'06 Front Wheel Oscillation

[RadioHowie]

You guys were right!!! It was rock solid, wobble GONE!!! This is with a brand new PR2, un-balanced at about 42 psi.

TOLDJA TOLDJA TOLDJA!!!

 

[Woketman]

Is that Spanish??? ;-)

Just got back from a longer test ride. She is ROCK steady now on the front end. Smoother than the Enterprise (NSS-1701 that is) lugging around at Warp Factor one!!!

Oh the happiness exuding from my pores.......... (sigh)

 

[SLK50]

Sometimes a change to something as simple and innocuous as a tire can have

the most profound effect on a motorcycles dynamic.

Happy it worked out so well for you.

Here's to miles of smiles.

 

[stevec677]

I cast my vote for steering head bearings. What do I win?

A free trip to lovely Albany, NY!!

That's the whoopie prize.

Steering head bearings can not CAUSE deceleration wobble, but tightening them can help dampen it out if the oscillating input is small enough.

So I guess I lost. Is that why there is 10" of snow outside?

If I understand correctly, the cause is a cupped front tire, but tightened stearing head bearing will mask the problem (as will a stearing dampener). Is this right?

 

[RadioHowie]

I cast my vote for steering head bearings. What do I win?

A free trip to lovely Albany, NY!!

That's the whoopie prize.

Steering head bearings can not CAUSE deceleration wobble, but tightening them can help dampen it out if the oscillating input is small enough.

So I guess I lost. Is that why there is 10" of snow outside?

If I understand correctly, the cause is a cupped front tire, but tightened stearing head bearing will mask the problem (as will a stearing dampener). Is this right?

Correct! But to put everything in perspective, OVER-tightened steering head bearings will mask the problem, but creates other problems, like damaging the bearings and races, and causing the bike to "wander".

What happens is this....like a steering damper that's set too agressively, over-tightened bearings will tend to hold the wheel in the direction it's pointed. So unless you're pointing dead, zero degrees straight ahead, if the steering assembly is cocked slightly off center, the bike will go in that direction. So the rider makes an input to straighten up...now the bike goes in the opposite direction. Correct the direction again and your weaving all over the damn road.

How did I figure all this out?

I put one of these on my ZRX:

Put it there to control front wheel oscillation when the wheel was up in the air!

It was adjustable on the fly, and I soon discovered that putting the damping up too high prevented the wheel from "centering" itself while riding. The bike would wander to the left, I'd correct, then to the right, I'd re-correct, then back to the left, etc.

Drop the damping force and the bike would ride straight and true, but was still effective in keeping the front end from going nuts when it was "off the ground" due to hooliganism.

A correctly tightened steering head bearing is tight enough to keep the assembly located in the triple tree correctly, but not too tight to cause binding. Over-tightening will prevent the dreaded 45mph head shake, but can, as I pointed out earlier, damage the bearings and races, and cause the bike to not hold a straight line.

As the OP discovered, and was pointed out by MANY replies, that 45mph head shake/wobble/oscillation is almost ALWAYS a problem with the front tire.

Too many of us have BTDT and got the tee shirt.

 

[Woketman]

OK, I now have the rear Michelin on. I decided that I lacked the testicular fortitude to mount the tire myself. So I took off the rear wheel and was going to at least remove the Bridgestone and put on my angled valve stem and take it to the shop. But that rear tire was a LOT harder to break the bead than the front, so I gave up. Had the shop do the whole deal. $56 later, I am riding smooooooooth!!!

I love these PR2s so far!

 

[03HiYoSilver]

Woketman,

Congrats and thanks for sharing your success! It is hard to believe these ridiculous suggestions work until you try them.

Looking forward to your follow up report in about 10,000 miles or so.... we may be waiting awhille....glad you did it today. I'm impatient.

 

[bikerkash]

Every so often you will get a tire that has balance issue no matter who made it. Some Manf. have more quality issue than others. I have had these issues occur whether it's on a newer bike or a higher miler bike. I have always found this issue to be the tire itself. It appears something in the manf. process didn't go quite right. I have never found these tire to be a danger just a small problem with a slight front end wobble at speeds under 50 MPH when you ease your hand pressure off the bars. The amount of air pressure does not seem to have an effect on this issue. My experience has been the heavier the bike the more it is prone to these type of issues. I have had BMW LT's which were very prone to this problem, the FJR not so much.