Puzzled....
The driveside crankcase half on my 1957 Dynamo Dommie 88 does not have a location for a seal from housing to crank. The roller bearing race fits flush with the outer edge of the crankcase. Engine number is 36521.
But - when I took it apart (too long ago to remember exactly) I am pretty sure that there was a seal. Looking at crankshaft there is a wear ring where a seal has run - and the inner edge of the sprocket also has a wear pattern maybe from something spinning behind it. I found what looks like a homemade washer with wear that appears to be from something the same size as the seal and I wondered if the previous owner had just fitted the seal on the crank, fitted the washer to try to hold it in place and then just fitted the sprocket.??
Anyone know what should be there?? It does not look as if there is anything that can properly locate a lip seal.
The other "interesting" thing is that the four stud / bolt holes that are to retain the inner primary chain-case go right through the crankcase - no wonder the fixings were hermatited in. Is that normal??
I have looked through many photographs of Norton engines online but have not seen another like mine (with no seal location) - or with four hole on the primary chain-case - most seem to have three.
Help please!!
Crank seal
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Help!!
Thank you John,
The more I think about this the odder it all seems. I have the brown registration book and the bike was first registered in 1957, but in 1960 apparently it had a new frame fitted and a new engine. Both K122 36521. I think that K means 1955; 122 means Dominator 500 (yes, that's what I've got) and the engine serial number (36521) seems to go back to 1951 or 2. That all seems odd.
Even odder when I think about it is this crankcase set up. Surely there MUST be a seal between crank and inner chaincase otherwise dirt would go straight into the main bearing, and oil would go into the inner chaincase and onto the floor.
The lip seal that I have is the correct ID and OD - so it probably the correct seal - but with nothing to locate it - how did it do anything? I can only assume that this homemade washer thing that must have gone behind the engine sprocket pressed against the seal and together they did something??
Has anyone else come across a Dominator engine with no crankcase drive-side seal location?? It's as if it has been machined away on my engine??? I must be missing something - or barking up the wrong tree....
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Are you sure that the …
Are you sure that the "washer" is not actually part of the crank case that's fallen off? There certainly should be a seal there, and the bearing is removed inwards after the cases are split. (Looking at the Haynes manual, the seal is clearly shown. But it's not visible in my parts list, which has the same drawing as the Neill manual...was it a later addition? My 1963 has a seal.)
In the 1956 version of 'Franks', no seal is shown. But the bearing is shield from the outside by the thin portion of the crankcase. That seems to have broken off yours, so the bearing is not positively retained.
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Sorted - I think....
Yes - thank you. It looks like my old engine has been well and truly brutalized.
The "washer" is definitely home made - and three additional holes have been drilled into the crankcase (right through it!) to presumably hold the chaincase inner tighter to the crankcase.
After a long search on Google I found this engine - which is what I am pretty sure mine should look like. You can even see the same fret marks on the c'case where the chaincase inner has contacted it.
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Mad Mods
Hi Aston........it looks to me like somebody has seriously modified your Dynamo crankcase. Possibly in order to repair some bad damage to the seal area.
There should only be a single threaded on the right side of the case hold the primary inner in position. I would say that the four holes in view are/were being used to hold the large Aluminium disk in place to act as a crankshaft seal holding device.
I have attached a few photos of Model 7 and early Model 88 engines to show what your LHS case should look like ....including one with the shaft seal in position. The seal should sit in a recess with a shoulder ring to help keep it from blowing outwards. The other case shows the kind of damage that owners try to fix by bodging.
Good condition Dynamo cases are selling really cheaply really at auto-jumbles and for £30 to £50 you could get hold of a set in first class ready to use condition.
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Replacement Crankcase on the way....
Thank you Philip,
Thank you for your help and wisdom.
I have taken your advice! Replacement crankcase (£50) on the way!!
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Hi Aston,
Its quite a few years since I had a dommi, so from memory, I don't think they had a seal on the crank, just a plain washer maybe between the bearings, but I am sure someone with more knowledge than me will advise you.
on another point the stamping and file work on the case where the engine numbers are looks a little suspect, has it had a replacement case at some time? Not that it matters,
Regards John O