Front Wheel Oscillation-Part 3: The Resolution (merged)

[nicocorea]

Hi folks. I bought my 2008 M50 about a month ago in Albuquerque NM. I have 1500 miles on the bike and for the most part, I think it's a wonderful machine. But there is a troubling issue with it...

At between 40-55 MPH, the front seems to gently hop up and down as if the wheel were slightly egg-shaped, or it had a flat spot on the tire. At higher speeds, it smooths out. I first mentioned it to the dealer when I brought it in for the 600 mile service. One of the techs took the bike for a ride and said he couldn't detect anything abnormal. So I rode another few hundred miles thinking "it's just me." But as I racked up the miles, getting more and more familiar with the bike and with riding on a wider variety of roads, there was no more fooling myself: the front end absolutely moves up and down at the same rate as the front wheel is spinning.

So I returned to the dealer and asked them to balance the front wheel. They put wheel on the balancing machine and reported that the wheel was balanced, but that the tech noticed a "flat spot" on the tire. They agreed to replace the front tire free of charge. I was happy as a clam! I wasn't imagining things after all! They replaced the original IRC with a Dunlop--but it was free, so I didn't argue. But when I rode off the dealer's lot and got up to speed, alas, the hopping was still there--in fact, it was more pronounced! So it wasn't the tire after all, I thought, it must be the wheel itself.

I decided I needed an unbiased, independent opinion. So I took a recommendation from a fellow rider at work and took the bike to a motorcycle wheel specialist that he recommended. They came back to me with the following report: they verified that the front end is indeed "hopping", the wheel is perfect, but the tire is out-of-round.

What is the chance that I get two bad tires in a row? So I took the bike back to the dealer and explained that the tire replacement made the problem a bit worse, that I had another shop take a look at it and they verified the hopping, and that the other shop's conclusion was that the new tire was bad.

The manager himself took the bike for a ride and--surprise--said there's nothing at all wrong with the bike. I argued with him for a while, but to no avail. Finally I told him I wanted to buy a new tire. He had none in stock, but I ordered a Metzeler ME880 because I've heard good things about them. It should be here early next week.

If the new tire doesn't solve this problem, I'll have no idea what to do next!

Anyone out there have any ideas?

[Windwalker7]

Hmmm! I'd think that if the tire were out of round, it would be hopping at all speeds.



Are you sure that when the dealer replaced the tire that they really did replace it. I'm kinda wondering if they just didn't just clean up your original tire.


Seems odd that they just happened to have a tire to replace it that first time, but when you wanted to buy another tire, they were out of stock.

Maybe try another Suzuki dealer.

[nicocorea]

The hopping is barely noticeable below 40, but it's still there. But between 40 and 55, there's no missing it. And above 60, the bike is smooth as glass.

No, the original tire was an IRC and the new one is a Dunlop. And the Dunlop was definitely new; it had those pink lines on the treads that disappear after a couple of miles.

But thanks for the input!

[omegajim]

this is actually not too surprising.

It has to deal with harmonics essentially; to the best of my knowledge, at certain speeds ( in this case 40 - 55 and probably again at 80 + I would bet) the out of round/ out of balance condition will be pronounced.

The same things happen in cars when a tire is out of balance.


I admit it is unlikely that you would get 2 bad tires. I would also check to see what pressure your forks are at. And that they are equal.

Last but not least, pay attn to when the tire is mounted, there should be a dot (lightest part of the tire determined at the mfg) and that should go where the valve stem is.

[Everett Keith]

When I got mine the rims didnt have any wheel weights and it would vibrate at high speeds but when I got the 880's put on and balanced I can do 110 and its smooth as silk. If the rim is right them its got to be the tire. My 2 cents

[KD57]

The tire can be balanced, but still be out of round. The only way to verify it's the rim or tire is to remove it, and using the axle, place it in a set of V-blocks, and place a fixed point ( I use calipers) near the tire and rim. Spin it and observe. Any out of balance or out of trueness can immediately be seen.
Before you remove it from the bike, spin the front wheel and observe if the brakes are grabbing at a certain spot, which can give the sensation of hopping.

[intimid8er]

This may sound dumb...........

Here goes......

Check the pressure of the tires. Make sure they are set to factory spec. Both front and rear.

I know it sounds crazy.

I had a similar problem when I first took delivery of my M50. It would oscillate up and down at I believe 52 mph if I remember right. I went through all the troubleshooting, and it turned out to be air pressure. Plain and simple. The explanation from the dealer when I told him I solved the problem, was "The Tech is used to filling sport-bike tires on solid rims at 46 lbs. That's probably what he did with yours when he went through the P.D.I. (pre-delivery inspection).

[Easy Rider]

Originally Posted by KD57

The tire can be balanced, but still be out of round.

Indeed. I remember seeing a report YEARS ago in some mag. that mc tires are notorious for manufacturing defects. IIRC, the average was something like 30%.

So........if that is still true today, not surprising that you may have gotten 2 bad ones in a row.

[Clint]

It doesn't sound like a tire problem to me, but a problem with suspension. Any tire is out of round to some degree, and any tire is out of balance to some degree. It's the suspension's job to manage that.

Check tire pressure, as mentioned already, and set your sag carefully. Very few riders understand the importance of adjusting their shocks and springs to their weight. It isn't really about comfort, but road-holding ability and therefore safety.

These articles are geared toward sport riders but are equally relevant to cruiser riders.

Basic Spring and Sag Setup
Ask the Geek - Set Your Static Sag - Sport Rider Magazine

[DaveAlvarado]

Are you sure that you didn't have an out-of-round tire the first time, and an out-of-balance tire the second time? Did they re-balance properly after changing the tire?

[nicocorea]

Thanks for the tips, RowdyRed94.

Do you know if the preload or the pressure in the fork is adjustable? If so, do you have any advice on how to do it, or should I take it to a shop?

[Clint]

If the preload is adjustable it will have a screw mechanism on the top of each tube, usually with a large screwdriver slot or hex head. I'm sure another owner can tell us for sure.

[intimid8er]

Originally Posted by nicocorea

Thanks for the tips, RowdyRed94.

Do you know if the preload or the pressure in the fork is adjustable?

Unfortunately, it is not. The only way to adjust the forks in the M50 is find or make some cartridges that will affect the spring compression. Or change the oil out in favor of a heavier blend to improve damping.

[omegajim]

Unfortunately, it is not. The only way to adjust the forks in the M50 is find or make some cartridges that will affect the spring compression. Or change the oil out in favor of a heavier blend to improve damping

what?!?

I guess that's how they sell the bike for that price; no way to adjust the pressure in the forks.

seems like a market waiting to be tapped, with all the s/c/m50's running around here.

[Clint]

There are likely a number of options, but cruiser riders rarely concern themselves with suspension unless there's a problem. You can upgrade the fork internals, replace the tubes (big $$), or change the oil, like Tim mentioned.

[intimid8er]

Originally Posted by omegajim

what?!?

I guess that's how they sell the bike for that price; no way to adjust the pressure in the forks.

seems like a market waiting to be tapped, with all the s/c/m50's running around here.

Jim. That always killed me about that bike. Or Cruisers in general for that matter. I've posted many rants back in '05 about the shortcomings of cruisers vs. standards. And by shortcomings I refer to the relatively high price for lack of equipment and technology vs. a standard or sport(ish) bike in the same price bracket.

Some of my rants included. Why TF does the M50/C50 come with a drum rear brake and crappy under powered front disc brake?

How about a gas gauge (I know later models do.....)?

RPM gauge? Adjustable shocks?

Look at say a Katana vs the M50 the amount of technology on the Kat compared to the M is jaw dropping. Yet they retail for roughly the same price.

The manufacturers often don't go out of their way for the cruiser segment. It shows. But in all that, it is a HUGE profit center for them. Both ways.

A.) They can slap together a machine from the established in house parts bins, or create some from machines whose toolings has been amortized twenty times over, so there is no real overhead to speak of.

B.) They tout the excuse that there is no need to load a cruiser up with fancy trappings or technology simply because we...the cruiser nation.... eschew technology or geegaws on our bikes, as evidenced by the fact that we strip them down upon receipt of them, and build them back up (with useful functional items I might add...in addition to the bling factor) with aftermarket parts. In which, if they are lucky, smart, and sharp enough to produce the right aftermarket parts, they'll capture more profit from the same owner, instead of let's say, Kuryakyn, or Highway Hawk getting that dollar. (Yamaha is damn good at this...along with Harley.) So in summation of point B: The manufacturer's stance with cruisers is...."What's the point of putting stuff on, because y'all change it anyway." (I don't have links to back it up...Do your research though..Google it...read enough about bikes, you'll see the evidence, to back this statement up.)

C.) We all keep buying the crap they produce. So there is no real incentive to change what they're doing, and how they're doing it. They find the same zombified residents of Cruiser Nation over and over when doing market share research, and other surveys, who are more than willing to express their love of 50+ year old technology being repackaged over and over again, without the slightest dissent.


To that effect....(Harley is seeming to forget...the Baby Boomers aren't getting younger, their riding years are getting shorter, and they've by and large ignored Gen X in all their marketing over the past ten years.) the metric vendors do offer a wide variety of product in their showrooms. Nobody puts a gun to your head, but it would be nice, when you're looking at the amenity laden V-Strom for the same price as that M50, to have some of those "standard" features roll over to the cruiser.

[omegajim]

amen

sounds like they need to offer 2 models of the cruiser......

1) the same old same old
2) the high performance adjustable damn near everything model. - dual front disc, rear disc, tach, fuel gauge, adjustable front and rear fork (with air compressor to adjust on the fly) and the capability to top off the tires ON THE GO.

talk about dreamin.........

[nicocorea]

Some may remember my post a couple of weeks ago with the same title. (see http://www.motorcycle-journal.com/fo...cillation.html)

In a nutshell, my front wheel seems to hop in the 40-55 MPH range, as if the front tire were out of round. The dealer replaced the original IRC with a Dunlop for free but the problem was still there. Another shop checked the wheel, verified it was good, and said the Dunlop was bad. So next I bought a Metzeler ME880 (which is a wonderful tire, but that's a subject for another thread). Problem is still there, but the speed at which the oscillation occurs has narrowed to 50-56 MPH.

Many of you folks offered helpful tips and I've considered and tested each of them.

Some of you suggested tire pressure as the culprit. I've experimented with different tire pressures. That just changes the way the bike rides, but does not affect the oscillation.

Some of you mentioned fork pressure and sag. The M50's front suspension is not adjustable. But I did the following experiment to test the hypotheses: I went to an empty road that is very smooth. I accelerated into the oscillation speed range. I applied front brake while giving gas, in order to force the fork to compress while maintaining my speed. No affect on oscillation. I did the same with the rear brake. Nothing. Finally, I leaned way back and accelerated hard, to extend the fork. No affect on oscillation.

Some suggested checking to see if the brake might be grabbing (as if the rotor were wharped). I jacked up the front and spun the tire. It spun freely.

Also, the oscillation is unrelated to the drivetrain: it occurs in any gear (well, 4th or 5th anyway), while accelerating, while decelerating using engine braking, or while coasting with the clutch squeezed.

Finally, both the Dunlop and the Metzeler were mounted with the dot at the stem.

SO, the only hypothesis I have left is that the rear tire is the culprit. It does have two huge weights clipped on to the left side of the rim, and another large one directly across on the right side of the rim. Can any of you imagine any way that the effects of an out-of-balance or out-of-round rear tire would be felt in the front?

[Easy Rider]

Originally Posted by nicocorea

Can any of you imagine any way that the effects of an out-of-balance or out-of-round rear tire would be felt in the front?

Yes!

Did you try changing the pre-load adjustment on the rear?
But......
Having all that weight at one place is not a good sign. It might mean that somebody tried to compensate for an out-of-round tire or rim with weights......or somebody just blew the balancing.

The good news is that now you have a spare front tire. Keep it out of the heat and the sun until you need it.

The bad news is you still have the problem.
I think you need to leave it at a reputable shop (if you can find one) for a couple of days so several of the service people can ride it and put their heads together for a solution.

Guessing at a fix is starting to cost you money.

[nicocorea]

Yes, the bike was delivered at the 3 setting and I had them reduce it to 2 at the 600 mile service (I'm only 155 lbs). Didn't affect the oscillation.

You're right, I'm going to drop it off at a different dealer tomorrow and see if they can figure something out. And yes, this is starting to cost. Already at about $200--but that includes a Metzeler on the front--definitely an upgrade from the stock IRC. I dig the bike, so if it costs me a few hundred dollars to get it riding as it should, so be it...