Alternator question

[BrianSmith_S2]

I need to replace the alternator on my 1994 ABY coupe.

based on body code my ABY has either Bosch 120 Amp or Valeo 90 Amp alternator

The Bosch 120 Amp p/n 0123 505 007 appears to have a 6 ribbed pk pully wheel,

the Valeo 90 Amp p/n 436 386 has a 4 ribbed pk pully wheel.

I cant see any manufacturers markings on my duff alternator, but its fitted with a 4 ribbed pully as is the main drive/crank pulley. I might be stupid as this may indicate its the Valeo alternator i need, but just wanted to clarify before purchase.
The pk belts have common pitch so a 4 pk belt should be ok on a 6pk pully, but as the Valeo is a lower rated item im hoping a forum member has had the same replacement issue as me and will have a solution.

Brian

[s2driveruk]

I'd say that was a Valeo...the bosch units have a rib in the middle which that one doesn't look to have and its usually orange. At least mine was.

If you want it just checked and rebuilt, I have used a local guy in Burghfield nr Reading and it wasn't expensive.

http://burghfieldstarterandalternatorcentre.co.uk/

[Rikki Kitto]

Mine had a four pulley on it then when it came back from a recon it had six, still works fine

[Error404]

4 rib pulley is ABY, 6 rib is AAN - alternators are the same, pulley is interchangeable.
AFAIK the 120A unit was supplied with AC equipped cars.
That one doesn't look like a Bosch to me. HTH

[TimE-J]

I'm going to go with a valeo as well.

[BrianSmith_S2]

I'm going to go with a valeo as well.

Thats the route im wanting to go, but no one seems to supply them

So plan B is the bosch unit and keep the 6pk pully or change over my 4pk if this easy to do?

Whats the best way to lock the rotating shaft and undo the nut holding the old pully on?

[TimE-J]

The centre rotating shaft should have an allen key slot in the end of it to hold the shaft while you undo the nut holding the pulley on but the nuts are usually so tight that this option won't work. If you have access to an impact gun that should remove the centre nut without much hassle and there would be no need to lock the shaft. I've just contacted my parts supplier and they dont seem to list a valeo either so maybe the bosch is the only option. In theory there shouldn't be an issue with running the 6 rib pulley with a 4 rib belt as quite a few other manufacturers do have extra ribs on some pulleys.

[TimE-J]

do you happen to know what the problem with the old alternator is, i'm just wondering as it looks like the regulator is quite fresh on your old one.

[BrianSmith_S2]

do you happen to know what the problem with the old alternator is, i'm just wondering as it looks like the regulator is quite fresh on your old one.

I replaced the voltage regulator just in case that was the problem, but made no difference.

As far as i know its the original alternator, 226k miles and +20 years old so i cant grumble really

[TimE-J]

Well thats true, when I rebuilt my s2 I just had the alternator reconned by a local company that my work uses so might be a cheaper option for you.

[Error404]

Pulley just swaps straight over. As Tim said hold the shaft with the hex socket, nut is IIRC 22mm. Mine wasn't overly tight. Impact gun would make life easy

Out of interest, what are all the extra wires going onto your alternator?

[saltinot]

Brian, I am building another ABY for my B2 90q and have an alternator like you have currently. It has the more solid housing and is also a 120A. Either version works

For reference, a couple of pics of my 120A Bosch alternator which has the ABY/ADU 4pk pulley.







A before pic with the pulley removed. Like TimE-J said, an impact does the trick for removing the nut. A gear puller to remove the pulley is also key.



Pic of the back with the cover removed.

[BrianSmith_S2]

Cheers for the photos and info, i better go invest in a gear puller

[Jamo]

4 rib pulley is ABY, 6 rib is AAN - alternators are the same, pulley is interchangeable.
AFAIK the 120A unit was supplied with AC equipped cars.
That one doesn't look like a Bosch to me. HTH

[Fat Audi 80]

I also agree. You have the 90 A in your hands. The 120A Bosch one is the one Tom posted. I have successfully swapped from the 90A to 120A...

HTH

Cheers

Steve