Wobble at 55-60

[Guest jakescot]

Ride an 2003 RSV with a sidecar. Have a front end vibration at 55 up to 60. Only there, no other speed. Occurs in 4th or 5th. Straight roads or curves. Bike has 19,750 on it, going in for the 20K in the next couple of weeks. I doubt it's cupping, not willing to believe that-seems every shop says 'cupping' so they can sell a tire. So, any suggestions? I think it's a balancing issue. Front tire is a Dunlop D404F. Thanks.

[dingy]

Put your fingers across the center line of the tire, lightly feel around diameter. You MAY be able to feel cupping if it is bad.

 

Why do you doubt it is cupping.

 

Balance will cause vibration more than wobble.

 

Gary

[BuckShot]

Ride an 2003 RSV with a sidecar. Have a front end vibration at 55 up to 60. Only there, no other speed. Occurs in 4th or 5th. Straight roads or curves. Bike has 19,750 on it, going in for the 20K in the next couple of weeks. I doubt it's cupping, not willing to believe that-seems every shop says 'cupping' so they can sell a tire. So, any suggestions? I think it's a balancing issue. Front tire is a Dunlop D404F. Thanks.

 

Do you have a steering stablizer?

[GaryZ]

My experience with front tire cupping;

Handle bars "wag" at approximately 50mph. Feels like it could easily turn into a full-blown tank slapper. Scary stuff.

 

I have experienced this three times on my Ninja using Dunlop tires (D220, D207, D208) and I have had one experience on my VR (Dunlop E2). The Ninja D207 and D208 tires were soft compounds and I think the weight of the ZX11D Ninja could be contributing to the cupping after only 3.5k miles. The E2 on the VR tire was simply wore out.

 

I now have an E3 on the VR and a Metzeler M1 on the Ninja.

[barend]

Ride an 2003 RSV with a sidecar. Have a front end vibration at 55 up to 60. Only there, no other speed. Occurs in 4th or 5th. Straight roads or curves. Bike has 19,750 on it, going in for the 20K in the next couple of weeks. I doubt it's cupping, not willing to believe that-seems every shop says 'cupping' so they can sell a tire. So, any suggestions? I think it's a balancing issue. Front tire is a Dunlop D404F. Thanks.

 

you say you have a wobble in the thread title, but then in the body you relate to it as a vibration. I'd personally differentiate between the two and methinks it would also suggest a different source. so the bigger question is why is it doing whatever it is doing?

Have you always had this problem, is the rig set up properly? toe in, lean out? What is the condition of the front tire, have you checked steering head bearings, wheel bearings, slop in the attachment points, etc. Also, you should be able to reach that speed in third, does it occur then? What about RPM's when this happens, is there a correlation? Do you have anything attached to the forks (deflectors, whatever), which may cause air turbulence or harmonic resonance? Tire pressure? Does it do it without the sidecar attached? Are all your wheels true? Have you hit any major potholes? I'm just throwing stuff out here Jake. Maybe it'll trigger something you haven't looked at , or make you remember what may have changed when this started.

 

I can't really relate since I am running a leaning sidecar, but I can tell you that I have a "less stable" handlebar when my front tire is near the end of it's life. Like right now, I could maybe get another 3K miles out of it and I can tell a difference in handling. Oh, I'm running the same style front tire.

 

Good luck!