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Positive stop mechanism

Submitted by george_phillips on Thu, 21/04/2016
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Help, help help. What have I done! The gear lever on my '55 ES2 (laydown box) failed to return to its detente position a couple of times on the last run so I decided I'd have a look. I removed the outer cover and the return spring cover plate (thinking that the return spring was the culprit and needed "tweaking"). Looking at it it seemed OK so I gently withdrew the pawl carrier assembly only to hear an ominous click. When I then tried to reinsert the assembly it stopped about 6mm short of full insertion (or so it seemed). I tried tightening the return spring cover plate but this only locked the gear lever in a fixed position. What on earth have I done? How do I get out of this mess? I know how I got into it! Does it mean a gear box strip? Help!! George

Submitted by richard_payne on Thu, 21/04/2016

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I haven't got a laydown box here to run through step by step, but don't worry. Nothing that you've done under the outer cover can have any effect behind the inner cover.

This is going to be a return spring or pawl spring issue I suspect. You do have to spread the pawls to engage with the ratchet.

Do you have access to a copy of the Pearsons Edgar Franks book ? ...You ought to ! Smile

Submitted by george_phillips on Thu, 21/04/2016

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Your first comment is a great relief to me Richard. Regrettably I don't have access to that book. I have an exploded dwg of the gearbox plus two or three Haycroft "Book of the Norton" albeit they all say the same thing. Have you any suggestions on what I should do? George

Submitted by george_phillips on Thu, 21/04/2016

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Hi Richard - looking at the exploded dwg it seems to me that the problem of non re-insertion could be that the pawl was pulled off the ratchet when I removed the pawl unit and thus clicked closed. Thus when I tried to push the assembly back in the pawl prevented it. I'll look again in the morning. What would be the cause of the sloppy or non return of the gear lever? I can't see how the "return spring for pawl carrier" Part No D12/410 helps to centre the gear lever as it is on the same shaft. G

Submitted by richard_payne on Thu, 21/04/2016

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The pawl carrier return spring does indeed centre the assembly. Any movement of the pawl carrier will move one leg due to the small pins on the plate while the other is restrained by the return spring cover plate.

These springs are a bit prone to a greenstick fracture before they break completely. Have you had a good look at the spring ?

The other cause could perhaps be sloppy springs on the pawl itself although they'd have to be really knackered (or the ratchet worn) for it not to engage.

I fitted an NOS return spring to a Doll's Head box (I think they're the same spring) and it broke second time out. I carry a spare nowadays !

Submitted by george_phillips on Thu, 21/04/2016

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Yep. I can understand that now, Richard. Doh! I'll check the two springs in the morning. I see that both are available in the NOC shop. very grateful for your help. George

Submitted by george_phillips on Fri, 22/04/2016

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Just to tidy this thread up a little and in answer to Richard's post, I removed the whole pawl assembly; checked the two springs (OK); opened up a little the pawl carrier return spring (the big one); reassembled it all; offered it into the end cover and found that my earlier error had been pushing on the pawl carrier. By pushing on the ratchet plate itself the whole lot slid into place so my earlier cry of "What have I done?" was unfounded. i hadn't done anything! It is now all back in place and I'm waiting for the weather to lift to check it out. Thanks for your patient help Richard.

Submitted by george_phillips on Sun, 24/04/2016

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Lovely day so took it for a run. Gear lever still floppy now an again (mostly again!). Does the return spring (the large cil one) have to touch the pawl carrier pegs and the return spring cover plate at the same time? Mine doesn't. There is some free play between the two positions. It's all back together now so I can't explain from sight but I'm fairly sure that for the spring to touch the pegs and cover at the same time is not possible? Can any one throw any light on this?Cheers - George

Submitted by barry_carson on Mon, 25/04/2016

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the one in the photo has play in it as you are describing don't know if thats through wear though. about 2mm either way between the spring and the plate. anyway sorry for butting in i am sure Richard will know more about these gearboxes than me. just trying to help . Baz

Submitted by george_phillips on Mon, 25/04/2016

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No probs Baz - I'm grateful for your interest. My confusion is working out how the spring n your pic, which is retained between the two pegs, can possibly touch the retaining cover which is "outside" the two pegs? Despite this he books seem to say that the spring should touch both the retaining cover and the pegs at the same time? George

Submitted by george_phillips on Mon, 25/04/2016

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Another bit of info. The outer shell is stamped GT (ES2) whilst the inner box is stamped GB (Model 77 I understand). Would this be a point of confusion? Is the positive stop assembly the same in both boxes? I don't want to order up replacement parts for the wrong box! Cheers G

 


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