Bosch Voltage regulator

[Mless5]

What's the scoop on V regulators for 140amp Bosch units? Searched high and low and it (1197311238) doesn't seem to be available and BMW 12311747920 is either not available or costs almost as much an entire alternator. Shame to toss mine because it is had such low miles. Any input on possible interchanges or where can I grab one without paying arm and 3 legs?!

Alternatively, can brushes be swapped between these regulators?

Thanks.

[AJLM34A]

https://www.rockauto.com/en/moreinfo...glaPOGEo0%2F7W

Or see if there is still a local place that rebuilds them and will sell you one.

[Mless5]

https://www.rockauto.com/en/moreinfo...glaPOGEo0%2F7W

Or see if there is still a local place that rebuilds them and will sell you one.

Thank man!

[shogun]

I have some fitting Hella voltage regulators for Bosch alternators, Hella voltage 5DR 004 242-051 14.5V regulator, new, for BOSCH alternators only, fits for E36 320/323/325/328/E36 M3,Z3,E34 530/540/520/525, E32 740, E31 840 with BOSCH alternators. replacement for BMW # 1247892,1432964,1730604,1739365,1747920, 12311247892 ,12311432964,12311730604,12311739365,12311747920,1 2317739365,12311738351
Using it on my 98 M3 also, if you cannot find locally, let me know, but not sure how long it will take to ship from Japan in these days.

[Mless5]

Thanks for the PM shogun, I'd be happy to, but I am afraid it will take forever. I'll keep it in mind.

[ax77]

What's the scoop on V regulators for 140amp Bosch units? Searched high and low and it (1197311238) doesn't seem to be available and BMW 12311747920 is either not available or costs almost as much an entire alternator. Shame to toss mine because it is had such low miles. Any input on possible interchanges or where can I grab one without paying arm and 3 legs?!

Alternatively, can brushes be swapped between these regulators?

Thanks.

I just rebuilt a 140amp bosch. Yes you can replace just the brushes. I got them for $8 but looks like the price went up. I rebuilt the alternator for under $30 which included both bearings and brushes. If your regulator is fine just replace the brushes. Let me know if you have questions.

https://www.ebay.com/itm/BOSCH-Alter...72.m2749.l2649

[Mless5]

ax77 - thank you, I will get a set to have one handy to rebuild another bad spare I have.

It seems like I was able to locate an interchangeable Bosch regulator on ebay for reasonable $!

[shogun]

The ones ax77 linked to ebay apparently do not fit your car. I checked with my car: This part is not compatible with 1998 BMW M3 Base Sedan 4-Door 3.2L.
Some general info:
There are Bosch alternators for example for my E32 750 with M70 engine with 140A, that has a slip ring OD 28mm, and for the E36 M3 the Bosch alternators are compact alternators, and there the slip ring OD is 14/16mm, the carbon size of the voltage regulator is different. I have new Hella voltage regulators on stock and just checked both, the one for the 28 mm slip ring has abt 8x5mm, total length abt. 35mm the other one for the E36 Bosch compact has 5.9 x 3.9mm, total length abt. 24mm.

minimum length of carbon brushes on alternator voltage regulator is 5mm. 5mm = what stands out of the voltage regulator, here shown for the M30 engine https://workshop-manuals.com/bmw/5_s...ulator_switch/
Check slip rings for wear, disassembling alternator and fine-grinding as well as polishing slip rings if necessary.
Check for truth of running of slip ring. Max. eccentricity for slip rings is 0.03 mm. A bad slip ring with deep grooves can destroy new a carbon brush very quick. When the slip ring looks like this, it has to be replaced
http://www.e32-schrauber.de/bmw/date...r/P1000507.jpg
with less wear, you can machine it http://www.e32-schrauber.de/bmw/date...r/P1000510.jpg
http://www.e32-schrauber.de/bmw/date...r/P1000526.jpg
The material thickness of the slip ring is only 1.6mm! http://www.e32-schrauber.de/bmw/date...r/P1000631.jpg

[Mless5]

Correct, I spent some time today and it doesn't look like it would work sadly. I did find on on ebay in US that should work - we shall see when it arrives in a day or 3.
I appreciate your pointers, these items have been checked already. My fairly new alternator is failing a test on voltage regulator part, so I decided to start with that part first.

The ones ax77 linked to ebay do not fit your car. I checked with my car: This part is not compatible with 1998 BMW M3 Base Sedan 4-Door 3.2L.

There are Bosch alternators for example for my E32 750 with M70 engine with 140A, that has a slip ring OD 28mm, and for the E36 M3 the Bosch alternators are compact alternators, and there the slip ring OD is 14/16mm, the carbon size of the voltage regulator is different. I have new Hella voltage regulators on stock and just checked both, the one for the 28 mm slip ring has abt 8x5mm, total length abt. 35mm the other one for the E36 Bosch compact has 5.9 x 3.9mm, total length abt. 24mm.

minimum length of carbon brushes on alternator voltage regulator is 5mm. 5mm = what stands out of the voltage regulator, here shown for the M30 engine https://workshop-manuals.com/bmw/5_s...ulator_switch/
Check slip rings for wear, disassembling alternator and fine-grinding as well as polishing slip rings if necessary.
Check for truth of running of slip ring. Max. eccentricity for slip rings is 0.03 mm. A bad slip ring with deep grooves can destroy new a carbon brush very quick. When the slip ring looks like this, it has to be replaced
http://www.e32-schrauber.de/bmw/date...r/P1000507.jpg
with less wear, you can machine it http://www.e32-schrauber.de/bmw/date...r/P1000510.jpg
http://www.e32-schrauber.de/bmw/date...r/P1000526.jpg
The material thickness of the slip ring is only 1.6mm! http://www.e32-schrauber.de/bmw/date...r/P1000631.jpg

[shogun]

I had a problem 10 years ago with my original M3 Bosch alternator, the battery light suddenly started dimming all the time, checked volts and only 10.5V were produced. Changed the voltage regulator and checked the slip ring, still 10.5V and battery light dimming. Turned out that some diodes were defective in the rectifier. Bought new diodes, but the plastic housing of the rectifier broke when trying to open the housing to solder/press in in new diodes.
Just for info the data of my original M3 alternator: 80A, 0 120 485 048, KC>14V 50-80A, Made in Great Britain, BMW # 1744562, accdg to ETK new p/n 12311744562, 12341234667, reman 12311744566.
A new rectifier costs about $50-80, so it might be easier one buys a reman alternator.
I had another used E36 alternator in stock Bosch 140A, installed a new voltage regulator and that works since 10 years without a problem.
For the defective one I bought a rectifier: rectifier for Bosch 0 120 485 048, KC (R) 14V 50-90A : Bosch # 1 127 319 816
Alternator Rectifier Diode Assembly, Number of Diodes: 6, Diode Amps: 50, Stud Size: M8-1.25, Unit Polarity: Negative, Mounting: Rectifier OD, Mounting Distance: 4.409in / 112mm, Diode Style: Avalanche, Diode Type: Press Fit, Includes Brush Holder?: No, Includes Capacitor?: Yes, Includes Trio?: Yes, Notes: M6-1.0 Trio Terminal, Reference #s Bosch 1 127 319 009, 1 127 319 617, 1 127 319 623, 1 127 319 816, 1 127 320 862, 1 127 320 882, Other ABO1239, RB101H, 172-24087 Application: Bosch Alternators 12-31-1-247-287, 12-31-1-247-311, 12-31-1-247-487, 12-31-1-247-488, 12-31-1-730-580, 12-31-1-730-602, 12-31-1-735-792, 12-31-1-739-362, 12-31-1-744-560, 12-31-1-744-562, 12-31-4-353-353, 0120485048, 0123310006, 0123315004, 0123320012, 9120485048, 9123690001, 0123325010, 0123325011, 0123325015
https://www.maniacelectricmotors.com/77201028.html
but when I compare prices of cpl. new alternators in above link to my rectifier price, easier and reasonable priced would be a cpl. one instead of repair. Anyway, whatever you prefer, there in the link are the parts you might need, there are of course other shops also specialized in alternators and motor starters

[ax77]

The ones ax77 linked to ebay apparently do not fit your car. I checked with my car: This part is not compatible with 1998 BMW M3 Base Sedan 4-Door 3.2L.
Some general info:
There are Bosch alternators for example for my E32 750 with M70 engine with 140A, that has a slip ring OD 28mm, and for the E36 M3 the Bosch alternators are compact alternators, and there the slip ring OD is 14/16mm, the carbon size of the voltage regulator is different. I have new Hella voltage regulators on stock and just checked both, the one for the 28 mm slip ring has abt 8x5mm, total length abt. 35mm the other one for the E36 Bosch compact has 5.9 x 3.9mm, total length abt. 24mm.

minimum length of carbon brushes on alternator voltage regulator is 5mm. 5mm = what stands out of the voltage regulator, here shown for the M30 engine https://workshop-manuals.com/bmw/5_s...ulator_switch/
Check slip rings for wear, disassembling alternator and fine-grinding as well as polishing slip rings if necessary.
Check for truth of running of slip ring. Max. eccentricity for slip rings is 0.03 mm. A bad slip ring with deep grooves can destroy new a carbon brush very quick. When the slip ring looks like this, it has to be replaced
http://www.e32-schrauber.de/bmw/date...r/P1000507.jpg
with less wear, you can machine it http://www.e32-schrauber.de/bmw/date...r/P1000510.jpg
http://www.e32-schrauber.de/bmw/date...r/P1000526.jpg
The material thickness of the slip ring is only 1.6mm! http://www.e32-schrauber.de/bmw/date...r/P1000631.jpg

When I was looking for the brushes I didn't go by part numbers of what was compatible. I measured the brushes and found them based on that. I see the sellers description doesn't show the dimensions but you should be able to find them. They were perfect fit for the bosch 140a alternator that came in some e36's.

[Mless5]

They one I picked up on ebay was a no go, even thought it was listed as a replacement for bmw part #. Can't believe it is this hard to find a correct part in USA let alone at a reasonable price point!

[ax77]

They one I picked up on ebay was a no go, even thought it was listed as a replacement for bmw part #. Can't believe it is this hard to find a correct part in USA let alone at a reasonable price point!

if you really want to replace the regulator this is the one that I found that should be the correct one

https://www.amazon.com/gp/product/B0...Q1X21AON&psc=1

[Mless5]

if you really want to replace the regulator this is the one that I found that should be the correct one

https://www.amazon.com/gp/product/B0...Q1X21AON&psc=1

Thank you! Got it in and it did fit.