Alternator interchangeability with E12 E28 etc.

[CeylonstonE9]

I am missing an alternator and starter like most other parts... Car is 72 CS 3.0

Starter is interchangeable so I will look for an E12 starter.

Now my question.....
Is the alternator same as E12 or some other more common Bmw's with M30 engines ?

I found this but it says fits for 74. Is there a different alternator on 74 cars ?

Shop – Newparts.com

Genuine, OEM & Branded Aftermarket Parts at the best prices. Includes a 2-year warranty and easy returns. Shop Today!

www.newparts.com

 

[Thomas76]

1 wire vs 3 wire regulation comes to mind. This tells you if the voltage regulator is internal or external to the alternator. Both of my E9s (70 & 74 us) had external regulator near the battery, but now have been converted over to modern internal with the external bits removed.

 

[jmackro]

I found this but it says fits for 74. Is there a different alternator on 74 cars ?

Shop – Newparts.com

Genuine, OEM & Branded Aftermarket Parts at the best prices. Includes a 2-year warranty and easy returns. Shop Today!

www.newparts.com

I don't know the answer to that question (whether a '74 takes a different alternator than earlier cars) but the one pictured on the newparts site looks like what Thomas76 is describing: an internally-regulated model. That should bolt right on to your engine, provide better voltage regulation and simplify the wiring. It won't be 100% original for your '72, but it's what many of us have installed. If you install an internally-regulated alternator and are concerned about the appearance of originality, you can leave the old, external regulator in place with the wiring removed.

 

[Mike Goble]

I use a readily available and cheap AC Delco CS-130 105 amp alternator for my E3, no appearance of originality but bolts right in and works like a trained pig.

 

[Ohmess]

If you are not trying to keep everything original, install a smaller fixed magnet starter motor such as the Bosch SR440 or SR441, they are a lot more efficient than the original starters.

Alternators from the e24 will fit too, and have a higher amperage output than the earlier alternators.

 

[HB Chris]

The critical issue is that the e12 uses an M8 mounting bolt, e9 uses an M10, looks can be deceiving.

 

[teahead]

Right. I have an E12 no external regulator, alt on mine. I had to modify the bolt. Don't remember exactly what I did.

 

[sfdon]

Trying to use a AL45x in a later bracket - you need to shim.


Coupe is AL45x
No bushings requires no ground cable
Bracket is narrow
12311257279
Supporting bracket



Bolt changed:

05	Hex bolt	M10X80	1		07/1978	31111136251	$1.11
05	Hex bolt	M8X80	1	07/1978		07119912558	$2.89

e12 is AL41x
AL41x has bushings in it
and spacers
the brackets are different in width
the e12 bracket is wider
12311261120
Supporting bracket

12521285011
Ground cable

RealOEM.com - Online BMW Parts Catalog

BMW parts 5' E12 528i Alternator, individual parts

www.realoem.com

 

[billpatterson]

1 wire vs 3 wire regulation comes to mind. This tells you if the voltage regulator is internal or external to the alternator. Both of my E9s (70 & 74 us) had external regulator near the battery, but now have been converted over to modern internal with the external bits removed.

Hi Thomas

I too will be converting to a reman'd Bosch AL45X. Can you describe the changes to the wiring including the removal of 'external bits" for this internally regulated alternator?

Thanks!

Bill

 

[HB Chris]

It’s very easy. You will remove the plug with three wires from both Alt and Regulator. Regulator no longer needed but you can leave it there for originality. There is blue wire from the harness that ends at the regulator, remove it from that Bakelite plug and extend it to the Alt D+ terminal. Main red wire goes from battery to Alt just like before, done.

 

[teahead]

E12 installed

 

[Thomas76]

A little slow to the response but looks like others got you covered. Thats it! Even your charge light will function on the dash!

 

[billpatterson]

Thank you guys!

I looked up pictures of a 2002 resto from a few years back. Same solution with an upgraded alternator. I like it!

Regards,
Bill

 

[bluecs]

When converting from original E9 alternator to E12 alternator,

A. Does the pulley from the E9 need to be used? Or is the E12 pulley the same as the E9?

B. There is a bolt size difference requiring shims. What exactly are those shims and where do they exactly need to be placed?

 

[bluecs]

E9 Alternator is 55 amps. E12 is 65 amps. To what amps is it safe to increase the alternator?

 

[Stevehose]

Have you considered buying a rebuilt e9 alternator at higher amp? Some of us have the BNR 85 amp from eBay. Plug and play although I reused my pulley. Amperage rating is a function of the alternator's ability to meet current demands from various loads (a/c, blower motors et), it doesn't crank it out all the time.

 

[Ohmess]

Further to Steve's comment, you can go as high as you want on amperage. The alternator has a mechanism to only provide the amperage you need.

 

[bluecs]

Does anyone know if the E9 alternator pulley is the same as '75-'76 3.0si pulley?

I've checked RealOEM, but I prefer to confirm.

 

[teahead]

you can always swap pulleys if they are diff.

 

[bluecs]

I have a slight wobble on my alternator pulley. That is why I'm inquiring.