Exactly what type of Cast Iron are early twin cranks?

Information relating to the Matchless G9 or AJS Model 20 500cc twin
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peterg123
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Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

I have contacted Gleeson in the USA, famed for their submerged arc crankshaft rebuilding machines, and will be helpful to know exactly what sort or grade of cast iron the early 1950's AMC cranks were made of if anyone knows.

Gleeson machines are reasonably common in UK I would imagine, depending on their answers I'll post here...might help rebuilding worn out early cranks which are many.

While on it, what are the radius dimensions for regrind?

Thanks folks.
SPRIDDLER
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by SPRIDDLER »

Grinding info here but not sure if it's visible to you as a non-subscribing guest:

http://archives.jampot.dk/technical/Spe ... _twins.pdf
'There is a tide in the affairs of men
Which taken at the flood............'
peterg123
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

I got the following from "Working at AMC"

"Meehanite GB300 is a pearlitic gray cast iron that has a minimum tensile strength of 300 MPa (44 ksi), when determined on test pieces machined from separately cast, 30 mm (1.2 in.) diameter test bars."

Sounds like the right stuff.
peterg123
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

Groily
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by Groily »

Gleason Inc certainly make some interesting claims for their process and their machinery, and obviously are accustomed to handling some pretty heavy-duty crankshafts.
Anyone interested, see https://www.gleasonengineering.com/why- ... ering.html.
Presumably they have sold their kit quite widely - but probably not quite as far afield as Nairobi!

I would nonetheless still give Barry a call at T&L Engineering in the UK (if you haven't already) to get his latest take on the options - he has actually built up some of these particular journals and knows very precisely the specific issues that can arise. He is also armed with the correct grinding tooling for getting to the centre main journal and could probably also provide a ballpark quotation for the job, assuming the crank is salvageable.
peterg123
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

Thanks for this...actually there are like 2 maybe 3 Gleeson machines in Kenya! I wanted to get the info direct from Gleeson as they may not have the correct wire for cast Iron.

I am confident that for a non-race 500 CC G9, a crank would be salvaged..they rarely broke from what I have learned, even at 550cc and 600cc versions. It seems for the CSRS a faulty batch ofcranks was the main culprit that forced a change to Noddy.

I will contact T and L anyway... as I would likely buy a crank in UK and then have him work on it.
Groily
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by Groily »

That's good news Peter, who'd have thought? Maybe needed out there to keep trucks and plant equipment going in a harsh climate and demanding conditions.

It's quite true that the shorter stroke cranks probably won't break - but as I said earlier in the discussion I did break one of mine (a Model 20's) after it had been built up to standard, which is why I think you're right to be investigating very thoroughly. That one lasted precisely 50 miles!

I always thought the 650s were OK actually, until power outputs went up with CSRs and so on - but in whatever case there are still plenty of non-noddy ones doing solid work in ordinary G12s and Model 31s. I had one reground at T&L not so long ago, it was pronounced 'fine' - and I would have used it myself had I not got a new one from the Club. Someone else in the club has it now and I hope it's going strong still. Three local friends with pre-nodular 650s are running around very happily too - which is why I think the frailty thing was maybe over-stated in bar-room conversations back in the day, when people were more focused on 'How fast will it go mister?'

Good luck!
peterg123
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

If you flog any Brit Bike with youthful abandon and disregard for oil changes and so on, you can get the same thing. I have a T100SS Triumph with a broken rod and have seen A7s.

Reading up the blog of the man who worked at AMC, they had a big production run of mis-cast non-noddies, and in Kenya it was rare to see a CSR without the tell-tale scar, usually the drive side. My own pre-noddy let go in spectacular style to provide instant engine cut-away model ! :-)

Barry does metal spray as opposed to Gleeson submerged arc, for 430 quid a crank plus VAT. I am waiting to hear what Patrick Gleeson says in the USA.

Meehanite was chosen because it has very good machining properties it seems as well as good strength.
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by Groily »

Talking a small fortune there then Peter. Not to mention freight costs. Must be an expensive process in time and materials as I've always found T&L pretty fair on charges.
Be interested to hear what the US guy says.

Best and most economical route to 'happy' may end up being an advertisement for a better one . . . .??

And yes, pretty well anything will break if we try hard enough. Bizarrely, maybe, on my 650 with the pre-noddy crank, it was a rod that had let go - the crank survived. Whereas when my 500 broke its crank, the rods survived and were still straight and not oval either. They've done a good 100,000+ miles since then, of a total of around 300K. These things are built to last!
peterg123
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Re: Exactly what type of Cast Iron are early twin cranks?

Post by peterg123 »

Thanks Spriddler that helped I was able to download
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