English French German Italian Spanish

loose distributor

Submitted by john_evans1 on Mon, 29/05/2017
Forums
Singles

Having finally got my norton running reasonably well I am currently plagued with an obsure problem which has led to four roadside stoppages in two weeks.

The distributor..d81 ...comes loose,and the bike stops after much popping and banging.

The problem is that the clamp will not secure the distributor once the revs build up. It pops out of the housing and adversely affects the timing.

The body is a snug fit in the timing cover and the clamp is ok.It had a hexagonal nut which I exchanged for a a square variety which I made up. I can tighten this until the clamp distorts but it will not hold eveything in position.

I had contacted Al and Mike with a view to fitting electronic ignition but it seems I am stuck with the distributoras a means to mount any system hence not worth the expense unless I can secure the unit. I would like an E,I. system which dispenses with the current set up but it appears not to be available.

Does anyone have viable suggestions on how to secure the distributor? The clamping surface of the unit appears to be sound and a decent interference fit with the clamp.

Thank you

Submitted by michael_sullivan on Mon, 29/05/2017

Permalink

John: I would check the distributor drive chain system. I am thinking that the distributor drive chain has become stretched to the point that when running it is jerking the distributor driven sprocket. Check the conditions of the sprockets also. There is not much lubrication going on in there.

I would also check that the clamp is square on the inside where it clamps against the distributor body. It is possible, I think, that the distributor housing bearings are shot. Habe you been lubeing the bearings on some kind of a regular basis?

Let us know.....

Mike

Submitted by john_evans1 on Mon, 29/05/2017

Permalink

Michael.. thank you for your input.

The chain is not brilliant but I have run with worse. Sprockets are ok fortunately.

It is an interesting theory and one I had not considered because I assumed that a shaft turning freely would not suffer from whip.

The bearings are good and lubed montbly. I keet the lube hole centred by locating it with a dowel when setting the timing.

The clamp was distorted but i realigned it on a bar turned to size. When clamped tight it distorts again but cannot be rotated independent if the body of the points housing.

I will check out your theory tomorrow by running at high revs with the cover removed to observe the timing chain. I cannot think of any other way to do it?

John

Submitted by barry_carson on Mon, 29/05/2017

Permalink

i had a similar problem with a car i had. i fitted some new points with the new securing screw .started the car run it around a bit it was ok. after a quick burst up the road the distributor launched itself from its mounting clamp and was left dangling on the leads under the bonnet after a bit of head scratching i found it to be the new points securing screw was longer than the original one. so when the bob weights would fling out they would catch on the screw and jam the distributor throwing it out.

Barry

Submitted by john_evans1 on Tue, 30/05/2017

Permalink

I ran the bike this morning to test the loose chain theory.Apart from annoying the neighbouring dog there was no problem with the distributor coming loose. Does this uns ientific approach discount the theory?

Regarding the car distributor issue,my points have not been replaced nor have the a/r springs. The current issue has only developed in the past two weeks but results in a breakdown whenever I venture more than 10ml from home. I always fix it well enough to return but it is getting tiresome.

Are there any other ideas?Mike P told me he has never experienced this problem but does have used distributors available at £50 each..I want to fix this one if I can as there is no guarantee I will not suffer similar issues with another unit. If not,then it will be a good option.

Submitted by michael_sullivan on Wed, 31/05/2017

Permalink

John: Have you checked the condition of the clamping plate pinch bolt ill. B114, pn 415087? And the nut threads also.

Maybe the threads are stripped and letting the clamping plate work loose?

Mike

Submitted by john_evans1 on Wed, 31/05/2017

Permalink

Yes mike.The bolt is ok and threads good. I found it had been fitted with a hexagonal nut so made a square one to replace it. This does not turn.

Whatever the problem was,after the last breakdown I now need a new distributor.Stripping it down again revealed the mounting flange is now broken,no doubt due to flapping around when it comes loose.

A wanted ad has been placed.I do not want to pay too much as my problem may still exist.

Thank you all for the suggestions.

Submitted by john_evans1 on Sat, 03/06/2017

Permalink

Possibly there is a solution to my problem.

Examination of the distributor reveals the broken flange upon which the clamp mounts.

I decided to mount the unit in my lathe and machine away the damaged area.

I then machined an alloy sleeve to be an interference fit in the distrubutor shaft which retaining the standard o/d.

I heated the bush and drovehome.All that is required now is the drill and pin it to maintain position.

All looks good so i will report further once completed.

If it works then many other damaged units may be repaired by this method?

Submitted by john_evans1 on Sun, 04/06/2017

Permalink

Problem sorted..A brief test run revealed no problems from the ignition. I have to assume the casing had been breaking down for some time hence the fact the dizzy was coming out of the casing when the revs were high.

 


Norton Owners Club Website by 2Toucans