Author Topic: Correct Bearing References for Post-war bikes  (Read 8390 times)

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Offline aggettd

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Correct Bearing References for Post-war bikes
« on: 12 Feb 2008 at 18:56 »
I'm in the process of ordering some new bearing for my T35. I've checked Nevill Heath's book Spannerama, and he has some sealed bearing references for wheel and gearbox output shaft bearings. Those given are:

Front wheel bearings: RLS52RS
Rear wheel bearings: 62042R5
Gearbox output bearing: 6205-2RS1/QE6

I also am trying to source a new crankshaft output bearing. The old one has the following markings:
"France U1 SNR 4206"

I've talked to two suppliers and they have something close for three of the bearings above (the 6204, 6205 and 4206) but they can't get the exact numbers, just the main numbers with the subsidiary numbers being only close.

Can anyone tell me if the numbers are correct, or what the correct numbers are, or give me better numbers?

Thanks in advance,

David A


Offline eddie

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Re: Correct Bearing References for Post-war bikes
« Reply #1 on: 12 Feb 2008 at 19:40 »
Hi Dave,
              The numbers given are correct - the front wheel bearing is a RLS5. The 2RS suffix refers to 2 rubber seals. The same goes for the rear wheel. Using these bearings means that you will not be able to grease them via the normal grease nipple. If you want to continue the normal greasing, get bearings with a 1RS suffix, and then fit them with the seal to the outside. Likewise, the gearbox output bearing should only have one seal if the gearbox oil is to continue lubricating the bearing.
             The crankshaft bearing is a 4206, but be careful, they are available with varying numbers of balls. Go for the bearing with the higher load capacity (more balls). The original style bearing with a metal cage is becoming harder to obtain, but I prefer these to the newer style with plastic cages - I dont like the idea of plastic inside an air cooled engine.
                          Regards,
                                         Eddie.

Offline aggettd

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Re: Correct Bearing References for Post-war bikes
« Reply #2 on: 12 Feb 2008 at 19:57 »
Eddie:

Thanks so much for such a quick reply.

Is there a good reason to either keep both the seals, or remove the inner so it can be greased? I had assumed (in my ignorance) that the double-sealed bearings would last longer because the seals would keep dirt and moisture out. However, if removing the seals (or ordering them with only one seal) will help them last longer, I'd do that. Do you, or others have any experience with running the newer sealed bearings?

Finally, in the 4206 bearing, is the "U1" notation important? I seem to recall from somewhere that it referred to production tolerances. What annotation would specify the numbers of balls in the race?

Sorry to be so inquisitive but I'm on a steep learning curve.

Thanks again.

David A

Offline Doug

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Re: Correct Bearing References for Post-war bikes
« Reply #3 on: 13 Feb 2008 at 01:21 »
Dave,

I find things such as wheel bearings last longer if you keep the bearing seals intact for the very reason you stated, less likely to contaminate the factory applied grease. I replaced my Mark 3 front wheel bearings with modern ball bearings with double seals some years ago. I left the grease fitting in-situ, but were anyone to grease it, it would only harmlessly fill the space in the hub between the bearings.

If you need a better example, how many modern motorcycle wheels are out there today running on permanently sealed ball bearings with no provision for greasing?

Do smear a film of grease on the internal parts when reassembling with sealed bearings, so they do not rust!

I am not familiar with the "U1" notation as a tolerance, here in the states tolerance or precision is usually denoted by ABEC numbers, ABEC 3 being general tolerance (or looseness!) ABEC 5 being a cut above, and ABEC seven used for precision things such as grinding and machine tool spindles. Even the crankshaft bearing on the Dougie does not need to be any special precision bearing above and beyond the norm. But it might well pay to select one that is a 'maximum capacity' designation. And the "U1" designation might refer to that. Maximum capacity bearings have extra rolling elements (balls, rollers, ect.) for increased load and/or longer fatigue life. Often they require slots cut into the inner and/or outer race to load the balls before the cage is installed.  Do you have the maker's name for the bearings (other than the country of origin), as though the 'core number' for the size are industry standards, the designation for the options such as shields, seals, none, tolerance, extra capacity tends to vary manufacturer to manufacture (the subsidiary numbers you noted.)


-Doug

Offline eddie

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Re: Correct Bearing References for Post-war bikes
« Reply #4 on: 14 Feb 2008 at 07:49 »
Dave,
         Whether you use sealed wheel bearings or not, is down to personal preference. I still use the original open type - then I can make sure they are well packed with grease when fitted. If you decide to use the sealed type, keep the original felt seals as well - they will help to keep the road grit away from the bearing seals which are only thin section and can soon get ruined by just a small amount of road dirt.
       Regarding the rear main bearing: This is now given the number 4206 but I have checked out an original bearing that I have - the details are: Make Hoffmann, number 5829, size 30mm x 62 x 20, 2 tracks with 15 balls in each. Perhaps your bearing man can come up with an equivalent item.
                                       Regards,
                                                    Eddie.

Offline aggettd

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Re: Correct Bearing References for Post-war bikes
« Reply #5 on: 14 Feb 2008 at 14:14 »
I've finally found a bearing supplier locally here who I can talk to with some confidence. All the bearings are available, so it looks like I'll be all set early next week when they arrive.

One final question. The plastic seals on sealed bearings are rated to be tolerant to 240 degrees Fareheit. Can anyone think of a reason why I shouldn't leave both seals intact on the gearbox final drive output bearing, or is this again just a matter of personal preference?

David A

Offline Doug

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Re: Correct Bearing References for Post-war bikes
« Reply #6 on: 14 Feb 2008 at 14:20 »
Dave,

Personal preference. I used a double seal, the outer to keep external grime out of the bearing, and the inner to keep wear debris from the transmission and shifter forks out of the bearing!

Also the seals on the ball bearing units are primarily to keep foreign matter out. They are not double lipped like some independent seals. So if you want to use the seal bearing to supplement the ineffective original Douglas arrangement, it is the inner seal on the new ball bearing that will do the most to stop migration of transmission oil out through the bearing.

-Doug

Offline Ray Dodds

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Re: Correct Bearing References for Post-war bikes
« Reply #7 on: 15 Mar 2013 at 20:18 »
just got an skf 4206 but to find it has a plastic ball cage has any body used them in the crank case and to what results.

Offline eddie

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Re: Correct Bearing References for Post-war bikes
« Reply #8 on: 16 Mar 2013 at 11:09 »
Ray,
        Whilst the bearing stockists consider the plastic caged bearings to be suitable for use in our air cooled engines, I feel more at ease with the metal caged units as originally used. Not only is the plastic more likely to be affected by the heat, but this softer material could be more prone to picking up any impurities - causing premature wear in the bearing. When I was involved with postwar spares, our local bearing stockists informed me that the metal caged units are available, but only a relatively small batch is produced at a time (usually only once a year) - so it was a case of us 'grabbing them when we could!' I guess the situation has not improved in the intervening years

   Regards,
                Eddie.

Offline Ray Dodds

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Re: Correct Bearing References for Post-war bikes
« Reply #9 on: 16 Mar 2013 at 15:30 »
Thanks Eddie Thats just what i was afraid of but i do change oil very 1000 miles and have installed a magnet in the drain plug so i guess its going to have to do, i will let every body know how i get on