Something isn't right

[kinchy]

I just had a new set of tires put on the RT. Continental RoadAttacks. What symptoms would I experience if the front tire/wheel was slightly out of balance?

[Uggles]

Er..... How about a wobbly wheel on the road??

Cheers

[DaveTheAffable]

I just had a new set of tires put on the RT. Continental RoadAttacks. What symptoms would I experience if the front tire/wheel was slightly out of balance?

Just FYI - I'm on my second set of Conti Road Attacks on my K1200RS... and I REALLY like them. YMMV

 

What symptom do you have?

[kinchy]

If I let go of the grips (coasting downhill at 35-40MPH) the handlebar shakes. I'm getting a slight vibration when coming to a stop. The pressure is 36F and 42R, I checked it post ride, the front tire/wheel spins normally when off the ground. Do these tires provide that more road feel than Z6s?

Maybe it's me?

Thanks for the help...

[DaveTheAffable]

Hmmm... wobble at 35-40mph is one symptom (balance?), vibration while stopping is another (rotor/brakes problem?)...lol.

 

Maybe some with more experience than I can chime in here. I'd certainly consider having the front tire rebalanced.

 

I had someone put a weight on a rim 180* out, and then not respin it on the electronic balancer to be sure it was right. He later said, "The electronic balancer is so accurate I never question it." That would have been fine... if he had spun it one more time to catch his own error.

 

Anyone else?

[T__]

I just had a new set of tires put on the RT. Continental RoadAttacks. What symptoms would I experience if the front tire/wheel was slightly out of balance?

 

Wayne, when a tire/wheel is SLIGHTLY out of balance you usually get a front end 1st order vibration that gets worse the faster you go.. If you have a front end disturbance at low speeds (under 20 mph) I seriously doubt you have a wheel balance problem.. If it only shakes when the brakes are applied it is probably a bent brake rotor or oxidized rotor surface.. If it vibrates at only higher speeds then probably a wheel balance problem.. If you have a front end disturbance at all speeds including low speeds (no brakes involved) it is probably a bad tire (either out of round or a 1st order radial vectoring problem)..

 

Sometimes rotating a bad tire 180° on the rim then a re-balance can decrease a tire disturbance problem..

 

If you didn’t have the problem before the new tires & do now you know what the cause is..

 

Talk to the place that sold you the tires..

 

Twisty

[ShovelStrokeEd]

It isn't balance, as Twisty said, that will almost always increase vibration with speed.

 

The two most likely causes of trailing throttle shake are the tire itself, may be out of round or have a poorly applied tread band. Second are the steering head bearings. Usually impact damage (spralling) puts a slight notch in the races and, as normal perturbation caused by road surface irregularities causes the balls or rollers to climb slightly out of the notch, the weight of the bike will pull the front back.

 

Either of these effects can get pretty violent but may be prevented by simply keeping one hand on the bars as the initial forces are weak, they just magnify as the system goes in and out of resonance.

[Dave C.]

Did you install the tire onto the fork assembly using the proper procedures? IIRC you put the axel in and snug it then drop the front down and apply pressure to the wheel assembly by pushing it against a wall or some other non moving object and then torque down the axel and pinch bolts.

 

The first time I put my front wheel back on I had a vibration and followed the proper procedure and the vibration went away.

 

Dave

[awagnon]

If it only shakes when the brakes are applied it is probably a bent brake rotor or oxidized rotor surface.

 

My RT started shaking when I applied the brakes. I thought for sure it must be a warped rotor. I took it to a very good independent BMW mechanic who checked the rotors with a micrometer, and they were better than new. Turns out the Pilot Roads have worn unevenly and the problem seems to be getting worse as they wear. They have lots of tread left, but I may end up having to change the front tire early just for this reason.

 

 

Did you install the tire onto the fork assembly using the proper procedures? IIRC you put the axel in and snug it then drop the front down and apply pressure to the wheel assembly by pushing it against a wall or some other non moving object and then torque down the axel and pinch bolts.

 

This is a very good point. I've seen this on other boards with the recommendation of having someone sit on the bike when the final tightening is performed. I think I'll see if this will help my problem.

[94aero]

Is the rotation direction of the tire turning correctly?

[SWB]

Did you install the tire onto the fork assembly using the proper procedures? IIRC you put the axel in and snug it then drop the front down and apply pressure to the wheel assembly by pushing it against a wall or some other non moving object and then torque down the axel and pinch bolts.

 

That's news to me. The BMW manual I have indicates:

• 
  
• Install front wheel
  
• Install spacer bushing and speedo drive.
  
• Apply Molykote paste to the axle.
  
• Tighten retaining screw.
  
• Press forks down firmly several times
  
• Tighten clamping screws
  
• Install brake calipers
  
• Install mud guard
  
• Check ABS sensor gap
  
• Torque nuts and bolts to specs.
  

 

Nothing in there about tightening the wheel assembly with the forks under pressure, just bounce the forks (presumably) to ensure the axle they seats correctly. That's how I tightened mine after R&R the bearings, but I haven't road tested it yet.

[awagnon]

Is the rotation direction of the tire turning correctly?

 

I don't know about the original poster, but mine are and they are still wearing unevenly.

 

Press forks down firmly several times

 

I think this is the same principal. Sometime the front wheel and axle are tightened with the bike on the center stand without doing this or loading the front suspension first.

[tomk99r11]

Stiction is the term I think?!

[BFG]

My ridin' buddy's (K1200RS) last pair of tires were RoadAttacks. The front wheel had a bad wobble between 40-50mph when he got off the gas. We re-mounted, re-balanced, and re-torqued everything. Still shook. We recently replaced the front tire (worn out)with a different one and the wobble was gone. Bum tire. Mail order. Should we have taken that new RoadAttack off the bike and sent it back for a replacement? Maybe. That seemed like a big hassle so he just wore it out after a bit over 4,000 miles.

 

If the wheel is balanced and mounted correctly then you may have a bum tire, too.

[Dave C.]

What I wrote was about applying pressure AND THEN torque down the bolts not hold the pressure and torque. I guess that I can't write that well.

 

Dave