Help please - Camplate Plunger in 1960 M20

[Cliff-1959]

Hello, I hope one of you helpful people might be able to help me.

I was talking to a Cheshire member at a meet last year, (Peter?) and he asked me if my bike jumped out of first gear, which is does.
He said it was an easy fix, (should have rung alarm bells!)

He said just undo the larger nut under my gearbox, remove a spring, then the camplate plunger. Replace it with a new one and it will be fine again. I found the part in my parts manual, number 040034 and tried to find one. None in the UK, but a chap was listing a "British Made" one in the USA so I ordered it and a new spring.
It arrived, so I removed the nut and found that the spring was badly twisted but after some cursing it came out - BUT no sign of the old campmate plunger??
I tried to fit the new one, but I could only get about one turn on the nut before it locked tight. At this point it was obviously jamming something, because I couldn't move the gear selector either.
I tried to fit it in every gear and neutral without success.
So does anyone know what I am doing wrong, or is it maybe the wrong part? The plunger that I bought does look quite long, it's about an inch and three quarters long.
Any advice would be much appreciated.
Thanks,
Cliff

[robcurrie]

That is the wrong plunger, way too long, here is the correct part in Club Spares:
http://www.amoc-parts.com/store/comersu ... duct=22744

Rob C

[ajscomboman]

Wrong G/box Rob, that plunger is for a Burman not an AMC.

[robcurrie]

OK, sorry, but the plunger is similar length.

[Cliff-1959]

Thanks for the replies, I actually bought one from club spares before I had a parts book. It "looked" right so I gave it a go
It looks about the right length, but it was way too wide. This must be the Berman part that you mentioned above. If anyone needs one, let me know.
The part I got from the USA fits snugly inside the nut with the spring between them, but as I said, it looks way too long. Does anyone have one that they could measure? I imagine this part would be OK if it was machined down a bit.

[robcurrie]

Cliff, attached is a picture of the plunger, spring and "nut". The plunger is 25.4mm long, diam. 11mm, the spring is diam. 7mm x 38mm long.
Cheers
Rob C

20160518_180602-1_resized.jpg

[Cliff-1959]

Rob,
What a helpful reply!
I have been sold the wrong part obviously. I managed to track down another one from Andover Norton, so I am hoping that it is like the one in your picture.
Thank you very much for taking so much trouble.
Virtual beer on the way to you LOL
Cheers,
Cliff

[robcurrie]

Glad to be of assistance, now I can put my bike back together so I can go to work again tomorrow.


Cheers

Rob C

[zwarts]

Not clear why you had to send to USA for this part - both RGM and Norvil have these listed. In your first post you mentioned "no sign of the camplate plunger". It must be there somewhere or you would not have been able to select any gears at all! Could it be stuck in the housing and that's why you couldn't get the replacement plunger back in??

[Cliff-1959]

Not clear why you had to send to USA for this part - both RGM and Norvil have these listed. In your first post you mentioned "no sign of the camplate plunger". It must be there somewhere or you would not have been able to select any gears at all! Could it be stuck in the housing and that's why you couldn't get the replacement plunger back in??

Hi,
I didn't try those suppliers, the ones I did try were all out of stock. (I have added them to my suppliers list now though.)
When I removed the nut, the spring was badly bent - I was worried it might snap actually. I can now look up into the gearbox and clearly see the camplate move as I select different gears. If the original plunger was still in there, it would block the view.
The only issue when riding the bike is that it jumps out of first quite often, (I sometimes get a false neutral between 3rd and 4th.)

I really don't know how I can select gears with it missing, but my lad went for a quick spin on it after we had removed the bent spring and it worked fine apart from first.

The new plunger arrived yesterday and it is exactly the same size as the one in Rob's picture, about half the length of the one I got from the 'States. I will probably be fitting it tomorrow, so I will report back