Wheel/axle spacer tube... What's it for?

Seriously...

Was removing the front bearings yesterday and ran across that damn spacer... Again! Does it really need to be there? All it seems to do is get in the way of actually being able to knock the bearings out.

 

Is this a real question? Yes it needs to be there!

Spacer - [ˈspeɪsə]n1 - a piece of material used to create or maintain a space between two things.

Yamaha would not put it in there if it was not ment to hold major safety components in place. As a general rule; If its cosmetic feel free to ditch it if you don't like it. If it is part of mechanical components, it is there for a reason. Keep it in its place! I highly doubt a spacer is cosmetic. If it was I'm sure the Harley guys would offer that spacer in chrome

 

Sure... But we all know that Yamaha engineers of that era had a propensity for designing things in such a way that would render a simple maintenance procedure into an exercise in frustration.

As it is, the "spacer" only maintains a space between the inner races. Given that the outer races are seated in the wheel hub, is it really necessary? I mean, the inner races aren't going to go anywhere without the outers, are they? I've wailed on those things trying to push them out and they don't seem to like being separated...

Like your location, btw... :wink:

 

LOL! I will agree with you 100% engineers are notorious for designing things that are a pain for mechanics. Thats where the creative engineers come up with tools to solve their designs. Have you tried using a press to take them out? Most bearings I have ran into need to be pressed out with a machine. Although a trick I have learned is to get an impact socket that matches the size then litely and evenly tap with a hammer.

Yes they sell T-shirts that are screen printed SL,UT with a small comma so I thought I would pass the humor along.

 

I too have been working on the front axle. I've been experimenting with the axle nut torque. I think I've got that figured out. The big thought in the back of my mind is the problems manufacturers have had in resisting high-speed wobble. Like the ST1300 had when introduced as a British cop bike. Eliminating any parts designed to increase support or reduce flex in the hub is a terrible idea. Especially if you remove it simply because you don't think you need it.

 

It's been awhile since I did my bearings, that said, IIRC they do not go clear through the front wheel. Attempting to press them through would probably get you a cracked wheel depending on the strength of the press.

I used a blind bearing puller and they come right out. The spacer probably helps keep them in line with each other.

 

That's kinda the problem. Without the spacer, it would be a simple thing to place a drift against the inner race and tap (or wail) on it with a hammer. But with the spacer in place you can only get a tiny edge of it. Combine that with what I believe to be the original bearings that are more or less fused to the hub, and you have yourself a rather frustrating afternoon.

Yeah, I know there are bearing pullers that make the job easier, but I don't happen to have one...

Okay, fair point... But is it designed to supports the hub? I could totally see Yammie engineers putting it in there just to make it easier to guide the axle through the hub...

 

That spacer is absolutely necessary. It's there so the bearings don't bind when you tighten the axle up. If you assemble the whole axle in order(without the wheel) it would be Nut-washer-fork leg-spacer-bearing-middle spacer-bearing-speedo drive-fork leg-axle.
If you didn't have the middle spacer, the inner races of the bearings would be pushed inwards which binds the bearings.

 

Okay... That's what I was afraid of. Back in it goes. *sigh*

Thanks for all the input, Guys!

 

The good news is that once the bearing moves even a little the spacer gets enough wobble you can get good purchase on the bearing.

Making sure your drift has a sharp edge will make it work better for those first few strikes.

 

Actually, I disagree with the comment on the Yamaha engineers. Although I agree that engineers tend not to think about questions like, "how easy is this to take apart, or to service, or is it blocking something else?" But I actually think that these bikes have very clean engineering. There aren't a lot of those "weird things" that you can't figure out why they're there. And most of the parts are put together in a simple way that keeps the part count low, but doesn't necessary try to combine 5 things in one.

If you want to see the exact opposite of that, try working on a 1987 Chevy Celebrity. That car has (I'm not making this up) an oil filter holder/oil drain plug that's ALL ONE PIECE. That's right ladies and gentlemen, a 4-inch diameter bolt. Try to get something like that off when it's seized. And also try getting a gasket to seal all the way around it.

I'll give you a hint--5 foot long cheater bar, monkey wrench and bracing your feet on the frame of the car. Nothing like that on these bikes (basically).

 

Overall I agree with you that the Yamaha engineers actually did design a decent machine. My statement was more generalized on engineering as a whole.

Yes many American cars that were produced in the last 30 years have been much harder to work on than most makes of Japanese cars.

I love the 5 foot breaker bar, every once and a while I have to resort to that. I forget how much torque you can get with 5 feet. That will take off almost anything (provided that the object doesn't twist with it).

 

That designed-in "serviceability" is how and why we can even DO this.

All of the switch pods, controls, even the gas cap and ignition switch assemblies are made to be able to be taken apart and serviced; cleaned, lubed, etc. No one-way, one-time plastic "barbs" to break off.

The XJ is elegant in its sophisticated simplicity. It's a hold-over from the "old-school" era, augmented with modern up-to-date engineering.

Too bad nobody builds stuff like that anymore.

 

Finally I may be able to contribute.

Look at the cutaway picture from left to right we have

The large end of the axle
A spacer tube
The first bearing
The inner spacer tube with the little flange
The second bearing
Then the speed drive housing
The lower fork tube
Washer and axle nut

Note the large end of the axle is only supported by the fork tube on the left in the picture; there is no shoulder in the fork tube for it to resist the pull of tightening the axel nut.

All of the parts along the axle stack up to create a solid column of steel and aluminum that is compressed together when torqueing the axel nut.

The spacer in question keeps this compression from overloading the wheel bearing inner race. Without the spacer when the axle nut is tightened the bearing inner races would be forced inward destroying the bearings.

FlyGp

 

Can you make the axle pale blue and the spacer and nut the pale yellow you now have the axle in?
Then the different shades of yellow/orange would be the components of the "column" with the axle through the middle. As it is now, the spacer in question is kind of hard to see.
Neat work, BTW.

 

Fitz

Thanks for the feedback;

I changed the colors in the picture



link to full size pic.

Axle is light blue
Spacer is orange
First bearing is purple
Spacer with flange is red
Next bearing is purple
Speed drive casting is yellow
Fork tube is green
Nut and washer silver

Wheel rim and other irrelevant parts are turned off in this view.

Thanks again for the feedback

FlyGp

 

The spacer was sectioned in the other view; I liked that better.

The fork legs should match; and the nut needs to be some shade of yellow or orange to indicate its participation in the "column" we discussed.

And most importantly, you need to turn the hub back on; the relationship of the bearings to the hub and spacer is the whole object of this discussion.

Good stuff; thanks for listening.

 

Another attempt, Fitz thanks again for the feedback.



link to full size photo

FlyGp

 

TA DAA!

THAT one illustrates the "stackup" as well as why we need the spacer. You can see how tightening the nut would mash the centers out of the bearings without the spacer sleeve in there to prevent it.

Thanks for listening.

 

No make it spin. or is the orbit?