Engine Shock Absorber Cap

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Engine Shock Absorber Cap

Post by George Kaplan »

Building the G3 up I knew that I was missing the engine shock absorber nut and needed a new spring, both of which were ordered on Monday and turned up today.

I did have what I thought to be the shock absorber cap (part number 000831) so didn't order one.

However now that I have put the parts together I realise that the part that I have that I thought was a cap isn't correct. I could order a new one easily enough but it would be a simple part to make.

Can anyone advise on dimensions? I can figure out the diameters from the ID and OD of the spring but I could use some help with the other dimensions which, amongst other things, will determine the spring pre-load.

Any help that folks can offer would be much appreciated.

Image

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John
56G80S
Member
Posts: 3354
Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: Engine Shock Absorber Cap

Post by 56G80S »

IKBA but from experience the square section springs lasted longer than the round ones and the turned "cap" better than the pressed steel ones.

Perhaps I've just fallen foul of different years and different models.

I hope someone can help with the dimensions but not splitting the tin chaincase to measure up!

Johnny B
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Re: Engine Shock Absorber Cap

Post by George Kaplan »

Thanks for the comment Jonny B.

Because I am unsure of what year my engine is exactly I correlated various part numbers for the spring accross various years and the part number for the spring was always the same. I then ordered from club spares but didnt know if it would be square or round section spring until it arrived.

The turned cap comment makes sense and I have checked the picture on the club spares site and it appears to be a pressed steel one so that confirms that I would prefer to make a cap.

Hopefully someone can help with dimensions for the spring pre-load.

Jiohn.
FergusandTed
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Posts: 26
Joined: Thu Feb 04, 2016 1:47 pm
Location: Suffolk

Re: Engine Shock Absorber Cap

Post by FergusandTed »

Hi George
What's are the dimensions of your spring I ask because I posted yesterday for information on a spring for my 18 which I have a turned cap for The springs the right length for a 500 and Sq section but seems to larger diameter
I can post a pic of the cap if it helps
Mick
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Re: Engine Shock Absorber Cap

Post by George Kaplan »

Hi Mick,

I have just picked your post up but I am at work now so I cant post the spring dimensions until later when I get home. The spring that I have is the G80/18 500cc spring because my engine is 500cc so I went with the (presumably) stronger spring.

A picture of the cap would be good. If possible could you provide the dimension from the underside of the flange to the end of the cap that faces the engine? Any other dimensions would be great too.

John
Mick D
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Joined: Mon Mar 24, 2014 5:44 pm
Location: Aberdeenshire

Re: Engine Shock Absorber Cap

Post by Mick D »

Hi

There seems to be quite a few possible variables here - cap, spring length, wire size, crank spindle etc. - if I were manufacturing a cap I'd fully compress the spring and use that dimension to determine the under flange to end dimension of the cap, (ensuring the spring does not prevent cam operation).

Regards Mick
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Re: Engine Shock Absorber Cap

Post by George Kaplan »

Mick D wrote:Hi

There seems to be quite a few possible variables here - cap, spring length, wire size, crank spindle etc. - if I were manufacturing a cap I'd fully compress the spring and use that dimension to determine the under flange to end dimension of the cap, (ensuring the spring does not prevent cam operation).

Regards Mick
Thanks Mick. If no one has the dimensions then I had planned to do exactly what you describe, determine the length at which the spring is at maximum compression and work from there. However if the original cap dimensions are available then that would seem to be a reasonable starting point.

Whilst I agree that there are numerous posible variables, the cap has the same part number for 350's and 500's across all of the years that I have checked. This would seem to sugest that the cap dimensions did not vary significantly.

John
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Re: Engine Shock Absorber Cap

Post by George Kaplan »

FergusandTed wrote:Hi George
What's are the dimensions of your spring I ask because I posted yesterday for information on a spring for my 18 which I have a turned cap for The springs the right length for a 500 and Sq section but seems to larger diameter
I can post a pic of the cap if it helps
Mick
Hi Mick, the dimensions of my new from club spares spring are:

Uncompressed length = 1.656"
Min compressed length = 0.883"
OD (uncompressed) = 2.047"
ID (uncompressed) = 1.555"
Wire = 1/4" diameter


John
56G80S
Member
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Joined: Wed Oct 12, 2005 10:45 pm
Location: N YORKS UK

Re: Engine Shock Absorber Cap

Post by 56G80S »

I just now realise I have a spare turned "cap" and have to go to the lock up tomorrow. I think I know exactly where it is (ha ha). I'll pop the battery in the vernier and measure it.

If the little grey cells work.

Johnny B
George Kaplan
Posts: 160
Joined: Tue Apr 25, 2017 1:24 pm
Location: York

Re: Engine Shock Absorber Cap

Post by George Kaplan »

56G80S wrote:I just now realise I have a spare turned "cap" and have to go to the lock up tomorrow. I think I know exactly where it is (ha ha). I'll pop the battery in the vernier and measure it.

If the little grey cells work.

Johnny B
If you could do that it would be much appreciated.

Thanks,

John
Locked