General Dynamo noise

[ozza]

Cheers guys.

Got the fan off this evening after 2 hours work removing rear cowling :bang:

Oh my god - how many bolts!

The centre of the fan is clearly fatigued with breaks in the metal so that does need replacing.

There is one shim between the hub and the fan.

There does also seem some play between the hub and the shaft so I will probably need to get one of those as well.

Not sure how free the dymano is meant to spin, feels a little tight maybe.

Also the cone looks like it's seen better days but not sure if you can order them.

Sure hope this fixes it. :worship:

 

[fiat500]

It sounds like there might be a chance that the fan was not spaced away from the cowling properly in the first place.
If the dynamo shaft is damaged it's probably best to get a rebuilt one as otherwise this means replacing the whole armature in any case.
The dynamo should rotate smoothly with just a bit of resistance felt as the brushes click over the commutator. Either the bearings are worn or dry or it has been badly assembled with incorrect tolerances on the end-play.
You can easily get the cones and I would order a few shims just in case.
I haven't setup a new one from scratch but I imagine it might be a bit of trial and error. In that case very handy you have slogged the long way like me and have all the cowling off the car.
Always look on the bri-i-i-ght si-i-de of life

 

[ozza]

The shaft is in good nick as is the key. I think the two area of play are the key to the hub where the hubs worn and the fan itself where it's fatigued.

Hopefully replacing these bits will prove successful.

I'll keep you posted!

 

[ozza]

Anyone know where I can get these shims from OD 46 mm ID 25 mm?

 

[Toshi 975]

Anyone know where I can get these shims from OD 46 mm ID 25 mm?

To be honest from memory I have never come across shims on any 500 or 126 engine that I have dismantled . There are large fabric/plastic washers either side of the fan mounting faces which I assume are there to give a good grip on the original fans then the alloy fans come with a large coned washer that bites into the alloy to get a good hold.

 

[fiat500]

There don't have to be shims but I have always encountered several behind the rear cone which locate the impeller to have clearance from the cowling.
I guess the perfect combination of components would negate the need for them.
My cones were steel discs with no plastic that I remember.

 

[Vitesse]

I think I am with Toshi I don't recall shims, only some form of fabric washer behind the coned washers, that I replaced with gasket cork ones.

It's a lot easier with the engine out of the car, as you can install the Dynamo into the fan housing and attach the fan, tighten it all up and spin it by hand to see if it spins alright and doesn't catch anywhere. If it does get a screwdriver and wedge it between the fan and the inside of the housing and bend the fan out of the way so it doesn't. Always works for me.

Tony

 

[stevehg]

Anyone know where I can get these shims from OD 46 mm ID 25 mm?

If you've got a tractor supplies place nearby, they might have some, or can order in.

A quick google threw up this one online, no idea how thick it is though...
http://www.thexmod.com/item_detail.asp?id=17654

cheers, Steve

 

[Toshi 975]

To be honest from memory I have never come across shims on any 500 or 126 engine that I have dismantled . There are large fabric/plastic washers either side of the fan mounting faces which I assume are there to give a good grip on the original fans then the alloy fans come with a large coned washer that bites into the alloy to get a good hold.

Sorry I take it all back. I thought I would check this out for sure got out a few dynamos and alternators. The first ones I looked at both had a shim behind the rubbery grip washers at the keyed boss end. Looked at a couple more and they had no shims so maybe they just got lost or were not necessary in the first place.

The top row come from an alternator, shim on left. Middle row shows 3 of the grip washers. One was missing but I found that they often stick to the fan. Bottom row are parts from a dynamo. I could probably find all the parts you need if you have not already ordered them.

 

[ozza]

Thanks Toshi.

I have a new hub and cone arriving today and the fan came yesterday.

There were no plastic, felt or grip washers on mine when it came off, just one metal shim between the hub and fan and one washer between the cone and nut.

Will try to reassemble the same way as see how it goes.

 

[fiat500]

Thanks Toshi.

I have a new hub and cone arriving today and the fan came yesterday.

There were no plastic, felt or grip washers on mine when it came off, just one metal shim between the hub and fan and one washer between the cone and nut.

Will try to reassemble the same way as see how it goes.

That sounds about right. I checked with one I purchased earlier


DSC_6292 by Peter Thompson, on Flickr

 

[ozza]

You've guessed it............... I needs some more shims, it fouls the front cowl(towards the back of the car).

Either the fan or hub is different

 

[Toshi 975]

When you say it is fouling the tinware is it real interference or just a bit of rubbing. The generator is accurately located to the crankcase and the fan to the generator . There is however some clearance on the holes for the tinware mounting bolts. I fitted the tinware, generator and fan to an engine last week and the fan was rubbing badly. I eased off all the tinware mounting bolts and gave the tinware a thump with a wood block in the right direction and it solved the problem.


The pics above show extracts from the early Fiat 126 factory service manual so running a dynamo. There is no mention of what I have been referring to as the grip washers. However most 500 and 126 engines I have messed with have them and they are definitely not an aftermarket addition. I guess that they do help with grip but I also wondered if they perform some sort of deadening function in terms of noise or vibration. They also serve as a thin shim being about 0.010" when compressed.

 

[ozza]

Hey Toshi.

I think this is all down the tolerances of new parts.

The fan did not fit the hub flat but some filing helped fit it.

The new hub was super tight on the shaft but I used the nut and washers to ease it into place.

Now with 1 spacer (all that was on there) between the hub and fan the fan rubs on the dynamo side housing (I only have the rear/top tinware off).

So tonight I will try adding some custom 0.5mm washers I have made up to off set the new fan from the tinwork and maybe a thump as you say.

My fear is by offsetting the fan back to clear the front tinware, it will foul the rear when I add that back.

Will have to try it tonight and maybe shim out the rear tinwork with washers if necessary.

Fingers crossed.

 

[ozza]

Fixed! Back on the road!

 

[fiat500]

Yay!!!!!!!!