fitting new rear wheel bearings

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M Cooper

M Cooper

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Dec 29, 2012
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Hi Everyone,
I've owned my 1975 m2 850 Commando for 18 years and have decided to give it an overhaul.
i have fitted new bearings front wheel steering and rear wheel but an having alot of trouble.
when i tighten up the wheel the wheel locks up.

The rear wheel used to RUN FREE but when i rode it for a few miles it would lock up so i used to adjust it with load of free play and was then ok. i new this was an issue but never got around to fixing it.
Could someone PLEASE go through the procedure .
I have a single bearing fitted on the speedo side with the felt and holder.
the longer side of the tube that connects each bearing is on the speedo side.
On the hub side i fitted a single bearing with the washer felt and felt holder.
there is no speedo spacer that is shown in the manual but have never had one.
the spacer that slides into the bearing through the speedo drive on the wheel is as shown in the manual.
when i tighten up the wheel it locks up.
if i loosen either side slightly is frees off.
should the bearing on the brake hub side or the wheel be a double bearing?
Some one HELP..................!!!!

Michael (London) UK
 
First off, there is the confusion of the 75 MKII. Please confirm this. Is it a rear drum or disc brake?
If a 75 disc brake then,
Drive side BEARING 6204 20x47x14mm
Disc side BEARING 6203 1RS 17x40x12mm

If drum brake then
Main drum is 2x BEARING 6203 1RS 17x40x12mm
Brake hub, BEARING 17x40x16mm double row

If upgrading to sealed bearing on a drum brake, some are wider then others, but is available in 16mm width rather than the common 17.5mm width.
 
Its Rear Drum, Disc up front. The bike was an American export brought back home.
I checked it recently with Norvil. It has a metal air cleaner box if that helps and the chassis numbers add up to a Mk 2.
 
fitting new rear wheel bearings
 
So, have or are you upgrading to sealed bearing? If so, does the double row bearing measure 16mm or 17.5 mm?

Have you changed any other part, like the dummy axle for instance? This particular item can vary from model to model.

Have you changed the brake hub? Many of these need to have the drivers trimmed because they bottom out into the main hub before fully tightened.

Offer up some details of exactly what have and what you have not done in this process.
 
My rear wheel is hanging from the rafters waiting for me to address the rear brake and new bearings are sitting in a drawer in the shop. In fact if I wasn't sitting around drinking coffee, goofing around on the guitar and reading posts here I could be working on it. Let me know if you need specific measurements before I put anything back together. There is an old thread here that has a lot of rear wheel info:

rear-axle-puzzle-t6077.html?hilit=dummy

Give that a read and let me know if I can offer up anything. Maybe you can get me off my butt and into the shop. My playing isn't getting any better anyway!

Russ
 
I Changed the hub a fair few years ago and had the hub and shoes machined by a Norton Specialist in the summer. but the problem was still there after i refitted the wheel. as stated earlier locking up after a few miles. since then i have fitted the bearings only all other parts are original to the bike.The Norton part numbers are single row sealed bearings 065542 and double rowed sealed bearings 067688
The Bearing that came off the wheel are two open single bearings 11mm and one open double 15mm
the bearing in the hub must be correct as it has a circlip and went in fine.

but does the wheel have two single bearings? as there was a problem as i mentioned before.....
Allso when the hub is bolted up tight without the wheel the hub is very loose. and when i turn it it sounds very raspy.......



~And thanks Russ i'll have a look at the other thread.~
 
Thanks for that very helpful.....

The problem i'm is how to identify the fault as when i take the wheel of the hub everything is loose as a goose........not like any other bike rear brake i had......!!
i've had this bike 18 years and its never broken down.......thought id be kind and renew and rebuild.....maybe i should have left her alone.....she was running great apart from six inches of travel on the rear brake.......!!! which is not good. i have had the front brake machined and fitted an insert and when i first tried it i almost feel off .......never had a proper front brake before.....lol
 
Do take a look at the earlier thread posted above. There are some good photos and drawings there to make sure you have all the bits and have them in the right order. The stub axle always feels loose in the drum when it has been removed from the bike. If I understand correctly, there has always been something not right about your rear axle assembly but you have gotten by with it by not tightening everything down? Makes me wonder what is missing, or if incorrect parts where substituted in the past.

Russ
 
Don't know if this will help or not, but here goes. The bearing spacer has a long and a short side that the inner races go over. Unlike what you may think, the double bearing goes on the short spacer and the single bearing goes on the long spacer. At least that's like mine, which may be different than yours. But I was having the same problem with mine when installed incorrectly. When everything is right, the axle should tighten things up on the inner race and the spacer and the wheel should be free to turn. You can do this on the bench without the swing arm and see what is tightening up and binding. You may need a spacer to take the place of the swing arm space.

If you've had the hubs machined, I don't know. I think that means you have a different double row bearing than standard.

Is it a brake issue?

Of course yours may be completely different than my early bike.

Dave
69S
 
Thanks Dave.......i have fitted a double bearing on the cush drive side but i had a single on it before......i have fitted the long spacer bar as you have said but not fitted it on the bike yet as the stainless washer, felt and metal, surround don't totally fit true in the hub it pertrudes 1mm above the hub? would have though it would be perfect fit.???
any ideas
A guy who mailed me earlier said it should have two 11mm width bearings.
 
You better check with the MK2 experts. I may be leading you astray here with my non-cush drive bike. But in any case, when you tighten down the axle, it should not bind up the wheel so it won't turn. The wheel turns on the outer races and the inner races tighten with the axle and spacer. You need to check all your parts and if you've machined the hub, then you have to deal with that. As I remember the long and short ends on the spacer both stick out past the bearing, but I could be wrong. I remember playing with mine for a while to get it right.

The service manual is a good place to start looking, but as I remember it doesn't talk about the long and short ends on the spacer.

Dave
69S
 
If there is on top hat spacer through the speedo drive, as my 1st Combat
came w/o, then when axle nipped up the speed face bows in and can bind on the wheel to spin. The only thing that hold the drum stable is long axle in its dual row bearing and the chain pull, as there must be some slack in the stub axle and drum or rubs some of its own.
 
Didn't really understand that....!! but i have a speedo drive spacer coming tomorrow and a new stub axle.......ill let you know how i get on.............
 
I think he's talking about the lock ring and the bearing in the drum. Mine doesn't have that part. But yes, I've heard that can be a problem.

Dave
69S
 
Hey Guys thanks for all the advise........the problem has now been resolved and ill post what happened tomorrow.......
 
Ok here goes......When i was installing the first bearing into the brake hub i didn't open my vice wide enough and so when i fitted the double bearing the stub axle wasnt fully located.....as i drove the bearing in it sounded like it was fully home but due to the vice not being fully open and the stub axle not sitting fully. i could fit the circlip and as i had not looked at the bearing properly that i took out i then fitted a single bearing.........now the circlip went on..........!!! i then fitted the wheel bearing front and back and this whole nightmare ended when i took it apart and started again...............so thanks for all the tips and advice it was that that made me go back and start from the beginning...............
the Commando is now running sweetly due to its new Amal carbs ........


Michael
 
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