new tires scary at speed

[Guest]

Anybody able to explain why after putting on new tires, the front end wants to wobble at speed ? Either I've gotten used to it or it is slowly going away with miles accumulated. I went from S rated Michelins that unhappily yielded anly about 7,000 miles to H rated Skinkos (that already seem like they will outlast the Michelins by twice the lifespan) to save a few bucks. Could the feel be that different ?

Could the mold release agent on the tire surface cause this ? Tire pressures are at spec but I did not balance them although, they are not vibrating until I go MUCH faster. Could an unbalanced tire/wheel make the front end wobble. If I let it keep doing it, the whole bikes starts to wobble. It gets scary ! Little Suzy was dead solid with the Michelins.

Going up or down in tire pressure does not seem to make any difference. Steering bearings feel tight, no freeplay and no detent.

At first, anything above 55 mph was a concern. Now I have to go above 65 -70 to worry at all. At first it would do it all by itself every tiem I got going fast enough. Now it seems like it needs to be aggrevated by a sidewind or air movment from another vehicle. 85 is ok all by myself on the road ... for the most part but then I'l go over a bump and I can feel it start again, a little.

[mmattockx]

If bumps are starting it then it probably isn't the new rubber. That sounds more like a suspension issue. What sizes did you go with? Which model of Shinko? How fresh is your suspension? When you say tire pressures are at 'spec', what is 'spec'? Mold release compound is just slippery and is gone after a ride or two. Did you change anything else when you changed rubber? Who mounted the tires? Is it possible that a shop chimp screwed something up for you?


Mark

[greg78gs750]

not balanced, eh? hm. that would be the first thing i would check.

[nejeff]

I just read your other update, your bike maintenance may be suspect. 30,000 miles and one oil change (no filter??) and no wheel balance on your new tires?

hmmm is right

[TxGSrider]

I'd get the tires balanced first.

[Buffalo Bill]

Wobble is not vibration, unbalanced tires would cause vibration and then you could trace it to the tires because it would come on gradually with speed, not get more intense just vibrate faster.
Wobble is caused by front end fork issues, loose, worn out stem bearings, uneven fork condition, like they need new oil, poor fork-axle adjustment, they're binding.
Rear swingarm bearings loose, worn out.

[RichDesmond]

Wobble is not vibration, unbalanced tires would cause vibration and then you could trace it to the tires because it would come on gradually with speed, not get more intense just vibrate faster.
Wobble is caused by front end fork issues, loose, worn out stem bearings, uneven fork condition, like they need new oil, poor fork-axle adjustment, they're binding.
Rear swingarm bearings loose, worn out.

All that, plus worn out shocks are a big contributor. It's a bit counter-intuitive, but front end wobbles are more commonly caused by issues are the rear than at the front. But keep in mind, a wobble is a system issue, it's rarely just one thing.

That said, a different front tire can really exacerbate it. Usually, a worn tire makes it worse. The wobble will slowly get worse as the tire wears, and when you put a new tire on it goes away. However, a brand new tire can make a previously solid bike shake. I had that happen with my V-Strom, put a set of Tourances on the bike mid way though an Alaska trip. Pulled over twice between Anchorage and Valdez to double check that all front and rear end bolts were tight, the bike had so much decel wobble I thought I'd screwed up putting wheels back on. Got home and went back to Pilot Roads and the wobble was instantly gone.

[cowboyup3371]

Proper maintenance is a very good and honorable act

[Doug]

Did I read that correctly, you did not balance them?



Oh.

[GSXR7ED]

Wow!

I'd get your entire suspension checked if a "wheel balance" doesn't fix the problem. I have a fork stabilizer on my bike simply because MrBill pointed out that the fender was the only stability below the triple tree.

Anyway...replacing the fork oil may also be an option so while you're in there take a look at your springs and all seals that need to be replaced.


Ed

[fasteddie313]

I can't believe no one has said ALIGNMENT!!

Sounds like bad alignment to me, the rear wheel.. Maybe you changed your chain tensioners or whatever and changed your alignment when you removed your rear wheel..

Get a long straight edge and put it across your back tire so t is parallell with your rear wheel sticking up next to your front wheel.. Keep the front wheel parallell to the straight edge, note the distance from the front wheel to the straight edge, repeat on the other side of the bike and note the difference of distance from the front tire to the straight edge from right to left..

Adjust your chain tensioners side to side to get your chain at proper tension and your rear wheel in proper alignment with the front, same distance from straight edge on rear wheel from left to right..

[nejeff]

I can't believe no one has said ALIGNMENT!!

Sounds like bad alignment to me, the rear wheel.. Maybe you changed your chain tensioners or whatever and changed your alignment when you removed your rear wheel..

Get a long straight edge and put it across your back tire so t is parallell with your rear wheel sticking up next to your front wheel.. Keep the front wheel parallell to the straight edge, note the distance from the front wheel to the straight edge, repeat on the other side of the bike and note the difference of distance from the front tire to the straight edge from right to left..

Adjust your chain tensioners side to side to get your chain at proper tension and your rear wheel in proper alignment with the front, same distance from straight edge on rear wheel from left to right..

He has a shaft drive bike so not likely a chain tensioner issue

[fasteddie313]

He has a shaft drive bike so not likely a chain tensioner issue

Right you are..

[mmattockx]

not balanced, eh? hm. that would be the first thing i would check.

I'd get the tires balanced first.

Did I read that correctly, you did not balance them?




Oh.

You guys do realize that road racers almost never balance a tire and it doesn't bother them aside from some vibration? Balance will not cause wobbles, unlike all the other stuff mentioned by Buffalo Bill and RichDesmond.


Mark

[jabcb]

All that, plus worn out shocks are a big contributor. It's a bit counter-intuitive, but front end wobbles are more commonly caused by issues are the rear than at the front. But keep in mind, a wobble is a system issue, it's rarely just one thing.

That said, a different front tire can really exacerbate it. Usually, a worn tire makes it worse. The wobble will slowly get worse as the tire wears, and when you put a new tire on it goes away. However, a brand new tire can make a previously solid bike shake. I had that happen with my V-Strom, put a set of Tourances on the bike mid way though an Alaska trip. Pulled over twice between Anchorage and Valdez to double check that all front and rear end bolts were tight, the bike had so much decel wobble I thought I'd screwed up putting wheels back on. Got home and went back to Pilot Roads and the wobble was instantly gone.

Had a similar experience with an 85 CB650 Nighthawk.
Replaced a worn-out front tire & then had a rather irritating deceleration wobble.
Replaced the front tire with a different brand with different tread pattern & it was fine again.