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Laydown gearbox bearings

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Laydown gearbox bearings

Posted by george_phillips at March 10. 2018

Hi guys

Having extricated the main gearwheel bearing (part no A2/316 on a G102 box and hopefully the same on a GB8?) plus the layshaft LH bearing (part no B2/322 - same query as above) I know need to know whether I simply buy two new bearings from the usual suspects or whether I have to consider the C2/CN/C3 etc situation?

The main beating popped out fairly easily after heating. The layshaft bearing had been glued in with some gunge which makes me wonder if I need a C2 fit? I don't want to buy one, find out it's wrong (if that can be done without damaging it) and have to return it.

I have all the details of the old bearings if that will help.

Thanks in advance for any help.

George

Re: Laydown gearbox bearings

Posted by dan_field at March 10. 2018

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

Re: Laydown gearbox bearings

Posted by george_phillips at March 10. 2018

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

Re: Laydown gearbox bearings

Posted by richard_payne at March 10. 2018

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.

Re: Laydown gearbox bearings

Posted by colin_mosley at March 11. 2018

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!

Re: Laydown gearbox bearings

Posted by richard_hudson1 at March 13. 2018

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 bearings without going to one of the usual spares suppliers. 

 

Re: Laydown gearbox bearings

Posted by george_phillips at March 14. 2018

Very kind of you, Richard. I'll deal with that this morning. Presumably by ref. no. you mean part.no? G

Re: Laydown gearbox bearings

Posted by george_phillips at March 14. 2018

Here goes: M/shaft RH bearing 40099 (Might be RGM's ref. The problem is that whilst the bike is a '55 ES2 normally fitted with a G102 g/box, mine is fitted with a Dommie (I think) box GB8 and I don't have a parts list for that one. My list shows it as A2/321); L/shaft LH bearing B2/322; M/shaft LH bearing A2/316. All the rest are bushes/washers. Many thanks for your help. G

Re: Laydown gearbox bearings

Posted by dan_field at March 14. 2018

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

Re: Laydown gearbox bearings

Posted by george_phillips at March 14. 2018

Difficult to read Dan but here goes (some of it may be incorrect);

 

M/shaft bearing outer race - SKF RLS 9  GT BRITAIN OTLS(?)

Inner race - SILO (?) - RLS 9 11/4

L/shaft bearing outer race - EXPLORER  SKF  6203 - 2RSH - ITALY 12 - ??199C

Inner race - nil.

Hope this helps.

G

Re: Laydown gearbox bearings

Posted by richard_hudson1 at March 14. 2018

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 RLS 9 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 2RSH part means it has or had 2 contact seals when new and the Explorer series are a better 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

Re: Laydown gearbox bearings

Posted by george_phillips at March 14. 2018

Great info, Dick. I realised that the 11/4 means 1-1/4" which ties up. I've looked them up on "Simply Bearings" Is there a big deal of difference between "EU Budget" bearings and good quality or high quality, bearing (hoho) in mind the usage in  a Norton gearbox? My own view is that I don't want to have this lot out again so better quality would be the way to go. Thanks for decoding the suffixes. That helps a lot. Cheers - George

Re: Laydown gearbox bearings

Posted by dan_field at March 15. 2018

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

Re: Laydown gearbox bearings

Posted by robert_tuck at March 15. 2018

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.

Re: Laydown gearbox bearings

Posted by colin_mosley at March 15. 2018

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.

Re: Laydown gearbox bearings

Posted by george_phillips at March 15. 2018

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

Re: Laydown gearbox bearings

Posted by richard_hudson1 at March 17. 2018

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

Re: Laydown gearbox bearings

Posted by george_phillips at March 18. 2018

Hi Dick

At least you got your boiler on in time fr the cold spell! The bearings have now been received from Simply Bearings. I went for the better quality ones. I haven't yet had a chance to check their fit. I'll take yu up on your kind offer of the pdf.

I now have to replace the layshaft (slight corrosion) so am trying to source one - see separate thread!

George

Re: Laydown gearbox bearings

Posted by george_phillips at March 19. 2018

When I started this thread I was under the mis-apprehension that the CN/C2 etc referred to the fit of the inner race over the shaft. Having received Dick's document I now see that the clearance referred to is "the total distance through which one bearing ring can be moved relative to the other in a radial direction (radial internal clearance) or in the axial direction (axial internal clearance." It's nothing to do with the fit of the bearing on the shaft,

I note this purely in case anyone is following the thread and - like me - was unsure what C2/C3 etc was all about.

Hope this helps.

George - with thanks to Dick.

Re: Laydown gearbox bearings

Posted by george_phillips at March 19. 2018

I shall attempt to attach the doc that Dick sent me - with his kind permission.

Attachments

Re: Laydown gearbox bearings

Posted by george_phillips at March 19. 2018

And page 2.

Hope they transfer OK.

George

Attachments

Re: Laydown gearbox bearings

Posted by dan_field at March 19. 2018

Yes sorry George that’s 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

Re: Laydown gearbox bearings

Posted by george_phillips at March 19. 2018

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

G

Re: Laydown gearbox bearings

Posted by richard_hudson1 at March 23. 2018

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 contact bearings etc. if anyone is interested.

Dick

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