Front forks /wobbly steering

[ricardo]

Hello everyone.
I've removed my front wheel to investigate. Pads are good. bearings seem to be ok but how can I be sure? I noticed that with the wheel off the forks will rotate independent of each other . Is that correct. I always imagined that they would stay in the alignment they are in when the wheel is in place.

Ricardo

[K2-K6]

The bottom of the fork legs are effectively "floating" with no rotational location,  that's correct.

They are only aligned by clamping the wheel spindle when correctly assembled and tightened. So all ok if clamps and threads are in good order.

The front mudguard is considered as brace to help,  but if it has rubber mounts it can't really contribute much.

Initially you've not flagged anything untoward there.

[ricardo]

Many thanks
Ricardo

[TrickyMicky]

Whilst you have the front wheel removed, it's nice and easy to check if it is out of balance. Hold/support the wheel spindle, and just give the wheel a gentle spin, when it stops, make a chalk mark at the 6 o'clock position. Repeat this a few times, if it stops at the same place each time, then your chalk mark is the heavy spot and a balance weight should be affixed diametrically opposite, correct weight determined by trial and error I'm afraid! When giving the wheel its slow spin, if the wheel bearings are in good order, you should not be able to detect any noises or feel any harshness when holding the axle. As you have the front wheel removed I assume the front of the bike is supported leaving the forks free to  move, Slowly move the handlebars from lock to lock, there should be no resistance or roughness throughout the travel, especially at the straight ahead position. Lastly, once again as the front end is free to move, ensure the bike is secure, then grasp the bottom of the fork legs and push and pull them in the fore and aft direction, if your steering head bearings are good there will be no movement at all.
   Eons ago, when I had a CB750, it had a front wheel which was only very slightly out of balance. Did not take any notice until one day when going on holiday, two up with a very heavily loaded rear carrier, i closed the throttle at about 40MPH and took my hands off the bars to adjust my goggles, HOLY SHIT! It went into the biggest tank-slapper I've ever had. Please take those few extra minutes to check those few items. Happy riding, and stay upright. Michael.

[K2-K6]

The point Micheal made about checking the smooth turning of fork yokes has particular significance in this problem. Absolutely any roughness however small can cause error.

The original headstock bearings are ball and race type.  If there is an indentation just very slightly off true straight ahead geometry (you'd feel this in checking) then it can cause the front forks to "sit " in that alignment,  which would turn the bike in one direction slightly.  The natural steering geometry will "try" to make the bike go straight down the road with no input to the bars.  The conflict between the two can make the forks oscillate in and out of that bearing dip,  making the steering wobble. Even adjusting the chain and getting a slight bias on rear wheel alignment can bring this in or out of play.

The headstock bearings are ideally replaced for taper roller bearings which ordinarily resist deterioration under use much more effectively.

Something else to look for in detail,  the wheel spindle clamps look universal but are directional.  There's an arrow cast into them that should point forward in direction of travel,  they would be clamped first by the leading stud to get them seated metal to metal ( that part of the casting in longer to facilitate) and only then the rear stud tightened to finally pinch the spindle.  It's a subtle design,  but often missed.

[ricardo]

Many thanks. I'll run-through that lot.

Ricardo

[ricardo]

I've just checked the steering. From neutral position theirs drop all the way round to the left. Extreme to the right its a little stiff at the end of the range.

What should do please.
Ricardo

[TrickyMicky]

Make sure it's not cables/wires/brake pipes bunching up in one direction.

[ricardo]

I think that's the reason for the R turn stiffness. I'm not sure how it affects the swing to the left
Ricardo

[taysidedragon]

The only way to be sure that it's not being caused by wiring or cables is to disconnect them all from the bars and then turn them from side to side.

[ricardo]

Wow. Quite a job!  Sound advice though. I'll investigate

[Rob62]

Removing the cables is a bit ott in my opinion... so long as there is no free play or notchyness and the steering moves freely it is ok.

[K2-K6]

As above,  agree that cables although you can feel them at max turn have little effect when riding.

At most you're going to be 10degree each side of straight ahead,  unless manoeuvring at very low speed.

Although I took "wobbly " to mean the handlebars are shaking when you ride it,  rather than just staying straight if you take your hands off the bars. If that's the case then it is just the central range of bearing movement you need to inspect with the most scrutiny.

[TrickyMicky]

Don't worry about the steering falling to one side or the other. If you look at the steering set-up, you will see that the forks are forward of the steering stem/axis point, so when you turn the bars the forks actually move round in an arc. Because the steering stem is at an angle, this means that the forks actually drop either side of centre. When it is all re-assembled, take bike off the stand so it is on its wheels, then turn the bars from lock to lock and you will see that the bike actually moves from side to side roughly at the point in line with the front of the tank. This set up is to give the optimum steering and handling response for a road bike. If you look at a speedway bike the forks are very close to the vertical, no good in a straight line but good for drifting, drag/sprint bikes are totally the opposite, acutely angled forks for straight line running.
   Just as an aside, if you've ever wondered what keeps your bike so stable, whilst you have your front wheel removed, using both hands hold it up by the wheel spindle and rock it about. Now get a mate to spin the wheel and then try to move it about and you will feel the gyroscopic effect. Be lucky, Michael.

[ricardo]

Bikers thanks.
No the steering doesn't vibrate or shudder. It feels as if the steering is imprecise. I seem to have to always be turning the bars  to keep the bike on a straight line. Probably more noticeable while on a bend
On another bike I once had with excellent steering it behaved like this  when my front tyre was below pressure
Does that mean anything different.?

Ricardo.