steering shake/ tank slap - Honda Motorcycles - FireBlades.org
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post #1 of 20 Old 02-20-2015, 1:01 PM Thread Starter
 
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steering shake/ tank slap

Morning Blade lovers, I had already do a post about this a few months back but i did not get much comments, I am having a issue on my 954, under hard acceleration above 8K to redline my bars start to like wobble, not like a tank slap about 10-20 mm a side. it does this 1st-3rd gear . Here is my setup stock springs Scotts Damper set half way. I have a Penske rear shock. my rear setting is pretty good, I have 1 inch of sag. I read online that the 954 have small wobble under hard accell.
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post #2 of 20 Old 02-20-2015, 1:21 PM
 
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Re: steering shake/ tank slap

Mine had the same problem. Once I installed a damper, it hasn't been an issue.
If you are still having a problem with a damper installed than you need to check things like tire pressure, steering stem tightness/bearings, wheel bearings etc. as it could be a case of something else being loose or out of alignment.
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post #3 of 20 Old 02-20-2015, 1:43 PM
 
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post #4 of 20 Old 02-20-2015, 1:52 PM Thread Starter
 
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Re: steering shake/ tank slap

Ya but i talk toa suspension shop, they said if you put a damper and issue goes away thats not fixing the issue, thats like putting a bandage on cut . its not actually fixing issue they say. It could be bearings, or suspension geometry is not correct.
When i turn up the damper ya it goes away but thats not fixing issue.
Tire pressure i run F 34 cold setting Rear 32
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post #5 of 20 Old 02-20-2015, 2:13 PM
 
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Re: steering shake/ tank slap

If it's persistent than no, you're not fixing the issue by adjusting the damper way up. Oscillations in the front wheel are not unusual though when it gets light. That's why all modern sportbikes (and race bikes) run dampers.
I would get my wobble when coming out of a corner and getting on the throttle. I never experienced any issues other than that. I run a stock setup on the front/rear.
If your tires are good, have you ever checked or replaced the bearings in the steering stem? That would be the first area I would go to, checking for looseness or play.
When you put the rear shock on did it raise/lower the ride height or have you changed it by raising/lowering the front end?
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post #6 of 20 Old 02-20-2015, 5:28 PM
 
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Re: steering shake/ tank slap

Hi

The front will go light if the back is too soft. Your back tyre is too soft for a start isn't it?

If the front goes light it will be more prone to wobble.

Pete
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post #7 of 20 Old 02-22-2015, 3:42 AM
 
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Re: steering shake/ tank slap

Hold on tighter. That's what I do. Jk. Petes right. Increase the compression on the rear shock and see what happens. Speed up the rebound on the fork so it can extend quicker. You are welcome.
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post #8 of 20 Old 04-13-2015, 10:25 AM
 
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Re: steering shake/ tank slap

Why do you run such a low rear pressure? Would usually be 42psi at rear, reducing that will also reduce the load on the front tyre allowing it to wobble when weight shifts rearwards under acceleration
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post #9 of 20 Old 04-13-2015, 10:39 AM Thread Starter
 
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Re: steering shake/ tank slap

all my friends that race , and did race run around that number 30-33 Rear. Last weekend I went on a ride w a buddy and he used to race AMA and on his RC51 he ran 18 psi on front and 30 rear cold. so he can get traction. and he has new tires. i think 42 is the MAX on the Michelin.
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post #10 of 20 Old 04-13-2015, 10:45 AM
 
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Re: steering shake/ tank slap

That reduced tyre pressure would be for people who are getting some serious heat into the tyre, which heats the air inside it and causes the pressure to increase as a result.

If you're just riding around normally or predominantly in straight lines you won't be heating the tyre to a great enough degree (pun intended) to increase the pressure.

Try inflating the tyre to 42psi (this is the pressure your tyre manufacturer recommends) and you should see your problem solved. You should only reduce the tyre pressure if your riding heats the tyre to such an extent that the pressure would otherwise be too high.

Bear in mind also that if you ride in the wet with such a low tyre pressure, you will greatly reduce traction due to the fact that the treads on the tyre surface will close as the tyre concaves inwards, so they won't be clearing water in order for the tyre to grip.
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post #11 of 20 Old 04-13-2015, 11:24 AM
 
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Re: steering shake/ tank slap

The higher your tire pressure the smaller your contact patch is. And the tires flexibility will be reduced to a noticeable degree. Which means you lose grip.
How many threads have we seen here where guys inflate to 42 psi and wonder why they lowsided.
And the following advice is always to reduce pressure to around 28 - 34 Rear and 30 -36 Front psi. Depending on the type of tire and riding style - commuting vs. canyon/mountain roads.
I would NEVER inflate to anything above 32 psi for the rear, unless riding two-up. even then, I'd max at maybe ~36.

There are tons of threads discussing tire pressures, and believe me - 42 psi is ridiculous.
18 psi on the front seems way to low for a normal sport/street tire as well. 30 -34 is more like it.
I've been experimenting with tire pressures on my bike for the last three years. I record the ambient temperature, and cold psi before a ride. Then I pull over during spirited riding, check tire pressures and heat (with a laser temp reader) in the tire. The Dunlops, Bridgestone, and Michelins that I've run: they are all pretty close and I run Cold pressures of about 28 Rear and 30 Front. (That's when cold temperatures are in the 60 to 80F degree range.) That's where the contact patch, flexibility, and stability is once the tire is warmed up.

I know this doesn't exactly address the headshake your experiencing, but could affect it somewhat.
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post #12 of 20 Old 04-13-2015, 11:43 AM
 
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Re: steering shake/ tank slap

Not to take this off topic but in the interest of a balanced view, I've never had any loss of traction in over 20k miles of very mixed riding on a vfr800, using the whole tyre and running 36/42, which is what the bike's manual recommends
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post #13 of 20 Old 04-13-2015, 5:33 PM
 
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Re: steering shake/ tank slap

I also owned and rode a VFR800 for two years. Put about 15,000 on it, and I've put about 22,000 on my current bike. Been thru about 9 or 10 sets of street/sport tires now.
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post #14 of 20 Old 04-14-2015, 8:35 AM
 
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Re: steering shake/ tank slap

Quote:
Originally Posted by jondog9 View Post
I also owned and rode a VFR800 for two years. Put about 15,000 on it, and I've put about 22,000 on my current bike. Been thru about 9 or 10 sets of street/sport tires now.
You've got a bit more experience than me, so please take this for the genuine question it is: why do the bike and tyre manufacturers recommend 36/42? I know this is off topic but I've an opportunity to learn something here

FWIW I still feel that the OP's low pressures could be part of his problem but I'm warming to the idea that tyre pressures are more flexible than I previously thought
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post #15 of 20 Old 04-14-2015, 8:44 AM Thread Starter
 
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Re: steering shake/ tank slap

I believe thats the setting for a average weight rider about 160 pounds and all around riding , not hard acceleration and leans
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