I've run into a little problem with my alternator project. The fan spacer I purchased from Ricambio doesn't have enough standoff from the rear of the alternator housing to full seat to the bearing, so fully seating it on the shaft makes it come into contact with the housing itself. The spacer has .097in standoff, but there's .125in of a gap between the housing and the bearing (pic 1). I didn't measure this at first and tapped it home (pic 2), but was thankfully able to get it off without damaging the alternator.

Is there supposed to be a washer or spacer to add sufficient standoff? Does anyone know the specific distance needed or what the installed clearance between the fan spacer and the alternator body is? It feels like the spacer should be installed the other way around, but then it's not keyed for the fan.

I'm a little stuck here, so would appreciate any help you can provide.

Thanks,
Matt

About to leave to go to the dentist Matt, as soon as I get back, I will look at the installation on the '695' engine that I am building up and come back to you with the answer.

Hi Matt,

do these help? The first photo shows the hub still attached to the shaft. I can't tell if that hub is what you are showing in your pictures. The hub is internally keyed (Woodruff key) onto the generator shaft and it then has flat machined edges that key onto the fan itself.

On the white towell are four thin washers that get used if the fan rubs inside the housing and then finally on the towell a big cone shaped washer and a nut that holds it all together.

Highlighted on the parts diagram is the hub that is still attached to the shaft in the first photo and one of the thinner washers.

(The parts manual refers to the parts as hub, and washers).





Regards

Joe R

Back from the dentist,and I have had a good look at MY fan installation. I can't (easily) remove the fan-drive adaptor, but it would seem to have quite a fair bit longer 'shank' than the adaptor you have been supplied with. The only sensible way that I can think of for easily getting round the problem is to remove the 'woodfruff' key and then make some thin shims (or even 1 washer of the required thickness) to bring the adaptor out enough to enable it to turn without fouling the alternator body. If I can come up with a puller to remove the adaptor on my alternator, I will remove it, and measure the depth of the shank for you.

Hi Matt, just looked at an alternator I had to hand and the recess at that end is almost non existent , probably about 0.5mm so you may well have a missing spacer. On the other hand there is quite a deep recess at the pulley end.

I have managed to find my spare adapter (for a 'steel' fan)and like your one, the shoulder is less than the amount that the bearing is in from the edge of the alternator. My '695' fan is an alloy item, and it came with an adapter, which seems to have a much longer 'shank'. Being that the alternator shaft has a shoulder at the inner end of the thread (which the washer and nut at the outer side of the fan abut), I wonder of the factory push the adapter all the way down the shaft---only to the point that the outer edge of the adapter is flush with the shoulder. I still think that my "plan A" is the most sensible way to go if you are worried.

Thanks for the responses gents. I debated just pressing it until it's good enough, but any tightening of the nut would compress it closer to the alternator body. This appears to be the same adapter that all of the various parts places sell - it was marked "Made in Italy" and came in a generic bag from Ricambio.
tjmra - not entirely. I have the rubber pads that sandwich the fan itself. My problem is the fit between the 'lower' fan mount and the alternator body/bearing. It does give me an idea of how much threaded shaft remains with the fan fitted, but I don't know how universal the shaft length is.

I think I'll try to find some washers/spacers that fit as close as possible without rubbing any moving surface.

My next hurdle are the mounting studs/nuts for the alternator-fan housing themselves. I tried riv-nuts, but it looks like they're going to stand too proud and foul the fan itself. So it looks like I may be cutting them down and/or tack welding a stud in place. I see why people give up and just order 126 tin work, but I've got plenty of time, enjoy a challenge, and bought a new MIG welder, so...

[EDIT] - my online search for washers that meet the right criteria is not going well. Upon closer inspection, I might be able to grind down the alternator housing itself, until flush with the case screws, to provide clearance. I'll need to take some measurements, but that looks like it might buy me enough room.

I mentioned the deep recess at the other end just in case the spacer had been put on the wrong end .

Thanks Toshi. Everything else appears normal and the mount for the pulley has a significant standoff compared to the fan (approx 1 inch). I found some 17mm ID thrust washers with a 30mm OD that look like they will just fit and clear, so I ordered a few of them and will report back when they arrive.

I started to attempt to remove the housing to see if it'd be an easy grinding job, but the screws started to strip, so I'll wait for the washers (expected tomorrow). Based on pictures of 126 alternators online, a lot of them seem to have washers outside of the bearing as either a spacer or cover and/or the housing is flush with those hub bolts.

It's a poor image that I'm attaching, but the measurement of the standoff on this random mounting boss I pulled from the collection is 8mm; quite a lot more than yours, with 2.4mm Matt. Obviously, your plan will get you out of this, but something odd is going on with that component; I don't think the alternator is at fault, nor is it missing anything.

fiat500 said:

It's a poor image that I'm attaching, but the measurement of the standoff on this random mounting boss I pulled from the collection is 8mm; quite a lot more than yours, with 2.4mm Matt. Obviously, your plan will get you out of this, but something odd is going on with that component; I don't think the alternator is at fault, nor is it missing anything.

Click to expand...

That's what my generator/dynamo fan mount looks like. It has a healthy amount of standoff but is too small for the alternator shaft. These are those times where I wish I had a milling machine easily accessible. My tinkering knows no bounds, but my budget certainly does.

I think that there is a plastic material type washer item 4018701 on tjmra picture which fits before the fan. If this helps

This is the part on Axel site

That looks like a Magneti Marelli alternator, is it the one with the big green plastic cover on the other end?

Mine are Zelmot or aka Elmot but one thing I have noticed is the gap between where the woodruff key is and the start of the thread is much less on the picture in the first post than it is in the picture I posted on the thread about me changing the bearings and brushes. Also the gap between the other end of the woodruff key slot to the bearing looks less. You can see in the second picture where the bearing used to be to get an idea.

I can measure the distance from either side of the woodruff key if that helps at all?

vince1972 said:

I think that there is a plastic material type washer item 4018701 on tjmra picture which fits before the fan. If this helps

Click to expand...

I have that piece from the old dynamo install, but that isn't the issue at hand. That provides a damper between the fan spacer and the fan itself. My issue is clearance between the spacer and the alternator body.

Vitesse said:

That looks like a Magneti Marelli alternator, is it the one with the big green plastic cover on the other end?

Click to expand...

It is indeed a Marelli alternator. I'm not sure the woodruff key distances would help, as everything clears there. It's a "bottoming-out" issue against the alternator housing vice the bearing face that's the problem. Ideally, there would be a shoulder on the alternator shaft that would provide a standard standoff, but barring that, the adapter should have a taller shoulder.

JumpJet said:

I've run into a little problem with my alternator project. The fan spacer I purchased from Ricambio doesn't have enough standoff from the rear of the alternator housing to full seat to the bearing, so fully seating it on the shaft makes it come into contact with the housing itself. The spacer has .097in standoff, but there's .125in of a gap between the housing and the bearing (pic 1). I didn't measure this at first and tapped it home (pic 2), but was thankfully able to get it off without damaging the alternator.

Is there supposed to be a washer or spacer to add sufficient standoff? Does anyone know the specific distance needed or what the installed clearance between the fan spacer and the alternator body is? It feels like the spacer should be installed the other way around, but then it's not keyed for the fan.

I'm a little stuck here, so would appreciate any help you can provide.

Thanks,
Matt

Click to expand...

Forgive me if being very stupid (I don't have a 500) but does it go on the other way round?

jackwhoo said:

Forgive me if being very stupid (I don't have a 500) but does it go on the other way round?

Click to expand...

Nope

JumpJet said:

It is indeed a Marelli alternator. I'm not sure the woodruff key distances would help, as everything clears there. It's a "bottoming-out" issue against the alternator housing vice the bearing face that's the problem. Ideally, there would be a shoulder on the alternator shaft that would provide a standard standoff, but barring that, the adapter should have a taller shoulder.

Click to expand...

What I am wondering is, looking at the case it looks refurbished? It’s just the location of the woodruff key slot looks much closer to the bearing than it should be? I found this picture on-line which shows what the gap should be. Can you take it apart just to confirm the armature rotor shaft is sitting correctly and there is no room for it to allow a bit more movement? Maybe the bearing is not far enough down the shaft?

Vitesse said:

What I am wondering is, looking at the case it looks refurbished? It’s just the location of the woodruff key slot looks much closer to the bearing than it should be? I found this picture on-line which shows what the gap should be. Can you take it apart just to confirm the armature rotor shaft is sitting correctly and there is no room for it to allow a bit more movement? Maybe the bearing is not far enough down the shaft?

Click to expand...

That picture is actually pretty helpful to give me an idea of the gap - thank you! As far as the bearing position, I'm not sure that would matter, as the bearing is bound by the housing itself, so being seated further 'down' the shaft would only provide more exposed shaft. I would still run into the issue of the spacer seating to the housing vice the bearing. There's virtually no gap between the bearing and the housing, certainly not .030, so I'm not sure how it got to this point.

...unless I'm not understanding your point ??

JumpJet said:

That picture is actually pretty helpful to give me an idea of the gap - thank you! As far as the bearing position, I'm not sure that would matter, as the bearing is bound by the housing itself, so being seated further 'down' the shaft would only provide more exposed shaft. I would still run into the issue of the spacer seating to the housing vice the bearing. There's virtually no gap between the bearing and the housing, certainly not .030, so I'm not sure how it got to this point.

...unless I'm not understanding your point ??

Click to expand...

If the alternator is the same as the Zelmot one in the way it goes together. One of the bearings, is as you say, located in the casing. In this case the one next where your issue is. The other is actually pushed down the shaft before reassembly and then it pushes into the housing at the pulley end when you join the two halves together to reassemble. If that bearing has a bit of wiggle room to slide down the shaft a bit more it would allow the shaft, with the woodruff key slot, to stick out further at the end you are having the issue with. Of course this is all irrelevant if both bearings are pressed into the casing at each end. I have never taken a Magneti Marelli apart to see.

It looks like the fan spacer is correct which would suggest the problem lies with the alternator? I have seen several pictures of the bearing at the pulley end, where the bearing appears to deeper in the casing or slightly further out.