Front End Shaking

I've never experienced this before on any of my bikes. Here's the story;

A few weeks ago I had a new front tyre fitted. I noticed that the shop hadn't changed the balance weights and I assumed that the balance was OK as it was. The guys in the shop are experienced bikers and I would trust them with my bike anytime.

When I took the bike out afterwards I did one of my 'flat-out' runs, which I do from time to time, the front end started shaking at 80mph. This continued up to 100mph. I shut off and the shaking ceased as it damped out on decleration through around 80mph. Below that it was fine. This didn't feel like a wobble or an oscillation, it was shaking at an amplitude which was unpleasant but not unsettling. The shop rebalanced the wheel and they said it was out of balance and I noticed that the weights had been rearranged.

Today my 'flat out' run told me that it's still shaking, 80 to 100mph.. This is coming through the handlebars and under my feet.

I changed the fork oil about 2 years ago. I also fitted recent new discs and pads recently. Prior to the tyre change my SW was fine up to 100mph, apart from the usual buffeting. I always thought that poor balancing would create a wobble.....but shaking?

I'm puzzled. Anybody know what might be causing this?

It does sound like wheel balance, but I would also check the tyre for damage (unlikely the mechanic would have spotted that) and the rear because if that's worn it could be fighting against the front causing those symptoms.
Till then you'll just have to stay at legalish speeds.
Having said all of that mine gets a bit squirrely at high speeds on anything other than super smooth tarmac.

The rear tyre is also new. I've always thought that the rear tyre should be balanced but everybody says no.

I use the same piece of road when I'm testing and I don't think this is squirreling. The shaking is rather 'heavy'. I wonder if this might have something to do with the springs or oil but why would it happen overnight, so to speak?

Loosemarbles wrote:

... snipped ... The rear tyre is also new. I've always thought that the rear tyre should be balanced but everybody says no. 

Don't know who "everybody is that say no to rear tire balancing" but as far as I know and do, the rear tire always gets rebalanced on replacement. Why wouldn't it?

Perhaps if you have your own static balancing set up you could insure that the rear tire is balanced. But IMO the shops aren’t equipped to do that to our oddball 13” wheel. It does require a special tapered adapter. However there is Ride On which does a pretty good job of addressing that balance issue as well as offer some protection to punctures.

Having been thru over 400 motorcycle/scooter tires in the past 67 years and about 95% work done by me. #1 first I put newly mounted tire on my balance stand...check for lateral run out. up down run out, is inflated tire really round.....if it isn't throw away and start over. In US scooter shops do not balance small wheels---at least for past ten years I have been using "Ride On" as balance medium=it works fine. Not cheap.

I like matched pairs of tires----lately Heidenau working great for me....and in DDR days on my MZ's.

Doubt if Silverwing will go 100mph----had 2 new ones

Key word here is Assumed they balanced the tire. Old weights they didn't. It could be the tire. SW front is harder to balance-to get it centered than most wheels. 

Google this guy Marc Parnes he makes a very good balancing tool for bikes and has SW cones. Tool works great but must have some time to do it right. $ 105 dollars. If you use it enough pays for itself.

...and I thought this would be an easy fix! I suspect the runout on the front axle maybe beyond limits so, do I buy a new axle? I can't justify buying a runout gauge. The Marc Parnes gadget looks intruiging though.

After considering all the input above I am inclined to start by gettting the rear wheel balanced, somehow. I'm gonna ask the shop if they have means of doing it. I only go to 100mph when I'm being chased by the cops, which, luckily isn't very often.

BTW John, my SW will do 100mph (on the clock) and I think a little more but I've never tried!

I'll post my findings over the winter time. This is going to be a slow fix...!

At one point in time I used a mechanic that swore by the balancing beads. Paul

Never did understand balancing bead thing ? A proper static balance is the way to go in my opinion and always works unless tire has a problem. Flat spot, excessive runout high spot or damage from an impact to sidewall. Cords can break in some cases but rare most tire damage is from heat, under inflation or punctures.

I mount and balance my tires except one time between jobs Covid thing they put the front on backwards and had the same weights on it. Never left the dealers lot and had them fix it told them forget the balance I'll do it myself. $50 bucks to boot never again.

When I got my bike, It had new tires fitted by dealer, I "assumed"   they where balanced, I could see balance weights, my initial test rides where limited to 60mph sprints, etc., after puchase, I finally got it to my "secret test area", it shaked bad after 75mph, I balanced the front tire, big improvement, but still some at 90ish, balanced rear and perfect, basically repositined exhisting weights. 

 Had this cheap balancer for over 20yrs, is chinese made, fairly sure similar available in your area.
https://www.harborfreight.com/motorcycle-wheel-balancing-stand-98488.html

John Grinsel, a silverwing either indicated or actual will do 100mph but not much more.

With near 100,000 miles on 2 new SilverWings----True 100 mph?? Who cares, bike is a scooter and a pretty good one.

True, I have done the magical figure once or twice on the silverwing and to be honest I didn't find it comfortable or particularly safe so whoever's wants to try it on a regular basis and scream the tits out of their motor just to get the ton well it's up to you.

vmaximus wrote:

True, I have done the magical figure once or twice on the silverwing and to be honest I didn't find it comfortable or particularly safe  so  whoever's wants to try it on a regular basis and scream the tits out of their motor just to get the ton well it's up to you.

 My point testing high speed was to check for anything unusual and make sure it was safe to do so, no vibrations, weird noises, etc. Is better than finding out when you need to go fast and find you have and issue or worse , the vibration/out of balance that you feel only at high speed, is there all the time, at lesser speeds it's just not as noticeable, but it will slowly damage bearings, etc.

SW will do 105 mph my 2013 speedo is accurate confirmed by GPS. Engine is at REV limiter 8,500.

Sure SWing will do 100+  but its best cruising around at 0 - 70MPH two up on a sunny day going for a ice cream down by the coast but whatever its so practical at getting from A to B in style. Enjoy it!

On the subject of weave, check tire pressures , wheel balance , wheel run out, wheel bearings, tire pressures and balance of bike front to rear, a heavy rear load would cause some instability at higher speeds.

I would offer my Swing as a donor to swap some parts around but I'm a fair way away unfortunately. 

Hope you get it sorted dude

Loosemarbles, I'm still trying to get my head around the fact that you have to test you bike/scoot between 80 to 100mph to check if every thing is ok when the majority of UK riding is generally 70mph and below, now it seems to me that if there was not a problem before you had the tyre fitted then the new tyre/balancing is the probable cause assuming nothing else was touched or altered. If continuing to ride with this fault and as zrx212 says it could lead to damaged bearing and i have no reason to doubt him, its not a big problem to take the wheels off and change the bearings, these are easily obtainable from any quality bearing supplier as with new seals then that eliminated 1 probable cause. Just a note when i had my Yamaha vmax i had a serious problem with weave over a certain speed that i never did solve in spite of doing all the so called mods which where kicking around in the day, tyre pressures checked, balancing done, head race/bearings changed and torqued down to as near as practicable to the correct factory settings. So if its still doing it generally its not going to get better by its self so take it back and have the tyres re checked.

In the past I have experienced the problem where a precision balanced front tire exhibited signs of imbalance. The problem was corrected by balancing the rear tire.

Testing bike at 3 figure speeds in case one day you need to do 3 figure speeds...............lol you planning a bank job buddy

I still say take it back or remove the wheels and have the tyres  checked again and re balanced. My first Max that i had for 23yrs as I've said i never cured the weave problem no matter what i did and the second V Max never had the weave problem and neither has my S/wing so I've been lucky with 2 bikes and unlucky with 1. Previous Brit bike that i had never ran long enough to get many faults only engines conking out on a regular basis, its only when i went onto Jap bikes that they became reliable and to be fair better and generally ran with little to no faults. Anyhow good luck with finding the cause and rectifying the problem.

vmaximus wrote:

Previous Brit bike that i had never ran long enough to get many faults only engines conking out on a regular basis, its only when i went onto Jap bikes that they became reliable and to be fair better and generally ran with little to no faults.

You must mean "Japanese bikes".

I have been using Dynabeads (https://www.innovativebalancing.com/HowItWorks.htm)  for over 30 years and also selling them. So far every one using it are happy with it. I personaly ride a Silverwing and put into my tires 2 ounces  in each and it is perfect. I know it might be expensive at the first time  but when changing your tire  take the beads and install them into your new tire... To take it out of the old tire, take a spray can cap, slowly roll your tire and the beads are going straight in the cap. dump it in the new tire. ... Never pay again for balancing. Beads are reusable ass long as you want.  

Your tire is always perfectly balance and you will make more mileage/kilometers on the same kind of tire then any other balancing way. Why ? beacause the beads are balancing your tire every time you stop and go...  

Michel

I'm a longtime mechanic that is have 40 years in and have used beads in some tires with mixed results.
Customer requests beads that they bought and then installed them only to have the vehicle back with complains of wobble shimmy vibration. Now what?  I have to break the tire down and vacuum out those beads and properly static balance that wheel then all is great.

I've put beads in and tried a static balance and every time it calls for different weights to balance it. If they worked that would not be the case. If beads work why not just put some water in there would do the same thing until it freezes.      

Did you really mention '' 40 years mechanic and why not just put some water in there would do the same thing until it freezes ???  


I am 65 and owned over 44 motorcycles and always made my mechanic ...  I sincerly hope to find someone to tell me how long a tire will stay perfectly balance as long Dynabeads will keep them.... If your guy's were complaning they may diden't have anought beads in the tire... I own 1990 BMW Paris Dakar and had to put 5 ounces in the front wheel to have it perfect  

I  saw some guy's complaining like that on forum and they never use them
Now what ?

Michel

Problem is sometimes beads just don't work don't care how many are in there. I'll never use them. I've owned a few bikes too and always did my own maint.- repairs.
One thing I never checked if a worn tire still balanced after it was done but didn't need to had no problems with it.

Works for you be happy. Ride ON

The pros and cons of using beads is covered on this forum and having read it all I don't think they are for me. It suggests that they only work in the centrifugal plane but not horizontally. I can't determine whether my SW is shaking up and down or side to side, or both.

My plan is to get the rear wheel balanced and go from there. It's always great to have a mystery solved by means of debate and investigation. I'll post my progress, I have to get to the bottom of this and share my eureka moment.

The preload on your steering head bearings has backed off a bit from old age. The steering head bearings have to have a slight amount of preload on them or the front end will shake. The pre-load acts as a steering dampener. With the bike jacked up in the front, you should have a slight amount of drag on the front steering as you swing it left to right. Now I don’t mean a lot of preload, just enough to where you feel a slight drag on it. I had to do this on my silver wing and my FJR.

An interesting observation Toolman. I did wonder whether my head stock bearings were giving up but the bike has just passed an MOT and I'm sure the guys who did it would have warned me if that was the case.

I'm going to check the service manual on this pre-loading stuff and investigate. Is this a difficult job?

The preload on the steering head bearings has backed off a little bit due to wear but not to the point where you can feel slop in the front suspension. It is not a difficult job if you’re the least bit mechanically inclined. Obviously the plastic cover Has to come off and then unbolt the handlebars, and you get down to the nut which there are two of. When you tighten the bottom nut to get the preload set that is where you have to be careful. When you tighten the jam nut on top it will actually tighten the preload a little more. So it may take a couple of three times to get the pre-load set right. I am not an expert at motorcycle suspension, but when I hang out with my motorcycle buddies, I told them about the deceleration wobble I was experiencing. Every one of those guys said tighten up your headset bearings. So that’s where I learned it.

Another note, I don’t remember where I saw this somewhere on the inter-web, but there is a way I’ve seen that mechanics set the preload on the bearings with a fish scale. To be clear, I’m talking about those little scales that fisherman carrying their boats to weigh a fish after they pulled it in. They attach the fish scale to one fork tube and pull on it to check the preload tension on the bearings. Also, if when you do tighten up the bearings, if you feel any kind of clunking or grinding, you should get a hold of a proper mechanic or take the bike to the dealer and have the bearings and races replaced.

IIRC setting the preload tension on the spanner nut by using a fish scale type device is pretty much what the FSM calls for. The more frustrating issue will be in adjusting the octagonal locknut. Here is a link to an earlier conversation about dealing with that:
https://www.silverwing600.com/t7786-steering-stem-socket

Scale was standard procedure for Kawsaki 1200 Voyager.

Yet another gem from this forum and another job to put on my bucket list.

I had mentioned in an earlier post that I had to tighten up the headset bearings on my SW and my fJR. Well now I have a lot of miles on my FJR tires, the wobble is coming back. So tire stiffness has a lot to do with it. Just FYI.

I gather that the SW front tyre is prone to cupping and I've had it happen on one of mine. My current tyres are new.

Frankly, I'm beginning to think that this front end shaking is my imagination. I zoomed up to 90mph the other day (after installing my new OEM 28g rollers) and it felt quite smooth. I wonder whether turbulence and buffeting could be half the problem?

I over-tightened the head bearings on a bike one time and the bike would not stay in the road without constant correction. The weight of the bike and the rake of the forks normally make the wheels line up but being overly tight prevented that from happening easily. The tightening of the jam nut caused the problem.

The fish scale method is difficult because the brake hoses create some force in one direction and having the weight of only one caliper and disc really adds to the problem. I add the pull on each fork together and divide by 2 in trying to reach the desired number in the manual. Sometimes I just settle for the steering staying centered with the front wheel off the ground. Works for me.

Loosemarbles wrote:

I gather that the SW front tyre is prone to cupping and I've had it happen on one of mine. My current tyres are new.

Frankly, I'm beginning to think that this front end shaking is my imagination. I zoomed up to 90mph the other day (after installing my new OEM 28g rollers) and it felt quite smooth. I wonder whether turbulence and buffeting could be half the problem?

Loosemarbles - I wonder whether your problem is the same as mine? I have had 2 Swings and the first was a darling. When I bought the 2nd I swapped both front & back tyres from the old bike onto the new. Both sets of tyres were nearly new but I prefer the Mitchelins over the Bridgestones. I was alarmed by the handlebar judder and thinking there was some issue with the new bike, we had it in bits and replaced fork oil, balanced both wheels and eventually gave up and lived with it.

Happily the judder has quite gone away with a new set of tyres one year later. I believe the issue was just the tyre itself. Something when they made it.

Just live with it and enjoy the ride. It will probably be resolved when you replace the tyres.

I'd be interested to hear what your revs are doing at 100mph?

Thanks Might Mouse, some interesting comments so it's not imagination. I had a blast up to 90mph today and sure enough, it's there! I never had this problem during all my tyre changes over the years, until the last tyre change; I've always used Bridgestone Hoops. The front tyre is about 700 miles old but this problem was evident when the tyre was brand new.

I changed the fork oil about 3 years ago and the springs were within limits.

I think I'll live with it for now and see if it settles down. BTW, I can't remember exactly what the rpm was at 100mph but a flicker of memory is telling me about 6500..????

The variator on my scooter is at its maximum by 60 miles per hour by GPS and is at 4900 RPMs. Every 10 mph above that requires 800 +/- engine RPMs. Therefore the following GPS speeds should apply in my case:

60 4900 There are variables among these scooters. Beware the speedometers.
70 5700
80 6500
90 7300
100 8100
104 8500 Redline Will Silver Wings pull to redline?

I have tested this hypothesis only to 80 mph. That's enough for me.

Thanks for posting your findings Wingman. Are you using OEM rollers or any aftermarket rollers/sliders in the variator?

I seem to recall several occasions “cruising” in the (indicated) 80 - 90 mph range but never seeing 7000+ rpm. And I am using 26gm sliders along with an HiT clutch.

Those RPMs are with stock rollers. For reasons that I have not been able to figure out, 24 gram sliders do not drop high end RPMs in my current scooter the way sliders did in other Silver Wings that I have owned. It must be a variator thing but I see nothing amiss. I run a glass packed muffler so I left the rollers in to quieten the bike some in my neighborhood plus I like the very smooth transitioning of the variator.

Cosmic_Jumper wrote:

Thanks for posting your findings Wingman. Are you using OEM rollers or any aftermarket rollers/sliders in the variator?

I seem to recall several occasions “cruising” in the (indicated) 80 - 90 mph range but never seeing 7000+ rpm. And I am using 26gm sliders along with an HiT clutch.

 
 I agree those rpm vs mph numbers seem a little higher, my only cvt mods are a non stock Erlandson GBoost belt and Malossi white/touring torque/contra spring, NO DRP sliders/weights. stock rollers, I'm at aprox 7000 at 90ish+..., with less than 2k on full cvt service. I'll double check those numbers ASAP.
  
 IAC something is a miss on 1Wingman1 CVT if not seeing a drop in rpm with DRP sliders, 

vmaximus wrote:

John Grinsel, a silverwing either indicated or actual will do 100mph but not much more.

Mine has been up to 120 and still wanted to go faster. At that time I was 150 lbs heavier than I am now.

My second hand Silverwing came with a severely worn front tire. The wobble was real! No yoke. New tire w. balancing and hey presto: wobble all but disappeared! Only now after just 3000 kilometers on the new tire I can feel the wobble coming back. Bummer.

I went for a ride today to try to analyse this thing. I'm convinced that the movement is 'up and down' and not 'side to side'. It's not a wobble, or at least it doesn't feel like it.

I'm going to pre-load the head bearings. I'll have to use my personal judgement as I don't have any means of using a scale, besides, the brake caliper and hoses make things awkward.

At present, when lifted from the ground, my steering will float from lock to lock as if on air. From what I gather, there should be a very slight 'drag' in the movement. Just like when fitting a car wheel hub in the old days, when I didn't even have a torque wrench. It worked back then.

Loosemarbles wrote:

... snipped ... I went for a ride today to try to analyse this thing. I'm convinced that the movement is 'up and down' and not 'side to side'. It's not a wobble, or at least it doesn't feel like it. 

I just thought of something Loosemarbles. I once had a rear tire go "out of round' on me.  It was the strangest thing.  I could feel the up & down movement and when I pulled in for gas, I spun the wheel (on centerstand) by hand and the tire looked like an oval egg mounted on the rim.  

I've never seen a tire go and stay out of round like that before. I assume it was a belt shifting/separating problem.  I ended up riding for about another hour the rest of the way home on it but changed it out ASAP.  

Maybe check your tire(s) roundness?