Just got some new brushes for the dynamo, can anyone tell me what's involved in replacing them.
Thanks Claudio

Claudio,
I've attached a schematic of the generator - you should be able to work it out from the diagram. I'll also dig out my generator and take a few photos tonight.
Chris

Here are the photos.

So -

1) Remove generator
2) Remove pulley (don't lose the small woodruff key)
3) Remove the two long bolts that hold the ends of the generator on the stator
4) Remove pulley end of generator
5) Replace bearings while you are at it - optional
6) Replace brushes - each one is held in with a phillips-head screw and tensioned against the commutator with a coil spring
7) Test/check stator & armature
8) Reassemble - you'll need to hold the brushes back into the holders when you replace the pulley end of the generator.
9) Replace and tighten the long bolts
10) Replace pulley
11) Test generator and reinstall

What could possibly go wrong .....

Chris

Chris, thanks for all that info, just a couple of questions

At the risk of sounding thick, is there any reason why the brushes cant be replaced without having to remove the dynamo, from the diagram it looks like you can just remove the pully end in situ?
The only reason i ask is that it seems like some of the tinware needs to be removed to get the dynamo out?

Claudio

You can try - I've never done it but others on the list may have had success.
It may prove to be difficult as the nuts on the ends of the long bolts need to be controlled somehow. I might remount mine on the spare tinware and see how easy or not it is to dismantle.
I guess the other thing is the bearings - by the time the brushes need replacement, so might the bearings. Also, if you've got it all apart you can check and clean it well so it's then good for another 40 years .....
Let us know how you get on,
Chris

Makes sense to remove the whole thing, how much of the tin ware do i need to remove
Claudio

I would guess at least the top where the airbox & carby linkage are and the front piece holding the generator so you can get at the impeller. There is another woodruff key here as well.
It's fiddly but not impossible.
When you are reassembling it, mount and tighten the generator nuts but leave all the tinware screws loose until you get everything in position, then tighten them up.
If anyone else knows of an easier way, please chime in.
Chris

Chris

Thamks

Hpefully should be fairly straightforward, although even the smallest of jobs tend to turn into a drama when i get involved.

Claudio

Claudio,

I think you will need to pull the dynamo out. It will be possible to remove the front pulley and brush end plate when the dynamo is still mounted to the car, but getting the brush end plate back on will be the difficult part. If you look at Chris’ last photo in post #3 you can see that the brushes are spring loaded towards the commutator (Commutator is not in the photo but it is significantly wider that the bearing hole in the brush end plate).

With the dynamo out of the car you need three hands to put the end plate back on. (Step 8) Two hands to hold the brushes wide enough apart to clear the commutator and one hand to then ease the end plate into position. With the dynamo in the car I think this would be difficult to say the least.

Please note four important things I have learnt:
A) I mention the removal of spacers. The spacers all look the same, but they are different thicknesses. Please record where they came from and put them back on the same relative positions. If you don’t, you run the risk of having the fan rubbing on the inside of the tinware at the back, or the belt being too tight or lose at the front.
B) There is a potential to drop something inside the tinware. Be careful here, anything dropped inside the tinware takes a bit of work to get back out again.
C) The dynamo has a bit of weight to it so be ready for this.
D) Patience.

Historically what I do is:

Slip the rubber trunking off the air cowling at the back. (my arms are small so I don’t have to remove the any of the cooling tinware to do this, I reach over the top with a little difficulty).

Get a 17 mm socket on a short extension and reach around the back of the tinware and locate it on the nut that holds the fan (impeller) to the back end of the dynamo. (This is done through the opening you have just exposed by pulling the trunking off) (See my photo that shows what it looks like from the back.)



Put a ring spanner on the nut on the front of the dynamo to lock the shaft and loosen the fan nut at the back with your socket. (If at this point your body is contorted into an odd shape and you can't actually look look at what you are doing, you are on the right track.) Be careful, after the nut there is thick cone shaped spacer and then after that there is the potential for flat spacers before and after the fan unit. (See my second photo.) Take the nut off then the cone spacer and then any flat spacers. You will get to the point where the next part in sequence is the actual fan unit. Any spacers after the fan unit will only be evident after you pull the dynamo out. They will be hanging onto the end of the shaft. (I think these are the most important ones. They control the position of the fan unit within the tinware. Too many spacers and the fan rubs at the back. Too few and the fan rubs at the front. You only find this out when everything is back together correctly. If it is not correct you basically have to pull the unit out again and add or remove spacers.)



The dynamo is now held in place by two nuts that are visible when you look from the pulley end of the dynamo and a strap that goes around the dynamo body itself that is held in place by a pin. Two nuts are simple; the strap needs you to throw yourself under the car to see how it works. Basically you loosen the bolt that holds the strap and then you push the top pin out. This for me is always the difficult part (especially putting it back). Can't show a photo of this cos guess who does not have motor at home at the moment....

Then follow Chris’ notes 2 through 11.

Send me a PM with your email address and I can send you a document that will help.

As a general note to everyone, you can find plenty of sources of information on these cars that I would say are must haves. Firstly is the Haynes type workshop manual. A step up from there is a reprint of the factory manual, and finally is a more complete set of documents that you can get on CD. This includes (in PDF readable / printable form) the factory workshop manual, parts list, bodywork parts list, user manual and finally a second workshop type manual. I find the CD to be excellent. You may never want to rebuild your engine yourself, but the wealth of detail that it has on every aspect of the car is worth the outlay.

(Oops, if you are lurking here, perhaps we can put togehter a sticky for these sources?)


Regards

Joe R

I've attached a photo illustrating what Joe is saying about the tightness of fit between the commutator, brushes and the housing.

I'm with Joe - somehow you need to get the generator out.

Chris

I meant to attach this one as well - it is the metal strap that holds the generator to the support.

Chris

Claudio,

down under we are working like a well oiled machine....

Chris' second photo shows what I could not. You can see the bolt that you need to loosen and on the other end of the red strap you can also see the pin I was takling about. Loosening the bolt takes pressure off the pin so it can removed.

Regards

Joe R

Chris/Joe

Thanks for all the info, i had a go at trying to do the job with the dynamo in place, got as far as getting the pully off and slackening the 2 nuts off the long bolts, from this point it became obvious that the dynamo needs to be reomved.
Cant believe the amount of work required just to get the dynamo out, the strange thing is that i decided to delay the job until after a local classic car show and having put the pully back on and recoconnected the 2 wires the dynamo now seems to be working and the dash light goes out on start up
In winter i will pull the engine out replace the brushes, remove all the tinware and spray them and detail the engine and engine bay.
Claudio

littlemouse said:

Cant believe the amount of work required just to get the dynamo out, the strange thing is that i decided to delay the job until after a local classic car show and having put the pully back on and recoconnected the 2 wires the dynamo now seems to be working and the dash light goes out on start up
Claudio

Click to expand...

Italian cars - don't you just love them .....

Chris

Joe R.

A well written description, but a ten min job here masqueraded into a 90 min frustration.

Undone all the nuts and bolts, everything, but dynamo won't come out. Can feel the fan loose and the nut thing over the shaft in the middle of the fan loose, but the dynamo will not come out.

I've not taken the tin work off as that is a faff, so am reaching through the hole which is not too much of a faff in itself.

Aware of the woodruff key but is that that is holding it in? Maddening....!

Any help appreciated.

Thank you

T

It might be friction wedged as it's a tight fit in the aluminium cradle and a nylon "pip" on the dynamo locates it in that cradle. I had to use some gentle brute force

I have a selection of tools for a job like this ...

Chris

good morning Chris;
So THAT'S how you do it down-under!---wondered where I was going wrong

The only problem is, as the old saying goes, when you only have a hammer, everything looks like a nail ...

Chris

Bambino said:

I have a selection of tools for a job like this ...

Chris

Click to expand...

Everyone I know says I am 'tool' so I never have any issues......

(There is every chance you will only understand the connotation if you live down under.)

Joe R