Hello Frank,

I have it on 2 WM20 bikes and so it on other front mudguards,
So I guess it is original, and it is there because of the channel pattern in the mudguard.
Otherwise it would crush there, or widen the gap.

Noam.

email (option): noam10@gmail.com

Yes, I also have one with similar plate fitted, but you can also spot the print of a large round washer which I also found there. So doubt if it is Original, but would surely leave it there when there is not much rust under it.

Regarding the serrated washers, the prewar and early bikes did not seem to have them, but they are surely needed as the gearbox is easily moved (to the rear) without them and put great strain on the primary chain, sprockets and bearings. Think lot of the long bronze sleeve bushes of the gearbox have been destroyed by a moving gearbox.

You could look for a longer bolt but if is only just to short you maybe can chamfer the nut and the hole in the serrated washer so that the nut covers the thread fully. Or make the hole in the washer bigger and turn some off the nut so that you get a spigoted nut. (I have not tried these solutions in anger yet but could think they should work OK).

I useally try to adapt both bolts to accept serrated washers on both sides.

Cheers, Michiel

email (option): m.wijbenga@hotmail.com

Thanks for the replies. Well I never would have thought that plate was original as it looks very bodgy but it seems it must be.
Here is a shot that shows the crushing that has occured on the top side of the guard.
I suppose it should knock out ok.

My Wm20 gearbox bolts did not have any serrated washers but my ZB34 that I am working on has two.
I bought a new front bolt for that but it was too short to fit the washer on so had to source a longer one. There was about 15mm difference in length I think. I'm not sure if they have the same part number but are easily confused. I'll take a photo of the two tomorrow.

email (option): mfarnay@bigpond.net.au

I need to make a correction here.
It is the rear gearbox bolt that is too short. The one with the adjuster on it.
There is about 8mm difference in the length of the two bolts. Enough to get a serrated washer on the longer one but not enough on the shorter one.

email (option): mfarnay@bigpond.net.au

Hello Mark,

If you want to use the short one in combination with a serrated washer you could adapt it by taking a few mm of the thick part of the bolt and file the flats a bit further. And take the same of the distance piece so that you have more threads sticking out.

As result you may also have to file the fork which take the adjuster a bit deeper. This brings the adjuster a bit closer to the mudguard but there is usually enough room for it.

But it a bit of a shame to adapt such a nice looking bolt...:slightly_smiling_face:

email (option): m.wijbenga@hotmail.com

Thanks Michiel. I guess I'll just have to keep my eyes peeled for another long bolt and a couple of serrated washers.

Looks like the guard stays as it is!

email (option): mfarnay@bigpond.net.au

Mark
Do you need the serrated washers?
You didn’t ask the bolt factory!!!