Author Topic: cb550 rear end weave (Read 3177 times)

paulages · « **on:** June 26, 2006, 12:00:13 AM »

i thought i was noticing a weird feeling from my rear end (no, not that one) around town, but today i got out on some windy roads, and the problem became very apparent. when going through windy curves, my rear tire feels like it's floating a little bit, almost as if it were on ice, but not so bad that i feel like I'm gonna eat #$%* or anything. it's subtle enough that it took a while for me to tell if it was in my head or not.

say I'm going 30 mph through a left hand hairpin curve...it feels like the rear wheel is floating to my right as I'm turning. it seemed worse going downhill on a rougher road, which led me to believe it could have been the shocks not rebounding quickly enough.

1) new pirelli speed demons/ correctly sized for the rims and inflated properly.
2) didn't replace swingarm bushings (i know, stupid move), but tested them and had them tested by my mechanic for play. seemed fine.
3) stock shocks on the ride, but replaced them with boge progressives. haven't retested yet.

any ideas? the shocks? play in the swingarm? Lloyd...more variables i didn't list?

Mark M · « **Reply #1 on:** June 26, 2006, 03:22:38 AM »

Start with the cheapest things first.

Check tyre preasures - front and rear.

Check wheel alignment - not just from the marks on the swingarm but to see if both wheels are inline.

Check wheel bearings - get the wheel off the ground and check for any movement.

Check Head bearing adjustment - as it's more evident downhil, l when there is more weight up front.

The last time I had that 'floaty rear end feeling' it was the contents of my oil tank making a break for it. The back end had swung round to almost full lock (reduced steering lock on my CR rep) and was just starting to straighten up with me thinking 'Wow I cant believe I'm going to save it!' - that's when the rear got a good hold and high sided me off like a rag doll.....

A little tip, dont feed an engine breather pipe back into the only oil tank breather, it will preasurize the oil tank which will then blow off it's oil lines!

Tim. · « **Reply #2 on:** June 26, 2006, 04:30:46 AM »

Others have had the same issue with no conclusive cause. Interestingly I have the same feeling, not on tight turns but rather on longer sweeping curves. I also run the Sport Demons at stock sizes (110 rear) and Boge shocks / Progressive brand springs up front. Tires have a couple thou' on them, shocks/springs a few hundred.

puppytrax · « **Reply #3 on:** June 26, 2006, 05:43:37 AM »

Tires/road surface may have something to do with it...I usually only get that feeling on steel deck bridges or asphalt with rain or wakeup grooves cut into it...

crazypj · « **Reply #4 on:** June 26, 2006, 06:40:29 AM »

Did you have the tyres balanced? I've found 550&400 weave if tyres are even a little bit out. lot of people didnt believe rear tyrew was problem until it got 'fixed'
try inflating about 3~4psi more, may heve some sidewa;; flex (if it makes things worse, go the other way)

DME · « **Reply #5 on:** June 26, 2006, 08:42:22 AM »

Another important thing to check is your wheels and spokes.

1. Tap the spokes lightly with a screwdriver. Do they give a nice, clear "ping" a the same frequency on every spoke?

2. Grab the wheel on it´s uppermost part and push and pull sideways quite hard. Is the wheel rigid with no movement?

If the answer is no to any of these to questions it´s time to give your wheels a well earned service!

Cheers
Daniel

paulages · « **Reply #6 on:** June 26, 2006, 11:38:15 AM »

the entire bike can't have more than 500-600 miles on it since new wheel bearings, new tires (inflated properly), new rear rim (balanced), new spokes (trued and tensioned), new tapered steering bearings (adjustment seems fine). i'll double check the alignment today.

tintin---your problem sounds exactly the same. it doesn't do it at all on quick sharp turns, even if i lay it over pretty far. it only seems to do it in the "long sweeping curves."

i'm going on a similar ride today. i'll report back if the shocks seem to help.

number13 · « **Reply #7 on:** June 26, 2006, 11:57:21 AM »

Might not apply to your sitiuation, but I had a funny
feeling like that on my 500. I eventually found it to be caused
by a plaastic cafe fender I had on the front wheel rubbing and
depositing stripe of PVC along one edge of the tire.

Tim2005 · « **Reply #8 on:** June 26, 2006, 03:15:38 PM »

Paul, I'm wondering, are Pirelli Speed Demon's the same as their Sport Demon's; if so you might find my views on them in this old thread relevant. Though your test ride with the new shocks might well resolve it anyway, hopefully!

http://www.sohc4.us/forums/index.php?topic=3352.0

Tim. · « **Reply #9 on:** June 26, 2006, 05:18:47 PM »

Quote from: Tim2005 on June 26, 2006, 03:15:38 PM

Paul, I'm wondering, are Pirelli Speed Demon's the same as their Sport Demon's; if so you might find my views on them in this old thread relevant. Though your test ride with the new shocks might well resolve it anyway, hopefully!

http://www.sohc4.us/forums/index.php?topic=3352.0

I've never had a problem with grip - this is definitely not a grip issue. Just a tracking issue. Likely alignment, which it would seem to me would be more noticeable in a long sweeping curve as opposed to a straight line or quicker turns. I've actually never checked my alignment properly, so I suppose it's time

paulages · « **Reply #10 on:** June 26, 2006, 09:51:22 PM »

Quote

I've actually never checked my alignment properly, so I suppose it's time

likewise. felt it in a couple of curves today, but didn't get a chance to hit any good roads to test it on.

TwoTired · « **Reply #11 on:** June 26, 2006, 11:04:54 PM »

Quote from: paulages on June 26, 2006, 12:00:13 AM

any ideas? the shocks? play in the swingarm? Lloyd...more variables i didn't list?

I will ask if the tire profiles are the same front and rear? ( I don't know much about pirellis)

Have you ridden the tires long enough to lose the mold release agent off the tread face AND the tread grooves?

Does it have the same behavior on both left and right turns?

Does your chain get too tight when the bike squats in the turns?

Just fishing really...

paulages · « **Reply #12 on:** June 27, 2006, 02:06:15 AM »

chain too tight...now that's a good question. i think i am running it a bit on the tight end. hadn't readjusted it, because i still need to swap out a new chain for my double-master-link one. will do that tomorrow. i believe the answer is yes to the other questions. seems pretty worn in. the tires are sized quite differently (130/90/16 rear, 100/90/18 front), but are matched to each other. seems to do it on left and right hand turns.

Tim2005 · « **Reply #13 on:** June 27, 2006, 01:21:14 PM »

Good thinking on the chain- also didn't realised you had non-stock rims. Rear shocks may be more important than usual as I vaguely remember that a 16" wheel with tyre is heavier than an 18" one, hence would require more damping to keep it under control.

We'll get there soon...

paulages · « **Reply #14 on:** July 17, 2006, 01:25:44 AM »

took those same roads today with southbound, going way too fast, and the bike handled perfectly! i machined an extra spacer out of a peice of an old hub assembly, which gave me a bit more thread length on my axle. i discovered that, though i am running the stock spacer configuration on my rear end, i had a bit too much slop in the axle itself.

up to 70mph through curvy roads and i never left 2nd gear! that is until we dumped into some weak-end warrior harleys at the bottom of germantown road (for the portland heads). what a buzz-kill...

theunrulychef · « **Reply #15 on:** July 17, 2006, 05:00:34 AM »

Glad to hear you've solved your bout of the shakies. I've got the same symptoms, although I believe it to be more of the plasic front fender (no fork brace) & shorter shocks on my F2 (about an inch too short). I'll test out my rear axle this weekend - have to put the damned center stand back on.

Paul - when you swapped your stock wheel out for the 16", how did that effect your rear ride height? Did the larger tire make up most of the difference, or is the bike on a bit of a rear slant? I'm swapping out my comstars for the spoked GL1000 front & a 16x3.5 in the coming months. Don't suppose you had to put different rear shocks on? Any "fat rear" tips or things I should watch for?

-Jay in Philly

paulages · « **Reply #16 on:** July 17, 2006, 09:59:15 AM »

it does look like it has a slight change in the riding height/geometry, but i've never measured the difference. there don't seem to be any obvious negatives. i'm running a set of those boge progressives everbody was snatching up off of ebay a bit back. i love the 16" rear. it hugs the road really nicely, and looks mean in the process.

Tim. · « **Reply #17 on:** July 17, 2006, 10:28:05 AM »

Quote from: paulages on July 17, 2006, 01:25:44 AM

took those same roads today with southbound, going way too fast, and the bike handled perfectly! i machined an extra spacer out of a peice of an old hub assembly, which gave me a bit more thread length on my axle. i discovered that, though i am running the stock spacer configuration on my rear end, i had a bit too much slop in the axle itself.

up to 70mph through curvy roads and i never left 2nd gear! that is until we dumped into some weak-end warrior harleys at the bottom of germantown road (for the portland heads). what a buzz-kill...

Help me understand what you did to solve the problem (and how much you'd want to make me the spacer to solve the same issue on my bike

)

paulages · « **Reply #18 on:** July 17, 2006, 12:06:05 PM »

my problem was simply that i couldn't tighten my rear axle enough. the nut was all the way in, and there was still play in the axle/swingarm. inside the hub assembly is a spacer which of course fits perfectly around the axle. all i did was cut this (i had a couple extra laying around) into slices of various thicknesses and added the best fit on the end of the axle, outside of the swingarm, giving me a little more threads on the other end. there is still a tiny bit of movement in my swingarm bushings, but the noticable problem went away.

tintin-- i have more of those washers i made, but they were crude enough that you could surely sort something out easier than having one of these shipped to you.

super pasty white guy · « **Reply #19 on:** July 17, 2006, 03:08:49 PM »

For anyone looking for washers of a certain thickness, the word of the day is "arbor shim" or "arbor spacer". I just spent 3 days looking for appropriate washers for my steering bearing replacements before I found this out.

See: http://www.fastenal.com/web/products.ex?N=999604633

By the way, anyone need a steering washer? I had to order mine in packs of 10.

Dave

Tim. · « **Reply #20 on:** July 17, 2006, 10:55:54 PM »

Quote from: paulages on July 17, 2006, 12:06:05 PM

my problem was simply that i couldn't tighten my rear axle enough. the nut was all the way in, and there was still play in the axle/swingarm. inside the hub assembly is a spacer which of course fits perfectly around the axle. all i did was cut this (i had a couple extra laying around) into slices of various thicknesses and added the best fit on the end of the axle, outside of the swingarm, giving me a little more threads on the other end. there is still a tiny bit of movement in my swingarm bushings, but the noticable problem went away.

tintin-- i have more of those washers i made, but they were crude enough that you could surely sort something out easier than having one of these shipped to you.

Were any parts missing? Is it possible the spacer you had on the bike wasn't original? Seems like it couldn't get that way over time and that something had to be missing and/or wrong.

paulages · « **Reply #21 on:** July 18, 2006, 07:10:59 PM »

i checked and double checked, but it seems that i had the stock spacers, etc. on the bike. it seems like at one point i was trying to use a '78K hub but it wouldn't work out. i don't know...something was obviously wrong, but it works now.

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Author Topic: cb550 rear end weave (Read 3177 times)

theunrulychef