Strong Vibration over 100mph??

[TashbaN]

So here it goes. I ride a 2008 Fz6 with a little over 9k miles.
I just recently changed the front tire to a Michelin Pilot Road 4 to match the rear.
I had the tire removed, and rebalanced already, then everything else looked over after experiencing an aggressive up and down vibration when hitting speeds from 100-110. (on smooth roads with no wind)
This problem only occurs when reaching such speeds, and has nothing to do with the engine revs.
There are no obvious causes to this problem that the dealer, or the tech who installed the tire could tell without taking a wrench to it.
Tire pressure is normal,
tire is not defected,
the front forks do not appear defective,
the steering bearings are fine, and nothing on the front end seems to be warped.
Is it possible the tire needs to be balanced by a "high speed balancer" like they use at race tracks? Dynabeads, or weights? I am unable to find much info from any previous forum posts, though there seem to be those who have experienced similar issues.

 

[Ohendo]

Not sure of your problem, but you're sure to get an answer on one of the three threads you started on the same topic.

(Looks like the other two have been taken down. In any event, welcome! Good luck with your vibe issue, FinalImpact's advice is always good to follow.)

 

[FinalImpact]

So here it goes. I ride a 2008 Fz6 with a little over 9k miles.
I just recently changed the front tire to a Michelin Pilot Road 4 to match the rear.
I had the tire removed, and rebalanced already, then everything else looked over after experiencing an aggressive up and down vibration when hitting speeds from 100-110. (on smooth roads with no wind)
This problem only occurs when reaching such speeds, and has nothing to do with the engine revs.
There are no obvious causes to this problem that the dealer, or the tech who installed the tire could tell without taking a wrench to it.
Tire pressure is normal,
tire is not defected,
the front forks do not appear defective,
the steering bearings are fine, and nothing on the front end seems to be warped.
Is it possible the tire needs to be balanced by a "high speed balancer" like they use at race tracks? Dynabeads, or weights? I am unable to find much info from any previous forum posts, though there seem to be those who have experienced similar issues.

Thanks in advance.

Hi and Welcome with Post # 1!
A previous tire (S20) had that issue. Replacing the tire cured the issue. Its now rock steady. FWIW: both were balanced with a simple static balancer using tape weights which are not in the center of the wheel. One is fine and the other was not. In my case, I'm pretty sure it was the tire. Also the suspect tire had a very soft carcass. Not sure if that played a role or not.

VERIFY:
- wheel is true for lateral and radial runout
- tire has no lateral or radial runout

FSM has spec's
Radial wheel runout limit 1.0 mm (0.04 in)
Lateral wheel runout limit 0.5 mm (0.02 in)
You'll need a dial indicator to check it.

However, at low speeds imbalance is far more acceptable than at higher speeds. So maybe try another shop before replacing the tire.

 

[FinalImpact]

Not sure of your problem, but you're sure to get an answer on one of the three threads you started on the same topic. :spank:

Tks for heads up.... ^^

 

[Erci]

Is it possible the tire needs to be balanced by a "high speed balancer" like they use at race tracks? Dynabeads, or weights?

To put it simply, no. If there is nothing wrong with the tire, simple static balancer (as well as a shop dynamic balancer) will easily get it good enough to not feel any bad vibes at 100+. I static-balance my own tires and hit 135+ on every lap.. no vibes whatsoever.

You mentioned the tire is not defective, but how do you know this? I had a similar issue with Metzeler Z8. Tire looked absolutely fine, but after talking with manufacturer, they replaced the tire and vibes are gone now.

 

[TashbaN]

You mentioned the tire is not defective, but how do you know this? I had a similar issue with Metzeler Z8. Tire looked absolutely fine, but after talking with manufacturer, they replaced the tire and vibes are gone now.

Thanks for the feedback guys!

Regarding what I said about the tire not being defective, I only meant in terms of what the naked eye could see (perhaps I was a little too optimistic).
It very well could be that the tire has some internal defect? What you say about your experience makes me think so.... It has been balanced by a professional twice. The bike runs smooth as butter up to the 100mph mark.
I'll look into speaking with Michelin about replacing the tire to be safe. It's been over a couple weeks since I've had it though.

 

[Erci]

Thanks for the feedback guys!

Regarding what I said about the tire not being defective, I only meant in terms of what the naked eye could see (perhaps I was a little too optimistic).
It very well could be that the tire has some internal defect? What you say about your experience makes me think so.... It has been balanced by a professional twice. The bike runs smooth as butter up to the 100mph mark.
I'll look into speaking with Michelin about replacing the tire to be safe. It's been over a couple weeks since I've had it though.

I've had mine for over a month.. doesn't matter. Defective is defective. Hopefully you got the tire from a good shop. They should have no trouble working with tire manufacturer for you. Michelin isn't great when it comes to dealing with them directly, but the shop (if good) should take care of you.

Oh and my tire was perfectly balanced too, but still vibrated pretty bad at certain speeds.

 

[FZ09Bandit]

It's your conscious saying "stop or you will end up like fzbandit having to go see driver control" or having to write a letter to your company saying you will not drive, park, reverse, or sit in a company drivers seat (yes I cannot even drive the side by side mule lol .)

My 6 at 145 indicated was smooth as butter.

stop making so many threads!!!

 

[iviyth0s]

So it looks like you could either...

A) Shell out the cash for new tires

or

B) Keep it under 100 where it's happy until the tires run out of tread

The choice is yours and yours alone!

 

[greg]

I had this on a bike, the wheels weren't balanced correctly. I know you said they were done, but was it done well enough?

 

[TownsendsFJR1300]

I had this on a bike, the wheels weren't balanced correctly. I know you said they were done, but was it done well enough?

He could pull the ft calipers, raise the front wheel and loosen the axle.

If the balance is out enough, it'll show right there (as long as the ft brearings are in decent condition).


If their a month old, and this was the first time getting to 100MPH (since then), I would be going back to the shop and (as posted previously), have them contact the manufacturer for a replacment.

If that tire has a bad cord in it, etc, I wouldn't want to riding it at 70 and have it potentially let fail....

 

[FinalImpact]

JM2C: between the dust seals and the bearings & seals they offer too much start up friction to free balance a wheel on the bike IM.

At just under 20,000 miles my bearings are still so tight they DO NOT spin by shoving a finger in them and twisting. It took some internal snap-ring pliers to get enough grip to spin them by hand.

- You really need low friction contacts rollers or your wasting your time.

 

[TownsendsFJR1300]

JM2C: between the dust seals and the bearings & seals they offer too much start up friction to free balance a wheel on the bike IM.

At just under 20,000 miles my bearings are still so tight they DO NOT spin by shoving a finger in them and twisting. It took some internal snap-ring pliers to get enough grip to spin them by hand.

- You really need low friction contacts rollers or your wasting your time.

Yep, forgot about the seals, yes a bit much friction there.

I've re-checked my shops balancing using a homemade stand and a VERY STRAIGHT shaft slightly smaller than the axle. It works fine and has verified everytime that my shop had it right..

Try it after your next wheel balance, you'd be surprised how well it works..

 

[PhotoAl]

+1 on checking the tire, never had any issues with the front wheel vibrating at a particular speed. I see the tire folks static balance the race tires all the time. My concern would be the health of the tire, too much at stake for me to let it go if it were mine. Needs to be figured out.