1958 Model 30 Engine Etc.

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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Ironhead
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1958 Model 30 Engine Etc.

Post by Ironhead »

Hello All, Should there be a gasket between the crankcase halves, and on the timing side cover there's none in my gasket set.
Do I fit the engine plates to the frame then fit the engine, or fit the plates to engine then fit to frame?
I bought two bottom covers for the rear shocks from JSL in S/S they are lovely and shiny, I have been two hours trying to polish the S/S that are on the front forks with my polishing kit (fitted to bench grinder)and cannot get any where near the finish any advice would be welcome.
Alex.


Groily
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1958 Model 30 Engine Etc.

Post by Groily »

Don't do polishing so can't answer the last. The oil seal holders might 'only' be chrome?
But yes there's a small thin gasket that goes between the cases, but only around the oil filter chamber hole where it crosses the cases at the front; and the timing cover has a gasket all of its very own. People a million times wiser than me have said hereabouts that a fine gasket made of such as 'halite' to go all round between the crankcases is a good idea. Has to be fine as you don't want to upset the crankshaft end float etc. The filter chamber is under v high pressure when the engine is cold. I haven't got such gaskets and maybe that's why one of my twins leaks a bit!
The standard engine gasket set contains the small circular job, but I think the timing case gasket is a separate item or a DIY option. Check the JSL spares list. I have always made my own from rolls of standard gasket paper and they don't tend to be a problem area - although the screws can sometimes have weepy leaks up to their heads.
I fit the plates to the engine first - loosely - to give a bit of wriggle-room to align the fasteners which go through the lot. Not sure if it's a preference or a must. And whatever I do I find the bottom through-fastener can be a pain to get into position without stressing things or harming the threads. Best to get that safely in place before tightening anything else up, as once you squeeze those bottom rails life gets harder (on single downtube frames anyway). Also good to slacken the gearbox mounting bolts all round to help the process.
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Duncan
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1958 Model 30 Engine Etc.

Post by Duncan »

quote: Should there be a gasket between the crankcase halves, and on the timing side cover there's none in my gasket setAlex

The parts list will include for a thin paper washer (015034?) around the oil filter tunnel (it will probably be listed in the oil filter and relief valve section not the crankcase one). I followed Alan Jacobs advice and made my own gasket for the whole crankcase joint from Klingersil, so far it is still oil tight and makes more sense than trying to get an oil tight seal all around the crankcases with a piece of paper wedged in on one side.

Make sure your cases are flat and true, half an hour with a piece of plate glass and fine grinding paste will pay dividends if you want to avoid leaks, pay particular attention to the oil gallery between the barrels as there is not much of a mating surface here.

As I had some Klingersil left I made a gasket for the Timing cover as well to ease its removal and replacement but in reality it is unnecessary as flat joint faces and wellseal do not normally leak from here.
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Ironhead
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1958 Model 30 Engine Etc.

Post by Ironhead »

Thanks Groily and Duncan, my next question do you fit the gearbox to plates as well as engine then put in frame,I did a trial run today with the plates I have two spacers, one for centre stand that i have fitted, the other one i think is for between plates on footrest rod which leaves a gap between plate and frame should there be two spacers for here, and one side of the rod is a lot longer thread which side do's this go.
Thanks Alex
Groily
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1958 Model 30 Engine Etc.

Post by Groily »

I wish I could remember Alex, but I fear I can't. There be those who know everything however. Engines go in easily with gearbox and rear plates already there, which sort of answers part of the Q. For the spacers, I always put them onto whatever fastener they came off in the same order when the thing is dismantled in a faint attempt to remember what goes where on reassembly! But I know that's no help if yours are all in a box. Basic point is, if the gaps aren't filled or things ain't straight, something's missing or in the wrong place.
Eric
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1958 Model 30 Engine Etc.

Post by Eric »

Some owners use Hylomar as a sealant for the crankcase halves. It needs only the very thinnest of coats as any excess will be squeezed out anyway, and as it can go inside or outside the engine you will have no control over the bits that go inside and may eventually end up blocking oil ways, so don't overdo things.

The joint can be further improved by dosing a thin cotton thread with Hylomar and placing that into the still tacky Hylomar you have already applied placing the dosed cotton all around the joint going on the inside edge of the stud holes, again don't overdo the use of the Hylomar.

Other sealants including Wellseal can be used its your choice.

For the oil filter tunnel the thread should go all the way round otherwise half of the joint will be unsealed.

The thread cannot make up for poor faces on the joint, the advice from Duncan is still very appropriate.
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