My sons "new" AJS Model 20

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 12:57 pm

Thank you!

I will use a lighter weight oil. Perhaps SAE 30? I'm already concerned about the clutch and gears, as yesterday we went to put it in gear and heard grinding. We didn't want to force it. The mechanic said if you put it in second gear first, then into first, it should help. Maybe I need to expect things to be a bit more "rough" this way than my Harley Fat Boy but I cringe when I hear grinding. Additionally, there is no fluid in the chain case right now so we are trying to limit how much we ride it as well as how much we are willing to force it into gear.

I think I found the seal on the spares site. Are all the "new and improved" seals the same design? I haven't had the band off but does the new design seal sandwich between the outer and inner plate or does it go inside the band?

From the spares site:

018652AD SEAL FOR TIN CHAINCASE. ALTERNATIVE DESIGN

Seal, tin chaincase - improved design.
Alternative to 018652

Price : £5.61 each Other currencies

Price incl. tax : £6.73 Other currencies

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Re: My sons "new" AJS Model 20

Postby Cerberus » Mon Jul 17, 2017 1:08 pm

I've fitted one of the chaincase seals to my 56 G9. No leaks so far.

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Re: My sons "new" AJS Model 20

Postby Rob Harknett » Mon Jul 17, 2017 1:11 pm

Daveinater wrote:
Rob Harknett wrote:You say you may have a few questions to ask. Remember you only have 90 days free use of the club forum. May be a good idea to join the club.

Hi Rob!

Thank you for the information!

I joined the club before I posted. I'm just finding my way around here....is it not showing I'm a member? I also paid for the spares discount subscription thing.:shock:

Re: the part number 373, I've seen the part you're referring to on EBay but what is throwing me off is the fitting coming out of the back of the speedo appears to be a male end with a cross-drilled hole, Amd part number 373 appears also to have a male end (with a cross drilled hole as well). Not sure how these would fit together. I must be missing something.... :?:

Welcome to the club Dave, perhaps your membership status had not been processed when I first replied, or I need new glasses.
I thought that pt. no. 373 was male, however, you can see what you need, but it needs to be female. Check what length you may need. You will need space to get a firm grip on the extended trip knob. It needs quite a firm pull down, then turned to turn the miles back to zero. You have seen comments about the tank, which I did suggest you tried to fix. Many reasons now been given why you should keep what you know is quite sound. Before ordering any parts from the club , make a list of all you may need. Order when you think the list is complete. This could save you money on postage & packing

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Re: My sons "new" AJS Model 20

Postby SPRIDDLER » Mon Jul 17, 2017 1:14 pm

Daveinater wrote:...we went to put it in gear and heard grinding. We didn't want to force it.


The clutch plates can become a bit gummed up and 'stick' together. It can help to free the plates before starting by operating the kickstart a couple of times with the clutch lever held in. Th'engine won't turn over but the freed clutch plates will spin. Otherwise it may mean the clutch (not just the clutch cable) needs adjusting. I won't go into adjusting the clutch here as a browse of the manuals will explain it perfectly, and worth doing (no special skills needed) whilst you have the chaincase outer cover off to fit the new seal.

I haven't had the band off but does the new design seal sandwich between the outer and inner plate or does it go inside the band?


I believe the improved seal is the same design as the Diederich one. It fits between the chaincase halves and under the ali band (as did the leaky original AMC one), but it's a bit larger section so you'll probably need to get a longer bolt (not on Club spares inventory) for the clamp on the band, and possibly need to add a spacer washer to the bolt/stud which passes through the centre of the chaincase. It'll all become clear when you fit the new seal.
I poke badgers with spoons.

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Re: My sons "new" AJS Model 20

Postby JimFitz » Mon Jul 17, 2017 1:25 pm

Hi Dave and welcome to the club.

The new seal is a T section, the vertical section of the T sits between the chaincase halves and the aluminium band sits over the whole lot. As it sits between the joint faces you will probably need to add a spacing washer to to the central fixing stud to compensate and avoid possible distortion. If you do not have enough thread on the stud then you can back off the nut on the other end of the stud to pull a little more through.
The seal needs to be carefully cut to length and I put the joint midway on the top of the chaincase.
You will probably need a longer BA screw on the fixing band to pull the whole lot tight.

It is not advisable to run too long without oil as this helps cool the chain and clutch and lubricates the clutch roller bearings. It may be worth checking for tight spots in the chain tension to avoid having to disturb the chaincase seal in the future.

SAE 50 is a bit thick for the chaincase SAE 40 is ok, SAE 30 is even better.

Jim

Sorry Sprid for repeating your advice - our posts crossed.
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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 1:39 pm

This is all great advice and clearly explained! Thanks Gents! I did just get ahold of John Diederich, nice man, and he is sending me a seal. You both mentioned I'd probably need a new screw for the band. You mention BA screw. Are these British threads? Will I have an issue finding a screw here in the US that will work? (May be the dumb question of the day, but worth asking).

Thanks for the great explanations guys. I can envision it while I read it. Well done!

Dave

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Re: My sons "new" AJS Model 20

Postby SPRIDDLER » Mon Jul 17, 2017 1:42 pm

JimFitz wrote: Sorry Sprid for repeating your advice - our posts crossed.


Please do, Jim. I've never owned or even ridden a twin. You actually have one and know what you're doing. In any case I've now just about exhausted my knowledge of twins. :oops:
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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 1:47 pm

Come to Senoia Georgia, Spriddler (its the Hollywood of the South....many film and TV shows filmed here, including The Walking Dead :-0 ). You've already earned a free ride! Lol :-)

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Re: My sons "new" AJS Model 20

Postby SPRIDDLER » Mon Jul 17, 2017 1:49 pm

Daveinater wrote: You mention BA screw. Are these British threads? Will I have an issue finding a screw here in the US that will work?


The ends of my band have just clear untapped holes so I use any old nut and bolt of the correct length and diameter.

(May be the dumb question of the day, but worth asking).


It's comforting to know that even someone who can fly a jet needs to ask questions ;)

Daveinater wrote:....many film and TV shows filmed here, including The Walking Dead :-0 ).

Thanks for the invite and I don't wish to seem ungrateful but I think I've already seen some of them at Jampot rallies. :twisted:
Last edited by SPRIDDLER on Mon Jul 17, 2017 1:55 pm, edited 3 times in total.
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Re: My sons "new" AJS Model 20

Postby Daveinater » Mon Jul 17, 2017 1:53 pm

Hahaha. I have a buddy who says "even a monkey can fly an airplane." I beg to differ, and I've challenged him to a contest in one of our Delta flight simulators. He has been "too busy" to do so. Lol.

Having said that, I'm not the smartest guy around, and I'm a "researcher" and ask lots of questions. (My wife says I ask too many. :? )

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