Ihave had a n oil seal collapse and oil spewed out from the Magdyno oil seal.
have removed the oil seal, the old fibre one, which had collapsed completely.
But when I looked at the shaft it appears to be offset as shown by the orange circle in the pic.
( the pic isnt of my bike , I just used it to illustrate)
I am wondering if shimming is the best option, but worried that maybe the teeth of the gears may now be worn. The mesh well and have a little play. If i shim the Magdyno will it create too much back lash and is it a problem. I can fit a new oil seal, I now have some but the shaft is creating a gap to the side of it when I try to fit it.Obviously not good.
Advice apreciated.



Paul C

Hi Paul..can you post a picture of your engine?...Ian

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

I could but need to take the cover off again.
I have managed to clean the old oil seal recess and fitted a modern oil seal. Have fitted the gear and the cover.
The timing is out so need to strip down again.
So will take a pic.
Just worried that as I am taking it to bits again I was hoping to get advice on the possible need to shim.

Paul C

Is that aluminium seal holder fitted in the correct location? Could it be to high up in the case?

Henk.

email (option): ahum@quicknet.nl

OK Techies,

What about shimming the magdyno? How do you know you have it correctly?

I have to do mine.

Cheers

email (option): britool51@hotmail.com

I apply the same technique as I use for the gears of my lathe. Insert a strip of paper between the gear teeth; the gears must then rotate freely. If you feel too much resistance, adapt the shim thickness.

email (option): viaconsu # planet dot nl

Hans, you just beat me to it!


If it’s already on the bike and you are just taking it off to work on then replace it use the shims that were there when you took it off. Otherwise, too much play between the magneto drive pinion and the idler pinion will be noisy and too little will whine and not be nice to the ears or the components. I’m not sure what the clearance should really be but I put a fag paper between the gears and turn the engine over. If the paper rips another shim is called for. It is a pain repeatedly tightening down the magdyno to test the clearance but it is a one-of job.

Cheers
Pete

email (option): petercomley@web.de

A problem , now I have had another look (took off the cover and gear.)
You can see the new oil seal I have fitted but found i can move the magdyno side to side (with slight pressure with a lever either side of magdyno)
It appears tight with the strap securing it.

1st pic shows how far left I can get magdyno.



2nd Pic as far right I can get it



3rd pic as far left again



As you can see slight change in position of shaft to oil seal. After I moved Mag.
This isnt good.
looks like I may have to remove Magdyno.
Is it possibly the locating pins underneath which bed on the engine, maybe worn.I fear they may be a bit.

Paul C

Just had a look at some drawings.
The engine should have slots which allow side movement of the Magdyno, so it can be slotted into the hole where the gears are.
The Magdyno has 4 pins on it which should prevent movement towards the front of the bike and to the rear, which means the Magdyno should not do what mine is, sliding to the front of bike and to the rear.
Need to take off and have a better look.

Have taken the dyno off and can see asome wear on the engine mounting for the mag.
The pins have worn a bit off the alloy away.
Looking at the mag ( a reconditioned unit )


it looks ok. didnt check before fitting the replacement.


How can I get over this?

Another photo shows the wear a bit clearer.

I did Kit's and his was the same, there was more wear on the points side pins than on the other, and a similar amount of wear on the mount on the crankcase,what was happening is that it angled the magneto back slightly so the end of the shaft appeared high in the hole. I got a better mag body and this improved it's positioning slightly, his pins were missing, so I put a Harley crankcase roller in there (perfect interference fit)If anyone else needs any let me know

email (option): davmax@ntlworld.com

Badly worn crankcases can be recovered by skimming the mag platform on a milling machine. Index (zero)of an unworn part of the casting and take off an amount equal to a standard thickness of sheet metal. (20 gauge or 18 gauge will normally be sufficient.)
It is then a simple case of making a plate to fit under the mag of the appropriate material thickness to return everything to the correct position.
Mag bodies will only take a light skim without breaking into the bottom of the drive end housing, and obviously the locating dowels must be removed first.
Correct position here can be restored after machining by shimming using standard Lucas magdynamo shims.
If the mag body is very badly worn another trick is to remove the locating pins and spot face the area directly around the pin to provide a flat, level surface at the four points. Using this method rather than skimming the whole mag base allows more material to be removed...Round spacers (like washers) of the correct thickness can then be fitted to restore the correct hieght from the mag base to the armature centerline. Non standard locating pins may be required as well if the base is heavily worn so that the correct amount of pin protrudes after work is completed...Ian

So machining or maybe welding up the hole, is only options.

Must be a possibility to make some modified pins to replace in the mag for these slots to cover the problem. The mag will still slide to wards the gears but will spread the streaa across the sideofthe pins. They will needto be lined up well.

I searched for this issue in the forum here and came across this entry.

This issue with the worn-in engine halves caused by the Magdynamo is giving me a bit of a headache in my restoration.
We also had the idea of placing a thin metal plate between the two components after leveling the surface again with the milling machine like a few of you guys also had.

I have a few more detailed questions and hope you know more about them.

- The most important thing: How did you clamp the two engine halves in the mill?
Did you build an adapter plate and what did it look like? I'm still not entirely sure how to best mount this.

- I was thinking about removing about 0.5 to 1 mm from the housing halves to level it out again. I wanted to do the same thing with the Magdynamo, although I'm not so sure whether its housing walls are too thin for something like that. Afterwards I would have attached a 2 mm metal plate to the housings to compensate for the "loss".
A good friend said it was enough to remove something from the motor halves and just carefully level the Magdynamo on a glass plate with sandpaper (of course without the 4 retaining pins). What's your opinion?
I also wanted to mention - the cover of the Magdynamo (on the side of the gear) should not be sanded down when leveling... it is definitely too thin with its walls. But I measured the engine halves and saw that the cover doesn't rest at this point either way and is therefore "hanging in the air" so no compensation needs to be created here.

- Which brings me to the next point: How would you fix the metal plate? I would have anchored it in the housing with 4 small countersunk screws, if that's possible and I have enough "flesh" on the support surface... but I'm not sure - especially since such small threads in a cast aluminum are probably not productive (except with Helicoil threads but then it will be a doctoral thesis... :sweat_smile: ). Maybe you can overlap the metal plate on one side and attach it there.

Attached you will find a few pictures for visualization. The picture of the engine halves on the workbench is not mine, but a demo picture from the internet (I know these are not matching engine halves, etc.), I was only concerned with the worn contact surface.
The photo with the halves already welded is mine. The depressions have already been welded on here and I would now like to level them as mentioned.

The pictures of the Magdynamo are also mine - please look at the bottom of it - how worn it is.

I look forward to your suggestions and ideas! Thank you very much!

email (option): beachbraker@gmx.de

If I see more of them I will make a Jig plate Florian, but for now I have a large angle plate I mount to the timing side.
Only take just enough material to clean the faces, I would hope it would be well under 1mm
For the magneto remove the mounting pins and make some new ones that are a good fit in the crankcases.
The spacer under the magneto can be located using the four pins.
Small adjustments can be made using these.

https://pesltd.uk/?product=66-2347

Think long and hard before taking a cut.
Paranoia is your best friend.

Mark

email (option): pes.sales@btconnect.com

Thank you so much Mark for your incredibly valuable tips in this case.
I take your words very seriously and appreciate them very much.
Thanks also for the tip about the holder in the mill.

I'm also more of a fan of this - removing as little of the original material as possible and preserving everything in its original condition as best as possible.
Therefore, in this case I will try to apply a little more material to the worn areas on the engine halves and then ideally just remove the protrusions in the mill.
As a result, I would have to estimate 0 - 0.2 mm of removal on the surface of the engine halves.
With the dynamo I would also do it as you recommend - unfortunately I can't weld anything on here... but I think here too I'll only remove a minimal amount of material to create a flat surface - nothing more.
I take out the pins and replace them with better ones - crescent-shaped ones, which distribute the forces better across the adjacent material.

As I make progress I will share it with you all.

email (option): beachbraker@gmx.de

The magdyno platform wearing is very common as no one ever checks if the strap is tight. They put the magdyno on the bike and tighten the bolt and never ever check it again.

Before every time you ride your M20, put a spanner on the bolt and make sure it is tight!

I once saw an M20 with the magdyno literally dancing around on its platform to the point I was surprised the gears were meshing. The unconcerned pilot kicked it into gear & chuffed off.