How to refurbish your alternator (S3)

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Lucky
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How to refurbish your alternator (S3)

Post by Lucky » Sat Jul 11, 2015 7:06 pm

So, I recently took a couple of alternators apart, mostly to make them look prettier it also was a good opportunity to clean them out and make them work better. Which is always good. I got an increase of half a volt out of it, using no new parts at all, just cleaning out loads of carbon build-up and grime. I thought I'd pop up a quick How To for anyone wishing to do the same so here we go.


First step is to get the pulley off. This has a big nut (22mm if I remember right) and spring washer holding it on, and because it mounts to the central spinny armature part of the alternator, it's hard to undo because it ermmm... spins. If you have an airgun impact wrench it'll be a piece of proverbial. I haven't so I had to get it in the vice. I wedged a couple of big bolts in the pulley sheave to lock it in place and stop it spinning and then used a big breaker bar. I only used bolts cos they were handy, and ~12mm bar or whatever would do, and if you want to avoid knackering the pulley then some kind of padding (I used old rubber hose) might be an idea too. I'd also advise soaking everything it WD40 or GT85 or the penetrating oil of your choice at least a couple of days before trying to undo anything. Some of the fasteners will be a right PITA to get out if you chew the heads up...

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Behind the pulley will be two spacers, a thin washer and a thick roundel. Make sure you note the order in which they go; the thin one seals the front alternator bearing and the thick one spaces out the pulley from the front housing. You will then be faced with three bolts that essentially hold the two halves of the housing together, here arrowed red;

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and on the rear of the device, there are some connectors for the electrics (which you've already undone in order to get the thing off the car) but the output post has an insulating spacer and nut on it that will need removal too. We'll come back to the bush retractor hole (my terminology, lol) later

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This is the output-to-battery post. Again, note the order the fasteners go on. The eyelet for the power cable goes between the first nut from the left and the spring washer

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Right, back to the front cover again. Now you've undone the three long bolts (I'd recommend a socket rather than screwdriver, they will be seized!) you could be able to lift the cover off complete with its bearing. You might need to pry it up gently or clout it from the back-side with a soft-faced mallet to persuade it. There are three other bolts in the front cover, shown here;

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These fix the front bearing retainer plate and unless you want to change the bearing, there's no need to remove these. They bolt through a triangular-ish plate on the inside of the housing that holds the bearing captive thus;

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with the front housing off, there are another pair of spacers on the central shaft you need to find before they fall off. They are the same as the external ones, a thin washer and thick spacer, but go in the opposite order thus;

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It's not essential for yours to be quite that rusty and horrid, but if the alternator's been stood for any amount of time the odds are they won't be beautiful. They clean up OK with fine wet'n'dry. Now, unless the rear bearing is really tight, you ought to be able to wriggle the armature out on its shaft. If not, put the front housing back on, do the pulley nut up to hold the housing captive and drift the shaft out from the rear bearing by whacking the back-side of the front housing. Then you'll end up with this;

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One of the alternators I did had been stored for ages and the armature was properly rusty and full of spiders nests. And spiders, eeek. Unfortunately, because of how it works, the thing has to be made from iron (it whizzes round inside the coil windings, magic happens and electrickerty is made). This means it and the attached cooling fan, will be rusty even on a working unit

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I cleaned mine out very carefully with soft nylon brushes on a Dremel, so as not to damage any of the wiring. which is pretty robust, to be fair but better safe than sound. Then I used a shedload of brake cleaner sprayed and wiped off. It's amazing how much grime comes out! Once dry and clean, I rust-converted it which seals the surface to stop it rusting further but doesn't interfere with the spinny-magic-electricness qualities of the iron

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Inside the rear housing are some more fixings that hold the electronic unit in place. This model alternator has internal regulator rectifier stuff wired in, which is neater and straightens the current generated both in terms of AC/DC and voltage fluctuation. It's all in one block hard-wired to the copper coils and retained to the rear housing by three screws;

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The circular housing where the contactor bushes are labelled above is where the rear bearing of the armature seats. Those three screws are made from cheese, and you will chew the heads up trying to get them undone unless you're super-careful. Access is tight, and I used an impact driver with a long socket extension to reach in and loosen them off. When I re-built the unit I replaced them with stainless dome-head allen bolts as it's a lot easier to get in with a ball-headed allen key should it ever need re-stripping. The two bottom bolts screw through a plastic U-shaped bridge piece that surrounds the brush housing, the top-left bolt goes through the electronics housing directly. Once you get them out you can separate the electronics unit from the rear housing completely;

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Again, I Dremelled this clean and used a load of brake cleaner. Once that was done, I masked off all the wiring and electronics to just leave the iron ring. This I etch-primed and sprayed body colour for prettiness. Now it's as apart as you want to make it really. Unless the alternator was knackered there's no real percentage replacing bits for the sake of it. It'll be pretty obvious if the bearings are mullered cos they'll grumble and feel notchy. It's the same as replacing any bearing; if you don't have a press you'll have to do it the old-fashioned way by drifting them off and then re-seating the new ones using a suitable-size socket on the INNER race. You can de-solder the electronic components if any need replacing. I didn't because one I knew worked and the other I was willing to take a punt on! So now you have a nicely cleaned, painted (if you want) set of parts. I replaced all the fasteners on mine too rather than use the eezee-rust eezee-strip originals

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Now, how to put it all back together? It's easy enough re-seating the windings and electronics; you might need a gentle tap with a soft mallet to re-seat the copper is all. Then screw down the electronic to the backplate, remembering to put the bridge piece back in too. The main trick concerns the spring-loaded contactor bushes. They press against the copper rings by the rear bearing of the armature and collect that magic that's been accumulated. Because they're spring-loaded you need to retract them to get the bearing back into it's housing. But how can you hold them in and insert the armature? It prevents access from the front, and the rear housing is a blind boss. Remember the "Brush retractor hole"?

what you need is a strong, but thin, steel pin to stick into that hole from the back. I used a big darning needle but a small allen key would be just as good

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Now, from inside, press home the spring-loaded bushes and slide the needle through past the bushes to keep them in place. This is where small hands, and preferably three of them, is an advantage. I've got neither so it was a bit of a faff. The best technique I found was to press the bushes home with an allen key (as it already goes around a corner, handily) while leaning the housing onto the needle against the bench. As soon as there's clearance the needle will slide across the top of the bush. eventually, after much faffing you'll end up with this;

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which isn't the best pic but hopefully you can see in the pink ring that the needle is retaining the bushes happily. Now you can tap the armature rear bearing home into its housing. It should go in fairly easily, it's not a massively tight fit. Put the spacers back on the front; thick one nearest the armature fan, thin one against the front cover bearing. Then the front cover and do up the three long bolts holding the two halves together. And there you go. One lovely shiny alternator, better than new

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I painted mine with Projekt Kote enamel because it's the silveriest metallic paint I've yet found, though it doesn't like lacquer and I expect it will degrade quite quickly from engine bay heat. However, hopefully before that happens, I'll have a nice polished alternator to replace it with anyway. Now bask in the glory of your lovely engine bay upgrade and worry about how to get the rest of it looking as nice. You might also need to worry about how to get the pulley nut back on (don't forget the spacers before you put the pulley on). I took mine round to my local garage and begged them to whizz the nut up with their windy gun, which they were happy to do free of charge. Happy days!

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ian65
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Re: How to refurbish your alternator (S3)

Post by ian65 » Sat Jul 11, 2015 9:33 pm

what a great write up s(c)
That alternator looks mint now Nik h[b[ top work......... very inspiring..... I've been meaning to refurb mine but didn't want to knacker it up..... this has given me the confidence to crack it open now, cheers 0-0
1986 Series 3 13B Turbo II
http://rx7fb.com/viewtopic.php?f=2&t=2400
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

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DKWW2000
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Re: How to refurbish your alternator (S3)

Post by DKWW2000 » Sat Jul 11, 2015 9:41 pm

Clear, concise & easy to follow, thanks. I will put a add in wanted as I guess mine could do with a refurb.

Thanks for taking the time. s(c)
RX7 FB S3 - RX7 FC TII Vert
Rotaries Previously Owned:-
2 x NSU Ro 80s - 2 x S2 RX7s - Suzuki RE 5 - DKW(Hercules) W2000 - Norton (Krauser) Commander

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DKWW2000
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Re: How to refurbish your alternator (S3)

Post by DKWW2000 » Wed Aug 12, 2015 6:04 pm

Managed to get a spare & followed Nik's instructions & Refurbed.

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I also replaced the Bearings & Brushes but got carried away with the polishing mop :oops:
Green paint is John Deere Tractor
I think I might give it a coat of lacquer.

Thanks Nik W(p
RX7 FB S3 - RX7 FC TII Vert
Rotaries Previously Owned:-
2 x NSU Ro 80s - 2 x S2 RX7s - Suzuki RE 5 - DKW(Hercules) W2000 - Norton (Krauser) Commander

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ian65
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Re: How to refurbish your alternator (S3)

Post by ian65 » Wed Aug 12, 2015 7:18 pm

bloody hell Pete that's nice h[b[ ..........................................................and you do like your tractors in that part of the world don't you, what with TWOCing them and painting everything the same colour as them :)
1986 Series 3 13B Turbo II
http://rx7fb.com/viewtopic.php?f=2&t=2400
1992 Peugeot 205 1.9 GTI
1975 Honda SL125 Street Scrambler

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DKWW2000
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Joined: Sun Jul 06, 2014 10:16 pm
Location: English Riviera - South Devon

Re: How to refurbish your alternator (S3)

Post by DKWW2000 » Wed Aug 12, 2015 8:19 pm

ian65 wrote:bloody hell Pete that's nice h[b[ ..........................................................and you do like your tractors in that part of the world don't you, what with TWOCing them and painting eveyrthing the same colour as them :)

There's MFMassey Ferguson) Red, DB (David Brown) White, Fordson Grey/Blue, JD John Deere Green & Ursus Rust :lol:

TWOCing, When they do a burn out it smells for weeks & leave 3" of rubber on the road :roll:
RX7 FB S3 - RX7 FC TII Vert
Rotaries Previously Owned:-
2 x NSU Ro 80s - 2 x S2 RX7s - Suzuki RE 5 - DKW(Hercules) W2000 - Norton (Krauser) Commander

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myatt1972
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Re: How to refurbish your alternator (S3)

Post by myatt1972 » Wed Aug 12, 2015 10:04 pm

Welcome to the shiny alternator club 0-0
Keith...

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Hobbawobba
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Re: How to refurbish your alternator (S3)

Post by Hobbawobba » Wed Aug 12, 2015 10:32 pm

Looking nice... Here I am still finishing up sanding on 240 grit. I need to get a move on! :lol:

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spirit r
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Re: How to refurbish your alternator (S3)

Post by spirit r » Wed Aug 12, 2015 10:57 pm

myatt1972 wrote:Welcome to the shiny alternator club 0-0
All the more e-fan, all the more overhauling, all the more shiny alternator, all the more club members :x
Thomas

Lucky
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Re: How to refurbish your alternator (S3)

Post by Lucky » Thu Aug 13, 2015 10:12 am

Looks superb, Pete. Therapeutic, isn't it? :lol:

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