[SOLVED] "is this tank slapper"?

[keratos]

I have heard of something called "tank slap" where the handlebars oscillate left to right, sometimes violently and at speed.
 
I bought my fazer two weeks ago from a local shop (not dealer) with a new 12 month MoT.
 
When I ride , on any road, hands off the bars (6am so no other traffic!) at any speed 5, 10, 50MPH the handlebars start to oscillate slowly at first getting faster. Maybe a turn every 2 seconds upto quite vigerously. If I put my hands on the bars I can easily control it - not much resistance - at any speed but my fingers get very numb. (another post on the forum)
 
Question:
1. Is this tank slap or something else?
2. What causes it? Is causing it?
3. Is it safe?
4. Should it have passed an MoT
 
I'm thinking of going back to the shop so could do with some replies.
 

[Paulfzs]

its a form of tank slapper yes but its a mechanical issue, it will pass an mot as they don't test bikes by riding them no handed, the issue could be one of many thinks, had this on my xj 600, was fine with my hands on the bars but after 30mph hands off my bars went insane! couldn't find what was wrong but after changing my front tyre it was fine but eventually starting coming back but not as bad.


Its probbaly down to your front wheel being off balance, get the wheel off stick the spindle through it and put it on a set of axel stands and spin the wheel, if it wobbles there is your issue.


it is perfectly safe aslong as you hold onto your bars, i rode like it for about 4 months before i fixed it but i didn't set out to fix it.

[red98]

go back to the shop matey...un-safe...wheel balance,wheel bearings,swingarm bearings,tyres and pressures,forks...could be any of the above ,go back and have a chat ,see what they say 

[fazersharp]

Tank slapper----------- oh I always thought that was refering to your danglies "slapping " the tank during any big "moment"

[andybesy]

I recently addressed a "tank slapper" wobble. Here's what I learnt.

Like yours only an issue without any pressure on the bars, but mine was different to yours in that:

1) It was stable at most speeds but occurred consistently and immediately between 40 and 45 mph.
2) It would immediately (at these speeds) wobble very fast, say 4 oscillations per second (none of the starting slow then building in speed you describe)

As soon as speed dropped below 40 mph nice and stable again subject to road surface.

I took it to my local Yam dealer to get checked out and asked that they check all the bearings etc for safety. They told me:

1) It wasn't unsafe (I mean due to failed bearings etc, not that the wobble wasn't unsafe)
2) It's usually caused by the top box rack (even without box attached) or uneven front tyre wear (although there are many other causes, but those are most common)
3) They could change the front tyre (it was due anyway) and slightly loosen steering head taper bearing to see if it helped (but no guarantees)
4) Bearings were fine (visual inspection of from wheel, others checked for play)

Having had the front tyre changed it's a lot better. Not gone completely, but minimal enough that it's not a practical problem. Nice to have had the bike checked safety wise too.

I suggest that:

1) your wobble doesn't sound too bad given that it starts quite slowly
2) But if it makes you uncomfortable get it checked out and try to fix it

Start by looking closely at your front tyre.  How many miles has it done, and how is the wear?

Do you have a rack?

Andy

[Fazafou]

I don't think I've ever had a bike that didn't do that.

Tyre wear, brake disc alignment etc etc etc etc will all cause a tiny wobble of the bars.

The fact is you shouldn't ride like that so unless it's noticeable with your hands on the bars don't worry about it

[Frosties]

go back to the shop matey...un-safe...wheel balance,wheel bearings,swingarm bearings,tyres and pressures,forks...could be any of the above ,go back and have a chat ,see what they say 

+1. Take it back and ask them to sort it - couple of months time it could get worse and by then they'll tell you to feck off!. Get them to look at it as soon as fella.

Good luck.

[keratos]

Ok. Taking it back to PB Motorsport in Blackpool; see what they say after work. I will report back.
Thanks everyone.

[red98]

Good luck matey 

[HarryHornby]

THIS is a tankslapper.....

[Motorcycle Accident]TT-Tankslapper-19sec

[keratos]

Mine is a tanktwitcher in that case

[keratos]

Just got back from the bike shop. Not the one I bought from but the guy who does all major service/repair work, MoT and alike for last 10yrs or so....CHRIS at CS Cycles of poulton-le-fylde . Chris summarily inspected bearings ,head, races etc and believes it's the wheel balance. We noticed the weights, well THE weight on front wheel is only on one rim side,not both. He was on his way home and has shut down  so will do a thorough look and rebalance the front tomorrow. I will report back.
Still riding....s.l.o.w.l.y.!

[unfazed]

Don't think it is a serious problem, mine was doing it since its first tyre change and still does it 84000miles later.

Balancing the front wheel improves it for a good while but it is always there. I remember years ago all fords cars had it at 40Mph and ford said it was harmonic resonance 

Since I do all my own work and know everything is ok it never bothers me.

90% of the 600 I have ridden do it.

Never was sure why one would want to take their hands off the bars while riding at any speed 

[keratos]

Don't think it is a serious problem, mine was doing it since its first tyre change and still does it 84000miles later.

Balancing the front wheel improves it for a good while but it is always there. I remember years ago all fords cars had it at 40Mph and ford said it was harmonic resonance 

Since I do all my own work and know everything is ok it never bothers me.

90% of the 600 I have ridden do it.

Never was sure why one would want to take their hands off the bars while riding at any speed 

cheers bud. yes, Ive read your many posts through this forums and you certainly have a lot of demonstrable experience and good advice. thanks for words of comfort.

BTW, FWIW, the hands-off was a suggestion caveated with lots of warnings about empty roads, early hours of the morning, no one around, wide quiet road, slow walking speed and gradually increasing, hands strong and close to the bars ready to take control...all that...a suggestion to diagnose whether it was a speed issue. The other suggestion was to take the wheel off and spin on a wheel stand - but I dont have one so took the racier option!  It does not appear to be speed related. As said, balancing looks the candidate and the bike is in the shop tomorrow. The oscillation is less severe than the video above, but its unnerving at speed and needs sorting.

[keratos]

well, had it balanced (it was 15g out on one side) and new front wheel bearings

Still the same; darn it.

Will be taking it back to the shop for Chris to test ride which he didnt do today. Cost me £30 too.

What I would say is that I can control the bars with one hand holding the grip with two fingers of the one hand and very gently. Take this ever so slight pressure off and the bar starts to slap. ???

[unfazed]

Sounds very like what mine has been doing for the last 80000miles

Check the wheel bearings front and back just to be safe .

[keratos]

Sounds very like what mine has been doing for the last 80000miles

Check the wheel bearings front and back just to be safe .

?? As said, i had the wheel balanced AND new bearings fitted ??

[darrsi]

With all the work you seem to be doing on it, i'd be inclined to get the fork oil replaced as well.


Low, very old or uneven oil levels could cause the wobbles.


If you consider it, 15w instead of 10w oil makes the front end feel much more stable in my opinion, plus at least you'll know it's been done.

[unfazed]

Sounds very like what mine has been doing for the last 80000miles

Check the wheel bearings front and back just to be safe .

?? As said, i had the wheel balanced AND new bearings fitted ??

What about the rear??

[keratos]

Sounds very like what mine has been doing for the last 80000miles

Check the wheel bearings front and back just to be safe .

?? As said, i had the wheel balanced AND new bearings fitted ??

What about the rear??

ah sorry , erm well the rear bearings replaced when I bought the bike ; wheel alignment also checked. hence focus on front end. weird how two fingers resting gently on one handle can prevent what otherwise becomes  a violent oscillation,

[unfazed]

Keep your hand on the bars and forget it, 

[keratos]

yep that is an option, but I've never experienced it before in 30 years of riding and many many bikes - quite alarming and one immediately thinks of my own safety and those of other road users and pedestrians god forbid something went wrong at speed.
I still want it checked over and will do this Thursday when it goes back into the shop.

[unfazed]

Always good to check to be safe, but don't let it put you off riding it.
I have seen an indicated 140 on my clock 2 up, been all round Ireland, UK, France and Spain touring two, been on track days, had some spirited high speed runs with friends and it has never been a problem.

[His Dudeness]

Mine does it too under hard acceleration. Just don't take your hands off and there's no problem. Like you said the slightest of pressure on the bars and it doesn't happen. Don't know why you'd want to take both hands off anyway unless you were showing off your skills to ladies

[jonesthesteam]

Had the same on my 2001 FZS, after reading up on the forum I replaced the front tyre, no more wobble, I think I read that they can sometimes do it after the tyre has done around 4k miles


Trouble is it costs you to see if it is the cause, but like others have said it could go to the red line with no issues as long as you have a light grip on the bars


Jonesy