#@%& Steering head bearings!

[ARCHIVE_jacemdom]

Mecanic teacher near Montreal, Canada

Salut.

Does someone know a mecanic near montreal that could could guide me into replacing my cam chain and tensioner on my zl900? I want to do it myself, but with some paid supervision...

How much does it cost if i go to a standard garage?

 

[Yossarian]

Here’s my frustration / vent:

Last season, my first with a ZL, the bike had a low-frequency weave at highway speeds. I loosened the steering head bearings a bit and it cleared right up. This season, I noticed a clunk in the front-end and figured the bearings were now looser than they should be. I tightened them up some and went for a ride. The clunk is gone, but now the bike is nervous between 20 and 45 miles an hour. At normal highway speeds (and above) it feels very stable, maybe even more than I’m used to. So am I too tight again, but not as much as before? Has anyone else been down this road before and have a clue for me?

Yes, I did check the air pressure in the tires. I suspect there’s new tapered bearings in my future, but I’d rather not do that this season. I’ve already lost too many days with my bike in pieces.

</vent>

 

[zlMark]

Could they be in need of replacement or a clean/repack?

 

[Stormy]

If the head stem bearings are tightened up properly, when you lift the forks free from the ground, the forks should fall (from slight bearing resistance) slowly to either side under their own weight, not drop quickly.

When you have the forks up on a stand, etc, and you turn the forks from side to side, do the bearings feel notchy or, do they sound/feel "clunky", if they are notchy or "clunky" the bearings will eventually need replacing, they may improve with just need a clean and a re-pack with grease, but if you are going to pull the bearings out to clean them, you might as well, spend a little extra time and replace them totally.

I'd also check the front tyre tread for "feathering", if the tyres are feathered, nothing will fix the wobble other than new tyres. I had this recently on my ZL and I tried everything to get rid of the wobble (about 35 - 60 km/h) and nothing worked, as soon as I replaced the tyres it disappeared.

It's better to have the bike "in pieces" for a day or two, than have riding problems due to poor or over-looked periodic maintenance.

Mick.

 

[wuputt]

My ZL1k likes to "wander" another words, I have to work to keep it in a straight line. I did find that when I have my progressive shocks set to the higher levels it gets much better. ZLmark rode my bike with his woman on the back and stated it almost made him dizzy cause he had to work so hard at keeping it straight. I had the shocks at the lowest level at the time. I had the same problem with it with old Dunlops and it is the same with the new Wildflares. I will replace steering head bearings during the off season but last time i checked em they were smooth and properly tightened. I really think it is due to my lowering the bike!

 

[gosupes]

I really think it is due to my lowering the bike!

I dropped mine down about 2" and it didn't seem to affect the steering. Unless you dropped the front without dropping the back which would lessen the rake of the front. That might cause a wander.

 

[wuputt]

I dropped both ends, rear a bit more than the front. I loosened the steering head up a bit last night, It felt a little tight so I will see today if that fixed the problem for me.

 

[Stormy]

Think about it, If you lower the rear, but not the front, because of the pre-designed lower and forward oriented geometry of the bike, it could cause the steering to become lighter than normal, therefore making it harder to keep in a straight line.

The more weight you carry or the more you shift the centre of gravity to the rear, the worse the steering problem will theoretically become, and this will be compounded by how much you work the throttle too. As you accelerate the torque of the motor would try to shift the centre of gravity to the rear, so to keep the steering controllable during acceleration, I would assume, the centre of gravity would have to be slightly more forward to compensate for the added torque.

If you have changed the bike's centre of gravity more to the rear (hence lowering the rear shocks), and if you accelerate hard, this will only cause the front end / steering to become lighter than normal and therefore harder to keep in a straight line. I don't know how you could measure where the normal or current centre of gravity is but, I would assume that an even or a more forward bias to the centre of gravity of the dry weight between the front and rear wheels would be how the engineers at Kawasaki designed the bike to be setup.

Mick.

 

[Kawasaki-krazy]

I don't know how you could measure where the normal or current centre of gravity is

Drill holes in various locations through the frame and engine and pass a metal bar through and lift until the bike balances level.

Let me know what you find out.

KK

 

[Stormy]

I don't know how you could measure where the normal or current centre of gravity is

Drill holes in various locations through the frame and engine and pass a metal bar through and lift until the bike balances level.

Let me know what you find out.

...that would be one way, I suppose !!!

Mick.

 

[Stormy]

Found this on the dynamics (centre of gravity) of two wheeled vehicles. Interesting read.
http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics#Center_of_mass_location

 

[Stormy]

 

[Yossarian]

Epilog:

I got some time today to give it another go. I loosened the steering head bearings less than a ¼ turn and tightened it all back up. I went for a ride and it seems to have done the trick. I plan on finding some new bearings altogether this winter, but at least I can ride the rest of the season with peace-of-mind.

I have the cross reference guide, but the list of bikes that use the top bearing is different than the list of bikes that use the bottom bearing. I’ll have to see if I can reconcile the two lists to see if there is a more popular bike that may already have a tapered roller bearing upgrade kit on the market. If anyone else has already done this homework, please clue the rest of us in.

Mick, thanks for being your usual calm voice of reason.

 

[wuputt]

I don't know what kind of bearings are in the head on these ZL's. My son had a Yamahaha Radian and he switched his bearings to tapered rollers. May be a good upgrade if they are std. bearings. Just need dimensions and get em from the local bearing distributor.

 

[vinny]

I agree with you Stormy, it sounds like the COG of the bike has shifted towards the bck of the bike - taking weight of the front end and making it more prone to weaving.
Worn or loose head bearings are definite possibilities. Lifting the bike and moving the front wheel slowly from sde to side will often show up and "sticky spots" - can be caused by bumping up kerb stones etc.

Nice diagram by the way ! Looks a bit like a flag !
Not sure which country though :stir:
Vin