Front end shake

[Guest]

Hey everyone, while I've got my bike ripped apart, I figure I might as well ask this question- between 35-50mph, I get a nasty shake in the front forks. It's like the forks aren't damping, and the bike is hitting a resonant point. Doesn't quite shake my teeth out, but it's really bothersome. Where should I start my investigation? Change the fork oil first?

[rudeman]

Check your tire for a slipped/broken belt. Make sure it's properly balanced...

[Gorminrider]

^^^ that ^^^ and everything else too! bearings on swing arm (and, I think you really have to disconnect the shocks to give it a GOOD shake)... triple tree and the fenders fork brace if this has one-is it bolted on per OEM? and sure fork oil levels ... I don't think I could ever get used to it and call it just "Bothersome" !

[850GT_Rider]

.......... it's really bothersome........

..... and REALLY dangerous. Check everything.

[StratJeff]

I don't think it's dangerous yet. As soon as I squeeze the brake or change speed, it disappears completely, and is stable as a rock above/below those speeds. I don't think it's the tire- it's fairly new Avon. I'll start digging.

[hjfisk]

I don't think it's dangerous yet. As soon as I squeeze the brake or change speed, it disappears completely, and is stable as a rock above/below those speeds. I don't think it's the tire- it's fairly new Avon. I'll start digging.

I have had Avons that wouldn't balance out with out a ton of weights

[rudeman]

I don't think it's dangerous yet. As soon as I squeeze the brake or change speed, it disappears completely, and is stable as a rock above/below those speeds. I don't think it's the tire- it's fairly new Avon. I'll start digging.

Sounds like you may have overtorqued the steering head. New tire or not, check to be sure.

[Joe Garfield]

Sounds like you may have overtorqued the steering head. New tire or not, check to be sure.

I recently rebuilt my front end and used the least amount of torque on the steering stem as possible to achieve no zero play, per the Suzuki manual (torque to specified value, loosen 1/4 turn, tighten to eliminate play). I also get the 'resonant frequency' bounce in the front end, and now that I'm reading about it, I think it's in the same speed range as the OP. I notice it mostly on straightaways at constant speed, but believe I've experienced it through a turn also.

I was told too little torque would lead to the 35+mph steering 'wobble' - I get that too.

FWIW, I have 1.0kg Sonic Springs and 15wt fork oil - filled per Suzuki manual volume (which does not coincide w/ Sonic's volume recommendation - been meaning to fix that, but others have done the same with no reported issue). I just had my front end apart and used a little *more torque. I won't know the effect until I ride it tomorrow.

[StratJeff]

I recently rebuilt my front end and used the least amount of torque on the steering stem as possible to achieve no zero play, per the Suzuki manual (torque to specified value, loosen 1/4 turn, tighten to eliminate play). I also get the 'resonant frequency' bounce in the front end, and now that I'm reading about it, I think it's in the same speed range as the OP. I notice it mostly on straightaways at constant speed, but believe I've experienced it through a turn also.

I was told too little torque would lead to the 35+mph steering 'wobble' - I get that too.

FWIW, I have 1.0kg Sonic Springs and 15wt fork oil - filled per Suzuki manual volume (which does not coincide w/ Sonic's volume recommendation - been meaning to fix that, but others have done the same with no reported issue). I just had my front end apart and used a little *more torque. I won't know the effect until I ride it tomorrow.

Any change?

[Dogma]

Which direction are these motions? Vertical suggests a tire, balance or damping issue. Side to side suggests steering bearings are a little loose.