Primary chaincase and clutch

It is not a certainty that all pressed steel primaries leak oil. These cases can be made oil tight with the original seal correctly fitted provided the cases are in good shape. The way to do it is to make sure the cases are oil tight before putting them on the bike. If the outer case is distorted due to over tightening the big nut by a DPO (A common occurrence) then it can be "Adjusted" with a large hammer and wood blocks until it no longer leaks. John Hudson published an article in "Roadholder" about this in the 1990s.

Although I don't have a Norton with an oil bath chain case, the primary drive and cover on my Royal Enfield is the same sort of design with the useless rubber seal around it. When I first put it back together a few years ago I used a new seal and put mastic on either side of the seal before putting it in place. A bit messy but its all hidden, and it did the job a treat.

I've had the primary case off since then for some maintenance and it was a bit of a mess and a hassle to clean up. I then re did the mastic and put it back on and it's not been as good since. It isn't anywhere near as bad as some I've seen but not as tight as the first time I did it. I think the mastic probably didn't take as well to rubber second time round. I think one of my next jobs on that bike may be to buy a new seal (they aren't that expensive) and have another go.

I'm sure the same method will work just as well on a Norton.

I considered this very point when re-assembling my 16H. I did some research and here is what I found.

When the "oil bath" was conceived, there was little alternative. By that I mean that you either ran your chain "wet" or let it fail.

Since then, many lubrication developments have been made and, of course, belt drives have taken over. Personally I don't have a preference on belt drives but I do like to keep things looking original. I use the original primary cases but don't put a bath of oil in there to leak out. It wil leak out. I mean it just will. Whatever you do, it's going to leak out. It leaked out when they were new, it's still going to leak out. Leak it will, to be blunt, it's going to leak.

Unless you use you bike every day as a commuter, good luck if you do, then an anual squirt of a modern chain lube will keep you primary in great shape. In truth even if you do use it every day, it will still keep it in great shape. If Norton then had access to modern lubes they would do it this way.

So forget about what seal to use, forget about how awesome the design is, or is not, throw away that seal and just bolt it up. Once a year squirt with decent chain lube through the access hole and enjoy riding the bike.

Hello everybody, I'm a new member here, though I have had my '51 es2 near on 19 years, and other Brit bikes of other makes for,..... well it seams like foreverever.

Re the primary seal, being unable to keep the oil in for even a few months, i ran my primary drive dry for years, only relying on the oil mist coming from the main bearing. This had no real advers effect, except the chain was replaced every 4 - 5K. I noted last year that a couple of Club mates here had NO leaks on their recently restored singles with the pressed metal case. I found that they were using a foam strip which held in the oil satisfactorily, even after removing and replacing the outer cover for clutch adjustments.

I did some research and came upon a TESA brand #749 foam strip 24 X 12mm with a VERY sticky backing on one side. The size was just right to fit on the inner cover lip, onto which I stuck the foam after de-greasing the lip thoroughly. I fitted thejoinat the top and after 8 weeks so far, it has held the 1/2 pint SAE20 oil without any problem. I think the piece of foam was about $7 dollars for the 1 1/2 meters I bought from FITCH RUBBER here south OZ. When I fitted the outer cover, I greased the foam so as to be able to slip it on, compressing the foam as it went.

If FITCH RUBBER is googled, the foam is listed with all the technical data about it.

Hopes this helps somebody.

Paul

I just had a bit of a look at Fitch, and they have changed their web page as I remember it since I last looked last year. But the foam tape I refer to is Polyethylene, Tesa brand, part No. 7495-24 (12 X 24mm) , inert to fuel, oil etc.

Paul

This is a timely post for me.

I am in the final stages of reassembling my 1935 Model 50 and have been considering the use of modern chain lube and, as our Aussie friend suggests, a foam based tape more as a dust seal rather than an oil seal. This sort of thing - http://www.tapes-direct.co.uk/index.php?main_page=product_info&cPath=142_177&products_id=788

The only slight drawback I can foresee with a squirt of modern chain lube is that the clutch roller bearings are now denied any regular lubrication. I have given mine a liberal application of grease and as someone else has said, if the bike if not used as intensively as it was in its hey day, then no problem should arise. I trust I will be able to confirm this theory in the coming weeks / months!

I used a sealant by Wurth cost about £15 a small tube but it can be used as a gasket seal. I found it a very good product and well worth the money. I put a light coating on the band and it has been leak free.

Hello John, the tapered sealing rubber band that was fitted to my inner case is/was 23mm wide, I just measured it. Thepolyethylenefoam tape I used measures 23.5mm (it is listed as being 24mm wide), it was a near perfect fit on the inner lip, I am unaware of the width of the inner lip on other Nortons, but i wouldimaginethey would be the same?,

Hi - just gone & rechecked my measurements. The hard rubber seal that came off my 1935 Mod 50 measures 24mm wide x 10mm thick at its widest (inner) edge & 8mm at the outer edge. The lip on the inner chain-case is exactly 24mm wide. I've no idea if this is an original case but it fits the bike perfectly at all fixing points with the engine sprocket & clutch shafts dead centre in the openings.

I have not been able to get hold of a replacement hard rubber seal (of the right size) hence the foam tape - which is supposed to be slightly compressed to make a good seal. As Paul said, my plan is to stick the tape onto the inner case flange & and smear grease on the outer case edge to make it slide on easily - famous last words?? I'll report progress in due course.

Hi, I found a supplier in Sydnery Australiafor the Tesa tape # 7495 24mm Wide 12mm Thick, $25.73 for a 7 metre roll.

Company called Harry Daines 02-96993977

Cheers

Andy

I have now done over 250m on my recently restored 1935 Mod 50 and can report that the 'foam tape seal' works a treat. As intimated previously I did not fill the chain-case with oil but simply sprayed the primary chain with a modern chain lube. I have removed the outer cover to check the chain and am delighted to report it remains nicely lubed and hasn't stretched whatsoever. In addition the outer cover goes on / off without excessive force being required. A photo of the fitted seal follows.

Just a caveat regarding using spray chainlube on the otherwise dry primary chain. I used my Domi to belt up and down the M6 between Edinburgh and Bristol with just chainlube on the primary chain. The chain would last one return trip. I had to bite the bullet and go back to as the makers intended - a chaincase that held oil. It was a bit tedious to get right, but it still holds oil 35 years on and doesn't eat primary chains. You are probably OK with a model 50on shorter journeys at modest speeds though.

Previously andrew_belenkin wrote:

I have now done over 250m on my recently restored 1935 Mod 50 and can report that the 'foam tape seal' works a treat. As intimated previously I did not fill the chain-case with oil but simply sprayed the primary chain with a modern chain lube. I have removed the outer cover to check the chain and am delighted to report it remains nicely lubed and hasn't stretched whatsoever. In addition the outer cover goes on / off without excessive force being required. A photo of the fitted seal follows.

Looks good Andrew, exactly like mine did before I slipped on the outer cover. As I said earlier, I had to smear a little grease on the outer cover where the seal sits to get it to slide on smoothly asthe foamcompresses.

Your next step is to add some oil to have the chain and clutch continuously lubricated. My seal is still holding out OK with no oil drips since fitting it last year.

Paul - Yes a smear of grease makes fitting/refitting a doddle.

I think I'll bite the bullet and put some oil in the chain-case, since its most probably needed to help cool an enclosed chain as much as lubricate it. Although at the speed (and distances) I ride my 50 I can't imagine I shall be stressing anything - but you never know, I may find a length of dual carriageway to tempt me.

I'm currently playing with the chaincase on my '51 ES2 and R.E. Collins comment about overtightening the big center nut - does it not pull up onto a shoulder? I can't see anywhere for it to pull up but there are bits missing from the bike as it came to me as a non runnner.

Can anyone enlighten me on how this center part is pttulled up tight and seels?

The Workshop Instruction Manual states "When fitting the oil bath front cover the rubber sealing ring may be found to have stretchd: this will in no way affect its sealing efficiency providing the stretch is not sufficient to cause the ring to wrinkle. Before placing the front cover in position the felt washer (Part No. 3427) must be placed on the footrest tube where it protrudes through the conical deflector inside the chaincase. It is not possible to to tighten the front cover securing nut solid, due to flexure of the cover, but it must be screwed down until it is clear of the serrations which hold the footrest hanger. Before the nut is finally home, it is advisable to give the cover a few hard blows with the ball of the hand"

There we are, it is that simple, I hope!

Regards

Derek Ambler