Head shake/tank slap on a 955i

[Roadinator]

Last week I headed out on a 1000 mile trip.  Loaded down with side cases, top box and large duffel bag.   I noticed if I took my hands off at around 45mph, it would shake pretty bad and I had to grab the bars again (is that tank slap?).  I will ride it this weekend and see if I get anything with no extras on the bike.  I did check the front rim/tire and it looked fine and rode true.  I checked tire pressure and it was fine.  I did have tools in one side case, but pull them out and tried it and it was a little better, but still there.  Is this normal?

Will report how riding with no hands goes with no weight 

[Chris Canning]

Crap shock or setting simple as that,in laymans terms with all the weight on the back you've turned your Tiger into a chopper!!.

[Dutch]

If the bike is stable when you hold one hand lightly on the bars there is probably no big problem. A movement at about 45-50 mph is rather 'normal' for a two wheeled vehicle. Starts slowly and when you don't put your hands on the bar it gets worse.

Situations like worn front tire, worn stearing head bearings and/or a lot of weight on the rear etc contribute to the weave.

A 'real' tank slapper is much more violent and usually occurs at higher speeds.

[metalguru]

 


And try notching the rear shock up 2-3 notches.

[Chris Canning]

Well I most certainly don't if your getting any movement at any speed never mind 45mph there's something wrong period,non of my bikes do, it's and why I've taken the trouble with suspension,if I turned the pre load down on my rear shock two up with kit the bike would wander all over the place because the weight is at the back.

I see the original poster hasn't mentioned the preload setting I assumed it was 5 as per the hand book,and hence why I said crap shock,you'd need the head bearing to be falling out and the tyres set at 20psi or less to get the same result as lack of preload.

My Tiger two up,full tank bag and 40lbs in the topbox will break into a gentle weave but I need to be doing close on 130 to get that.

[Dutch]

One of my previous bikes had it pretty bad on a worn front. Replaced and could get my hands of the bars again. In Roadinators case all the weight on the back will contribute (shifting weight from top box to tank bags would help at least a bit).

Maybe the tires (Heidenau K76 isn't it?) also play a part. Can imagine a bike is more stable on one tire than on another. But to be honest I have no idea if the K76 is better or worse than comparable semi-knobbies. Or even pure street tires.

[metalguru]

Was agreeing with you on that one Chris....(turned out wrong)!!!!!

Even with my lowered standard shock I have no weave at all apart from a slight wander at about 125-130 with luggage one up.

Roadinator, work out how much weight you were actually carrying, as the luggage is not rated for high weights although we all overload them after 4 bags of sugar!

Is the tread on the front tyre cupped or worn (close exam required)? Does sound like not enough tyre on the ground with too less weight being the culprit.

[Roadinator]

I rode today with no luggage and still had some shake.  I checked the tire and it is about 6 months old and looks in good shape.  I can stand on the pegs and look at the front wheel while riding and see no issues with tire or rim going down the road.  If I hold my hands very lightly on the handlebars I can feel the shake in the bars ever so slightly.  My rear suspension settings are set at the stiffest settings for two up riding.  Guess I can raise the front end and see if I get any movement from the head (bad bearings?).  Maybe I am overreacting to it?

[Dutch]

When you can feel the weave while holding the bars riding solo I'd say you're not overreacting. Checking bearings is easy when you have a center stand. Just put the missus on the back and the Tiger will lift the front  :icon_wink:

[Chris Canning]

How many miles has the shock done,can you tell the difference between the settings,how heavy are you,I assume your running 36/42 on the tyres.

[cosmo]

Doubt it's down to miles on the shock. I've over 53,000 on the OEM suspension, front and rear, and no head shake issues.

However, I DID have to change the steering head bearings middle of last year at about 45,000. Got the kit from AllBalls and all was good after. This may be the issue, though I've no idea of mileage on the OP's bike. Not that it matters overmuch, knackered is knackered.

Cosmo

[Roadinator]

Hey Cosmo.
Have 52K on it.  I checked for play in the forks and cannot feel any play.  Any other signs to tell if it is bearings?  I don;t mind replacing them as they seems pretty cheap, just the amount of work involved. 

[lukeman]

How much drag is on the steering when you lift the front off the ground while on the centerstand? 

I'm kind of in the same boat as you right now, I'm afraid to take my hands off the handle bar above 60 mph.  I had some pretty bad head-shake coming down an on-ramp at around 90mph full throttle which freaked me out a bit.  My steering has no drag which I think is part of the problem, having a light front end only exacerbates it.  Running K60s.

Here is an thread about it on ADV.

http://www.advrider.com/forums/showthread.php?t=788729

I guess it comes down to:

there are 3 main causes of headshake , or high speed wobble/death wobble
1. geometry 
the rake and trail ,can be adjusted by lowering or raising the forks in the triples, sometimes just dropping the tubes 10mm can make headshake go away, the wheels must be in straight alignment with each other or the front and rear will be trying to go different directions
2. wheel condition
tires should be fairly balanced , spokes tight and wheel true, certain tires just squirm and add to headshake problems, they are usually not the cause just a contributor, for instance the D908 is extra tall and causes wobble, if you raise the forks till the caps are flush with the top of the triple it helps a lot, If carrying a load or with a low profile tire in the rear it helps to lower the forks in the triple with the marks over the top of the triple
3. mechanical condition
forks pinch bolts not torqued properly forks out of alignment, you should stand in front of the bike with wheel between knees and twist the bars back and forth it should only flex about and inch, not flop easy about 4"each way , front axle not tightened in sequence, swingarm bearings, or motor mounts loose, motor mounts can be a major contributer as the motor just hangs in the frame by the swingarm bolt that runs thru the motor, bad wheel bearings, loose rear wheel,

[Roadinator]

 Thanks for the info Lukeman.  The ADV stuff helped.  I think it is light enough that I am not going to stress about it.  I can ride with one hand on the bar and have no problems.  Seems like I am never riding without cases and the more weight I have on the back, the more it happens.  Might make a little video to share soon.  Riding it to the beach soon for a little vacation, so I ain't foolin' with the bike 

[cosmo]

Hey Cosmo.
Have 52K on it.  I checked for play in the forks and cannot feel any play.  Any other signs to tell if it is bearings?  I don;t mind replacing them as they seems pretty cheap, just the amount of work involved.

Mine were so bad that the fork had a decided 'step' when moving just off centre with the wheel off the ground.

The work involved wasn't bad. No need to remove any part of fairing. Putting it up might be the hardest part. I basically pulled the wheel, then fender, brakes (wired out of way), then pulled the tubes, upper tree, then loosened and removed the lower. Popped the bearings out, put new in, instal is reverse of removal.

Worst bit is the lower race. You may want to cut that one off. Install involves a freezer (tree) and a warm with a torch. Make sure you have a pipe on hand to finish getting it on.

Cosmo