(74 Mk2) - rear hub bearing(s) removal - ???

joe czech · Oct 7, 2020

looking for a little up-front info. I want to break down my 74"s rear hub for service and clean-up, before installing my new stainless spokes. looks like there are two bearings with a spacer. my question, to remove the bearings, it looks like the speedo drive side has a screw in lock ring. if you remove the lock ring, is the speedo drive side bearing pressed in, or just a friction fit. can't see how you would press on anything to remove that bearing. unless i'm missing something. service manual is kind of vague. TIA....

marinatlas · Oct 7, 2020

http://www.classicbike.biz/Norton/Repair/70up_Commando/70upCommando.pdf

have a look in section H of that manual

kommando · Oct 7, 2020

Too long to remember how I did but taking out and replacing the bearings did not need a press, just a good hammer, sized drifts plus a long thin one to remove bearings from the far side. A propane torch heating the hub helped, not much heat needed.

maylar · Oct 7, 2020

Be aware that the lockring is left hand thread.

concours · Oct 7, 2020

Heat the hub to release the lockring

Derek Wilson · Oct 7, 2020

The bearings are pressed in. If memory serves me, the ID of the spacer is smaller than the ID of the bearing, so you can push on the spacer to force the opposite side bearing out. You just need a drift of the appropriate diameter.

The speedo drive lock ring comes out pretty readily, at least it did for me. Replace the bearings with sealed ones (-2RS suffix on the bearing part number).

FWIW

Jdub · Oct 7, 2020

Do I recall that going to sealed bearings requires machining the spacer? Also, I believe an axle can be used to drive the bearing(s) out - sorry, away from my manuals right now so cannot say for sure.

Derek Wilson · Oct 7, 2020

Jdub said:
Do I recall that going to sealed bearings requires machining the spacer? Also, I believe an axle can be used to drive the bearing(s) out - sorry, away from my manuals right now so cannot say for sure.

The front wheel needs to have the spacer machined to have sealed bearings fitted. The cush drive drum brake wheel uses two 6203 single row ball bearings, so no machining of the spacer is required.

When fitting sealed bearings to the older Atlas bolt-up style rear wheel, you do need to machine the spacer (fitting a 5203 double row ball bearing in place of the original unsealed 4203)

Not sure that the axle can be used as a bearing driver. I don't think the bearing recesses are deep enough.

L.A.B. · Oct 7, 2020

Jdub said:
Do I recall that going to sealed bearings requires machining the spacer?

A standard width (16mm) sealed double-row bearing is available, however, the double-row bearing, '71-on (850 Mk2) is in the drum sprocket and not the hub.

Rear wheel bearings

I'm intending to replace the bearings in the rear wheel of my '74 850. According to the books, thee are two single row bearings in the hub and one double row in the brake drum. I want to use sealed bearings for all 3 if possible, but I can't find a sealed version of the 17 X 40 X 16 mm double...

www.accessnorton.com

4203 2RS, Deep Groove Ball Bearing with a 17mm bore - Select Range

www.bearingrevolution.co.uk

joe czech · Oct 7, 2020

Jdub said:
Also, I believe an axle can be used to drive the bearing(s) out...

bingo - worked like a champ. big thanks for the tip. took about 15 or 20 minutes to completely break down the hub. right now, looks like a trip to the blasting cabinet and a soak in a chem film bath before reassembly. spoke kits came today along with the new airstop tube. bearings looked excellent, so cleaning and repack and I should be good to go. marked the hub for orientation and relationship to the rim, and took several pics of the before disassembly. hopefully things will go back together as originally built. trueing the wheel assembly looks to be the only major obstacle. thanks for the replies.

Jdub · Oct 8, 2020

Glad to hear it Joe, and sorry folks for the mix up on what wheel needs the milling to fit - forgot about that nice fat front bearing for our disc wheels.

I use a Hozan wheel building jig on which I had built so many wheels during my cycling years at a local shop. The only wheel I will not attempt to build is a front disc - that offset / dish is truly scary!

(74 Mk2) - rear hub bearing(s) removal - ???

joe czech

marinatlas

kommando

maylar

concours

Derek Wilson

Jdub

Derek Wilson

L.A.B.

Moderator

Rear wheel bearings

4203 2RS, Deep Groove Ball Bearing with a 17mm bore - Select Range

joe czech

Jdub

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