Steering head bearings...How can you tell if they are worn?

Hi Guys,

Just got my '85 XJ700 Maxim back from the local Yamaha Dealer. I had it over there for a safety certification so I can finally get it on the road.

The mechanic said that it needed a new front tire and the steering head bearings needed replacement.

Okay, I can see the cracks in the front tire...no problem. But the steering head bearings? I can't find any looseness, no bouncing or noises over bumps...If I pull on the bars and slam it back down again there is no strange noises...they look normal. I just don't get it.

Any suggestions?

Thanks

Gord

 

put the bike on the center stand, sit on it so it lifts the front wheel off the ground......turn the bars slowly. Feel any "notches" or "detent's" ?

Yes=yup, you need new bearings
No=you don't need any new bearings

I'd kind of be surprised if you need new ones.....you should have taper bearings in there......they last almost forever. I guess maybe you could have reached 'almost forever'.......

 

More likely they just need cleaned and repacked. Old grease can make bearings feel notched even when they are not.

 

Thanks Hogfiddles and k-moe. I'll give it that little test in the morning. Yes, I agree that old grease may be so dry that it may feel a little chunky. I'll see how it goes in the am. Thanks for the advice.

Gord

 

Okay... I'm new to the MC world. Got my 1st bike (83 750 maxim) on road a month ago. I can definitely feel a bump/notch/hick-up in the steering when I turn the bars from side to side. It seems to be a notch when bars are at dead center. Is that normal or are my bearings bad too? should you feel nothing but smooth all the way left to right? Also would this have anything to do with the handlebars shaking when I'm cruising and let go or is that a separate issue?

 

I don't know the Maxims well enough to know what type of bearings you have but there should be no notch at center. Years of driving straight down the road absorbing bumps etc. cause the balls to "dig and dent" into the races. If tapered from factory, then pulling and cleaning should suffice. Yes it can cause but its not the only cause for shaky handlebars.

My 82 Kawasaki was so bad that I had to fight it when making turns and my 82 XJ650 also had worn ball bearings. Both bikes got a set of tapered bearings and problem solved. My XJ had slightly bent handlebars so the indent was just off center.

 

Hi Dave and k-moe,

Thanks for the tip, I checked yesterday and it was a smooth turn from stop to stop.

I live on a gravel road as well, so I zoomed up and down the washboards with no shakes or rattles.

I'm really not quite sure why the mechanic at my local shop said they needed replacing in order to safety.

The only thing I notice with this bike is that it's a little "snakey" at about 80 to 100 kph i.e. It weaves slightly, tough to hold a perfectly straight line.

 

Taku and Pat (Taku first),
Taku,
I can take a pretty good guess why. ( "hey, tell him he needs new bearings----- then we can get a hefty bill out of him......and we don't even have to really do them")

A worn front tire will do that.

Pat,
Your 750 maxim will have balls on the race. Notchiness/centering is bad. Period. And I can guarantee you it's not really dead center, although you may feel like it is. (If you were to leave it "centered" and go for a slow straight-line ride, you'd surely find it drifts to one side pretty quickly)

Remove the balls and races , install tapered bearings. You'll never have issues again.

The reason for the shaking is simple…
1. The bearings want to "center" themselves, But the notch is not really center

2. The bike wants to go on a straight line

3. The two of them fight it out until either you grab a hold of the bars, or you flop the bike. Handlebar wobble will not get better, it will only get worse… And eventually turn into a tank -slapper

 

Thanks Dave,

The odd thing is these guys know that I do all my own work on my bikes, the only reason I brought it in for a safety is that I had to, can't write my own certificate as much as I'd like to.

But you are probably right, they were hoping to make an easy buck there from the guy who usually just orders parts.

I'll bring it to a Canadian Tire for the final safety, they don't work on motorcycles so they can't go with that scheme. On the other hand, they haven't a clue what they are looking at..."hmmm, it seems to have two wheels....the headlight works...that will be $60 please" just a $ grab there too.

 

I wholeheartedly agree Taku. Gov out west has can tire do safety for cars but certified bike shops do m/c in bc
Need to lobby dmv to stop Can tire from doing bikes as they will not find half the issues ie cracked frames out of round wheels that are a danger to owners
That's like going to an ear nose and throat doctor when your balls hurt!

 

Had that with sons Zx600r loose head bearing and too many wheelies from prev owner. We refer to it as auto-steer,
" some alien is riding my bike"

 

I actually think that the notch can be exactly centered, but the problem is more of a dynamics one.

Your steering stem is always turning slightly, one way or the other, compensating for changes in the road surface, wind, etc due to the gyroscopic stability of the front wheel. The response is smooth and predictable when the friction in the bearings is constant.

When you have notched steering, then the steering has to be pushed by a force great enough to overcome the notch. The bearings then turn more freely, and over correct. Now your steering is turned too far, and goes the other direction, where is hits the notches and then stops until the corrective force overcomes that notch, then the steering over corrects again.

At a specific speed (or multiples of that speed) this sinusoidal motion between corrective force and over correction will harmonically oscillate, growing in amplitude until it results in the loss of control (tank slapper). Things like providing a restoring force that is out-of-phase, or implementing a force that is related to the speed of the change in the steering instead of the steering angle (a damper) will help damp harmonic oscillation making it more stable (but doesn't actually prevent "some" oscillation)

I had this on my Turbo Seca where at 42 mph, the steering would oscillate, but only if I took my hands off the handlebars. The weight of my hands was enough to damp the oscillation, since the notches were very small. If I hadn't replaced them, they could have gotten bad enough where no amount of force that I apply could overcome it or the force I applied would be at the same frequency and make the loss of control worse.

 

My bet is that it's NOT dead centered, but I guess that's neither here nor there. We're both saying the same thing regarding the forces at work.... I put it simple, you put it scientifically. I know how it happens, been through it enough with my own bikes to see/feel how it works.

Either way, the bearing need to be replaced.

Dave

 

worn out bearings taste very salty

 

Thanks for all the input guys. I haven't tried Polocks taste test (yet), but it seems the steering head bearings on my bike have passed as ok.

I just picked up some OEM Dunlop tires from Royal Distributing ($50 rebate at the moment if you buy a set). I'll put them on over the weekend to see if I can get rid of the wandering in the ride.

I'm also wondering if a leaky fork seal may cause this wandering (the snakey feel I mentioned earlier) as well as a worn tire. I've ordered a pair of fork seals as well.

While I'm tearing apart most of the front end, I may take a poke at the head bearings anyways.

 

wow. that is the "sciencey-est" thing I've read since I left high school! good work. ManBot!

Like the tears of a broken XJ?