1975 MK3 inner primary cover locating tool

Hi,

I've been lurking around the forum as I've been very bold & not using my Norton much!!

Back in 2021 I asked the same question about the alignment tool for the MK3 inner primary. I know there is a tool for the MK2 and below Commando's but this does not work on the MK3. I did attempt to post on the same thread but it's now locked?

Some said you do not need this tool because of how the rubber seal is fitted but others have said the tool is more to do with the general alignment of the inner primary cover & ensuring this is centred on the shaft.

I've lived with a somewhat minor leak which I believe is coming from the inner primary cover. I think it's actually coming more from the large circular gasket that seals against the crankcase, but I know oil can travel in strange directions not always towards the back of the bike!

Anyway, does anybody know of a company supplying this alignment tool or is there any clever Norton member here who could make one up for me & I'll trade you for beer tickets

My plan is to strip off the primary 'stuff' in the next 2-3 weeks (lots of extra 'stuff' with the MK3!!) and see if I can sort out this leak.

Any help appreciated apart from you don't need the tool which I know could be true but If I'm going to the bother of stripping the entire primary I'd rather have this tool on hand just in case!

I've been curious about that tool too. I saw the one used on "Jessies Garage" on you tube which the guy made himself, very nice!

I have my MK III primary apart now waiting for new parts and wondered about my seal's status, so I carefully measured the gap between the crank and the seal with a machinists scale. I don't recall the dimension, but it checked out, equal all the way around! Not sure how the PO did it?

When I bought the bike from him, I also offered to buy any Norton specific tools he might have, but he said he didn't have any! Maybe he just didn't want to part with them?

Edfury828 said:

I've been curious about that tool too. I saw the one used on "Jessies Garage" on you tube which the guy made himself, very nice!

I have my MK III primary apart now waiting for new parts and wondered about my seal's status, so I carefully measured the gap between the crank and the seal with a machinists scale. I don't recall the dimension, but it checked out, equal all the way around! Not sure how the PO did it?

When I bought the bike from him, I also offered to buy any Norton specific tools he might have, but he said he didn't have any! Maybe he just didn't want to part with them?

Click to expand...

Thanks for the reply.

Best of luck with the primary rebuild, I've done this once before, so I know what's ahead of me

This resource is for the Atlas primary, but some oil control tips therein may apply to the Mk III.

There is no official tool that I know about. I made up a tool to do it myself. To get the seal properly aligned on the shaft, I had to loosen the gearbox and engine mounting bolts, then use ratchet straps to get everything lined up. PITA, but it worked.

A problem with the Mk3 inner primary case is the fact that the engine to the cradle bolt holes are drilled 3/8" clearance size, ditto the cradle itself and the g/box fasteners. This all adds up to the g/box shaft not aligning very well with the primary case oil seal. I have seen numerous times evidence of contact between the g/box shaft and primary case. The use of fitted bolts/studs keeps the engine and g/box aligned. The poor mans way is to use shim steel or brass as a liner of the bolts/studs. Swapping the 3/8 engine bolts for 10mm items takes up play as well.
If you can use a lathe ( or know someone who can ) The best way is to make up some fitted studs and ream the engine/cradle holes. The g/box bolts can get the same treatment (either wrap the bolt/stud with thin shim or make up fitted studs) Incidentally this is one of the improvements outlined in the tuning notes that were issued by NVT

texasSlick said:

This resource is for the Atlas primary, but some oil control tips therein may apply to the Mk III.

How to Make the Atlas/Dominator Primary Oil Tight

I don’t think anything has sold more belt drives than the Atlas/Dominator chain case proclivity to leak. The pressed steel chain case can be made oil tight. 1) Remove outer and inner primary chain case covers. 2) Inspect the inner cover sealing...

www.accessnorton.com

Click to expand...

Many thanks for the link, might get some hints & tips

A freind made me the tool that you are looking for it is basically a sleeve that replicates the seal dimensions, worth its weight in gold.

dobba99 said:

A problem with the Mk3 inner primary case is the fact that the engine to the cradle bolt holes are drilled 3/8" clearance size, ditto the cradle itself and the g/box fasteners. This all adds up to the g/box shaft not aligning very well with the primary case oil seal. I have seen numerous times evidence of contact between the g/box shaft and primary case. The use of fitted bolts/studs keeps the engine and g/box aligned. The poor mans way is to use shim steel or brass as a liner of the bolts/studs. Swapping the 3/8 engine bolts for 10mm items takes up play as well.
If you can use a lathe ( or know someone who can ) The best way is to make up some fitted studs and ream the engine/cradle holes. The g/box bolts can get the same treatment (either wrap the bolt/stud with thin shim or make up fitted studs) Incidentally this is one of the improvements outlined in the tuning notes that were issued by NVT

Click to expand...

Thanks for all the info., a bit above my basic spanner skills! but I will look into this & the tuning notes from NVT

texasSlick said:

This resource is for the Atlas primary, but some oil control tips therein may apply to the Mk III.

How to Make the Atlas/Dominator Primary Oil Tight

I don’t think anything has sold more belt drives than the Atlas/Dominator chain case proclivity to leak. The pressed steel chain case can be made oil tight. 1) Remove outer and inner primary chain case covers. 2) Inspect the inner cover sealing...

www.accessnorton.com

Click to expand...

Best idea for an Atlas is to install a belt drive. Problem solved.