Drum liner queries

Information relating to the Matchless G80 or AJS Model 18 500cc Heavyweight.
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Drum liner queries

Postby asterysk_usa » Sat Nov 16, 2019 8:29 am

Image

Is the liner (027144) an interference fit ? I was missing a couple of the screws so took them all off to see if the liner dropped out , it doesn’t ! Will probably just leave as is , there seems to be plenty of metal left in the liner

Part number for the screws is 021766 , anything special about them or can I just find a hex head bolt that fits and grind the head down

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1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Drum liner queries

Postby Andy51 » Sat Nov 16, 2019 9:02 am

Hi, according to the manual fitting of a new liner was a factory job, as it was most definitely an interference fit. Don't know about the bolts, but if you can't get the real thing, and I would strongly advise you to if you can, then I would play safe and use hi-tensile ones and be careful when grinding them not to let them get too hot and draw the temper. Andy

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Re: Drum liner queries

Postby asterysk_usa » Sat Nov 16, 2019 9:11 am

Does anyone has a photo of how the bolt heads look from the factory, I'm interested to see if the original bolts needed grinding
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Drum liner queries

Postby Groily » Sat Nov 16, 2019 10:48 am

Definitely an interference fit. Lot of heat needed to get liners out, and in!
Not sure if new liners can be had, tho' maybe there are some out there. I made one from a solid billet for mine - took 2 days, largely in back-gear on a Myford lathe with a toolpost extension, to get there! Not something I'd ever want to do again. But it's lasted 10 years so far, along with spokes and rim in SS from Central Wheel if I recall.
Spokes go in to full depth of nipple, yes. Some of mine needed a bit grinding off on the inside. I found on the front wheel they pretty well self-selected their hole in the rim if pushed home in the hub. After getting a handful in, the rest was not too bad. An advantage of straight-pull ones compared to some others!
Keeping fins clean isn't something I'm good at or care too much about on mine . . . others may have views on paint options.
Truing up the liner is something you might, probably will, have to do - but you would almost certainly have to with a new liner too.

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Re: Drum liner queries

Postby asterysk_usa » Sat Nov 16, 2019 10:49 am

Groily wrote:Definitely an interference fit. Lot of heat needed to get liners out, and in!

Truing up the liner is something you might, probably will, have to do


Is there a document which explains how this should be done ? thx
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Drum liner queries

Postby Groily » Sat Nov 16, 2019 11:37 am

liner.JPG
Not that I know of - but I know nothing!
When extracting my (damaged) liner I used an acetylene torch (carefully!) to get things pretty hot . . .
I made the new one to the same o.d. as the old one near as I could, which was an interference of a couple of thou or more on that diameter. It dropped in OK. Then I trued it up using a home-made tool based on a retractable & height adjustable fly-cutter bit, rigidly anchored anchored to the wheel spindle. Operated by spinning the wheel and playing with little leadscrews on the cutter assembly. Perfect? - Hmm, no. But not too bad for all that, given you can't get an assembled wheel in a small lathe!
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Re: Drum liner queries

Postby asterysk_usa » Sat Nov 16, 2019 12:01 pm

Groily wrote:
liner.JPG
Not that I know of - but I know nothing!
When extracting my (damaged) liner I used an acetylene torch (carefully!) to get things pretty hot . . .
I made the new one to the same o.d. as the old one near as I could, which was an interference of a couple of thou or more on that diameter. It dropped in OK. Then I trued it up using a home-made tool based on a retractable & height adjustable fly-cutter bit, rigidly anchored anchored to the wheel spindle. Operated by spinning the wheel and playing with little leadscrews on the cutter assembly. Perfect? - Hmm, no. But not too bad for all that, given you can't get an assembled wheel in a small lathe!


Which bolts did you use and did you have to skim them down ? thx
1954 AJS 18S Cyprus export (frame decode says 1954 but many components match a 1955).

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Re: Drum liner queries

Postby Groily » Sat Nov 16, 2019 1:16 pm

I used the orinals as I recall, cleaned up a bit to be sure they sat flush or near as dammit in 'my' countersinks. Didn't have new BSF screws of the right quality to hand. Not, though, that the parts are going to self-detach in a zillion years, with the awesome power of a SLS brake like that. The torque arm would sheer off the slider before the drum liner would budge - I reckon!

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Re: Drum liner queries

Postby ajsph » Sat Nov 16, 2019 2:23 pm

I know one he used a drum from an old BMC Mini
Poul

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Re: Drum liner queries

Postby Andy51 » Sun Nov 17, 2019 9:32 pm

Further to my last, I had forgotten that holding screws were socket head countersunk; I cannot see how you could grind one from a hex head. The manual does give some guidance for refitting liner for places where sending back to factory was not an option. Remove bolts, heat bare hub to 220 to 250 deg C for 20 mins, when a sharp tap shoul get liner out. To refit, heat to 210 - 215, when cold liner should drop back in. But why do it unless liner is badly worn? Book says bore new liner to 7.025 - 7.030 - how does your liner measure? You could skim it clean and measure it, a few more thou should be ok. Andy

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