Tank Slapper!!
Author
Discussion

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
Afternoon All,

Not been around for a while.....

Right, due to the house renovation not been out on the bike since November untill this weekend....So thought I'd take it steady to get back in the groove, so after half hours worth of stoppies, backing it in, no footed/no handed mono's,knee down action thought I'd get to the "proper" riding....wink

Anyway, after I woke up from this daydream and suffered my first tank slapper coming out of a long left hander, this did create a few beads of sweat and I don't like sweating.

So what cause's these tankslappers?, and how do I avoid them.

Tramp

Busamav

2,954 posts

239 months

Monday 7th July 2008
quotequote all
I was half expecing a naughty pic of a riders wife then biggrin


I have always thought it was front end problems,

ie head races and possible steering damper problems .


Chilli

17,320 posts

267 months

Monday 7th July 2008
quotequote all
Right, before anyone else comes in with the correct answer....I'll add my crap.

I understand it to be when the rear loses traction and spins/slides. Then it quickly regains adhesion and therefore abruptly changes the direction of the rear of the bike.....causing you to do the same. AND I have a theory. Shirley if whilst experiencing one of these slides you keep the throttle wide open, you'll just continue to light up the rear, but eventually come out of the slide....no??!!

Now then, over to anyone else who actually knows what they're talking bout.

catso

16,540 posts

298 months

Monday 7th July 2008
quotequote all
Chilli said:
Right, before anyone else comes in with the correct answer....I'll add my crap.

I understand it to be when the rear loses traction and spins/slides. Then it quickly regains adhesion and therefore abruptly changes the direction of the rear of the bike.....causing you to do the same. AND I have a theory. Shirley if whilst experiencing one of these slides you keep the throttle wide open, you'll just continue to light up the rear, but eventually come out of the slide....no??!!

Now then, over to anyone else who actually knows what they're talking bout.
Sounds more like the making of a highside but I suppose it could develop into just a slap if you manage to stay on and yes keeping the throttle pinned might save the crash if you can control the slide but most peoples natural reaction is to close it quickly and that causes the highside proper - been there, done that.... frown

black1

979 posts

228 months

Monday 7th July 2008
quotequote all
your front end needs stiffin up !


Chilli

17,320 posts

267 months

Monday 7th July 2008
quotequote all
SH!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!T.

surfsofa

406 posts

314 months

Monday 7th July 2008
quotequote all
Google turned-up this link :

http://www.msgroup.org/Tip.aspx?Num=190

Scary stuff. I'll put that on my list of things I hope will never happen to me along with diesel spills!

Busamav

2,954 posts

239 months

Monday 7th July 2008
quotequote all
I have only ever experienced a tank slapper once.

On my Honda CB750 , back in 75 on the A3 .

105 and flat on the tank and she started to go , got pretty wild too ,

untill i did something i was always warned against ,i risked all and hit the brakes as hard as i could , god was with me that day.

Youngsters on quick bikes shouldnt be allowed biggrin

rsv gone!

11,288 posts

272 months

Monday 7th July 2008
quotequote all
Caused by the front wheel being deflected by imperfections in the road. Sports bikes are more prone to it as they have more extreme steering geometry.

Incidentally, the article above recommends braking during tank slappers. That goes against everything I've ever heard about them. Under braking, the geometry of the front forks would become even more extreme.

I had a fairly big one on my R6 so put a damper on it. Next time I had to brake I had to pump the brakes as the oscillations can knock the pads back in the callipers.

My Aprilia used to waggle the bars but only one or two oscillations and it was very underwhelming (it had a damper, as does my R1).

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
catso said:
Chilli said:
Right, before anyone else comes in with the correct answer....I'll add my crap.

I understand it to be when the rear loses traction and spins/slides. Then it quickly regains adhesion and therefore abruptly changes the direction of the rear of the bike.....causing you to do the same. AND I have a theory. Shirley if whilst experiencing one of these slides you keep the throttle wide open, you'll just continue to light up the rear, but eventually come out of the slide....no??!!

Now then, over to anyone else who actually knows what they're talking bout.
Sounds more like the making of a highside but I suppose it could develop into just a slap if you manage to stay on and yes keeping the throttle pinned might save the crash if you can control the slide but most peoples natural reaction is to close it quickly and that causes the highside proper - been there, done that.... frown
well, I was impressed Chilli. Sounded like you knew what you where takin about, must be all this time you spend racing in Moto GP....

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
rsv gone! said:
Caused by the front wheel being deflected by imperfections in the road. Sports bikes are more prone to it as they have more extreme steering geometry.

Incidentally, the article above recommends braking during tank slappers. That goes against everything I've ever heard about them. Under braking, the geometry of the front forks would become even more extreme.

I had a fairly big one on my R6 so put a damper on it. Next time I had to brake I had to pump the brakes as the oscillations can knock the pads back in the callipers.

My Aprilia used to waggle the bars but only one or two oscillations and it was very underwhelming (it had a damper, as does my R1).
so you think a damper maybe in order, or would a proper suspension set-up cure it?......

Not to keen on spending to much cash on it, lookin at changing steed before the end of the year.

Dakkon

7,833 posts

284 months

Monday 7th July 2008
quotequote all
Busamav said:
I have only ever experienced a tank slapper once.

On my Honda CB750 , back in 75 on the A3 .

105 and flat on the tank and she started to go , got pretty wild too ,

untill i did something i was always warned against ,i risked all and hit the brakes as hard as i could , god was with me that day.

Youngsters on quick bikes shouldnt be allowed biggrin
Wow, your really old....wink

rsv gone!

11,288 posts

272 months

Monday 7th July 2008
quotequote all
The Tramp said:
rsv gone! said:
Caused by the front wheel being deflected by imperfections in the road. Sports bikes are more prone to it as they have more extreme steering geometry.

Incidentally, the article above recommends braking during tank slappers. That goes against everything I've ever heard about them. Under braking, the geometry of the front forks would become even more extreme.

I had a fairly big one on my R6 so put a damper on it. Next time I had to brake I had to pump the brakes as the oscillations can knock the pads back in the callipers.

My Aprilia used to waggle the bars but only one or two oscillations and it was very underwhelming (it had a damper, as does my R1).
so you think a damper maybe in order, or would a proper suspension set-up cure it?......

Not to keen on spending to much cash on it, lookin at changing steed before the end of the year.
....I just happen to have an Ohlins damper lying about the place. It would need a Harris fitting kit for your Kwak, though.

Busamav

2,954 posts

239 months

Monday 7th July 2008
quotequote all
The Trampwell said:
I was impressed Chilli. Sounded like you knew what you where takin about, must be all this time you spend racing in Moto GP....
I think he spent his time in WSB biggrin



Edited by Busamav on Monday 7th July 14:38

Chilli

17,320 posts

267 months

Monday 7th July 2008
quotequote all
Busamav said:
The Trampwell said:
I was impressed Chilli. Sounded like you knew what you where takin about, must be all this time you spend racing in Moto GP....
I think he spent his time in WSB biggrin



Edited by Busamav on Monday 7th July 14:38
Taught Sir Simon most of what he knows...

catso

16,540 posts

298 months

Monday 7th July 2008
quotequote all
Busamav said:
The Trampwell said:
I was impressed Chilli. Sounded like you knew what you where takin about, must be all this time you spend racing in Moto GP....
I think he spent his time in WSB biggrin



Edited by Busamav on Monday 7th July 14:38
'Win it or bin it' Frankie..........wink

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
Chilli said:
Busamav said:
The Trampwell said:
I was impressed Chilli. Sounded like you knew what you where takin about, must be all this time you spend racing in Moto GP....
I think he spent his time in WSB biggrin



Edited by Busamav on Monday 7th July 14:38
Taught Sir Simon most of what he knows...
Simon got some hedges that needed a trim then? wink

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
rsv gone! said:
The Tramp said:
rsv gone! said:
Caused by the front wheel being deflected by imperfections in the road. Sports bikes are more prone to it as they have more extreme steering geometry.

Incidentally, the article above recommends braking during tank slappers. That goes against everything I've ever heard about them. Under braking, the geometry of the front forks would become even more extreme.

I had a fairly big one on my R6 so put a damper on it. Next time I had to brake I had to pump the brakes as the oscillations can knock the pads back in the callipers.

My Aprilia used to waggle the bars but only one or two oscillations and it was very underwhelming (it had a damper, as does my R1).
so you think a damper maybe in order, or would a proper suspension set-up cure it?......

Not to keen on spending to much cash on it, lookin at changing steed before the end of the year.
....I just happen to have an Ohlins damper lying about the place. It would need a Harris fitting kit for your Kwak, though.
ermmmmm could be tempting.......(runs over to laptop to google "Harris") back in a mo.

shot2bits

1,273 posts

259 months

Monday 7th July 2008
quotequote all
If you're not riding the bike hard then you really shouldn't get the head shaking in a tank slapper stylee. My R1 (2007) is always shaking it's head in protest but it never really gets out of hand. I'd check how hard your front suspension is and get the stearing damper checked out - maybe replace it with one of the latest 3rd party models to cure your problem.

Just re-read your post - no damper?? That's your problem in combination with the suspension setup I reckon.

Edited by shot2bits on Monday 7th July 15:29

The Tramp

Original Poster:

918 posts

248 months

Monday 7th July 2008
quotequote all
shot2bits said:
If you're not riding the bike hard then you really shouldn't get the head shaking in a tank slapper stylee. My R1 (2007) is always shaking it's head in protest but it never really gets out of hand. I'd check how hard your front suspension is and get the stearing damper checked out - maybe replace it with one of the latest 3rd party models to cure your problem.

Just re-read your post - no damper?? That's your problem in combination with the suspension setup I reckon.

Edited by shot2bits on Monday 7th July 15:29
Sorry, should of mentioned, it's an 06 636, don't think it has a damper as stardard, so you think this could be cured with a suspension being set-up by someone who knows what their doing...