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Death wobble

Got a huge problem with my Silverado. It's an '02 650. Just put on new tires, yes their balanced, and notice when I get over 60 mph and let to of throttle to start braking I get a horrible shimmy and wobble!

HELP! If I give it a little gas and don't try and slow down so fast it settles down. At about 50 mph and lower, I don't really notice much or any wobble at all no matter how quickly I stop or power down.

My last set of tires I just took of were unevenly worn on the front and I think this is why I didn't notice it but a couple times.

Any ideas or advice? If I ever had to stop suddenly at high speeds I'm sure it would result in at least having to lay it down or worse.

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Motorcycle: 

39 Comments

are the rims bent,check all the bolts for the rotors,axel shafts are straight, maybe even the tire bead is not set, just a thought

Done done and done. All looking good as far as I can tell. Bolts were torqued to speck, axle was checked and lubed when put back on and bead is good.

hows the headset? tight-loose

Check the brake calipers..are they fitted properly?
Tire Pressures correct?
This might sound like an odd question, but are the tires the correct stock size and are the fitted the correct rotation direction? (check tire direction arrow)
Were the tires new stock ie had they perished from sitting in the tire rack for a few years / got a flat spot.

Did they do any other work while they had the wheel off? Bearings/spacers/brakesetc Any fork or steering head work (bad bearing) Any spoke damage?

Cheers, Steve

talking about tires there is a yellow dot on them, it should be by the valve stem

Tire balanced and date code last six months. Thought about the bearings. Will check and reseat and see I that helps. I did the work and was OCD with everything I did as always. Did brakes and already rechecked. I'll post after I check the bearings.

Certainly has me intrigued.

Try lowering the rear shocks adjustment (to achieve more rake on the steering) and see if it improves at all.
If you have a large windscreen on the front, that could also cause the front end to lower at 65mph through wind pressure which again alters your steering geometry.
Ensure that the steering head is not worn .
Heavy braking causes the front end to dive which reduces the trailing angle of the wheel/forks and can throw a bike into a severe tank slap situation .....wear your leathers whilst testing the bike, you could well need them .....good luck.

Also check rear swing arm for free play. If you can get the bike up off the ground enough, check the roundness of the tyre too. even new tyres can be out of round. Everything else has been covered here.

Re-rebalanced the front tire, it's good. Bearings good, rotor torqued to speck, and axle straight. Tire direction good and bead seated. Guess I'll start checking forks and geometry.

Any tips?

Are yu getting the wobbles through the whole bike or just the forks? If it just the forks then it is all front wheel related. If it is the whole bike them look at the head stem and swing arms. Also if you have had the rear wheel off check that it is seated correctly, even remove and check the splines if need be

Just through front. Starts to wobble at 60mph and greater when I let off gas to slow for braking. As long as throttle is on, there is no wobble at past 65, although the faster I go before I let off the more violent it gets.

Rear is seated well. I will get on it again in am and see if anything helped so far. I'll post back after.

Interesting that the tire was previously worn unevenly.
Thought this might be interesting: http://www.rattlebars.com/tirewear/

No bent or loose spokes? Rim not out of shape?
Not sure if you have a service manual (shop manual) and the supplementary service manual, which you can get here:
http://www.stargis.net/webslinger/650Vstar.htm
I'm starting to lean towards the steering head bearing.

Same here Steve or fork alignment

Have you used this tyre before or is it a different profile

It's the steering geometry causing it Ryan ..... How about a photo of your bike so we can all see what you've got.

Interesting situation. Phil might be onto something with the geometry.

Are the triple tree and neck bearings, yoke bolt and fender all good and tightened properly? Is the triple tree the original stock tree or is it an aftermarket triple tree with 6 to 8 degree rake to it? So, as Phill says a side shot photo of your bike might help. You might try to measure out your rake and trail and see if the geometry (make sure you have correct trail) is correct for that bike. If you lower the rear suspension it can potentially alter the rake & trail and steering/braking.

When riding the bike, braking and suspension travel can also alter the rake and trail dynamics of the bike. For instance, as you brake hard on the front brakes, suspension will compress under a dive thus decreasing trail and rake potentially producing wobble in the bike. Maybe your fork seals are leaking, low on fluid or you need new fork springs. Some fenders are built strong enough to be an integral part of the steering system and prevent fork twist. So, is the fender bolted on tight? Any alterations or loose components of your bikes suspension or steering can potentially end up with negative figures under extreme braking conditions.

Some aftermarket "universal" triple trees require extra spacers and special "adaptors" to make them fit properly. If it wasn't properly installed and one or more of the caliper spacers, washers or "adaptors" were left off that means control and braking may be adversely affected by additional spacer/fork twist.

Long winded, but just some ideas for you out of desperation. Good luck with the detective work and keep us informed...

Charlie

http://bikearama.com/theory/motorcycle-rake-trail-explained/

Just a thought, Rim spokes ok? , you may also have a warped or out of round brake rotor that may be causing the shake, won't notice it much at lower speeds but will at high speed....just a thought.....

Ok so here's an update. Re check front end. All torqued and properly adjusted. The only thing I haven't done is pull the steering bearing.

Have pondered the point about the fender. I did have a little slide off back in April into a field, took corner too fast, and slide into mud. Fender was bent, but was able to mostly straighten it out. I did ride at fast speed with old tires for couple months after and did not notice any problem. However, maybe it became exaggerated after replacing tires and fender is the issue.

On the other hand, I was riding this weekend and experimenting with different speeds of throttle off and various braking.

When I throttle off under 50, without braking and coasting for a bit, I get no wobble whatsoever.
When I throttle off over 55, braking or not, I get the wobble still.
I noticed, when I use rear brake at 50+ I get a TERRIBLE wobble!
Finally, when I use front brake at 50+, I get a controllable wobble.

Two things I ask of the community:

Any thoughts on the differences and where to start with back end?
And, any links or advice on how to check, properly, the geometry and alignment?

Ok the only thing that has changed other than your tyres is that you had the rear wheel out to replace that tyre so I would be pulling it off again and double checking everything. Make sure that the internals are secure and align correctly. Then I would be looking at swing arm bearings and then engine mounts. In section 8 page 5 (8-5) of the manual it lists a few things for unstable operation, most of which has been covered here already. One thing I forgot abut was the rear shocker and spring. Make sure the spring is ok and the shock hasn't lost the nitrogen and has a dampening effect. Also double check your tyre pressures. Use a different gauge if you have to .

Did you inspect the brake rotors for warpage and or hot spots? If there was any amount of residue while handling rims and brake calipers (finger prints, oil, grease, etc) after braking the rotors will develope hot spots and warp. That will cause the vibration/wabble. The higher the speed the worse the wabble. The events with replacing tires and having not had this problem before plus you have just about checked everything else that could cause it. Everything points in that direction.

Some things to think about or check:
http://www.650ccnd.com/shaft2.htm
http://vstar1300.pbworks.com/w/page/5760726/Wheels (from the V-Star 1300 community but still an interesting alignment idea)
http://ziariderblog.com/2010/05/v-star-650-spline-lube/ (just for handy info)

Hmm..assuming the rear wheel, swingarm, bushes, hub aligned/drive spline assembly is OK, I am still leaning towards the steering head bearing (any slop in the forks when the bikes is hoisted off the front wheel?)
http://www.starbikeforums.com/forums/showthread.php?t=6028

This may help.
Do you have a friend with the same bike? If so, swap wheels over and see if the problem transfers to the other bike.

Better still, just swap the whole Bike - but you do need to be bigger than him ....... lol

Here is another handy 650 item to add to your handy info folder:
http://www.650ccnd.com/documents/FinalDrivealignProc.pdf

Been researching Headshake/wobble/weave. The board will not let me post links to some good vids that were informative to me. In short it is a long known about and well understood issue to which there can be many different causes that initiate this phenomenon. Yours sounds like it may be weight distribution and maybe sag or suspension firmness adjustment. Next time it does it try laying down forward and see if it stops. Email me for links to the Youtube vids

T

If its caused by the steering geometry, when it starts a wobble, you would be most unwise to increase the forward weight thus decreasing the Rake and trail of the front wheel, it may well result in violent Tank slapping and you'll get thrown off ... Dress accordingly !!!

I have the same issue with my 11oo V Star but only if I take one hand off the bars,both hands off would throw me right off

I can ride over 100km with no hands, not even a shimmy or a shake.

How do you get on brushing your teeth ?....(just asking) ....

I don't, there a nice corn cob yellow just as nature intended.

LOL ....

Had the same exact issue as you Ryan. Went to a guy that worked on Yamaha's for years. He said either a bad tire or the steering bearing need to be tightened or repacked. I took the bike home, took off the bars, tightened the bearing, took it down the road at 70mph, let off the throttle and the bike is solid as a rock. If that doesn't work then I would have the bearings repacked. Hope this helps.

Finally got it fixed! I had to replace one of the new tires and was too busy to do it myself. Called mobile motorcycle repair and left the keys and money with my boys.
When changing the leaky tube, guy noticed a broken spoke and several loose ones. He said spokes will loosen up for a while when you put on new tires and tubes and that I should have been told to check them.
After just hand tightening them all, the wobble was nearly gone. I am pulling the tire off and tryin the wheel this winter and should be good to go.
Thankfully not an expensive fork or geometry problem.

Good to hear it is solved now. I didn't event think about spokes. Most of my bikes have mags so it wasn't in my train of thought!

Thanks for the feedback ... ( very rare )

I have a Yamaha 650 (2002) V Star Classic with a trike kit. Mine shimmies on rough roads or the lease bump that I hit. Is that normal for a bike with a trike kit. It also pulls to the right on a two lane road, but on the interstate it seems to be fine, please, any help would be good.

because the dished out tracks (tire wear grove) on roads are wider than a the trike and you are only riding in one of the tire groves. and your interstaes are cement arn't they? probally don't dishout like pavement. plus on a two lane it is crowned so the water runs to the right in the ditch. does it make sense

Check your top triple tree is tight ( centre bolt ) and check upper fork tube mount bolts in triple trees

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