Strange Shutter. . .then gone?!

[Kunkies]

Quick background first. . .

I was on my way to see my son yesterday, traveling about 70-75MPH on a control access interstate hwy., when I had to avoid a potential situation.  Evasive maneuver was, accelerate rapidly, jump two lanes to the right, and then back to my original lane.  After the risk was mitigated I looked down at my speedo and I was hovering around the 110-115MPH mark.  Slowed back down to 70-75; risk averted. 

What struck me as odd, was during evasive maneuvers my rear end shimmied for about 1 second and then back to normal.  I have never experienced that before.  Bearing issue?

. . . and for those who are wondering, no, I don't normally go 110MPH.  Not my style, yet this time speed was my freind.

[Tfrank59]

Wow, I have no idea what my bike would do at 110 mph – it might do way more than shutter for a second! – so I guess I'm not much help.  But I'm thinking that at those speeds it could be anything from a wheel out of balance to even a slight amount of slop in your driveline that would be exaggerated tenfold.  I'd be interested to hear what others say, but my take is you would have to get everything back to original pristine condition to run smoothly (and safely) at that speed.

[Steel cowboy]

Could have been uneven pavement or some road issues like tar snakes too. But it it went away try the maneuver again with the same actions to see if it happened again. Then it would confirm wether it's road or bike.

[Momz]

Check your upper shock bushings and both tire pressures.

[Kunkies]

try again!!?, aaaaahhh. . . no thanks.   

Tire pressure at time of "event", (Avon Cobras), 42lbs front/48lbs rear hot.  I have a Garmin TPMS.

Upper shock bushing; will check.  Although just a few months back I installed Progressive 12.5"  444[HD].  Torqued to spec', then checked after 1,000 miles; torqued to spec' again.

Thanks for the suggestions

[Paladin528]

i had my 99 I/S up there a couple of weeks ago on the superslab.  she gets twitchy at high speeds thats for sure  anything over about 80mph and she wanders and any significant fluctution in the rooad is noticible with a wobble.  kinda scary really  slower tha that and she is solid as a rock.

[Firefighter]

My 2000 IS will sometimes "Death Wobble" at 85 and up, (GPS speeds, the spedo would indicate 90 +). I have done lots to correct this but haven't found yet why this happens.

About a week ago I was testing after a tire change and was about 80 mph and the wobble started, thought I would run a little faster and see what happened, the wobble went from slightly un-nerving  to almost crashed in a second. I let off the throttle and slowed, but I almost lost it, wont try that again. The death wobble was so bad that my butt was sliding side to side on the seat, I think another second I would have ate the pavement.

I have tried lots of things and changes but can't figure it out. In past years I have been over 100 mph with my wife on the back with no wobble, so something has changed, or I have done something wrong.

I do know that wind speed, direction, and impefections in the pavement contributes to this.

[Bighead]

Firefighter you got something bad wrong I think I would be checking everything on that bike before I even went 60 on it. I don't ride to triple ding its often but have never had a problem when I did,no wobble or anything else. When I hit the slab on a long trip it is not uncommon to run 85 for a whole tank of fuel at a time and have never experienced this situation on either of my Valks.

[Moonshot_1]

I'm addressing a wobble issue as well. 99 I/S. 55k. Dunlop E3. Only when I release the handle bar and only on certain roads or certain speeds. Hwy. speeds are solid as a rock. In town speeds it is either solid as a rock or it loses it's mind. Recently it seems that the wobble is getting more intense but still is well behaved as long as I am holding the bar.
Kinda flighty around sweeping turns too.

Going to have the rear shock bushings replaced and I got those ordered and 10 min. later discovered a leaky front right fork. So going to have the front forks redone and the shock bushings replaced and see if that doesn't make it right.

If not, it is on to the head bearings. Perhaps a new front tire too.

Will post the progress when I know.

[Jess from VA]

Tires and shock bushings and suspension. 

But don't forget the Interstate is a sailboat full of topside fairing/shield and trunk, and at high speeds, the sailboat can have some effect on smooth running (and add in the vortex of wind being pulled/pushed along any busy freeway with semitrailers, along with any prevailing winds).  At high speeds, any quick sideways motion can set off some rocking or wobbles.  I've had it happen once or twice, nothing terrible, but a little unnerving. 

Not that checking things out isn't a good idea, it is.

[longrider]

In my opinion those of you who run the E3 run the risk of wobble.   I had the same issue a few years back.  Been riding Avon Cobras and she's smooth and straight into the triple digits

[doubletee]

Check your upper shock bushings and both tire pressures.

This.

[Paladin528]

I attribute the instability of the I/S at speed to the fact it has a huge windshield and fairing as well as other drag and instability causing accouterments hanging off of it. 
If I am alone on a calm day in the middle of nowhere, I can roll on the throttle all I want and it is straight as an arrow but on the highway with other vehicles around or any wind she gets squirrley. The laws of aerodynamics seems to be at play.  At this point I will leave it at that because at normal speeds, shes a beauty
 

[Firefighter]

I have been checking everything. I have changed two front tires, Avon on front and CT rear currently. Just rebuilt forks, new head bearings, new front wheel bearings, new progressive rear shocks, checked swing arm for play (have not had it off). Do the regular rear maintenance at 10 thousand miles. Everything seems tight to me.

This is not the tank slap that only happens when you take your hands off, this is a "death wobble" that you can look up and read about. I have no problems below 80 mph, sometimes I can go above this speed on smooth road or hiway, but wind or bumps will initiate this problem. I am still investigating/experimenting.

[Kunkies]

Agree on the E3's, thus moving to Cobras

[Punisher]

I have been checking everything. I have changed two front tires, Avon on front and CT rear currently.

What make/model/size CT are you running?

What pressure are you running in it (cold)?

How many miles on it?

Have you ever been at those "death wobble" speeds before with that car-tire and it didn't wobble?

[Firefighter]

Think I am hijacking this thread!

Yokohama Envigor H type 205/60/16, have 4000 miles on it. Have ride on formula in the tire.

40 psi front, and 45 psi rear

yes, I have been over 100 mph in years past with no death wobble, but not sure if it started with this tire as I don't usually ride that fast.

I have also posted about a wiggle in the handlebars that I cannot track down. If I straddle the bike, I can shake the handlebars back and forth fast and then stop and I get a shimmy or wiggle for a second, feels like head bearings which I have changed and re-torqued a couple of times. This might be my death wobble??

I have not had the swing arm off but I can't detect any movement.  Thanks for the input.

[The emperor has no clothes]

Think I am hijacking this thread!

Yokohama Envigor H type 205/60/16, have 4000 miles on it. Have ride on formula in the tire.

40 psi front, and 45 psi rear

yes, I have been over 100 mph in years past with no death wobble, but not sure if it started with this tire as I don't usually ride that fast.

I have also posted about a wiggle in the handlebars that I cannot track down. If I straddle the bike, I can shake the handlebars back and forth fast and then stop and I get a shimmy or wiggle for a second, feels like head bearings which I have changed and re-torqued a couple of times. This might be my death wobble??

I have not had the swing arm off but I can't detect any movement.  Thanks for the input.

F.F. Try going down to 34 on the rear. I don't know if that's it but its worth a shot.

[Firefighter]

I will try that, I may have in the past as I did experiment with some tire pressures but can't remember. Thanks for the help  Firefighter

[Steve K (IA)]

Agree on the E3's, thus moving to Cobras

It's not the E3 tire unless it's worn out.  

I'm on my second set of E3's.  These tires give me complete confidence in all road and weather conditions.  Plus 20,000 mile life is a plus.  (Dyna Beads installed)  Been up to 115 mph many times (I/S) and it is rock solid.
40# front & 42# rear

It's your bike.  Use whatever tire makes you feel good.  

For me...I will never put another Avon or car tire on either of my Valks ever again.

YMMV  

[Punisher]

Yeah, play around with the air pressure in that car tire as it can make a difference.

I know from experience that the Austone Taxi Tire benefits from higher than usual air pressure because of its aspect ratio (tread width to sidewall height).   Normal pressures used by other car tires is not enough on the Taxi tire or you could have a high-speed "float."   I call it a float because it didn't feel so much to me like a wobble but just a "floating" sensation in the rear.

Doing some reading I found where Goldwinger's were experiencing the same thing and started running 45-50 lbs of pressure which stopped it.   I bumped mine up from 40 to 45 and the "float" went away.  I have been up to 120 indicated on an IS for five miles and it was smooth as glass.   I can rip the pegs off in the curves with confidence in the grip.

I think the max cold pressure on the taxi tire is something like 60-65 lbs.

I agree with The Meat, start at 34 and work your way up to max cold.

[Ricky-D]

Tire pressure has little influence on ride-ability when the tire is in good condition and running true.

On the heavy bikes, the weight of the load will affect many issues, making them worse and especially

if you have a lot of junk in the trunk and bags that's not secured from shifting around. Cranking down on the

steering head bearings to dampen wobble is a invitation to disaster. Loose front fairings contribute mightily

to front end wobble at highway speeds.

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