Front disc hub different for MKII?

maylar · Sep 16, 2012

I had to replace the single ball bearing in my 74 850 front disc wheel and I notice that the parts drawings and workshop manual don't accurately describe my hub. The right side bearing (double row) is held in with a plate that's staked in place. To remove it would require grinding the staking dimples on the hub and prying the plate off. None of this is mentioned in the workshop manual. I'm wondering if this was a change to the design that's unique to the MKII and later?

Fortunately the double bearing is fine, and I found a sealed version of the single row for $10 at my local hardware store.

Onder · Sep 16, 2012

I have a Feb 74 Mk2. Im not home so I cannot look
at my teardown pix but I cannot remember anything
like that. Just the annoying springs to mind. If you
can wait until next weekend Ill have a look.

Hobot · Sep 16, 2012

The only thing I've ever read being different with LH mounted rotor was the retaining ring and bore were 'reverse' LH threaded so the wheel rotation didn't tend to unscrew it. Maybe what you have is the results of someone not knowing this till too late and their ok repair method to let someone else discover and deal with after they were long gone.

L.A.B. · Sep 16, 2012

hobot said:
The only thing I've ever read being different with LH mounted rotor was the retaining ring and bore were 'reverse' LH threaded so the wheel rotation didn't tend to unscrew it.

Where did you read that? :?

The 'Mk3' L/H side disc front hub has a circlip bearing retainer, not a threaded retaining ring-so it can be used with either a left or right side mounted brake!

maylar said:
The right side bearing (double row) is held in with a plate that's staked in place.

This photo from the Old Britts Tech section shows what I think also looks like staking? Is it similar?
http://www.oldbritts.com/wheel_upgrade.html

maylar said:
To remove it would require grinding the staking dimples on the hub and prying the plate off. None of this is mentioned in the workshop manual.

But what is mentioned is to drive the bearing out using a drift from the reverse side which should also knock out the washer and probably remove the staking without the need for grinding?

Hobot · Sep 16, 2012

OK set me straight on weirdo Mk3 hub. How does one re-stake it, just bash with chisel drift? Off to shop with a press? How many times can the hub stand that before not much staking area left?

It can be a real bugger to get purchase on the inner bearing race with anything but a sharp chisel like drift because the spacer tube has wings that stick out preventing it to shift off center much to expose a lip. I don't ever expect to live long enough to have to replace mine again but for those after me I ground/cut 3 notches out end of spacer so next fella won't hurt himself like me. Thank goodness they ain't in there so tight ya need heat to remove but not bad idea when sucking back in with threaded rod/nuts or bashing by hammer & socket or such.

L.A.B. · Sep 16, 2012

hobot said:
OK set me straight on weirdo Mk3 hub. How does one re-stake it, just bash with chisel drift? Off to shop with a press? How many times can the hub stand that before not much staking area left?

I don't follow?

Why do you think the "Mk3 hub" needs to be staked or re-staked?

maylar's "MkII" hub is (presumably) the pre-MK3 type, same as the one shown in the Old Britts photo, above.

Hobot · Sep 16, 2012

I had to replace the single ball bearing in my 74 850 front disc wheel and I notice that the parts drawings and workshop manual don't accurately describe my hub.

The above confused me, you got it handled so I'll just butt out.

L.A.B. · Sep 16, 2012

OK, well, as it says in the Old Britts info., if a sealed bearing is used, then the two metal retainers and the felt seal can be left out.

Unfortunately those three items as drawn in the exploded diagram are not an accurate representation of the actual parts.
Further confusion is caused by the item intended to represent to disc side felt seal not being marked with an item number (should be [11])

maylar · Sep 17, 2012

L.A.B. said:
This photo from the Old Britts Tech section shows what I think also looks like staking? Is it similar?
http://www.oldbritts.com/wheel_upgrade.html

Yes. Those would be stake marks I believe.

But what is mentioned is to drive the bearing out using a drift from the reverse side which should also knock out the washer and probably remove the staking without the need for grinding?

I suppose that would work. Still, I'd expect a note on the reassembly that re-staking is required. Didn't see that in the shop manual.

And the threaded ring holding the single row bearing is called "LH thread" in the book- doesn't that mean reversed? Mine was standard righty-tighty.

L.A.B. · Sep 17, 2012

maylar said:
And the threaded ring holding the single row bearing is called "LH thread" in the book- doesn't that mean reversed? Mine was standard righty-tighty.

Sure you were reading the correct section?

SECTION H7

DISMANTLING THE FRONT HUB, DISC TYPE
.........
1. Unscrew the bearing locking ring (right hand thread)....

Hobot · Sep 17, 2012

Postby rvich » Sun Jul 15, 2012 4:21 pm
It needs to be better documented that there is an error in the work shop manual in section H7 where it states that the lock ring is left hand thread. I found one mention of it in the forum a couple of years back. Apparently not all manuals are in error, just the ones available in the tech section and the one on my work bench!

I heated, beated, double-checked, and repeated. The lock ring is worse for the wear. I finally started wondering why it would be left hand thread and be on the left side of the bike and then referred to my Haynes manual. It took more heating, beating and repeating to get it loose in the proper direction, afterall, I had successfully tightened it to maximum torque! Jeepers. Amazingly when I did the bearings on my 750, I didn't have a workshop manual and avoided the affair. Some days you gotta trust the manual, then other days you gotta trust yourself. In nothing else trust in the forum.

L.A.B. · Sep 18, 2012

hobot said:
Apparently not all manuals are in error, just the ones available in the tech section and the one on my work bench!

Click to expand...

Well...one tech section manual does say right hand: http://britmoto.com/manuals/Manuals/750_man.pdf

Two say left: http://www.classicbike.biz/Norton/Repai ... mmando.pdf
http://rocbo.lautre.net/technique/norto ... index.html

If a bearing lockring is on the left side of a wheel, then logically one would expect it to be right hand threaded, and vice versa, as the normal wheel rotation prevents it from unscrewing.

Front disc hub different for MKII?

maylar

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L.A.B.

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