Dominator 88

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So found the source of the leak - at some stage someone must have drilled the holes which mount the dynamo bigger - to a point where they have broken through the wall of the engine case. The dynamo drive gear is throwing up the oil and it's just pouring out the engine cases past the bolts which are holding on the dynamo blanking plate. Going to be a tricky fix.....
 
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In the end I machined some PTFE plugs which fit tight into the recess holes in the crankcase and also over the 6mm bolts I'm using to hold on the blanking plate. That solved the problem enough for me to actually take the bike for a small ride up and down the street. Unfortunately, there are some gearbox issues to sort, so now the gearbox needs to come out....
 
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Not easy to get the box out, usually take the engine and box out together. Can fix most things with box in situ. The only time had to take the box right out was to free off a totally seized in top mounting bolt which was making primary chain adjustment impossible,well worth greasing this up if the box is out.
 
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With some modifications of the rear engine plates and replacing the bottom gearbox bolt with a stud, it is possible to remove the gearbox and have the engine still in the frame. Have done it as I'm not strong enough for lifting the engine/gearbox out of the frame alone. After that I've learned that you shall lay the bike on its side and lift the bike, leaving the engine and gearbox on the floor. But as norton bob said, much gearbox work can be done with the gearbox without taking it out.
 
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Ok that's interesting - I thought the box would come out pretty easily :-(

All the gears are there, with some difficulty you can get them, but it looks like it has neutrals between all gears and only if you wiggle the gear-lever do you eventually get them selected. Almost like you select what should be a gear, and then give the lever a wiggle before it finds it. And there is quite a lot of throw on the lever - it's not crisp at all.
 
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Ok that's interesting - I thought the box would come out pretty easily :-(

All the gears are there, with some difficulty you can get them, but it looks like it has neutrals between all gears and only if you wiggle the gear-lever do you eventually get them selected. Almost like you select what should be a gear, and then give the lever a wiggle before it finds it. And there is quite a lot of throw on the lever - it's not crisp at all.

Sounds like the selector might be the problem, drain your gearbox oil, remove the plunger underneath the g/Box, ( next to the drain plug) if spring and plunger is not worn, just remove the end cover for a look-see.
 
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All the gears are there, with some difficulty you can get them
are you rotating the rear wheel while shifting?

A "dog" transmission will very often not shift easily without active motion of the gear set
 
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are you rotating the rear wheel while shifting?

A "dog" transmission will very often not shift easily without active motion of the gear set
Yup - I have the bike on a stand so the rear wheel is free to rotate while the engine is running.
 
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The selector spring usually needs a bit of bending and experimentation to get the pawl to work well, some new springs are rubbish. Also worth making sure there are no tight spots on gear and shaft splines , (polish with carborundom paper) .
 
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Andymann, you haven't mentioned if your bike has an AMC or a laydown gearbox. If I remember correctly, the gearchange mechanism is similar. Decades since I fixed a laydown gearbox.
A year since I last renovated an AMC gearbox, so I might have forgotten some of the tricks.
Your description makes me feel that your present problem might be solved by taking off the outer cover and check everything visible. Check that the ratchet spring is not upside down and the gearchange return spring is ok. Of course the plunger spring shall be checked for length.
If you're satisfied that everything is ok that is in the outer cover, you'll have to go deeper inside the box.
With a big screwdriver force the gearchange quadrant to change gears. Use your left hand to rotate the rear wheel a bit to make gearchanging a bit easier. Unscrew the index plunger housing a couple of turns makes it easier to change gears.
 
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@Mike40M

Tell Andyman how to tell if spring is right side up!

I would if I knew lay down GB.

Slick
I'm an admitted non expert on these boxes. I had to go upstairs to the were?house and double check a few laydown boxes. While there is a spring...yes... it is so different from an AMC box and it is impossible to put in up side down. totally different shape and design...
 

N0rt0nelectr@

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I don't see any pictures and those would be a great help for us to see what you are talking about.
John in Texas
 
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Sounds like the selector might be the problem, drain your gearbox oil, remove the plunger underneath the g/Box, ( next to the drain plug) if spring and plunger is not worn, just remove the end cover for a look-see.
best course of action ^
most likley slugish binding selector action needs flushing cleaning and tweeking possibly spring NG.
Lot of work removing primary /engine/gearbox if only for a small repair under cover...:(
 
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best course of action ^
most likley slugish binding selector action needs flushing cleaning and tweeking possibly spring NG.
Lot of work removing primary /engine/gearbox if only for a small repair under cover...:(
You can get the end cover off without disturbing the primary surely?
 
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We're agreeing
Go for the easy stuff and the most likely hang ups . Avoid the big jobs unless found to be necessary.
 
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Hi All - apologies - Gearbox no is G102 A2062 - I wouldn't even know what a laydown box even looks like!

I'm going to tackle the box this weekend - will have a close look and take some pics. On that subject, what I'll do tonight is create an Album on FB with all the relevant pics - and post the link - that should make it all a bit easier to see!
 
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AM
I'm obviously in the USA so our fleet of early nortons is quite slim, So the opportunity to see and learn is quite small. Assume all my information is suspect...The Brits may correct or fill in with details which may be nice to know.
...AFAIK....You are an owner of a"norton" gearbox of the "laydown" variety (horizontal shifter housing) developed for the NHT. As the predecessor for norton singles was the upright shifting housing called "dolls head". The basic gearbox cluster and housing was the same/similar for both. Around 1957 AMC changed production and installed "AMC" gearboxes and dropped the "norton" box.
Look at any commando pix for the shape of the "AMC" gearbox. FWIW the future AMC box did evolve and had several versions.
 

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