why are alternator rebuild kits so hard to find?

I'm trying to find a rebuild kit for the 140a Bosch alternator in my wifes BMW 525i E34 (Bosch p/n 0 120 465 031). It charges just fine, but the bearings are noisy.

I know nearly every alternator ever made can be rebuilt by professional rebuilders, but why is it so hard for the DIY'er to find rebuild parts?

I've found VR assemblies for the alternator, and even brushes separately from the VR, and to be fair, thats usually all that goes wrong with Bosch alternators, but I find it surprising that no one seems to offer a full rebuild kit. Maybe my Google foo is weak?

I'm sure some smart donkeys will chime in and say to get off my wallet and go pay a rebuilder or buy a reman unit, but there are 2, no make that 3, good reasons not to do that.

1. I like rebuilding stuff

2. I work with EVs professionally, an alternator rebuild is well within my technical skills, and infact would be easy compared to some of the motors that I've repaired.

3. If I wanted to just throw money at it I wouldn't be coming to this forum for advice.

So, I guess I don't really need a kit, but that would be simple and convenient, but I do need bearings, so if anyone knows the specs for the bearings in this alternator, I would be grateful for the help.

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I have looked into rebuilding them before to, all I ever found were kits for other company's alts I did find out that other vehicles easier to find alts will swap on with a little work. Maybe that might be your fix?

Maybe your alternator is an uncommon type, at least in comparison to Ford or GM alternators? Rebuild and even output upgrade kits are easy to find for those.

EDIT: Beat by jere.

OT to jere: Where the hell is that avatar from? It make me cringe every time I see it.

HappyAndy wrote: but why is it so hard for the DIY'er to find rebuild parts? Maybe my Google foo is weak? I'm sure some smart donkeys will chime in and say to get off my wallet

1) I think its because people are helpless, and would NEVER buy one... "why do it myself when I can pay someone to do it for me while I drink a cold beer and watch idiots vote each other off an island?"

2) Nah, (see #1)

3) not on this forum If nothing else, I like the education I get when attempting to rebuild something that people usually buy new.

but the kicker for me was during my last visit to the states: A brake master cylinder rebuild kit was $25, a brake master cylinder that had already been "refurbished" FOR me was $19. I'm guilty of going with the cheaper/lazier option...

Hungary Bill wrote: < A brake master cylinder rebuild kit was $25, a brake master cylinder that had already been "refurbished" FOR me was $19. I'm guilty of going with the cheaper/lazier option...

I found that almost true with a clutch slave cylinder. Kit was $19 and the whole culinder was $25. And I was broke down in the parking lot of the parts store. I fixed it in the parking lot with borrowed tools. Ah the days of independent parts stores.

To the OP: Is it possible to tear down the alternator and get the part numbers off the bearings?

Take the bearings to a bearing shop. They should have what you need.

Like tr8 todd says. Bosch alternators use common ball bearings.

Now, for why its not really a great idea- the slip rings will be worn out, which requires special equipment, and the noisy bearings have been vibrating the rotor, so it may fail shortly after you put it back together.

I used to do them all the time, but found it was too much of a crapshoot to provide to a customer.

When I started wrenching for a living, we rebuilt all kinds of things - Alts, starters, calipers, wheel cylinders, etc..
Then one day a guy comes in and hands the owner a pamphlet showing that they rebuild everything, and do it using a progressive assembly line process that lowers the cost so much that it no longer made sense for us to rebuild things ourselves. So I became a parts replacer.
Not long after that, I went back to college. Then things got even cheaper when they moved the rebuilding to other countries. Then auto parts stores started phasing out rebuild kits because it was so cheap to just buy the part already rebuilt.
A while back the generator on my tractor went bad, and I was determined to rebuild it instead of buying a high dollar, low quality rebuilt unit. I did find a place in Akron that carries parts to rebuild almost anything electrical. PM me if you want the name. I can't think of it off the top of my head, but can find out. Just one warning - You'll have to call them, because they don't have a website.

google "alternator rebuilder xxxxx" where xxxxx is your nearest city/town. there's a mom and pop starter and alternator rebuilder in every town, and they'll sell you parts if you insist on DIYing it. when I sold the V8 944, i had the Hamburger mini-starter rebuilt at a local shop for $58. If I had done it before the end of the auction, i would still have a V8 944. :-(

Rock Auto lists the bearings for a 525i alternator.

My last mechanics job was for a John Deere dealer and one of my assignments was rebuilding things. Engines, drive lines, alternators, generators,starters,magnetoes, carburetors and on. Did much the same when caring for the forklift fleet of a local manufacturer. No body rebuilds things on their own anymore.

stuart in mn wrote: Rock Auto lists the bearings for a 525i alternator.

Yeah, what he said. http://www.rockauto.com/catalog/raframecatalog.php

stuart in mn wrote: Rock Auto lists the bearings for a 525i alternator.

Well I must be doing something wrong. All I find there are complete alts and VRs?

I wanted to have the bearings before I tear into it so that I can have the least possible down time, other wise I would just pull the old ones out and take them to a bearing shop.

On RockAuto, check for part numbers: (National) 201CC and 303CC

Or on the interactive catalog:

BMW->1990->525i->2.5L L6->Electrical->Alternator/Generator Commutator End Bearing

and

BMW->1990->525i->2.5L L6->Electrical->Alternator/Generator Drive End Bearing

...Unless I'm misunderstanding something or I'm just plain wrong...

Follow the path Ross outlined above. The bearings are listed right below alternators

RexSeven wrote: OT to jere: Where the hell is that avatar from? It make me cringe every time I see it.

Google image search when I typed in toe plates. It was so uncomfortable to look at I had to share and I didn't have an avatar.