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Discussion Starter #1
I haven't been able to find a dedicated thread to tank slappers but I would like to hear from all of you who have had them and stayed up. I've heard conflicting comments about this and really would be at a loss as to how to get the bike back under control. Some say speed up and other say slow down...etc.
All comments appreciated!:confused::confused:
 

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To oversimplify, there are two possible responses to a developing tankslapper.

1) Do nothing. Maintain a loose grip on the bars and keep doing whatever it is you're doing. Relax and it should stop. Overreacting will increase your problem.

2) Do something different. Whatever caused your tankslapper -- acceleration or deceleration -- do the opposite. Change the state of the system and the behavior should change. Shifting your weight helps, too.

I believe the usual school of thought is that gentle acceleration is the safest response in general (assuming you're pointed toward a reasonably clear space... :yikes: ).

Chopping the throttle or nailing the brakes is right out. Strong deceleration will plant the front wheel, and if it's not pointed straight when it happens to settle down, you got worse problems.

Again, all the above is a drastic oversimplification.

Once you've stopped and purchased new underwear, you might want to redistribute all the crap you're carrying on on the back of the bike. Overloaded luggage and inadequate rear suspension is a common root cause of handling problems, at least on a V-Strom. Some say the aerodynamics of a top case contribute to this as well.
 

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Had a mild one at 115 with the top case on:jawdrop:Got a Scotts and fork brace and all is good!
 

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The only one I ever experienced was on a '66 Yamaha Big Bear Scrambler at about 80 MPH, which was just about topped out.

I slid up on the tank as far as I could and slowly rolled the throttle off, but it continued to oscillate all the way down to about 30 MPH. Never rode that bike faster than 60 MPH again. Don't know to this day why I did not go down. I was 20 years old and stupid. Did not have on a helmet, jacket, gloves or anything. It would have been ugly had I hit the asphalt.

Wayne
 

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A lot of times it will solve itself. If the oscillations start getting worse though. you have to take control quickly. That will probably take your big muscle groups. Your arms may not cut it. Grip the tank tightly with your knees and pull back equally with both arms straight like you are rowing a boat. That puts your leg and back muscles on the job. I would also pull in the clutch and avoid braking so the engine power and the bike's kinetic energy are not feeding the beast. A Scotts steering stabilizer will prevent a slapper from starting. I tried using my arms to stop oscillations that started after closing the throttle at an indicated 119mph. Letting go of the bars and hoping the thing would resolve itself wasn't so much a choice as a necessity as I couldn't hold on any more. Broken bones, a separated shoulder and a totalled DL650 were the result. I ordered a Scotts six months before I could ride again.
 

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Discussion Starter #6
Undershorts and tank slappers.

I like your undershorts comment!:biggrinjester: I'll probably need more than that if it ever happens to me high speeds though.

So it sounds like what I'm hearing from you is keep a light touch and from Greywolf if that doesn't work then try a heavy grip to stabilize.

As far as speed is everybody in agreement to NOT slow down radically? Maybe ease off a bit? Or speed up a bit? :confused:

Not hard braking makes sense too unless the wheel is straight which in a tank slapper is never is for long anyway.
 

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I simply backed off the throttle very slowly and it worked, that time at least. I hit a series of washboard ripples about 75 feet long at 80MPH and that is what started the slapper. I moved up onto the tank a little because in my mind, I thought I needed to get more weight on the front end. Right or wrong, that is what I did.

You gotta have big cajones to accelerate if you already nearing triple digits and the front end is slapping! Even if that is the right thing to do, it is going to go against the grain for most folks who are already in survival mode.

Wayne
 

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The only real tankslapper I've had was on an H1 Kawasaki triple back in the early 70's. Don't recall how fast I was going, but it happened after a slight right hand corner going uphill and encountered the seam where the road and a bridge met. The bridge was flat and both wheels left the road. The tank slapper started on landing with the bike still in a slight lean. The best I remember, it ripped my grip from the bars and almost sent me over them. I have no idea how I got through it without going down or what I did, but I do know it scared the beejees outta me.
 

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hmmmm?.........

I have had a few bikes that would do a tank slapper and one that was successful in pitching my azz off the bike and what I have developed as a means to stop it is this, apply equal parts throttle and rear brake. Keep adding more brake but, keep enough power in it that the weight of the bike doesn't shift toward the front wheel. Using this method I can keep the front end from overpowering me and yet decrease my speed to the point where the wobble will stop. I have used this on BMW's and Honda's and Harley's and have been able to get the bike back under control. Can't say it will work every time for every one but, it is what I have taught myself to get rid of a strong head shake.

Any time any bike of mine has done this I immediately start what ever is necessary to fix the wobble or I get rid of the bike. The time that I didn't know what to do was the summer of 1978 and I have the pictures hanging on the wall in the garage of what I looked liked after a 65 mph slide down the highway with no ATTGAT what so ever. Lotta scabs all over every where on that one. Interesting side note on this incident is that I was running a Dunlop Gold Star TT tire on the front of a 750 Honda single cammer and I had a brand new tire and tube leaning against the couch but, the guys called and said cmon man we're going riding and instead of taking the 20 or 30 minutes to spoon the old tire off and the new one on and do a little spin balance on the screw driver trick, I paid the price for that decision.

I no longer take a chance on running any tire that isn't fresh enough to ride safely. The trouble is that it isn't always one thing that contributes to a speed wobble but, can be many single things or more than one thing coupled with something else. From the dialogs that I read on here and the events I have experienced personally it seems that the one biggest factor on the Strom is having a set of slab sided bags and running them up to and beyond a speed that is aerodynamically prudent? My bike has given me a little wiggle one time and it happened when I was in a strong Wyoming cross wind and I was a little over zealous in hammering the throttle. The wiggle never became violent but, I took action as soon as it started and managed to get my speed down and it stopped.

In 2001 I bought a brand new from the dealer BMW K1200 LT and it came with a small stabilizer mounted on the front end to control wobble and yet at about 40 or so if you let go of the bars it would just kinda veer back and forth. It is a topic of conversation on BMW Luxury Touring.com and has been for years.

My DL seems to be fine up to 95 and I generally ride at a speed lower than that so I seem to be ok on the wobble issue but, I think the bags are the culprit in my case since if I take all the bags off and just go ride the bike I have never had any kind of wobble at speeds well over the posted.


Flint
 

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Anyone ever had tank slapper while carrying a passenger. How much is that Scott's stabalizer and how hard is it to install?
 

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The Scotts has good instructions. Depending on how the frame casting halves line up, the raised boss on the top of the frame may need a little filing or grinding to fit the hole in the mount. You do need to take the fuel tank off. They are a bit over $450 from svracingparts.com
 

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This isn't a music thread?
 

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Immediately lay your chest on the tank to weight the front wheel. Search it on youtube, some good videos of the technique.
 

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On a local track, running 30 psi on the front and 34 on the rear, doing 120-127 on the front straight, slamming on the brakes for the left-hander, I had no problems at all. I did have a 750 Yamaha that did it, cornering, at higher speeds, like 60+....therefore, no more cornering at 60+:).
 

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1. heavy back braking may lock your rear wheel
2. it will unload the front wheel even further thus deepening the slap
 

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another question, does abs help?
Help prevent tank slappers? No. Lowering the front of a Vee or Wee to lower aerodynamic front end lift, a fork brace to help prevent front wheel shimmy and a Scotts steering stabilizer to dampen violent changes in steering direction are the main aids available.
 

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There needs to be a definition here there it front end wobble and tank slapper.
front end wobble is when you let your hands off the bars and the front wobbles some times violently. This more common on older motor cycles because of the steering geometry and frame construction. Also tire wear and condition. This normally will not put you on the ground if you do not panic. laying on the tank or slowing to around 30 to 35miles will stop this action.
This has happened to me on two different motor cycles. The worse case on a 80ies V65 saber. We did every thin in the world to get rid of it and nothing worked. The only thing to stop it was to drive it like a little old lady.
Tank slappers on the other hand happens when the bars go from lock to lock and if not corrected will put you down. This will happen when accelerating hard and the front wheel is severely lightened or in hard deceleration the front suspension is over loaded. The fix on these are fairly easy.
On acceleration the driver is normally the input for the slap trying to keep the bike straight. Because of the ark the front tire makes on the ground when turning left to right. The driver has to put a lot of pressure on the bars to bring it to center and over shoots the desired direction. this has happened to me on a 00 speed triple trying to beat fellow riders out of a parking lot. The fix slow a little and you're fine.
Declaration does not happen as much on newer bikes because of steering, suspension and frame advancements. It usually starts when chopping the throttle at high speeds and the weight is thrown to the front wheel. The front wheel is trying to squirm out from under the pressure. and can not move in a vertical direction. kind of like a loaded shopping cart rolling across uneven ground, wanting to dodge left and right as you push it. The easy fix is to accelerate to the speed you were going. Then decrease the speed at a slower rate.
There is the odd occurrence of front end lift from air flow, road damage and a strong side wind. most of witch are fixed by slowing your speed.
This is just my experience and research trying to fix problems with my rides.
Good Luck!:thumbup:
 
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