Wow what's with all the free space inside the wheel hub?

['03KDX200]

Hey I just wanted to ask a quick question, probably a dumb question, about why there's sooooo much free space in the wheel hub, between the outside of the wheel bearing spacer and the inside of the wheel hub? I'm doing the bearings on the front wheel of my 2003 KDX 200. First time doing wheel bearings too! It's going smoothly, no problems, I got the worn-out wheel bearings out of there with a punch with a minimum of drama. Next step is to install my All Balls front wheel bearing kit. Looks easy. I'm amazed how totally worn out my front wheel bearings were! I'm so glad I'm doing this. Anyways, I took a picture of what I'm talking about. Ok so there's the metal cylinder (spacer) that the axle passes through, situated between the two wheel bearings. I would have guessed that this axle sleeve would be at least somewhat tight in the wheel hub, but there is literally like a 1/4-inch of space all the way around the spacer, between the spacer and the aluminum wheel hub housing all around it! Wow is this because they want you to fill this entire cavity with grease? I mean I guess that wouldn't hurt anything but wow that's a lot of grease. Check out the picture: The metal spacer is shown in the middle, just leaning over to one side. Wheel bearings are removed. If there's nothing attaching the metal spacer to anything, I guess it just sits there spinning around on the axle, floating on grease, as the motorcycle is riden because nothing's supporting it.

20200317_230451.jpg (668.61 KiB) Viewed 1497 times

[KDXGarage]

It is normal.

The axle, inner bearing races and spacer do not rotate. The hub needs to be larger for strength, but not too large for weight.

[bufftester]

Yes, it's normal. As KDXGarage said the spacer doesn't rotate. No benefit to filling the cavity with grease, unless you just like carrying around a bunch of grease .

[SS109]

Yeah, the extra space is to get the strength it needs without excess weight. Once you install the bearings, the inner races of the bearings actually hold the center spacer solidly. It does not rotate at all.

To save yourself some grief, I recommend installing one bearing and then using the axle through it and the spacer to keep them aligned.

['03KDX200]

It is normal.

The axle, inner bearing races and spacer do not rotate. The hub needs to be larger for strength, but not too large for weight.

Ah ha! Ok that makes sense. I forgot the axle doesn't rotate.

['03KDX200]

Yeah, the extra space is to get the strength it needs without excess weight. Once you install the bearings, the inner races of the bearings actually hold the center spacer solidly. It does not rotate at all.

To save yourself some grief, I recommend installing one bearing and then using the axle through it and the spacer to keep them aligned.

Ok, great tip I'll do that. I can imagine if the wheel bearings weren't perfectly in line, it would make it impossible to get the axle to go through both bearings when putting the wheel back on.