Hi all

A couple of years back I had a mag destroy it self mechanically down to a mechanical problem with the Dynamo - key ways elongated & it shook the mag armature & bearings apart

Rebuilt with new bearings, repaired mag armature, new Dynamo armature,keys

When back together, I put on an nos Dynamo drive gear & reused the mag fibre gear, a modern repro it seems

In hindsight when the Dynamo & magneto were bench tested - the gear mesh felt a bit rough - not as smooth as I would have thought

Roll on many miles & just before the irish trip I began to hear a creaking sound, a dry bearing sound I thought - identified coming from the magdyno - I disconnected the Dynamo and ran without it - noise disappeared - doing about 450 / 500 miles in total until I removed it last weekend

Bearing on drive side breaking up again - the creaking noise being the fibre gear touching the body of the magneto - the bearing outer face was grooved as if it had been excessively loaded - lack of grease wasn't the cause - insulator showed signs of movement - almost worn through

So a simple rebuild - bearings, new insulators, nos Dynamo gear, nos Lucas mag fibre gear - so I thought

Testing various gears here new & used it seems some run a lot smoother together than others, in one direction more than the other - this explained the rough feeling I had before and I am now wondering whether this roughness could over the period of time caused damage to the bearing & caused it to break up - a constant vibration / roughness cannot help things - anyone seen this before ?

So tonight I choose to use a different mag body, one with 2 x E15 bearings (I had these available) as opposed to an E15 & E18 as on the failed magneto

Insulator in - drive side bearing in - keeps falling out - checked with 2 bearings & a bearing installing tool I had machined - even tried different insulators - no difference -

Points side bearing is spot on

I gave up in the end

Has anyone had problems like this before - modern bearings or insulators

Do these drive side bearings need to be pressed in or can they be tapped in ?

Some advice would be great fully received

Jo'b

email (option): Jonnyob1@googlemail.com

The replica magdyno drive gears are of Indian manufacture and needless to say the gear tooth form is incorrect...

This makes for a rough and noisy drive as described..and also the risk of an overtight mesh between the gears..

The result?..Overloaded bearings and failures...

NOS fibre gears are not so common these days...I always buy them when I see them and have fitted NOS ones to all my mags...

In the absence of a NOS gear a good used one is a better proposition than the replicas...

Also, don't think the incorrect fibre gears will 'run in' with time...They won't...I've already tried that previously without success...Ian

email (option): ian@wright52.plus.com

P.S....To cure loose bearings in the past I machined up oversize insulator 'cups' from nylon bar...Fitted with a bit of bearing fit Loctite they cure the problem of loose bearings...

Measure everything carefully before producing the 'cup'...Too much interference between the body, bearing and insulator and they will be impossible to fit...Ian

email (option): ian@wright52.plus.com

Hi Ian

I arrived at this same conclusion this afternoon

The disengagement of the gear was rough in feeling & the Dynamo gear sat very deep in the groove of the fibre gear

It must have had a negative effect on loading & stress on the bearings - lesson learned

I changed things around - new bearings, greased & fitted - nos fibre gear - narrow type, perfect engagement & disengagement

Just some fine tuning with shims behind the bearings to eliminate end float & the magneto is a good un again

Have you got any idea on end float - zero or perceptible ? Be interested with your experience in mind

BEST REGARDS

JO'B

email (option): Jonnyob1@googlemail.com

Hi all

Any idea on what is considered acceptable end float on the magneto armature ??

Should there be any ??

Best regards

John

email (option): Jonnyob1@googlemail.com