Front Suspension on 1938 M26

Information relating to Matchless and AJS Models built prior to 1939
upperstoker
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Re: Front Suspension on 1938 M26

Post by upperstoker »

The spring on the bike measures 8 1/4" so this could well be the promble?

Any recommendation on companies that can rework the spring to a new length or what is the likely hood of me finding a spare?
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Rob Harknett
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Re: Front Suspension on 1938 M26

Post by Rob Harknett »

Your spring looks stretched, did you measure it on its stand when the front wheel would be on the ground. In that position the links should lay horizontal. The damper knob should be tightened so the forks are quite ridged. Hardly any movement at all. The damper is does what oil does in teles. Stops the springs only from bouncing.
upperstoker
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Re: Front Suspension on 1938 M26

Post by upperstoker »

Hi Rob,

Yes, the measurment was taken with the bike on its stand and fromnt wheel just touching the ground. The links are as the image previously posted i.e pointing downwards not horizontal. So looks like spring is streched?
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Rob Harknett
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Re: Front Suspension on 1938 M26

Post by Rob Harknett »

I'm a bit puzzled. With the bike on its rear stand the front wheel should be a little more than just touching the ground. So why I wonder, are your forks hanging down to reach the ground. Are they tightened up in this possition. Will the links go horizontal with the bike off the stand with weight on the front end.
Ashampoo_Snap_2016.05.06_19h27m50s_001_.png
Links with THREADED holes go on the left, Links with PLAIN holes on the right.
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Duncan
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Re: Front Suspension on 1938 M26

Post by Duncan »

Alan

Just to confuse the issue some more, I have measured the spring of the 37 26M with 38 (model year) forks and the spring measures 8 1/2" if I add a little force to them the top cross piece will hit the spring (so I was wrong to say there was clearance) probably the lack of a wheel allows them to sit up a little.

Then I measured my 37 G2M with 39 speedo cup forks (I have the centre stand off at the moment so there is some weight on the forks) this spring measures 7 3/4" and the top link will hit the spring.

Both springs have 15 turns as best as I can see but there may be a small return at the end that I did not count.

The only conclusion I can come to is that it probably best to measure the spring out of the forks to get its true dimensions.

I am still not clear why the top and bottom links have different part numbers, this implies there is a difference?
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Rob Harknett
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Re: Front Suspension on 1938 M26

Post by Rob Harknett »

Spring measurement is not that critical. Even if it is a bit long, if the forks are in the " drop " link position the top front spindle will drop down onto the spring. With the links horizontal, the spring will clear the top front spindle by about 1" Set the forks up correctly in that position, put something under the front wheel if you have to. Adjust the links and lock up the lock nuts. Note the horizontal links & 1" spring clearance between the top front link and spring. Now look at my 36 AJS, on its battered and bent centre stand that needs wood under it to raise the wheels up so it rests on the stand. No weight on the forks, links hang down, top front link almost touching the spring. When off the stand and me on the bike, the 36 links are horizontal. The 36 bike spring is stretched, and needs damping until movement is about the same as the more sturdy spring. Yes the spring is stretched, damping will stiffen it up like a good spring. The 36 & 38 springs are 78 & 76 years old.
1-.36 links.JPG
2-36 spring.JPG
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Last edited by Rob Harknett on Sat May 07, 2016 1:30 pm, edited 1 time in total.
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Rob Harknett
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Re: Front Suspension on 1938 M26

Post by Rob Harknett »

1-38 links horizontal.JPG
2-38 spring.JPG
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upperstoker
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Re: Front Suspension on 1938 M26

Post by upperstoker »

Thanks Rob and Duncan,

Will get to work on setting the forks up as Rob has indicated and let you know the results. I have found a manufacture of a new spring should it be nesesary.

Kind regards

Alan
upperstoker
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Re: Front Suspension on 1938 M26

Post by upperstoker »

I am not able to set the links horizontal with the spring clearing the top front spindle by about 1". The spring simply forces the links to a 'dropped' position with the top cross bar touching the spring.

My assumtion is that the spring is streached quit considerably. I have taken the spring off the bike and it measures 9 1/4"
It has 16 turns plus the flats at both ends.

I am considering having a new spring made but would like to know how I could find out the lenght of the original specification? If not I might have to make a guess at say 7 1\2" to 8' max? I would appriciate your thoughts.

Alan
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Rob Harknett
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Re: Front Suspension on 1938 M26

Post by Rob Harknett »

Why make a guess Alan, I have stated my 38/26 spring that clears the top link by about 1" as seen in my pictures measures 7 1/2" Duncan got about 7 3/42 maybe he was bit more generous than me eyeing up the tape measure. I did say your spring does look stretched.
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