Topic: 1974 CB550 front end wobbles

[kcwillison]

I have a 1974 cb550. I've it about 2 years now and never had an issue with a wobble until a long road trip that I am guessing exhausted some part of the bike that is now causing the front end to wobble which only acts up between 40-45 mph.
I have replaced the swing arm and rear bearings, front tire- and balanced front wheel, front end springs and bearings. What else could be the case?

[Scott S]

Did you replace the swing arm bushings?
 Have you checked the steering stem bearings?
 What about having the front wheel trued (spokes)?

[riverfever]

Are you talking about a left to right wobble or a hop up and down?

[Bankerdanny]

Read this and bookmark the site it came from. Great advice: http://www.motorcycleproject.com/text/shucking.html

[alacrity]

I have a 1974 cb550. I've it about 2 years now and never had an issue with a wobble until a long road trip that I am guessing exhausted some part of the bike that is now causing the front end to wobble which only acts up between 40-45 mph.
I have replaced the swing arm and rear bearings, front tire- and balanced front wheel, front end springs and bearings. What else could be the case?

Hi

Your list of replaced items is a bit confusing -- could you be very specific?  Have you replaced BOTH wheel bearings with new sealed bearings? Have you replaced BOTH steering stem bearings (hopefully with new tapered bearings from AllBallz)?  Have you had your rim trued and spokes checked/tightened?  Is your alignment correct? Is your frame bent?  If your wheels aren't rolling true because of frame bend, they will "fight" gyroscopically and harmonics could be generated at a certain speed that you feel as vibration.  You said you replaced the swing arm bushings, but with what?  IF the swing arm pivot bolt (the shaft) was worn, or the swing arm main left-right tube had been galled out because of wear/vibration/worn bearing looseness, just changing the bushings to old style phenolic wouldn't fix that.  You may need a new swingarm. You may need brass bushings.  There are a limited number of parts here... all need to be correct. 

[kcwillison]

To be more specific, yes I have replaced BOTH wheel bearings with new sealed bearing and the steering stem bearing with tapered bearings. I took my wheel in to get my tire replaced and they replaced my tire and balanced my wheel. Would they not also check my rim and spokes?

I replaced and upgraded the entire swing arm and bushings.

My frame is not bent and the bike is aligned. This problem only started on a return from an 800 mile trip not involving any incidents with the bike, such as dropping or a crash.

The shake is right to left. If I remove my hands from the handlebars from the 40-45mph zone, the entire front end shakes right to left and if I didn't grip the bars again, I believe it would wobble out of control and go down.

[alacrity]

To be more specific, yes I have replaced BOTH wheel bearings with new sealed bearing and the steering stem bearing with tapered bearings. I took my wheel in to get my tire replaced and they replaced my tire and balanced my wheel. Would they not also check my rim and spokes?

I replaced and upgraded the entire swing arm and bushings.

My frame is not bent and the bike is aligned. This problem only started on a return from an 800 mile trip not involving any incidents with the bike, such as dropping or a crash.

The shake is right to left. If I remove my hands from the handlebars from the 40-45mph zone, the entire front end shakes right to left and if I didn't grip the bars again, I believe it would wobble out of control and go down.

Well they COULD absolutely have balanced the wheel using a static balancer and it would balance and STILL could be out of round, untrued, with loose or overnight (or both) spokes.  How much weight was added on the wheel?    Truing and testing for runout using a dial indicator is what would have been needed at the time, before a tire is affixed and obviously before it is balanced.   How tight/loose are those head bearings? Are you certain they were installed correctly to the proper depth and perfectly perpendicular to the stem that is affixed to the lower tree?  Had any of those front end components been in a head on crash in the past? Is the steering stem perfectly perpendicular to the lower tree into which it is affixed? Is it completely immovable in the lower tree? If it has been Farked, it might be a tiny bit loose in there?  Is your axle set up correctly with all the spacers etc in the right position and tightened properly? Are the clamps and pinch bolts at the bottom of the forks on correctly and properly tightened.  Start at the top... check every component all the way to the bottom...  The only obvious thing is what you are experiencing ain't right.

[Stev-o]

This is pointing at your tire. Is it new? What brand and what pressure you runnin?

May need a steering dampener!

[Retro Rocket]

If you haven't already done it, re tighten your steering head bearings, they aren't set and forget, they usually need a re tension once bedded in....

[rickmoore24]

+1 on the dampener. Are you running a front fender? Fork brace?

[strynboen]

take the air aut the tire/tube...and re set it on the rim
..losen it the vhole vay raund..give it some tire soap..and refill it...and thek carefull that it re seat total sentered in the rim.
..tires can be aut sentered on the rim..even after some time..

[beemerbum]

Interesting topic. My '77 K7 has developed an up and down bounce at speeds over 55mph. What causes this as opposed to a side-to-side wobble?

[Lostboy Steve]

My buddies enduro does that and its caused by his bead lock. So I would assume simple balancing should correct it. Thats why my wr doesnt have beadlocks

[Lostboy Steve]

As I've said before, my 550 wobbles if you let go of the bars at 40-50. Mine is caused by a poorly made wheel. Its a stock front DID wheel but where the weld is it has terrible run out. Nothing spoke tension will fix. I've replaced everything else but if I put the wheel on a dial indicator there's a 1" area thats weird where that seam is. I knew it was bad when I was relacing the wheels. Get yourself a fixed pointer (dowel resting on some bricks or something) get the bike on the center stand and spin that front wheel. You cant measure run-out like that but you'll at least see it.

[DaveBarbier]

I'm confused. Did you replace the bearings and whatnot before or after you experienced this wobble?

[DaveBarbier]

As I've said before, my 550 wobbles if you let go of the bars at 40-50. Mine is caused by a poorly made wheel. Its a stock front DID wheel but where the weld is it has terrible run out. Nothing spoke tension will fix. I've replaced everything else but if I put the wheel on a dial indicator there's a 1" area thats weird where that seam is. I knew it was bad when I was relacing the wheels. Get yourself a fixed pointer (dowel resting on some bricks or something) get the bike on the center stand and spin that front wheel. You cant measure run-out like that but you'll at least see it.

All the welded DID rims have runout where the weld is. Usually not an issue. Yours could be worse than normal I guess.

[Lostboy Steve]

As I've said before, my 550 wobbles if you let go of the bars at 40-50. Mine is caused by a poorly made wheel. Its a stock front DID wheel but where the weld is it has terrible run out. Nothing spoke tension will fix. I've replaced everything else but if I put the wheel on a dial indicator there's a 1" area thats weird where that seam is. I knew it was bad when I was relacing the wheels. Get yourself a fixed pointer (dowel resting on some bricks or something) get the bike on the center stand and spin that front wheel. You cant measure run-out like that but you'll at least see it.

All the welded DID rims have runout where the weld is. Usually not an issue. Yours could be worse than normal I guess.

It was alarming enough that I would have used a different one if I had it at the time. I can live with it, shouldn't be letting go of the bars anyway.

[kcwillison]

So did you ever get a new wheel and the wobbles went away? That is the exact issue I am having 40-50mph. Not really my favorite while cornering.