Con Rod Nuts !!!

Information relating to the Matchless G11 or AJS Model 30 600cc twin
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Con Rod Nuts !!!

Postby DavidHulse » Sun May 31, 2020 5:28 pm

I'm finally making progress with the assembly of my 1958 G11CS engine, or at least I thought I was!! I just tried to assemble the con rods with new big end shells and simonds nuts (014903) bought from the club spares scheme a couple of weeks ago. However, the hexagon section on the new nuts is only half the depth of the old nuts, as a result of which I can't apply the required torque (22 ft/lbs) before the socket slips off the hexagon, having bottomed out in the con rod cap recesses. I will post pictures in a separate post to follow. I've tried all the sockets I've got, and even an old 1/4W tube spanner, but nothing works. Is there a tool solution to this problem, or has the club made an error in sourcing nuts that are too shallow to do the job? I would welcome comments or advice. Thanks.

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Re: Con Rod Nuts !!!

Postby DavidHulse » Sun May 31, 2020 5:55 pm

I don't seem to be having any success posting pictures but hopefully the description above will be sufficient.

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Re: Con Rod Nuts !!!

Postby G15 Roy » Sun May 31, 2020 6:09 pm

There is a thin walled socket that the club sell that's what I have
always used.
Roy

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Re: Con Rod Nuts !!!

Postby 1608 » Sun May 31, 2020 6:40 pm

I have found it necessary to grind the leading edge of sockets flat before now to deal with some shallow nuts. But, I
wouldn't have thought you should have to go to those lengths. From memory those nuts need something like 22lb psi so they need to be reasonably deep. Can't quite remember, but should there be a washer under the nuts.

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Re: Con Rod Nuts !!!

Postby DavidHulse » Sun May 31, 2020 7:47 pm

Thanks G15Roy. I'll take a look at the tools section and see if I can order one.

Thanks also 1608; I'll look at that alternative, but I'd have to grind the walls of the socket thinner to get into the recess, which might be difficult without a lathe. There is a washer under the nut - a special one with a narrow outside diameter - but if I put in anything thicker to expose more of the hexagon, it would risk losing retention on the self locking part of the nut as there isn't much spare thread to play with.

I don't understand why they didn't just buy the deeper nuts that were used on the engines originally. :(

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Re: Con Rod Nuts !!!

Postby alanengineer » Mon Jun 01, 2020 8:21 am

3/8" drive sockets seem to have thinner wall sections than 1/2". Got me out of trouble many a time on the Matchless. Are you putting the correct washers under the nuts. If i remember rightly, they were thicker than normal

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Re: Con Rod Nuts !!!

Postby DavidHulse » Mon Jun 01, 2020 10:55 am

Hi Alan. Thanks for your input. Yes, I've used the special reduced diameter washers that came with the nuts from AMOC. They are a bit thicker than normal but not enough to get me out of trouble. I'm going to buy a new 1/4W socket and give that a try. The ones I've got, both 3/8 and 1/2 inch drive, are all too thick.

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Re: Con Rod Nuts !!!

Postby dave16mct » Mon Jun 01, 2020 12:12 pm

You'll need the thin 3/8 drive 1/4 whit socket to torque the heads down later. I'd take the oportunity to get a small 3/8 drive set of King Dick sockets and a short extension etc.
Dave.

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Re: Con Rod Nuts !!!

Postby DavidHulse » Mon Jun 01, 2020 3:05 pm

Thanks dave16mct.. Will do.

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Re: Con Rod Nuts !!!

Postby DavidHulse » Fri Jun 12, 2020 9:33 pm

Have obtained full size nuts from another source, plus a thin 1/4w socket, which has solved the problem.

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