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Tiger Time => Girly Talk (1999 - 2006 Tigers) => Topic started by: Roadinator on July 04, 2013, 01:37:37 AM

Title: Head shake/tank slap on a 955i
Post by: Roadinator on July 04, 2013, 01:37:37 AM
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  :icon_razz:
Title: Re: Head shake/tank slap on a 955i
Post by: Chris Canning on July 04, 2013, 09:39:18 AM
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!!.
Title: Re: Head shake/tank slap on a 955i
Post by: Dutch on July 04, 2013, 10:08:37 AM
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.
Title: Re: Head shake/tank slap on a 955i
Post by: metalguru on July 04, 2013, 04:53:10 PM
 :iagree


And try notching the rear shock up 2-3 notches.
Title: Re: Head shake/tank slap on a 955i
Post by: Chris Canning on July 04, 2013, 08:32:33 PM
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.
Title: Re: Head shake/tank slap on a 955i
Post by: Dutch on July 04, 2013, 09:47:06 PM
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.
Title: Re: Head shake/tank slap on a 955i
Post by: metalguru on July 04, 2013, 11:34:58 PM
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.
Title: Re: Head shake/tank slap on a 955i
Post by: Roadinator on July 05, 2013, 03:28:19 AM
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?
Title: Re: Head shake/tank slap on a 955i
Post by: Dutch on July 05, 2013, 08:44:35 AM
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:
Title: Re: Head shake/tank slap on a 955i
Post by: Chris Canning on July 05, 2013, 02:42:01 PM
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.
Title: Re: Head shake/tank slap on a 955i
Post by: cosmo on July 06, 2013, 04:27:34 AM
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
Title: Re: Head shake/tank slap on a 955i
Post by: Roadinator on July 06, 2013, 03:29:49 PM
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. 
Title: Re: Head shake/tank slap on a 955i
Post by: lukeman on July 08, 2013, 07:07:43 PM
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,
Title: Re: Head shake/tank slap on a 955i
Post by: Roadinator on July 09, 2013, 02:17:57 AM
 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  :hat10
Title: Re: Head shake/tank slap on a 955i
Post by: cosmo on July 09, 2013, 05:21:12 AM
Quote from: Roadinator on July 06, 2013, 03:29:49 PM
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
Title: Re: Head shake/tank slap on a 955i
Post by: Roadinator on August 10, 2013, 06:01:12 PM
Back at this again, as it seems to be getting worse.  Checked the front end again and the only thing I can feel is a slight sticking/lumpy point right in the middle of moving the handlebars left to right (of course while the front is in the air).  I'm guessing bearings can wear in a certain spot and riding straight seems to be the easiest place for wear.  Is this common?

Will order an All Balls kit unless someone has recommendations.
Title: Re: Head shake/tank slap on a 955i
Post by: Mustang on August 10, 2013, 07:06:58 PM
you need Steering head bearings ..................All Balls is your cure .

There's a thread in the Girly How To's to Guide you thru ..............
Title: Re: Head shake/tank slap on a 955i
Post by: metalguru on August 11, 2013, 07:30:35 PM
While you have the front end apart may be advisable to check the wheel balance too.
Title: Re: Head shake/tank slap on a 955i
Post by: lukeman on August 11, 2013, 07:43:38 PM
I realized upon closer reflection that the previous owner never balanced the wheels, I used some dynobeads front and back and headshake is completely gone at high speeds!
Title: Re: Head shake/tank slap on a 955i
Post by: blacktiger on August 12, 2013, 11:35:33 AM
I agree with all the above posts. Just to say the Tiger955 should be one of the most stable bikes on the road. You shouldn't be getting any head shake at all.

One thing no-one has mentioned........The fork legs should be flush with the top of the top yoke. If someone/PO has dropped the yoke down the legs you'll have steeper geometry which could be part of your problem exacerbated by notched head bearings.
Title: Re: Head shake/tank slap on a 955i
Post by: Roadinator on August 13, 2013, 05:31:20 PM
I was going to take a pic of the top of the forks in the tree.  They are not flush, but close and to me one looks a couple of millimeters different, but I could have had too many beers when looking at it.  Will snap a pic and post.  Guess I should get the front wheel checked for balance, although it has weights and the front tire is only a year old with about 5k on it.  It doesn't look like it is cupping (sp?).  I was surprised on how much flex the front forks have in them when yanking on them, but I remember watching Isle of Mann videos of the super slo mo lift off the ground and back down again and surprised to see the forks twist and move when they hit pavement again.  I think I will also do the fork oil and led lights in the dash. Just need to save a little money and make some time.
Title: Re: Head shake/tank slap on a 955i
Post by: Bixxer Bob on August 13, 2013, 07:59:09 PM
Fir what it's worth, I never had weave with my old  rear shock, with or without luggage. With the shortened Hagon on the back and the front lowered by 10mm I now have a slight high speed weave but only with the luggage fitted.  I suspect I need a bit more preload.
Title: Re: Head shake/tank slap on a 955i
Post by: John Stenhouse on August 15, 2013, 11:25:43 AM
The instability seems to be down to the top box, mine does it when I've got all the luggage on, take the box off and it goes
Title: Re: Head shake/tank slap on a 955i
Post by: Bixxer Bob on August 15, 2013, 11:33:46 AM
Maybe with the luggage John, but not on its own.  I use my 50l Givi all the time with no probs.  In fact the 'Bird seems better with it on; something to do with me leaning forward and airflow off my back I think.
Title: Re: Head shake/tank slap on a 955i
Post by: John Stenhouse on August 15, 2013, 11:37:09 AM
Ah, I've never ridden it like that so I wouldn't know. I'll have to try that now to add to the experiment. Funny you should mention the 'Bird as my ST1100 does the same with luggage and top box but never gets to the weave stage just feels a touch unstable.
Title: Re: Head shake/tank slap on a 955i
Post by: Chris Canning on August 15, 2013, 02:34:21 PM
I can make any of my bikes do(weave at high speed) all you have to do it take a couple of turns off the preload,where it gets complicated just adding preload will cure the weave but you'll end up with crap suspension,more preload means more compression and rebound to control it you'll end up with a pogo stick otherwise,of course you will also get some input from dropping the forks through yokes anything between 5/10mm.

Where it gets even more complicated if you end having to put too much preload on and having to add the extra compression and rebound to control the spring the shock gets hot and bothered very quickly,thats when you realise you have the wrong spring and need to go up one or more,The Ohlins on my 1100s has a spring one up from stock and it's never been enough and I've way too much preload etc a must for this winters list.

When I test rode a 1050 sport the other week told the sales guy just crank the preload up mate which he did,the suspension was crap but it steered like a mini moto.
Title: Re: Head shake/tank slap on a 955i
Post by: NortonCharlie on August 17, 2013, 08:43:42 PM
I had a bad front Tourance tire, if I had my hands off the bars and throttle around 35-40 MPH the front end started wobbling like crazy.  There was a bad bunch of tire made but those should have been gone years ago.  The steering head bearings sound like they need replacing anyhow, while it is tore down may as well change the fork oil.
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