Laydown gearbox bearings

C1 C2 and C3 relate to the internal clearances not the external ones as far as I know, Iâll be doing the same soon (AMC box) and will prob use RGM or Andover..... Or Simply bearings if they are a common size.

Aren't they the same size as the upright and AMC boxes ? - that means that the sleeve gear bearing bore is ground oversize and no longer conforms with the markings. A Norton dealer is the best option.

I've never had a gearbox bearing tighten up, even when using Loctite.

They are the same as the AMC and upright boxes. The standard sleeve bearing is available from the usual suspects (RGM and Russells etc) but I am not sure if they are of Far Eastern origin.

Unless modified, steel shims are relied upon to keep (some of) the oil in the gearbox on these units. I found a sealed bearing (it was double sealed but I removed the inner seal) for my upright box. I still used the shims and the result is a lot less oils specks on the rear wheel!

My brother has a '55 ES2 and Mick Hemmings did a mod to the casing so that it would accept an oil seal. A much better solution!

Previously George Phillips wrote:

Ooops. Thanks Dan. I'll check that out.

Hi George, Dan is perfectly correct, if you send the reference no's of your bearings I can give you the correct diameters so that you can check for any non standard dimensions and give you a modern equivalent to enable you to source good quality bearingswithout going to one of the usual spares suppliers.

George there should be a makers name and number stamped onto the side of the bearings?

Hi George,

I have had a look at your bearing data and the basic sizes should be:-

SKF RLS 9 are imperial bearings (as would be expected) with outline dimensions of:-

Length- 5/8" (15.875mm)

Bore-1-1/8" (28.575mm)

O/Dia.- 2.5" (63.5mm)

The GT Britain suggests English manufacture and the OTLS is a mystery.

The RLS9 11/4 bearing should be the same sizes and again the 11/4 is a mystery.

The 6203 Explorer bearing sizes are:-

Length- 12mm

Bore-17mm

O/Dia.-40mm

The 2RSHpart means it has or had2 contact seals when new and the Explorer seriesare abetter class bearings designed for better Dimensional and Running accuracy with less friction and 50% quieter.

To my knowledge Explorer bearings were not available when your box was made so it would suggest a retrofit by someone prior to your ownership. It is also puzzling that the box has a mix of Imperial and Metric bearings.

I don't think the expense of an Explorer bearing would be justified, especially in the 'quieter running' so a standard 6203 would suffice.

If the existing bearing has rubber seals a metal shields all you need to do is add the suffix -RS1 for one rubber seal or -2RS1 for 2 seals. If it has shields then the suffix would be -Z or -2Z.

Hope this helps rather than cause further confusion.

Regards.

Dick

George

I always buy good quality bearings, I bought some cheap wheel bearings and had to replace them after a few months, the replacement SKFs have been in there a few years.

Dan

At the start of this thread the C2,C3 internal clearance was questioned. In the case of a loose fit in housing bearing that has to be "glued in" a closer bearing internal fit may be acceptable and even beneficial. The reverse also can apply. On my 99 the mainshaft bearing in the inner cover is a very tight fit and goes notchy once installed. I fixed this by reducing the bearing outer diameter ,I could have bought another bearing with a greater internal clearance. As two different make bearings showed the same issue I can only think that Norton needed some new machinery in 1959.

I would agree that good quality bearings are preferable. The issue with the sleeve gear bearing is finding a top brand. I struggled a couple of years ago. I found one but it was three times the price, and when I got it found that the cage was made of some form of plastic! Probably no problem (I have seen this type of bearing uses as main bearings in Japanese two stroke engines with no issues) but I could not bring myself to use it on my Norton.

The Norton Owners club list one (£17.99 I believe) cheaper than Simply bearings.

As I mentioned in my earlier post, it is worth considering a rubber sealed version (the NOC one shows it as being sealed) and removing the inner seal.

Previously George Phillips wrote:

Fair points Colin but at least with Simply Bearings you know exactly what you're buying. All details are displayed. The NOC Shop shows a picture and a part number. I think I would rather cough up a bit more to be sure of what I'm buying. I'll certainly get at least a single seal bearing either way. Cheers - George

Hi George, I have been off line for two days following an electrical power surge in our street, it has taken several boilers etc. out and we have just got power back on this evening.

I didn't spot the 11/4 relating to 1-1/4", well done, but I'm sure you are right. The standard bearing is 1-1/8" so is this the ground out bore special you mentioned earlier? if it is I doubt that you will get one from a normal stockist, best have a quick measure first.

I have a PDF of the C2 to C5 bearing clearances from 2.5mm to 1120mm bores if anyone is interested, I tried to attach it but it was too large to send. Anyone who would like a copy needs to email me on dick@rchudson.co.uk and I will forward it.

Best of luck.

Dick

Yes sorry George thatâs what meant by internal clearances! For example the main bearings on my racing 2 strokes have a bigger clearance (because they run hot) so much that there is perceivable movement of the crank when cold, but not when hot.

dan

Previously George Phillips wrote:

No probs Dan. I had the wrong end of the stick. Jus proves the usefulness of this Forum!

G

Just got back from 5 days in Durham City and catching up with the thread. Well done George you managed to shrink the file. There are similar listings for roller bearings, angular contactbearingsetc. if anyone is interested.

Dick