AMC Gearbox seal

[Plugsnpoints]

My two penn'orth.......(just ruminating)....

If the nut won't shift by heaving with a box spanner and bar until the veins bulge it will sometimes loosen by putting a ring or open ended spanner on it an giving the spanner end a good thwack with a heavy hammer. The shock seems to do the trick. An impact driver/rattle gun is best buy would need a very deep socket. That thin nut seems to be a bit recessed into the sprocket so perhaps there isn't enough meat to get a ring or open ended on it securely.
If you can't determine exactly what the thread is (surely you can?) you could try it both ways as no harm will be done. Even whacking it the 'wrong' way will sometimes break the adhesion. Obviously you'll need to hold the g'box securely. Perhaps bodge up a bit of support for the g/box and clamp the chain in the vice jaws to hold it firm for a thwack or two?
P.S.
As Mick said, photos are confusing but it looks to me that the second thread of the right hand pair of the two threads is 'higher' (has slightly more thread showing above the nut) than the left hand ones where the second thread ring is touching the nut which makes me think it's a r/h thread.

Thanks Neville. I'm all confused now on what way to turn it now!

My gut says I should try unscrewing it anti clockwise now. At the moment the only thing I have to fit it is a hefty box spanner. I've been looking at buying a deep impact 38mm (1-1/2" across the flats) socket with a 3/4" drive as I have a bar for that.

There must be someone out there who's removed a gearbox sprocket nut who can advise me on what way to unscrew the nut? I know they're robust motorcycles but they must need changing from time to time!

[SPRIDDLER]

There are many articles if you search the archive under 'Transmission' for AMC and Burman.
Just as a quick example (my dinner's ready)
See page 70 here:
http://archives.jampot.dk/technical/Tra ... ebuild.pdf

Sprocket nut AMC box.JPG

[Plugsnpoints]

Ok, so Mick must've been right all along after reading that! That's very helpful. In fact I've just ordered a copy of the Classic Bike magazine with it in so I'll have a hard copy!

I'll attack it again in the morning. I was scared I'd break something if I turned it the wrong way (actually I didn't fancy the idea of having to face a third hernia op either! )

Thanks Mick, Neville and everyone.

Andy

[SPRIDDLER]

Excellent. I didn't realise that back copies of such ancient magazines were available.
BTW - it would be a good idea to show the year of your bikes in your Profile as it would save having to trawl through your old posts in other threads to find out that bike in question is a '57 (is it?) and therefore would/should have an AMC 'box.

[Plugsnpoints]

Excellent. I didn't realise that back copies of such ancient magazines were available.
BTW - it would be a good idea to show the year of your bikes in your Profile as it would save having to trawl through your old posts in other threads to find out that bike in question is a '57 (is it?) and therefore would/should have an AMC 'box.

Hi Neville, there's all sorts of magazines on eBay. I'll update my profile when I can. It's playing up at the moment and I'm unable to log in to the main site.

The 350 I have is an M16 dating from November '57, so in effect it's a 1958 model with all mod cons like coil ignition and an alternator.

Anyway-I have good news. I was fidgeting so popped out to the workshop again. This time I warmed the nut up a little with a propane torch, put a huge bar on it and it budged! All I want to do is to replace the seal behind it while it's out of the bike. I'll be able to carry on with it until the shiny bits arrive (rechromed bits and rebuilt wheels).

Going back to eBay, recently I bought bespoke AJS/Matchless engine stand, and an AMC gearbox stand from a fella who makes them. They're superb. they are rock solid at a nice height to work on. Highly recommended. I'm all for making life easier.

Just for the record, Mick was right all along. I do apologise for doubting him. It IS definitely left hand thread!

Like I've said before, this is like having a live Haynes book, but much better of course!

Thanks again chaps

Andy

[SPRIDDLER]

Anyway-I have good news. I was fidgeting so popped out to the workshop again. This time I warmed the nut up a little with a propane torch, put a huge bar on it and it budged!

When faced with stubborn jobs it's always worthwhile shrugging and nonchalantly walking off then nipping back and catching the bugg*r unawares.
Worked a treat when starting my sulky 500 single.

[Plugsnpoints]

Anyway-I have good news. I was fidgeting so popped out to the workshop again. This time I warmed the nut up a little with a propane torch, put a huge bar on it and it budged!

When faced with stubborn jobs it's always worthwhile shrugging and nonchalantly walking off then nipping back and catching the bugg*r unawares.
Worked a treat when starting my sulky 500 single.

You're right there. Despite my old man being a grumpy old git, I learned a lot from him. He used to have a cuppa and a fag when things weren't going well. I have found all sorts of tools in what was his workshop. Many are home made as well.

My favourites are his lead loading tools made from old files, and a tee handled long Allen key made from two old car pushrods brazed together.

I don't suppose it would be allowed these days, but he had full size oxy acetylene bottles in the garage next to the house! He could weld pretty much anything, and make things fit.

I guess it stemmed from necessity after the war with everyone. People had to fix their pushbike/motorbike/car to get to work. When I was a kid there were always revving engines on a Sunday, and worrying about getting a ticket (MOT) on your bike or car!

That's what I like about getting back into this stuff again. It's good therapy!

[ray.woolford]

At least you had the gearbox in situ that way allowing you to hold it on the back brake.Having agreed to overhaul an AMC box for a friend who then presented the gearbox to me with the sprocket still attached . Took me the best part of all day to get it off as there was nothing to hold against, broke my home made chain wrench, then found an old box spanner that fitted so welded a socket on the end so I could use my rattle gun same problem couldn't hold the other end. Having decided the sprocket had seen better days (well it has now) welded a bar across one side of the sprocket clamped that in the vice and defied my rattle gun to let me down after a struggle it finally let go.
There is a time and place for locktight and that's not one of them (other thread lockers are available).

[Plugsnpoints]

At least you had the gearbox in situ that way allowing you to hold it on the back brake.Having agreed to overhaul an AMC box for a friend who then presented the gearbox to me with the sprocket still attached . Took me the best part of all day to get it off as there was nothing to hold against, broke my home made chain wrench, then found an old box spanner that fitted so welded a socket on the end so I could use my rattle gun same problem couldn't hold the other end. Having decided the sprocket had seen better days (well it has now) welded a bar across one side of the sprocket clamped that in the vice and defied my rattle gun to let me down after a struggle it finally let go.
There is a time and place for locktight and that's not one of them (other thread lockers are available).

I had an old length of scrap Ducati rear chain wrapped around the sprocket clamped in the vice. I used a huge bar on the Box spanner in a clockwise direction. It let go after a fight.

I am now a bit cross with myself as I've buggered up the new seal whilst fitting it. It's easy to overcome though and I'm not going to cry about it. The spares dept. and Mr Surbey aren't open until the new year so I'll try again in a week or so. It'll all turn out nice in the end