G12 CSR primary chain tension - lower gearbox bolt access ? ?

[lochnagar]

Dear All,
I'm new to the delights of Plumstead's products, having spent the last 58 years working on Ducatis, and at the Bonhams October Stafford auction I purchased the A.R.E. museum G12 CSR. Now in the process of preparing for road use after mony a year in the museum which involves a partial strip and rebuild with a copious application of Copaslip on all external threads. Two problems encountered :-

1. How does one access the lower gearbox mounting nuts to slacken and adjust the primary chain tension - 18mm spanner fits but ?
Does one have to remove the exhaust and oil feed / return pipes ?
Or the removal of the primary chain case assembly ? (A daft idea as with the chain off what's there to tension ?).

2. Removal of the front footrests with the supposed retaining nuts and washers removed ?

Finally I've a need for the chain case cover and rocker box gaskets, who's the recommended supplier for Matchless spares ?

Any help will be greatly appreciated, Thanks.

[dave16mct]

Firstly do not use metric spanners, get yourself a set of Whitworth spanners and 3/8" drive sockets. You will probably find that you can just slacken the top mounting bolt and then adjust by moving the gearbox backwards if it's too slack. You will have to lever the box forwards if it's too tight. Better to be too slack than tight and don't forget you will have to adjust the rear chain afterwards. I don't understand about the footrests, they just pull off after the nuts are removed unless you've got the competition type which fit over the frame tubes. If you're not a club member you can get get all your spares from AMC Classic Spares.
Dave.

[ajscomboman]

Bottom fixing isn't a bolt, or shouldn't be! It should be a stud with no washers just nuts winding direct against the engine plates.

[dave16mct]

I never said it was a bolt. I said just slacken the top mounting bolt.
Dave

[ajscomboman]

I never said it was a bolt. I said just slacken the top mounting bolt.
Dave

Not you Dave, the original post said it was a bolt.

[RSC13]

Welcome Tullich 13. I have also recently joined the ranks of AMC owners with the purchase of a 1961 AJS M31CSR. I was watching the ARE bikes at Stafford, I had planned to bid on the bike you bought, but got impatient and bought the AJS a couple of weeks before Stafford. Will be interested to hear how you get on with it.
I also have a 1967 Ducati 250 Mk3 that bought from the Stafford auction as an unfinished project a couple of years ago, now complete and a lovely bike.
I managed to get to the lower gearbox stud nut with a socket and a wobble bar. I managed to just push the oil pies out of the way, but mine are rubber - I think yours are solid copper?
For spares, the three sources are the club scheme, AMC Classic, or Russel Motors.

[lochnagar]

Dear Dave, AJSCombo, RSC13,

Many thanks for the replies, and, MISSION ACCOMPLISHED !
Although I have a good selection of BSF / BSW King Dick and Britool spanners bought second hand in 1965 I always gravitate to the metric set and the 3/8 drive metrinch sockets as first port of call. With the 18mm spanner's jaws ground down for better access the two lower nuts were slackened to allow the gearbox to move a "ba' hair" back to tension the primary and aye RSC13, the CSR oil pipes are mostly metal.
The position of the top adjusting bolt (12mm) is interesting, its location stops the gearbox moving backwards.
When racing my Dunstall 810 Commando Featherbed in the early '70's a rushed gear change would have the box move forward until I added an adjustable stop to the engine plates between the engine and gearbox yet the G12 CSR has that same bolt to stop the box going backward, anyone have a box move back to tighten the primary ???
As for the footrests, I'll leave as be, they are of the type that fit over the frame tubes, at least the retaining threads will get the Copaslip treatment.
Reason I bought the CSR is because the laddie that introduced me to motorbikes in the mid 1950's was a Matchless man and that name evokes a memory of excellence, similar to Brough SUPERIOR and Grindlay PEERLESS, so the acquisition was in homage to one Bob Gilbert, 1937 - 1980.
My first road legal bike was a BSA C12 bought for £1 2/6 in 1965, traded in for an Ariel Golden Arrow which was replace by a Ducati 200SS in '66 and been with that marque ever since. Anyone with a Ducati problem give me a shout, my fleet goes from a 1958 125 Formula 3 to a 2008 Desmosedici with 20 others in between.
Next change must be to that centre stand, my 75 year auld 9st. 5lbs. 5' 8'' frame is incapable of pulling it back unless I make a wee ramp to run up the front wheel then place on the stand. Also the stand needs extending to raise the back wheel off the ground. I read of an easy lift replacement provided by Rob Swift, are they still available ?
Also on the to do list is modify that suicide side stand so when it's down it's down, I'm in control; that spring location will have to move forward.
Ducati had a similar set up so when I bought the 916 SPS in 1997 that modification was top of the list, Ducati dealers at the time did a roaring trade in replacement L.H. fairing panels !

[dave16mct]

CS (comp) models had a gearbox adjuster on both sides (outside the engine plates) to stop movement in competition. The (Easy on) centre stands are available from Rob Swift (AJSComboman) and I can recommend them!
Dave.

[RSC13]

Another thumbs up for Rob Swift's centre stand. I also had huge trouble getting the bike on the original centre stand. When I took it off I found that one stop had sheared and bent though 90 degrees so the stand was almost falling off, which explained why it had been getting progressively harder. With Rob's stand fitted it's now the easiest bike I've owned to get on the stand.

[Joker_Bones]

When racing my Dunstall 810 Commando Featherbed in the early '70's a rushed gear change would have the box move forward until I added an adjustable stop to the engine plates between the engine and gearbox yet the G12 CSR has that same bolt to stop the box going backward, anyone have a box move back to tighten the primary ???

I didn't have to go racing... just a ride round the block would sometimes move my gearbox forward.

Page 7 of this thread talks about what you and Dave have said:

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