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What is a "tank-slapper"?

Old 12-19-08, 11:36 AM
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What is a "tank-slapper"?

Hey guys,

Dumb question here (or perhaps not). I have heard different people use the term "tank-slapper" in different ways. Nominally they all refer to the back end stepping out and then over correcting back. But to what extent? Two examples:

mild: "well that was a bit of a tank slapper, but we managed to recover"

wild: "he got into a tank slapper and was totally gone by that point"

So, what is your definition of "tank slapper"?

-b
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Old 12-19-08, 12:11 PM
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The rear end wobbling left and right.
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Old 12-19-08, 12:32 PM
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its really more of a term in reference to motorcycles (obviously) but it sort of transfers over to cars.
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Old 12-19-08, 12:35 PM
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For me a tank slapper is a period of sideways sliding broken up by brief moments of traction which transition to a slide in the opposite direction. I don't call it a tank slapper unless you've gone for three slides in a row. It's usually caused by getting into a drift and then overcorrecting. I personally pulled a brilliant tank slapper down the front straightaway at the Edmonton Indy support race. I carried 90 mph through a corner I had previously carried 85 through. The car started to drift, I lifted off the throttle, corrected and it caught and started to slide the other direction. Again correct, again traction, again sliding the other direction. I think I went back and forth about seven times before I just couldn't keep up and got into a spin. I have the data from the Acquisition system and it just looks goofy. In the future I plan to just step back into the throttle and ride the slide out.

-Trent
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Old 12-19-08, 01:06 PM
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A tank slapper is a phenomenon causing pucker factor.

The pucker factor in this case increases with the square of the speed at which the tank slapper occurs.
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Old 12-19-08, 06:20 PM
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Motorcycle term, has nothing to do with cars.... It is when the front wheel on a bike is going left to right hence making the handlebars "slap" the tank...
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Old 12-19-08, 10:41 PM
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Speaking of which, in class at DE they said if you get yourself into a good slide, don't put more than 90 degrees into the wheel and don't hold it for more than a second or two. A really common mistake is to over correct, and when the car starts coming back the other way you can't get the wheel back over in time and you just end up spinning the other way, which is often worse than spinning in the original way.
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Old 12-20-08, 02:21 PM
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Originally Posted by wickedrx7 View Post
Motorcycle term, has nothing to do with cars.... It is when the front wheel on a bike is going left to right hence making the handlebars "slap" the tank...
Yup, but still applied to cars rather frequently.

The effect on the rider/driver is often the same.
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Old 12-20-08, 04:39 PM
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When I "tank slapper" happens in a car the driver usually looks like he's swatting flies on the steering wheel.

The other way I refer to them is when you look inside the car at the driver its all "elbos and armpits".
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Old 12-26-08, 09:04 PM
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http://www.youtube.com/watch?v=xUBwCX_Mv2Q
This is a tank slapper. There is no tank slapper in car terms. If someone is using the term they're using it wrong. IMO...
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Old 12-27-08, 12:31 PM
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Originally Posted by Hyper4mance2k View Post
http://www.youtube.com/watch?v=xUBwCX_Mv2Q
This is a tank slapper. There is no tank slapper in car terms. If someone is using the term they're using it wrong. IMO...
Maybe so.

Do you have have a better term to describe the phenomenon as it occurs in cars?

I don't like it when people refer to BMW cars as 'Beemers', but they probably aren't going to stop doing it. (BMW cars are 'Bimmers', bikes are 'Beemers')
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Old 12-27-08, 03:23 PM
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One of the comments to the videos on YouTube referred to this as "fishtailing", which seems to be the proper term here.

Wikipedia (which is of course the ultimate reference on all things cars ) lists the two terms as being equivalent.

http://en.wikipedia.org/wiki/Fishtailing

-b
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Old 12-28-08, 10:10 AM
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Originally Posted by wrankin View Post
One of the comments to the videos on YouTube referred to this as "fishtailing", which seems to be the proper term here.
That term came to mind, but I didn't mention it.

Personal preference: I just don't like it.
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Old 12-28-08, 10:14 AM
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I always figured the car use of the term originated with old F1 (or similar) cars, who's fuel tanks used to sit on either side of the driver.
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Old 12-29-08, 03:40 AM
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its called snap or instant oversteer. it happens from poor suspension design or over correction causing the suspension to bind and putting all tye load directly on the tires sending the car sliding. at least that's how I learned it.
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Old 12-30-08, 10:36 AM
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It is definitely a term for bikes. And its scary when it happens. Cars do a similar thing, but its not the same. The physics are different. A car does it usually when coming out of a hard corner and the driver lets up on the gas, which front loads the car and the back end loses grip, instantly sending it in a hard to control rotation towards the inside of the the turn.

I would say the fishtailing term is different, I would call fishtailing controllable because you are sliding the back out and not loading the front of the car. But doing this can quickly lead to a tank slapper when you abruptly let off the gas in a heavy drift. You will flip around in the opposite direction.

I'm not exactly sure why the motorcycle does it, but when it happened to me it wasn't because the back end came loose.
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Old 01-02-09, 07:41 PM
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Originally Posted by jkstill View Post
A tank slapper is a phenomenon causing pucker factor.

The pucker factor in this case increases with the square of the speed at which the tank slapper occurs.

I thought that pucker factor was also proportional to the inverse of proximity to
a solid object at which the incident occurs.
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Old 01-30-09, 03:38 PM
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Tank slappers on a bike are no fun. Usually happens in high speeds front end gets light. rear wheel trys to push the bike forward while the front wheel is turned just a slight bit. Physics will try to over correct and you start to get slaps. Get a good steering damper. It saved my *** quiet a few times.
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Old 02-26-09, 05:14 PM
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Cars fishtail

Bikes have tank slappers (usually occurs coming out of a wheelie)

/thread
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Old 02-26-09, 05:21 PM
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tanks slappers happen if you have to do an emergency braking maneuver on a motorcycle. your ***** slap against the tank.

as far as in a car.. its not really an accurate term.

You could consider it when the fuel sloshes from one side of the tank to the other during transition turns. But I wouldn't consider that tank slapping.... that's just fuel slosh.
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Old 02-26-09, 08:00 PM
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Originally Posted by Monkman33 View Post
tanks slappers happen if you have to do an emergency braking maneuver on a motorcycle. your ***** slap against the tank.
That's not a tank slapper, thats just unfortunate and painful!!
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Old 02-27-09, 11:24 AM
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There is one difference between a tank slapper on a motorcycle and what they might call a tank slapper on a car.

On a motorcycle the physics of resonance and centering forces on the steering make the action fairly independent of the driver input.

On a car the tank slapper should really be referred to as classic over-correction. It is pretty much caused by the actions of the driver trying to compensate for loss of traction.

On a car, it loses traction to the left by oversteer or understeer so the driver attempts to turn right. As the car slides and slows, eventually the tires grab traction but the wheels are pointed too far right. Now the car snaps right and losses traction to the right and the driver attempts to turn to the left. Repeat until you come to a stop.
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Old 03-12-09, 09:11 AM
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Originally Posted by FadedFD View Post
Tank slappers on a bike are no fun. Usually happens in high speeds front end gets light. rear wheel trys to push the bike forward while the front wheel is turned just a slight bit. Physics will try to over correct and you start to get slaps. Get a good steering damper. It saved my *** quiet a few times.
You sir are correct....I would say that if this happens to someone 98% will crash and burn without a damper....the other 2% are either motogp riders or lucky as hell...as far as car talk...its when you get out of your car, walk around to your tank/fuel cell and whack it with an open palm....besides that, if its used its out of context like "I walk car dog jiji fruit ufc dump truck and."
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