Hi everyone,
I have a problem with my m20 ....
whenever I enter a hole, even a small one, the rear stand will jump.
The rear stand is not original, it seems heavy but I have never weighed the original.
The spring is new ... What can it be?

thank you all

Massimo

Well I think you have touched on both potential problems...Spring tension is the only thing that keeps the M20 stand up and you should consider a pattern spring suspect in terms of conformity to the original specification...

There do seem to be some original springs available and I would get one if you haven't already...

How good the pattern stand is depends partially on where it was made and who made it I would have thought...You didn't say...

Most of the weight in the stand is at the upper end where it has less effect being nearer to the pivot. Whilst a big increase in weight might have an effect I don't think it would be to the degree you describe.
Additionally, it's not so easy to increase the weight of the lower end of the stand that much as there are no castings at that end...

Another feature that might be relevant is the position of the spring anchor on the pattern stand....If it's in the wrong place this could possibly reduce the mechanical force exerted by the spring...Ian

email (option): ian@wright52.plus.com

When you ride in a group of M20s you often see rear stands bounce, if it is heavier than it should be then I think it would bounce more.

But as long as its not hitting the road it shouldn't be a safety issue.

Rob

email (option): robmiller11(a)yahoo.co.uk

I had the same problem on my 1949 M33, I changed the spring and it stopped the rear stand bouncing.

the first time I mounted the spring without a tool and the spring flew away cutting the stud of the frame. I have two springs may be n.o.s. , now I try the other one.
I saw rear stands that are lower than others on the march. It may be that the spring works badly in this position.
My stand is not original, I could stretch a little the arm ......

on a short ride i don't worry about it but on long runs the stand gets an elestic strap doubled around the cross bar then hooked onto the rear carrier.
Constantly bouncing wore the hole in the frame quite oval in the first 50,000 miles and mushed up the frame stop both on the frame & stand.
Then again i do 300 - 500 mile day runs fairy regularly so it might not be a problem where you need to show your passport 3 times on a 3oo mile run.

email (option): bsansw1@tpg.com.au

When the rear stand is in the up position, but still quite near the road, it is usually because the owner has put the snail cam (chain adjuster ) the wrong way round.

I'm quite sure that neither of my M20 stands bounce. However it is impossible to put the springs on without the aid of a stretching tool. Ron

email (option): ronpier@talk21.com

yes, the wear of the stand-holes in the frame is mostly on the bottom/rear side so it not the use of the stand but the bouncing which causes this. And the RHS where the spring is fitted is usually in worse shape then the other.

And this wear has again great effect on the position of the stand when in use and causes extreme forces on the pivots when the stand is too far under the bike.

Maybe a grease nipple on the bolts would help to prevent this wear ? or a clip on the mudguard, vintage style.

Here an example of a tool which stretches the spring, can't do without:

thanks to all of the advice. I try to verify all these items.
As a last resort I too have thought of a vintage clips.

Massimo

I've knotted a loop of innertube rubber onto the lower mudguard stay at the pannier welded stud, it is then looped over the foot of the stand. This works a treat, quick to put on or off and if you put it on the near side it doesn't get dirty from the exhaust.
Richard