerks off to try and get grease in, the grease just goes everywhere, but inside, it appears to be full.

In the fall away test, my bearings where tight, I loosened then just a little and I would say I was close to an inch-inch and a quarter.

I rode the bike and it does feel a little more stable, I did not get the wobble sensation in the rear wheel nearly as bad, but it is a very windy day here today.

I will ride in calmer winds and re asses.

Thanks all.

 

[5twins]

Like I told you, you won't get grease in there until you add the extra fitting or mod the pivot tube. The original grease outlets in the pivot tube are hard up against the solid side of your new bushings. There's no way for the grease to flow into them.

 

[prue1]

Yes you did tell me that, thanks.

 

[RatyXS]

Tires balanced ?

 

[prue1]

Tires balanced ?

I will check that, thanks.

 

[hard_y_rd]

Speaking of balancing tires, anybody use dyna beads? Do you just put them in the tire? What about tubed tires?

 

[aldo5468]

I use Ride-On Tire Sealant in the tubed tires I have on my 650 - it provides the kind of balancing action that Dyna Beads do and some protection against punctures.

 

[RatyXS]

I did the beads, they worked for me. I might have to add a little more but then again I am on a hard tail so that super smooth ride isn't gona be there. Lol. Yes they work in tubed tires

 

[weekendrider]

Speaking of balancing tires, anybody use dyna beads? Do you just put them in the tire? What about tubed tires?

xsleo has been happy with them for several years. IIRC he has even reused them. You might pm him if he doesn't find this thread.

 

[Capt_Zoom]

If all else checks ok...are you confident that the frame is straight?

 

[5twins]

Honestly, I think think all this fancy new injecto-lube balance stuff is bullshit - at least when applied to an old bike like ours. I static balance with good old fashioned lead weights. It's been the standard for almost centuries, still works, always will. And being the cheap S.O.B. that I am, I even cast my own .....

 

[Gordon]

I have used the beed packet's, but only in Tractor Trailer tire's. As was allready suggested, tire balance is usually the culprit for shake. This is especially true at cruising speed's. Or a bad tire.As Leo stated raise the front end, puhs the brake pads back so they don't rub, and spin the tire's/ wheels looking for any abnomaly's like up and down, side to side, or tread pattern for weirdness.On the rear, do the same but remveing the chain helps to get even result's. There is alot more to look for in the rear, Like sprocket being uneven, hub loose, the swing arm play. All very good and problem area's, not just on the 650, but all high speed vehicle's. I don't think there is many complaint's on your riding mower.
Static balancing is good for a bike. Kinda hard to get them spun balanced. I guess there is a way, but I haven't seen a balancer for or would accept a motercycle wheel assy. My very old Snap-On static balancer works great on them.
BTW, What the hell is a whoble, Did you mean wobble? Just kiddin'.