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ES2 frame/gearbox

Submitted by george_phillips on Wed, 06/01/2016
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Singles
Me again. In removing the lower bolt from the gearbox I see that there is a gap between the gearbox and the frame and a further gap between the frame and the detente position of the primary chain-case inner portion. Is this normal? I can pack them out with washers but I am interested to know if it is the norm.Many thanks for any help.George

Submitted by john_tickell on Wed, 06/01/2016

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When I aquired my 1952 ES2 it was fitted with a model 77 twin gearbox and I had the same problem. When removed and compared with the correct ES2 laydown gearbox I found that the 77 box is narrower at that point. You could make up a couple of spacers to make up the difference but the 77 box uses a shorter kick start shaft and the kick start lever fouls the silencer, or it did on my bike. John

Submitted by george_phillips on Wed, 06/01/2016

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Fascinating John. That's exactly what my kickstart does. I assumed it was a new "multi-model" kickstart that simply didn't quite fit the ES2.Where would I get the width dimensions for the two boxes?I have noticed on the parts plate (JX part 65) that the bolt has a retained nut that could well fit between the rear plate of the p/chain cover and the cover itself with the loose nut tightening against the inside the that rear cover. Any views?CheersGeorge

Submitted by george_phillips on Wed, 06/01/2016

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Many thanks, Barry. The pic is looking back at the rear wheel so the bolt on the right appears to be between the gearbox and the primary chain inner cover, which is what I wondered. Good pic.CheersGeorge

Submitted by george_phillips on Wed, 06/01/2016

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Sorry Barry. I've looked a bit closer at the pic and can now see that what I thought was a bolt on the right is in fact part of the gearbox casting. So back to square one. At least it shows that the gearbox fits neatly between the frame tubes.George

Submitted by george_phillips on Wed, 06/01/2016

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Photo's come out a bit distorted, Barry, but it shows what I thought. The retained nut is on the outside of the frame and the loose nut (on that side) holds the p/chaincase against the retained nut. This means that to fit the bolt I will have to remove the primary chain, drive sprocket and clutch. Bummer!This could also be a reason for a dripping p/chaincase as the rear cover may well have distorted over the years.Many thanks for your input.George

Submitted by barry_carson on Wed, 06/01/2016

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must admit George it isnt one of my better photos just trying to show how the bolt fits if its same as your. Baz

Submitted by george_phillips on Thu, 07/01/2016

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I'm very grateful for your help, Barry. I didn't explain what I meant in an earlier email. I was trying to ask if the retained bolt sat between the inner p/chaincase cover and the frame. Your pic shows that it does so many thanks. Just got to find the correct sprocket extractor and clutch removal tool and I'll be sorted.CheersGeorge

Submitted by john_tickell on Thu, 07/01/2016

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In 45 years of owning and running 6 Norton singles I have never found the need for a clutch extactor but you will need a sprocket extractor. Will be in my garage later today and will measure the two gear box's. John

Submitted by john_tickell on Thu, 07/01/2016

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The '77' gearbox marked 'GB8' has a lower width of 3 5/16 inch and a kick start shaft length of approx 1 7/8 inch.

The ES" box marked 'G102' is 3 1/2 inch wide with a kick start shaft length of approx 2 3/8 inch. John

Submitted by george_phillips on Thu, 07/01/2016

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Brilliant. Thanks John.I'll try and nip out to the garage this afternoon and check mine.I've seen an earlier thread about removing the clutch without the need of an extractor but it requires a specific bolt size which I probably don't have. Any hints on the best sprocket remover?George

Submitted by george_phillips on Thu, 07/01/2016

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Just been out to the garage John and the width of my gear box at the lower bolt is 3 3/16" .This compares favourably with yours (I was using a retractable steel tape!)The box is marked GB8 1591. Sounds like I too have a Dommie 77 gearbox. I'll have to washer it up by 3 to 5 /16ths. The new bolt has arrived albeit without the nut for the timing end and is long enough to do the job. When you say you've never had need of a clutch extractor is that 'cos you've never had to remove a clutch (hoho) or 'cos you have some other cunning method? Presumably running the ES2 engine with a 77 box is not s prob?George

Submitted by john_tickell on Thu, 07/01/2016

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Hi George. My sprocket remover is a two leg type inherited from my dad, a life long motorcyclist, so is older than me! I have found once the clutch holding nut is remover the whole assembly just slides off the spline. As for running the twin gear box, no problem other than he kick start fouling the silencer. In fact now I have changed it over to the correct box I find it not as precise as the twin one which was no doubt why it was substituted in the first place. It had been attached to a side car for some of its life therefore the gear box would get plenty of use. John

Submitted by george_phillips on Thu, 07/01/2016

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Thanks John. Your help has been invaluable. I'll have ago at the clutch tomorrow and investigate a puller for the sprocket.Is there any way of dating my gearbox from the reference number on it in case I need spares? I'll also need model 77 spares list if I can find one - for the gearbox. I've already replaced the clutch pushrod thinking the box was an ES2 unitGeorge

Submitted by john_tickell on Thu, 07/01/2016

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I'm sure the numbers on top of the box mean something but I have no info. Hopefully some one reading this thread may be able to help. John

Submitted by george_phillips on Sun, 24/01/2016

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Hi John - hope you're still reading the threads. Would it be possible to tell me the width of the upper casing of the GB8 box?

Submitted by john_tickell on Sun, 24/01/2016

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Hi George. Will do this tomorrow morning but which width are you referring too? If its the top fixing width it's the same for both gearboxes. John

Submitted by george_phillips on Sun, 24/01/2016

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You've answered it John. Many thanks. Yes , it's the top fixing width I was after - to see if I needed to shim out any gaps between the gearbox and the mounting bracket.

 


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