minimum length of carbon brushes on alternator voltage regulator is 5mm

[shogun]

5mm = what stands out of the voltage regulator, here shown for the M30 engine http://workshop-manuals.com/bmw/5_se...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 slipring. Max. eccentricity for slip rings is 0.03 mm.
http://workshop-manuals.com/bmw/5_se...h_alternator)/
Disassembling and assembling Bosch alternator 90/115/150A
http://workshop-manuals.com/bmw/5_se...90_115_140_a)/
Replacing ball bearing Bosch alternator
http://workshop-manuals.com/bmw/5_se...h_alternator)/
Replacing diode plate Bosch alternator
http://workshop-manuals.com/bmw/5_se...h_alternator)/
Electric test on Bosch alternator
http://workshop-manuals.com/bmw/5_se...ch_alternator/
Replacing alternator belt pulley
http://workshop-manuals.com/bmw/5_se...r_belt_pulley/
Replace alternator belt pulley with overrunning clutch
http://workshop-manuals.com/bmw/5_se...nning_clutch)/

[shogun]

Just sold a Hella voltage regulator for the Bosch M70 alternator to someone in AL, he sent me a pic of the old one and mentioned: 05/91 E32 750IL at 150k miles, Bosch Alternator 0 120 468 072, Bosch Voltage Regulator 1 197 311 038 .
I purchased the car in 93 so I believe this is the original alternator.Here the old one, that was the rest of the carbon brushes after 150 k miles.

So better check yours, they do not last forever. In case someone needs one, I have some more voltage regulators from Hella on stock for the Bosch alternator for the M70 and M30 with 28mm slipring and also for the M60 Bosch alternator with 14/16mm slipring.

[SergeBMW]

Good info Erich, thank you. I remember a while back my alternator failed on my 735i, found it had abad voltage regulator, was also surprised to see the difference in brush size between new and old.

Sent from my ONEPLUS A3000 using Tapatalk

[shogun]

Here a pic of my old one and the new one, there you see the difference in length of the brushes http://www.bimmerboard.com/members/s...%20241_131.jpg
But, install it correctly, just remember a case where someone bought a voltage regulator from me and claimed lower voltage, here http://www.bimmerboard.com/forums/posts/723700/
and then he checked again, reply: Eureka! I found the problem, now I can go and kick myself in the ...!
The attached pictures tell the story. The voltage regulator replacement while in the car is very difficult and you can't see how it goes in. I should have used a mirror. The first photo shows the incorrect installation and the last photo is the correct installation.
Note that there are additional screw threads in the mounting surface above the actual voltage regulator. THESE ARE THE SAME SIZE DIAMETER AND THREAD PITCH AND ARE EASILY CONFUSED WHEN YOU CANNOT SEE THE ALIGNMENT OF THE VOLTAGE REGULATOR! I suggest using a mirror, if possible.
It is easy to mis-align the voltage regulator resulting in less brush pressure, even though it seems to fit and mounting screws seem to fasten normally. This was the cause of my low charging voltage and with further testing by a local parts store (Advance Auto) there was "pulsing" of the charge.
No wonder the plastic cover did not fit correctly! I though that the replacement voltage regulator was projecting outward because of different dimensions. http://www.bimmerboard.com/forums/posts/726562