Rear wheel bearing spacer tube: is it necessary?

trixynut · Post by **trixynut** » Thu May 03, 2007 4:28 pm

I've just had the bearings out the back wheel and in between them, in the middle of the wheel, is a tube referred to as a bearing spacer. It fits loosely in the wheel (just fell out when I removed the bearings) and presumably just prevents the bearings being smacked into place too far, although they sit in a housing in the wheel anyway.

As it doesn't contribute to the wheel structure, and as the bearings sit on a collar in the wheel anyway, and as the spindle that goes through the spacer doesn't need extra protection, is it really necessary?

I know this is a bit of a teccy question, but anyone any thoughts?

Reason for asking is cos I've knackered it, so can't now get the axle through, so wondering if I need to replace or just forget.

Ta,

Dave.

slow codger · Post by **slow codger** » Thu May 03, 2007 5:06 pm

Just a thought Dave but as it fell out then I would have thought that the bearings aren't hard up against it. Does it show any signs of wear, either at the ends or where the centre of the wheel would be on it? Final question, whats it made of ?

Dave E.

trixynut · Post by **trixynut** » Thu May 03, 2007 5:23 pm

The bearings were out, so it would have fell out anyway, but when they were in, it wasn't a loose fit, but could be moved with my finger. Made of aluminium, and no wear at all, apart from where I've knackered it trying to bash out the bearings with a drift.

My only other thought is maybe it stops the inner race on the bearing being pushed/squeezed by the wheel spacers on the axle when the axle nut is tightened? Although on the sprocket side, there's another bearing in the sprocket holder which takes the pressure from the spacer and has nothing behind it, between it and the wheel...

...my head hurts!

dandywarhol · Post by **dandywarhol** » Thu May 03, 2007 6:46 pm

Don't even think of riding without it!!!

It's accurately designed and sized to stop the inner bearing track from collapsing when the spindle nut is tightened....................

Greg · Post by **Greg** » Thu May 03, 2007 8:17 pm

What he said!!

The squeezing force that can be applied by the nut on the spindle is (as it needs to be!) immense. While (wheel) bearings are very strong in the vertical axis, they are pretty weedy id stressed horizontally. The tube is there to transfer the squeezing force along the spindle and allow the whole assembly including the inner races to be clamped between the faces of the swing-arm, leaving the outer races wit the hub free to rotate on the bearings themselves. Without the tube you'd inevitably push the inner races towards each other (the outer races are retained by the wheelhub) way way before you reach torque, by which time the wheel's banging around on the spindle and your balls are rolling all over the garage floor!

Greg

p.s. they're caged bearings so the rolling ball thing was a bit of a joke

trixynut · Post by **trixynut** » Thu May 03, 2007 10:10 pm

OK guys, good advice thanks.

Sort of what I thought re: the inner race being squeezed by the axle nut being tightened.

Suppose the lesson for me is that everything is there for a purpose!!

Dave.

Greg · Post by **Greg** » Thu May 03, 2007 10:35 pm

Just wait til you've re-assembled everything then find it on the garage floor...

My favourite was finding a gudgeon pin circlip in the parts tray when the whole bike had been re-assembled... it was a Suzuki GT750 - I was just a little peeved that day!

G

slow codger · Post by **slow codger** » Thu May 03, 2007 11:33 pm

Mine was a bolt left over from a Honda CB 250 rebuild. Ho Hum!

Dave E.

devlin · Post by **devlin** » Fri May 04, 2007 12:13 am

I'm enjoying the avatar display in this thread..........

trixynut · Post by **trixynut** » Fri May 04, 2007 8:59 am

Yeah, that is a mighty fine picture of Greg..

..or did you mean the boobies?

devlin · Post by **devlin** » Mon May 07, 2007 1:27 am

trixynut wrote:Yeah, that is a mighty fine picture of Greg..

..or did you mean the boobies?

BOOBIES!!!!!!

I do a double take everytime I see your avatar. Incredible.