Bike starts to "wobble" at higher speeds?

[posplayr]

Last night I stretched a string to check wheel alignment. Around the back tire and up to the front. I spread the string apart up front so when it passed the forward sides of the rear tire it just touched but did not deflect. I then measured the gap between the string and the front tire. Both sides forward and both sides aft were the same gap. Does that sound close ?

Checked the tire pressure. 35psi in both. The 15psi I put in the forks is still there too even with a pitted fork tube. Took the Saddle bags off but left the tail pack on. Went for a "run". It felt pretty good on one pass. When it started to buffet a bit I tucked in and the buffet went away so I rolled in some more gas. I got going so fast I blew right by my exit. Coming back It started to "dance" a little at 5K so I backed off and went home. Funny thing on that last pass I had my feet on the back pegs......

How close, normally you would be a few mm out? You want to be within 1-2 mm.

So it felt about the same?

Anyway sounds like you are close.

Are you carrying any errr..... extra weight on the rear (as compared to 30 years ago)?

Bumping up the preload a bit on the rear might help some. I also had my front fork with a lot of preload.

[bonanzadave]

Are you carrying any errr..... extra weight on the rear (as compared to 30 years ago)?

Extra cargo ? Ha ! No, like then Im still about a buck 8E.

New revelation. A friend stopped by to do a carb sync (the guy who crewed at Bonneville) and we looked at the rear end in motion on the centerstand. There is a little side to side movement. I want to find an runout caliper and show you guys a video......Stiff link in the chain ?

[Calvin Blackmore]

not sure if its been covered but dynamically balanced wheels greatly enhance a bikes ability to feedback actual road response.

I went for years thinking an annoying reverb in my spine was the price of two wheeled glory

had a spin blance and it was like oh my god

I jus tmean that the added vibration can impact on other sources and confuse you.

[posplayr]

not sure if its been covered but dynamically balanced wheels greatly enhance a bikes ability to feedback actual road response.

I went for years thinking an annoying reverb in my spine was the price of two wheeled glory

had a spin blance and it was like oh my god

I jus tmean that the added vibration can impact on other sources and confuse you.

I would figure out why the wheel is wobbling though; Is it out of round or bent?

If you have that kind of imbalance you vant fix, maybe this would help.

http://gl1800riders.com/forums/showthread.php?t=201280

[Calvin Blackmore]

I would figure out why the wheel is wobbling though; Is it out of round or bent?

If you have that kind of imbalance you vant fix, maybe this would help.

http://gl1800riders.com/forums/showthread.php?t=201280

nope just good old improperly mounted tire witht he heavy spot enhancing the wheeels heavy spot

Does the spot go opposite the stem
so hard to gauge when you are eaten by flies and anxious to ride

[bonanzadave]

I would figure out why the wheel is wobbling though; Is it out of round or bent?

If you have that kind of imbalance you vant fix, maybe this would help.

http://gl1800riders.com/forums/showthread.php?t=201280

Very interesting . Have yet to explore the dial caliper on the rear wheel. Still planning it tho...

Update: Made a couple runs last night with the Bags on. Not good. I thought for sure I lost air in the fork with the leaky seal. Nope. I de-aired them both and tried it again. Still bad. Got to looking at the front end and discovered the 4 bolts (up under the fender) holding the horseshoe brace were loose . This is it ! I found the missing piece ! Got those tightened up and went out again. Still bad. I went home and parked the POS. dejected .

[gs road racer]

Dave go here long read but may help you...

http://www.bikesetup.com/

[bonanzadave]

http://www.bikesetup.com/

Thanks RRer,

I just stopped working for 45 min . Thats a great site ! The newbie page & riding tips should be read by everyone on 2 wheels. The info in Braking could save your life.

Im gonna study the Setup & Suspension stuff a little more to see if it relates to my wobbles. This line got my attention..."The geometry makes a huge difference but for the most part the manufacturers have done the work for you already." I always come back to this cause out of the box this bike was rock solid at 3 digits. I gotta be missing something.....

[posplayr]

Dave,
I have scanned back over the thread. and see a couple of things. You say you are putting 15 psi of air into the forks. I would not run any pressure but instead add a section of PVC if you have to to increase preload.
This makes me also wonder if you have set your preloads or on the rear if you might not have the right spring on that progressive. To light of spring on the rear can give issues as well. So measuring sag would be the best way to see where you are at and then go from there.

Another thing about those bolts on the fork that were loose. Do you have a fork brace? If so did you ensure that the entire thing slides up and down (with the springs out) before tightenting? My GS750 had a very strange feel up front (like the front tire was hunting left to right about 1") to it when I first got it ; after a change of oil and setting the fork brace much of that disappeared.


Jim

[gs road racer]

Thanks RRer,

I just stopped working for 45 min . Thats a great site ! The newbie page & riding tips should be read by everyone on 2 wheels. The info in Braking could save your life.

Im gonna study the Setup & Suspension stuff a little more to see if it relates to my wobbles. This line got my attention..."The geometry makes a huge difference but for the most part the manufacturers have done the work for you already." I always come back to this cause out of the box this bike was rock solid at 3 digits. I gotta be missing something.....

Exactly and as POS put it sag is where to start as it determines ride height, that site is a great resource for all.

[bonanzadave]

Jim,

Does the same thing with or without air. No fork brace. Rear Progressives have HD springs. Everything set on 2. Top fork preload, bottom dampening knobs, Rear spring height. Forks moved very smoothly by hand when mounted without the springs installed.

Same wobble today after the upgrades as it was 5 years ago.

Looking back I was not able to get the lwr race out of the 3-tree so I put the All Balls bearing on the old race. It seemed very smooth.

[posplayr]

Jim,

Does the same thing with or without air. No fork brace. Rear Progressives have HD springs. Everything set on 2. Top fork preload, bottom dampening knobs, Rear spring height. Forks moved very smoothly by hand when mounted without the springs installed.

Same wobble today after the upgrades as it was 5 years ago.

Looking back I was not able to get the lwr race out of the 3-tree so I put the All Balls bearing on the old race. It seemed very smooth.

Dave,
You need some idea of what your sag numbers are. By measuring the:
a.) free length (totaly unweighted)
b.) static (without rider)
c.) loaded with rider

This gives you two data point, compression under bike weight and compression under rider plus bike

you are able to determine if
a.) the spring rate is sufficent
b.) preload is set for ride quality

Also putting a tie strap on the front forks helps to know how much travel you are using. Usually braking causes the biggest compression, normally you should not exceed more than about 2/3 of total travel on a relative smooth road (that is what I have found). If you do then a big bump will bottom out.

Did you set the head steering bearing friction? It should be firm but not notchy.

[Sandy]

I've been reading this thread and everything that could be a problem seems to be covered. This is a little off the wall but try loosening and retorqueing the engine mounting bolts. The engine does provide stiffness to frame and over the years can either work a little loose or even move in the mounting holes while still appearing to be tight. Loosen them all at once and retorque, not one at a time. It should only take a couple of minutes to try, might help, might not. The reason I say this is because when I had my Yamaha 750 triple I had to do this about every 15,000 miles to eliminate some engine vibration. The mechanic said that the engine can actually creep in the mounting holes and in this case caused some extra vibration in the bars. Procedure was to centrestand the bike, put some blocks under the engine so the front wheel was off the ground, loosen all the main mounting points at the frame (not the plates, although it wouldn't hurt to check those also) so the engine would now be at the top of any slack in the holes and retorque. This stopped the vibration for quite a while and over time the engine would actually migrate to the bottom of the holes. Only took a few minutes to fix. Maybe over time these move a bit causing either a slight misalignment in the frame or not providing a rigid enough mechanical bond to stop frame flex. Or maybe a misalignment from the bike being dropped. I haven't heard of this causing handling problems before but it's easy to check and who knows with these old bikes what new problems can crop up that we haven't heard of before.

[bill_khaos]

wobble

hey........seems that all has been covered... i had a simular problem on a fzr 1000.... at 150 it started shaking like the middle had a hing. you could control wobble with speed.... after having dealer go over everthing the the yamaha rep fixed the problem,,,, never would have thought it... it was the tires ... the way air went over and around the tires is what made it wobble,,, i put oem brand tires back on and wobble went away... just a idea????

[bonanzadave]

Sandy, Thanks for the input. My brother tipped it over in the driveway by bumping it with his truck. The wobble started not long after. Hard to remember it was 20 years ago. I thought I had a wrench on every bolt on the thing but just a couple days ago I found the Fork support horseshoe bolts loose. Im gonna check em all again.


Bill, The tires are brand new. Avon Road Riders. Lots of guys have em on 1100Es. Funny though....no one has yet to say they have no problem going wide open in 5th. Except maybe the drag racers. Has any body taken an 1100E with Road Riders up to 7Krpm in 5th ? I cant get to 6K ?

Edit: Well crap ! The back tire has only 20 psi. Stand by Ill be right back.....I hope.