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18D2 dissy oil seal?

Submitted by robert_tuck on Tue, 26/07/2016
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Nortons - General

One recurring problem I have is oil fouling the points, I don't think there is an oil seal inside the dissy, an O ring on the outside, yes, but inside the body??. I'm thinking of installing another breather ,perhaps on the inlet cover with a Duckbill type valve. Also possibly drilling the crankcase on the timing side to lower the oil level on the timing side , anyone done this?.

Submitted by ian_allen on Tue, 26/07/2016

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If your distributor body doesn't have an oil seal then it is from an ES2! Might be better to find one from a Dommi with the seal. I'm assuming its a Dommi being an 18D2 as opposed to the ES2's 18D1.

Regards.

Ian.

Submitted by robert_tuck on Tue, 26/07/2016

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Hi Ian, so there is a seal?, Any idea where to get one ?, I can remember stripping the dissy about 20 years ago but don't remember the seal.

Submitted by robert_tuck on Tue, 26/07/2016

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After a fruitless hour looking I have come to the conclusion that there is no seal in the design. And yes it is an 18d2.

Submitted by ian_allen on Wed, 27/07/2016

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Hi Robert.

Give me a day or so and I'll send some photo's. I replaced the seal in my Dommi's distributor a while back - it was quite pricey for a simple oil seal - I think I got it from Norvils'. Incidently, I also have a 1960 ES2 hence my original comment!

Regards,

Ian.

Submitted by charles_bovington on Thu, 28/07/2016

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I did not find an oil seal in my 18D2 when I dismantled it to fit new springs and correct problems of unequal timing and points gap. I believe you can machine the body to fit an oil seal such as that offered by Norvil.

Submitted by ian_allen on Thu, 28/07/2016

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Hi again.

I've just looked at my ES2 and its distributor is marked 18D2 and like I said, it doesn't have (or need) an oil seal. My 58 Dommi, which has been in the family since 1964, definitely has the seal and its distributor body is machined to take it. These distributors are liable to break the ring where the timing clamp fits- I fill the gap on mine with araldite to give a bit more support - so after all these years may have been swapped. The parts book lists the ES2 body as 21459. The Dommi's as 20684 and the seal as 188643. These are from the 59 list.

Hope this helps - I guess you'll have to look for one with the seal.

Regards,

Ian.

Submitted by ian_allen on Fri, 29/07/2016

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Hi Robert.

No, it fits inside the body under a nylon spacer under the auto-advance gear. I'll see if I can photo it tonight - it's all in bits.

Cheers,

Ian.

Submitted by ian_allen on Fri, 29/07/2016

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And here's one of the assembly. It is worth checking the clearance between the auto-advance gear and the points back plate when it is all assembled. I once discarded a rather tatty looking washer from behind the sprocket. Several miles later the auto-advance gear hit the plate and self desructed!

You can also just see where I've filled with araldite the inside of the ring that the timing clamp fits onto to provide a bit of extra support.

Hope all this helps.

Ian

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Submitted by robert_tuck on Sat, 30/07/2016

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It certainly does!, I too have had an 18d2 explode ( many years ago) . The tatty copper washer behind the sprocket must wear and allow too much end float . I can see another strip down looming. Thanks mate!!!.

Submitted by robert_tuck on Sat, 30/07/2016

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I really did not want to disturb the motor again so soon after my clutch and gearbox issues ( now solved), however if its coming to bits I would like to incorporate some means of strobe facility for ignition timing, thinking of adding a hole and grommet to the primary case in the alternator area and marking the alt/stator , Not really worried about orriginality more concerned about oil tightness, anyone done this?.

Submitted by ian_allen on Sat, 30/07/2016

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Get an old spark plug, discard the washer and knock the ceramic innards out of it, cut a thread through - say 5/16 CEI I think - and add a piece of studding, about 3" should do. Set your timing disc up on the bike. Put your ignition on full advance and lock it using the screw that holds the points cam and a suitable thick washer. Turn your crank to the required ignition point, screw in the spark plug body then the stud until it makes contact with the piston and lock it off with a nut. Re-check. You've now got a tool that'll set your crank at the right point without having to go through the rigmarole of taking the chain case off and setting up a timing disc and it's certainly more accurate than trying to measure fractions of an inch at an angle through the plughole!

Submitted by robert_tuck on Mon, 08/08/2016

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I've got the disributor in bits, the points are very oily so the seal is the likely culprit, I've got a new one but getting the old one out is the problem . wondering if pressing the shaft bush out and the seal with it is the way to go. Tried heating all up to 200 f but did not help . Also I found a large copper washer between the steel spacer and housing , don't think thats standard. After some research ,yes it is, and it has to be between the spacer and case,not next to the sprocket.

Submitted by robert_tuck on Mon, 08/08/2016

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All done now, the new seal was a couple of thou big so was a job to fit. Had to press out the bushing to drive the old seal out and heated up to 250f . It can all be done with threaded rod and washers and a big socket. After servicing everything electrical!, I find that the HT spark is far happier jumping the coil terminals than going down the copper core ht to the distributor, the lead checks fine with no resistance at all ,but its dud anyway somehow. One 99 for the classic TT, thank god. I can move on to the next bike, only 2 to go and a van to fix.

 



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