shakes after tyre change

[Den]

I bought the girl some new shoes yesterday, a set of Scorpion Trail II's. Al good until earlier today when I took both hands off bars to adjust gloves I noticed the bars shake left/right slightly. I couldn't actually feel it while riding and it seemed to happen sub 65kmh. My previous tyres were Tourance Next and I only ever noticed that happen once before while taking my left hand off the bars during a long sweeping right corner.

Could this be the result of poor balancing, a bearing issue or a defective tyre? Oh and the guy at the shop fitted an L shaped valve, which he assured me would not mess with the balancing.

 

[RCinNC]

Step one is to make sure the tire isn't installed backwards.

 

[Den]

I make sure they fit them correctly during installation


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[Dogdaze]

If tyres are mounted correctly then check for steering head (stem) nut tightness, this is prone to becoming loose, there is a thread on this and outlined in the service manual on how to check.

 

[Den]

Just read some old threads on that, damn! Would a quick check on the nut up top be sufficient or strip down to bearing to check the lower nuts?

I have noticed a rattle when riding over uneven surfaces. It went away for a while then started again recently. I assumed it was that little plastic cover under the screen, maybe I was wrong??


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[Dogdaze]

Start with the top nut, but check the two locking nuts with your fingers, it has been reported that those have been found to be finger-loose. If you do the complete check it will only take about 45-60mins, most of that is stripping away the handlebars and setting the bike ready for the torque settings.

 

[Den]

Righto, will have a look today. Hoping all is well, but then again if the nuts are tight as they should be I'll still have bars wobbling about. Will report back with findings. Is the top nut 27mm?


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[Dogdaze]

I believe it is, but not 100% as my bike is at another location, so cannot check, but you would have to take off the handlebars anyway to get to it

 

[Den]

Really? I too dont have my bike near me but I thought there would be enough space to tighten up using the 22/27mm combo wrench I use on my WRR axles?


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[Dogdaze]

The angle of movement is very limited between the the two handlebar risers, once you have the wrench on the , you'll see what I mean.

 

[RCinNC]

The lockrings under the steering head have a specific torque setting, and have to be tightened in a specific sequence. Too loose and the steering head can vibrate, too tight and there's too much drag and premature wear on the steering head bearings. You need a special tool and a torque wrench to tighten the locking rings. Yamaha makes one that looks like a a capital letter "G". I got mine off of eBay. I've seen another tool out there that looks like a socket with teeth on it, but I don't knew where to get one of those.

If the locking rings are finger tight, then they're too loose.

The parts identified in the diagram as Number 4 are the locking rings. You're also going to need a big torque wrench for the steering head nut (Number 7); it's torque setting is 97 ft/lbs, if I recall correctly.

 

[Don in Lodi]

The shake happening after a tire install makes the tires suspect to me. My experience with steering head wobble was an apparent slipped belt on a rear tire on it's last 10% of life. Happened twice. Loved the tire but I no longer use them. Since it's a 'new' tire, do be sure the beads have set evenly by giving them a spin and studying the tire sidewall markings closely. Perhaps one took an unusual amount of weight indicating a poor beading?I believe the steering head click is a separate concern and should be addressed of course.

 

[greg the pole]

The shake happening after a tire install makes the tires suspect to me. My experience with steering head wobble was an apparent slipped belt on a rear tire on it's last 10% of life. Happened twice. Loved the tire but I no longer use them. Since it's a 'new' tire, do be sure the beads have set evenly by giving them a spin and studying the tire sidewall markings closely. Perhaps one took an unusual amount of weight indicating a poor beading?I believe the steering head click is a separate concern and should be addressed of course.

I second that. If the issue was not there prior to the tires going on, it's unlikely the bike, but the new bits added to it.
I've ran myself ragged before on a way out of balance rear tire. Thought it was the rim, bearings, balance...turned out to be a bum rear tire straight from the manufacturer.

 

[Den]

Right, well I took the bars off and checked the top nut....flippin tight! The lower nuts were not finger tight either, tried to give 'em a twist with both hands and a fair bit of effort but neither budged.

I didn't think to check the beading so I'll have a look tomorrow. To be perfectly honest with you all, I'm assuming this is a 'new' problem as I've never noticed it before (aside from the long right turn mentioned in first post), however this could be because I never took my hands off the bars under 60 odd kmh. Maybe I never took my hands off at low speeds?? :question: Like I said it's not a shake I can feel while riding at any speed but I'm guessing this needs to be addressed pretty quick. Don't suppose the new rear could cause such a problem?

So whats next, check the bead and give it a spin?

 

[greg the pole]

as mentioned above, the top nut is usually the culprit. was on mine anyways. If the nut is tight, the lock nuts should be ok.

how many k's on the bike?
I doubt it's your wheel or steering head bearings. they are good quality and can take an absolute shit kicking before needing replacment (mine have 81 k km with little wear)

I still have my money on balance/tire/maybe direction of rotation...

 

[Den]

Hey Greg, she's on roughly 22K kms and the rotation is certainly correct...checked during install and this morning to lay my mind at ease.

I mentioned in my first post that they fitted an L shaped valve stem similar to these...

http://www.ebay.com/itm/90-DEGREE-ANGLE-METAL-CHROME-TIRE-VALVE-STEMS-HIGH-PRESSURE-BOLT-IN-4-PIECES-512-/131558552133

The wheel was balanced after this was fitted, but is there any chance this could be causing the problem?

I will take her in to the shop tomorrow hopefully and have them refit/balance the tyre.

I hope this isn't something major ???

 

[greg the pole]

I doubt, the L shaped valve has anything to do with it. especially if the wheel balanced out.
If I"m not mistaken, a balance will not pick up an out of round tire. the way I found out that my tire was pooched is to put it on the rotating machine, and watch the outside of the tire for excessive up/down movement.

an easy check at home is elevate the front fork (bike on c.stand, have someone sit on the passenger seat. Move the front fork back and forth to check for steering head play. then check your front wheel bearings (side to side play) grabbing the wheel from the top and bottom)

 

[Jono49]

Only just seen this, It's tyre balance all day long, and go back to the shop and get them to replace that 90° valve, as their only fit for scooters, I had them fitted to my Honda Blackbird and had a ride home on a breakdown truck, I was lucky to feel my rear break away on a corner just before it let go completely, the centrifugal force throws the valve stem outwards and bursts the nipple going into the rim! They should be banned or have a speed rating on them, 30mph would be enough go back to the tyre shop and get them to sort it out.

 

[Checkswrecks]

I'm with the guys suspecting the tire. Assuming that you don't have a wheel balancer, try backing the brake pistons into the calipers or even removing the calipers, support the bike with the front wheel off the ground, and give it a light spin a half dozen times. You are looking to see if the same part of the tire always stops at the bottom.


If that is OK, clamp the handlebars so they can't move. One way is to strap each to the luggage rack. Then tape a piece of stiff wire to something so the wire is at the periphery of the tire. Rotate the tire and see if it tracks true, both in left/right and rotation.

 

[RonH]

The chrome 90 degree stems work fine, assuming decent ones fitted. Thousands of GL1800 riders replace the factory rubber 90 degree stems with chrome ones because the rubber ones do fail. No help in your problem, but look elsewhere other than the stem for sure.