Gearbox type and plunger/push rod query

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stevewhitt
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Gearbox type and plunger/push rod query

Post by stevewhitt »

Hi Everyone
I noticed today that the plunger adjustment on the gearbox was not sitting correctly, and so a mystery started to unravel!
Firstly the parts book for my 1944 WNG lists a Burman CPSL gearbox, whereas the one on the bike is stamped CPBL. Not sure is this is important/relevant to what follows.
I withdrew the pushrod and it measures 11 15/16". According to the Drags site, for part number 3432-36 it should measure 12 11/16". I also note that the plunger fitted does not appear to have the same dimensions as the one on the Drags site (P/N 3050-35); it looks longer in the picture.

However, my problem appears to be that the push rod/plunger combination fitted is too long already; see picture which shows that the plunger is not properly located when the adjusting screw is within the lever.

There is something amiss, but is it that its the wrong gearbox or the right gearbox and something else other than pushrod/plunger length is wrong, or am I missing something else?

As always, your help and insight is appreciated.
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stevewhitt
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Re: Gearbox type and plunger/push rod query

Post by stevewhitt »

I may have moved this post on, a little.
A chap told me that the SL/BL is not relevant for parts ordering. It is the CP part which matters.
He also told me that the pushrod length is determined by the clutch type fitted, and that it is not uncommon to have to buy an oversize pushrod and cut it down to length, which I can do.
So that leaves the operating plunger, which I am sure is not of the correct type which is why it fits so loosely in the male part on the gearbox. I have hunted all over the web, and nobody has one in stock.
If anyone has one I could purchase or knows where I might buy one, please let me know.

Thanks

Steve
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Re: Gearbox type and plunger/push rod query

Post by will_curry »

I think the parts you need are 3050-35, the plunger and 3053-35, the adjusting screw.
Both of these seem to be in stock with Draganfly at the moment.

https://draganfly.co.uk/product-categor ... 6-58-type/
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Re: Gearbox type and plunger/push rod query

Post by stevewhitt »

Thanks Will, just had confirmation that AOMCC has one. Draganfly are on back order for 18 weeks.
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Re: Gearbox type and plunger/push rod query

Post by volker.halbach »

There should be a 1/4" ball in the plunger. Is it the right size?

The reason can also be on the clutch side. I have a pressure plate with a modified thrust button. Probably somebody modified it for a pushrod that was too short.
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Re: Gearbox type and plunger/push rod query

Post by Roger Gwynn »

Your plunger and screw are both homemade items. They do tend to be a bit sloppy in the hole anyway. Some plungers have a 1/4 ball inserted in the business end, some are just hardened.
The W/NG should have a 3 plate clutch on a CP gearbox, which usually has a 2 plate unless it is a 4F SQ4, 1948 KH or a 1939-40 VA or W.NG. So the length you looked up is correct
S=std tyres, B=balloon tyres, not fat sand type but slightly wider than normal. L=low ratio.
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Re: Gearbox type and plunger/push rod query

Post by simon.holyfield »

Roger Gwynn wrote: Thu Dec 08, 2022 9:45 pmS=std tyres, B=balloon tyres, not fat sand type but slightly wider than normal. L=low ratio.
Could you explain a bit more about the tyre sizes please Roger? It's the first time I've heard of that.
cheers

Simes

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Re: Gearbox type and plunger/push rod query

Post by stevewhitt »

Roger Gwynn wrote: Thu Dec 08, 2022 9:45 pm Your plunger and screw are both homemade items. They do tend to be a bit sloppy in the hole anyway. Some plungers have a 1/4 ball inserted in the business end, some are just hardened.
The W/NG should have a 3 plate clutch on a CP gearbox, which usually has a 2 plate unless it is a 4F SQ4, 1948 KH or a 1939-40 VA or W.NG. So the length you looked up is correct
S=std tyres, B=balloon tyres, not fat sand type but slightly wider than normal. L=low ratio.
Ah, having taken the clutch out today, I see that I have a 2 plate clutch - Probably explains most queries in my post!

I am told that 2 plates will be OK, but I am interested in converting to 3 plates. As far as I can see I need the 3 plate case and the 3 plate centre, plus of course another clutch plate and plain plate.

Asking around to see whats available.
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Re: Gearbox type and plunger/push rod query

Post by volker.halbach »

I have sent a PM.
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Re: Gearbox type and plunger/push rod query

Post by john.nash »

You can always add an extra plate by taking the lip off the back of the centre. You then take off the tabs on the outside of a clutch plate. That plate now goes in first, and bears on the clutch basket, followed by a another plain plate. Then it's all the existing plates in the same order.

I've done it and it's a cheap and effective solution - just two more plates needed and a little time with the grinder/lathe.

http://forum.arielownersmcc.com/viewtop ... xtra+pkate
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