Author Topic: Rear End Wobble Under Braking (Read 4037 times)

Loudpipe · « **on:** October 20, 2006, 01:47:43 PM »

Anyone know what could be causing this? I did a search and found that swingarm bushings could be a possibility. It does it most when I use the rear brake fairly heavily, and the rear of the bike will "shake its head" and then return to normal. The rear also feels like it's floating when going around turns at speeds under 50mph.

ProTeal55 · « **Reply #1 on:** October 20, 2006, 01:59:13 PM »

I vote 4 swingarm bushings..

Nate · « **Reply #2 on:** October 20, 2006, 02:13:07 PM »

When you say "float", what does that mean? Like it isnt firmly planted?

mlinder · « **Reply #3 on:** October 20, 2006, 02:34:47 PM »

Check tire pressure?

750goes · « **Reply #4 on:** October 20, 2006, 02:40:12 PM »

Tire Pressure, tire deterioration (old and stuffed)
Stuffed Bearings
Loose Axle
Crappy Shock absorbers
Lousy Road
Swingarm Bushes
Loose Swingarm Bolt

Check it out before it checks you out...

medic09 · « **Reply #5 on:** October 20, 2006, 04:05:36 PM »

Quote from: 750goes on October 20, 2006, 02:40:12 PM

Tire Pressure, tire deterioration (old and stuffed)
Stuffed Bearings
Loose Axle
Crappy Shock absorbers
Lousy Road
Swingarm Bushes
Loose Swingarm Bolt

Check it out before it checks you out...

I second that. My SR 500 did similar stuff and it turned out the previous owner hadn't put a cotter pin in the axle bolt after chain-tightening. The nut was working loose, and I was getting an ever-more-loosened axle...

jsaab2748 · « **Reply #6 on:** October 20, 2006, 05:22:02 PM »

All of the above and check for loose spokes too.

nickjtc · « **Reply #7 on:** October 21, 2006, 11:52:11 AM »

As above. How much tread on both tyres? How old are the tyres?

It might be worth doing a quick check of the front end too. Put the bike on its centre stand, get the front wheel off the ground and check for 'notchiness' of the steering as you turn the bars from side to side.

Loudpipe · « **Reply #8 on:** October 23, 2006, 02:13:01 PM »

Yes, it feels like it isn't firmly planted to the road, almost like it's on ice. The front tire is old as well, and the right front strut is starting to leave a little oil on the exposed part, but they are not soft yet and there is NO notchiness when turning from side to side. The front of the bike isn't really in question...it's definitly something in the rear.

Tires are pretty old. They've got decent tread, but the rubber is starting to get little cracks in it. Rear axle is tight as hell, with the cotter pin, and it's aligned right. I checked that as soon as I got the bike, and rechecked it the other day. As far as I can tell the rear shocks are fine. I get off the bike and press down on it hard and they go down and come back up quickly without bouncing at all. It's got Comstars, so spokes aren't an issue. If I grab hold of the rear wheel and yank back and forth on it, I can't get anything more than a little tire flex. The swingarm doesn't move side to side at all. I don't know how to check the bearings.

This help narrow down the possibilities any? Any other tests for me to do?

750goes · « **Reply #9 on:** October 23, 2006, 02:16:11 PM »

if possible, put up a picture of your tires, they may be the culprit, but would not discount your swingarm, bearings or even a worn axle - could be slopping about a bit...

Loudpipe · « **Reply #10 on:** October 23, 2006, 04:17:57 PM »

Here's a few pics of the rear tire. The red dust coating you may notice is dust (rust?) from the chain that has come off from when my dumbass sprayed WD40 on it.

Click for a bigger picture:

nickjtc · « **Reply #11 on:** October 23, 2006, 04:25:44 PM »

In the summer I noticed that Sophie got really squirmy when I crossed centreline markings. I put it down to 'just because'. My rear tyre looked like yours (but a bit more worn); as soon as i replaced it the handling was transformed.

If the tyres are 5 or 6 years old, or older, change them.

mlinder · « **Reply #12 on:** October 23, 2006, 04:27:09 PM »

That tire looks pretty much toast.

Loudpipe · « **Reply #13 on:** October 23, 2006, 04:28:56 PM »

Yes, I know I need new tires, I just didn't know if it would be causing the "wiggle" or not. Could it be that the sidewalls are just shot and flexing enough under braking to noticably cause the bike to move around under me?

mlinder · « **Reply #14 on:** October 23, 2006, 04:31:15 PM »

My guess is that huge bald section around the middle of your entire tire is losing grip when you brake, and fishtailing sightly back and forth.

Loudpipe · « **Reply #15 on:** October 23, 2006, 04:34:48 PM »

You could very well be right, but it was designed to be bald. I don't hear any squeeling (would I?), even though the previous owner did mention that the tire slid around a lot. I just figured that he didn't really know and was just guessing. Maybe he was right after all.

mlinder · « **Reply #16 on:** October 23, 2006, 04:41:21 PM »

What is the make and model of that tire? The middle of the tire is not supposed to look like that, I'd wager. It looks much worse for wear than I'd ride on.

/edit: I notice they are cheng shin. What model?

Loudpipe · « **Reply #17 on:** October 23, 2006, 04:43:59 PM »

It's a Cheng Shin of some sort. It doesn't say anything about model on it.

mlinder · « **Reply #18 on:** October 23, 2006, 04:48:53 PM »

Well, it looks seriously tore up. I wouldn't ride on it. I'd bet dollars to donuts it's your problem.

medic09 · « **Reply #19 on:** October 23, 2006, 04:52:08 PM »

Whatever else may be the case, that tire does not look like it should be ridden on (is that English, what I just wrote?).

Start by replacing it immediatley, for your own safety; and see what develops from there.

Loudpipe · « **Reply #20 on:** October 23, 2006, 05:05:41 PM »

Good thing it's cold as balls up here in Virginia. Gives me an excuse NOT to ride on the dangerous tire. Thanks for the help guys, even if you did kind of point out the obvious.

Good to know I don't have to pull a swingarm.

seaweb11 · « **Reply #21 on:** October 23, 2006, 07:17:47 PM »

"Good to know I don't have to pull a swingarm." Don't let that stop you

Seems to me you might want to know what's going on back there. Only takes a few mins to remove the rear wheel, tear it down and know whats up next season. Come on...crack a beer and git to it

seriously, it's not a big deal to remove the swing arm and have a boo.

750goes · « **Reply #22 on:** October 24, 2006, 01:23:03 AM »

that tire is screwed.....and if it is several years old I bet the sidewalls are not really flexible..........

there is most of your problem in a nutshell - but as Seaweb said, pull the swingam - when you are replacing the tire, then you can check everything you need to and have a clear conscience when you have your next ride........and it will be a lot safer as well..

Jim Shea · « **Reply #23 on:** October 24, 2006, 04:19:25 AM »

I had exactly the same problem on my 76F1. I had the bearings replaced and the problem has gone. Does the wheel move when you grab it top and bottom and on both sides?

Loudpipe · « **Reply #24 on:** October 24, 2006, 05:05:58 AM »

Quote from: Jim Shea on October 24, 2006, 04:19:25 AM

I had exactly the same problem on my 76F1. I had the bearings replaced and the problem has gone. Does the wheel move when you grab it top and bottom and on both sides?

No, which is the odd thing. The swingarm doesn't move either.

Quote from: seaweb11

Come on...crack a beer and git to it

Deal

Jim Shea · « **Reply #25 on:** October 24, 2006, 09:32:55 AM »

Have you tightened up the swing arm bolts? If the wheel doesn't wobble it suggests the tyre! A mate of mine found his VFR doing all kinds of wierd things on the front, replaced the tyre and it was perfect. As the tyre needs replacing anyway, this is a good first step before checking bearings ect!!

Hop on a Honda · « **Reply #26 on:** October 25, 2006, 01:04:55 AM »

That tire looks like its been on there forever. More than likely the compound is prehistoric then its become too hard and has no grip and no flex at all.
try a new set of Bridgestones or Avons maybe with 29PSI.
The ride will be much kinder to your ass as well as behaving in a corner & braking
Old tires seem to be like a good tire with 50 PSI!

Saftey has no $$$.
Dave Australia.

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Author Topic: Rear End Wobble Under Braking (Read 4037 times)

jsaab2748

Jim Shea

Jim Shea

Hop on a Honda