new brushes in old alternator voltage regulator

[Unregistered]

14 year old Bosch alternator's voltage regulator brushes are down to ~1/6" exposed length, and springs are nearly at full extension. So, time for new voltage regulator (sorta expensive) or at least new brushes (cheap).

Has anybody successfully installed new brushes in an old regulator? How to get the remnants of the old brushes out, and properly seat new ones?

Advise and guidance much appreciated!

[Unregistered]

14 year old Bosch alternator's voltage regulator brushes are down to ~1/6" exposed length, and springs are nearly at full extension. So, time for new voltage regulator (sorta expensive) or at least new brushes (cheap).

Has anybody successfully installed new brushes in an old regulator? How to get the remnants of the old brushes out, and properly seat new ones?

Advise and guidance much appreciated!

I have replaced the brushes but not on my own.Sent it to an electrician.He de-soldered the old brushes out and re-soldered new ones in.Very cheap fix and costs 7x less than a new voltage regulator.
A word of caution tho...the voltage regulator may not like the excessive heat of the soldering iron....

[ryan roopnarine]

alternator brushes come with a 1/8 diameter circular backing, holding the spring in, with a little nub so that it will fit through the contact hole for soldering. all's you really need to know, if you already can solder, is that you need to use silver solder, not regular electrical stuff....depending on the specific number of your regulator, bma may be able to get you a generic regulator for around 13 plus shipping, far more of a worry free choice than soldering brushes, plus you can fix the old and keep it as a spare.

[Scott H]

Just buy a new one, order it from BMA.

[ryan roopnarine]

this might save you a headache....

i don't think you mentioned which car you had.....if you have the alt out, and can verify the number on the transistor, i'd compare to my old post, here

http://www.bimmer.info/forum/showthread.php?t=1222

as the top one, which didn't fit my 140a bosch, was the cheapest, and i had to get the middle one, which had no generic equiv, and was over $60. if you order from bma, be sure to specify the number.

[Unregistered]

Thanks, all, especially Ryan, for your insight and suggestions.

My voltage regulator looks just like the top one on Ryan's attached picture. The only difference that I can see is the last digit in the part number, and that his is made in Spain. My (made in Germany) part number is 1 197 311 027, versus 028 suffix on Ryan's.

BTW, Ryan, what did BMA charge you for your 1 197 311 028, which did not fit your alternator?

[Scott H]

I'd rather pay $30 more for the part than the pieces of the part.........that $30 represents saved frustration. Maybe if you are Bill R or Winfred and have done this dozens of times, then go for the saving $ angle. If this was an interior trim piece or some part that doesn't matter, then I can also understand saving money, but this is the voltage regulator for your alternator.......why bother messing around?

Oh, the solid state circuitry in your voltage regulator can fail too......I suggest just replacing the whole thing, and that if your voltage regulator is truly 14 years old, chances are the electronics are aging as well.

[Bill R.]

if I was stranded in East jesus and there were no other parts available, otherwise replace the regulator and brushes as a unit..







QUOTE=Scott H]I'd rather pay $30 more for the part than the pieces of the part.........that $30 represents saved frustration. Maybe if you are Bill R or Winfred and have done this dozens of times, then go for the saving $ angle. If this was an interior trim piece or some part that doesn't matter, then I can also understand saving money, but this is the voltage regulator for your alternator.......why bother messing around?

Oh, the solid state circuitry in your voltage regulator can fail too......I suggest just replacing the whole thing, and that if your voltage regulator is truly 14 years old, chances are the electronics are aging as well.[/QUOTE]

[ryan roopnarine]

the top one was the cheap one.....about $35 for the bosch article from bma...the generic that fit that one was about 13 or 14. i don't fix cars for a living, but apparently bosch part no supercessions are not uncommon, so it might just be the new version of your regulator....country of manufacture is pretty irrelevant, if it says bosch.


Thanks, all, especially Ryan, for your insight and suggestions.

My voltage regulator looks just like the top one on Ryan's attached picture. The only difference that I can see is the last digit in the part number, and that his is made in Spain. My (made in Germany) part number is 1 197 311 027, versus 028 suffix on Ryan's.

BTW, Ryan, what did BMA charge you for your 1 197 311 028, which did not fit your alternator?

[ryan roopnarine]

my local tinfoil hat store/electronics/military surplus store has two very nice carbon brushes with the solder **** already on for 2/$1.50, a tempting proposition when bma told me that my regulator was AT LEAST $60 (didn't know exactly how much, he said), which is 1/4 the price of a new alternator. same store has starter brushes for $1.25 or 3 each.


I'd rather pay $30 more for the part than the pieces of the part.........that $30 represents saved frustration. Maybe if you are Bill R or Winfred and have done this dozens of times, then go for the saving $ angle. If this was an interior trim piece or some part that doesn't matter, then I can also understand saving money, but this is the voltage regulator for your alternator.......why bother messing around?

Oh, the solid state circuitry in your voltage regulator can fail too......I suggest just replacing the whole thing, and that if your voltage regulator is truly 14 years old, chances are the electronics are aging as well.

[Bellicose Right Winger]

If regulators are inexpensive...then brushes are an absolute bargain.

http://catalog.eautopartscatalog.com/zygmunt/quote.jsp?header=header.jsp&footer=footer.jsp&product=f412136736&partner=zygmunt&baseurl=http://www.bimmerparts.com/&clientid=bimmerparts.com&cookieid=1500RA8Z8

Knowing how to solder is a useful skill that any DIYer should acquire. $12 at Radio Shack will get you a 30W pencil soldering iron and a roll of solder. Then you'll be ready for voltage regulator & fan motor brush replacement and making permanent repairs/stereo hookups instead of using crimp connectors.

BTW, I've only used regular electronic grade rosin core solder for voltage regulator brush replacement and have never had a solder joint failure. This solder melts at ~370F. If the alternator/regulator/brushes gets anywhere close to this temp you've got far bigger problems then these solder joints.

Paul Shovestul



Just buy a new one, order it from BMA.

[Scott H]

is so important, that $30-60 for a voltage regulator isn't that much. It's not like it is a part that gets replaced every year either. If you F up the brushes and have to go in again to fix, you're just gonna wish you had bought a new part in the first place. I have yet to hear of a McGyver job that you have done successfully, Ryan. But then again, arguing with you never works either, so I don't even know why I am bothering.

A voltage reg for my car was $28 + ship from BMA



my local tinfoil hat store/electronics/military surplus store has two very nice carbon brushes with the solder **** already on for 2/$1.50, a tempting proposition when bma told me that my regulator was AT LEAST $60 (didn't know exactly how much, he said), which is 1/4 the price of a new alternator. same store has starter brushes for $1.25 or 3 each.

[ryan roopnarine]

i never said that anybody should replace the brushes by themselves if there are inexpensive other options available, and i certainly wasn't arguing with you scott. an hour after i measured 8.6 volts at my alternator, i called bma for a new regulator to be overnighted to me at a cost of 35 plus 18 for overnight shipping. after tearing it out, and monopolizing 1/2 of dan d's day assisting me and driving me to the hardware store, i was more than a little dismayed to find that the damn thing didn't remotely look like the unit it was supposed to replace. at that point, if i could have driven to the store, i'd have gotten two brushes and said screw a new regulator. 8 days AFTER finding my alternator dead, $65 for a regulator, and an additional $12 for more overnight shipping later, the car was putting out 13.9 volts. oh, and my maguyver skills are more than sharp, just 'cause they were never applicable to the car doesn't mean they are nonexistant. i've shut up 50-60 people with a impromptu barometer and altitude determination before.



is so important, that $30-60 for a voltage regulator isn't that much. It's not like it is a part that gets replaced every year either. If you **** up the brushes and have to go in again to fix, you're just gonna wish you had bought a new part in the first place. I have yet to hear of a McGyver job that you have done successfully, Ryan. But then again, arguing with you never works either, so I don't even know why I am bothering.

A voltage reg for my car was $28 + ship from BMA

[Unregistered]

Excellent points, well thought out and presented by all. Thank you!

Well, as I AM stranded in East Jesus and do have a Radio Shack soldering iron and some standard solder, I'm gonna replace the brushes and re-solder the nubs. I KNOW this part fits my car.

Friday, I got in my first order from the list's favorite parts supplier, who are very nice folks and have exccellent prices. Spent the weekend putting stuff on. Only found a couple of my new parts to be the wrong ones for my car, so I spent much of the time goose chasing, which reminds me of Ryan's experience with his alt. regulator saga. So, buying new parts is not guaranteed to provide the right parts, or to ease the frustration factor--maybe just the opposite. (My kids got to hear some new vocabulary, which their mom wryly calls "Car Talk.") After I re-brush the old unit, I'll check around until I'm SURE any new parts are correct, before ordering. BTW, Ryan, if you still have that first (wrong for your car but prolly OK for mine) regulator in your picture, wanna sell it to me? This may take a bit of the sting out of your frustration, and then I could keep my re-soldered unit as a spare.

BTW, there is a new ~$20 type pen-sized & battery operated soldering iron called "Cold Heat." It heats and cools virtually instantaneously with new technology. IF IT WORKS AS ADVERTISED, it would be an excellent addition to your car's tool kit. Google for more info on Cold Heat. (I have no interest or assn. with the mfr., but a blurb about it on TV news looked intriguing.)

[ryan roopnarine]

das volk at bma are good guys, when they heard and saw the pics about the problem, they accepted it for return, and said they would go halfzies on overnight shipping if i wanted to go that route (that's why the first was 18, the second would have been 24, but 1/2 of that is 12......), so, no, i don't have it anymore. if you do have incorrect products, or they've shipped you the wrong thing (or short shipped) they've fixed it for me within 3 or 4 days, and credit you when you return the old part.


Excellent points, well thought out and presented by all. Thank you!

Well, as I AM stranded in East Jesus and do have a Radio Shack soldering iron and some standard solder, I'm gonna replace the brushes and re-solder the nubs. I KNOW this part fits my car.

Friday, I got in my first order from the list's favorite parts supplier, who are very nice folks and have exccellent prices. Spent the weekend putting stuff on. Only found a couple of my new parts to be the wrong ones for my car, so I spent much of the time goose chasing, which reminds me of Ryan's experience with his alt. regulator saga. So, buying new parts is not guaranteed to provide the right parts, or to ease the frustration factor--maybe just the opposite. (My kids got to hear some new vocabulary, which their mom wryly calls "Car Talk.") After I re-brush the old unit, I'll check around until I'm SURE any new parts are correct, before ordering. BTW, Ryan, if you still have that first (wrong for your car but prolly OK for mine) regulator in your picture, wanna sell it to me? This may take a bit of the sting out of your frustration, and then I could keep my re-soldered unit as a spare.

BTW, there is a new ~$20 type pen-sized & battery operated soldering iron called "Cold Heat." It heats and cools virtually instantaneously with new technology. IF IT WORKS AS ADVERTISED, it would be an excellent addition to your car's tool kit. Google for more info on Cold Heat. (I have no interest or assn. with the mfr., but a blurb about it on TV news looked intriguing.)

[Bill R.]

alternator brushes, starter brushes , commutator connections etc, is that with regular rosin core solder in a connection you have in effect created a fusible link and even though the alternator itself may not get to 370, the wire and connection may depending on the current its carrying. Whereas with silver solder the wire itself will melt in 2 before the silver solder joint will fail...







If regulators are inexpensive...then brushes are an absolute bargain.

http://catalog.eautopartscatalog.com/zygmunt/quote.jsp?header=header.jsp&footer=footer.jsp&product=f412136736&partner=zygmunt&baseurl=http://www.bimmerparts.com/&clientid=bimmerparts.com&cookieid=1500RA8Z8

Knowing how to solder is a useful skill that any DIYer should acquire. $12 at Radio Shack will get you a 30W pencil soldering iron and a roll of solder. Then you'll be ready for voltage regulator & fan motor brush replacement and making permanent repairs/stereo hookups instead of using crimp connectors.

BTW, I've only used regular electronic grade rosin core solder for voltage regulator brush replacement and have never had a solder joint failure. This solder melts at ~370F. If the alternator/regulator/brushes gets anywhere close to this temp you've got far bigger problems then these solder joints.

Paul Shovestul

[Bellicose Right Winger]

melting temp then the rosin core...and is more desireable as a result. But in my experience rosin core hasn't been a problem. I've had the same good experience with fan motor brushes using rosin core solder. Perhaps the voltage regulator, by limiting the current to the brushes to control alternator output, keeps this in check. I also have a gut feel that current high enough to melt the rosin core, and get the brushes and connections this hot, would likely fry the regulator also. This isn't the case with starter brushes that need high temp solder. They carry far greater current and aren't current regulated. Your explanation makes sense until the part about copper wire melting before the silver solder. If this were the case you would never be able to make the silver solder joint because you would melt the wire before the joint was made. Have you ever made a silver solder joint with a Weller?

Paul Shovestul



alternator brushes, starter brushes , commutator connections etc, is that with regular rosin core solder in a connection you have in effect created a fusible link and even though the alternator itself may not get to 370, the wire and connection may depending on the current its carrying. Whereas with silver solder the wire itself will melt in 2 before the silver solder joint will fail...

[Bill R.]

referring to the fact that in a high current application the wire in the circuit would melt in two before the silver soldered joint would... To answer your question on the weller... no, i have never used a weller to silver solder anything.... all the silver soldering I have done was on commercial A/C lines with silvphos stick and a oxy/acetylene torch and on the connections when rewinding 125hp polyphase inductions motors, that was also done with a oxy/acetylene torch with a soft flame... I have also done some jewelry silver soldering but that was also with a oxy/acetylene torch.. I have no experience silver soldering with a soldering iron..



melting temp then the rosin core...and is more desireable as a result. But in my experience rosin core hasn't been a problem. I've had the same good experience with fan motor brushes using rosin core solder. Perhaps the voltage regulator, by limiting the current to the brushes to control alternator output, keeps this in check. I also have a gut feel that current high enough to melt the rosin core, and get the brushes and connections this hot, would likely fry the regulator also. This isn't the case with starter brushes that need high temp solder. They carry far greater current and aren't current regulated. Your explanation makes sense until the part about copper wire melting before the silver solder. If this were the case you would never be able to make the silver solder joint because you would melt the wire before the joint was made. Have you ever made a silver solder joint with a Weller?

Paul Shovestul

[Unregistered]

OK, instead of using rosin solder, why not re-cycle the old silver solder when installing the new brushes in my voltage regulator? (If only I can keep from frying the works in the process.) Or, is silver solder not re-meltable at some reasonable temperature?

That way, I could make both Bill and Paul happy, while still not getting stuck with the wrong mail-order unit, as befell Ryan. I've ordered the supposedly "right" aftermarket unit at the local parts place. It'll be here tomorrow, to compare with the stock unit for fit, etc..

[ryan roopnarine]

i tried that, and even though i am a certifiable nerd, with ham radio credentials since 11 (vis a....soldering skills), couldn't manipulate the solder in a way in which the brush leads didn't fall through the hole again. my old unit broke in the box that i carry it aorund in the car with, under no stress at all.


OK, instead of using rosin solder, why not re-cycle the old silver solder when installing the new brushes in my voltage regulator? (If only I can keep from frying the works in the process.) Or, is silver solder not re-meltable at some reasonable temperature?

That way, I could make both Bill and Paul happy, while still not getting stuck with the wrong mail-order unit, as befell Ryan. I've ordered the supposedly "right" aftermarket unit at the local parts place. It'll be here tomorrow, to compare with the stock unit for fit, etc..

[Bellicose Right Winger]

As I recall the brush pigtail is mechanically restrained by a crimp in the "nub" it passes thru in addition to being soldered. It's a lot easier to solder if you re-crimp before trying to solder.

Paul Shovestul


....couldn't manipulate the solder in a way in which the brush leads didn't fall through the hole again. my old unit broke in the box that i carry it aorund in the car with, under no stress at all.

[Unregistered]

Well, this thing will be crimped, knotted, and soldered all in one.

I trimmed each old nub with fingernail clippers, heated with soldering gun, and the old brush just popped out. (Be careful where you aim it, to avoid crawling around on the floor looking for the escaped spring. So, on the second one I encapsulated the assy. with a baggie to catch the spring.) Then, enlarged the nub hole a little with an ice pick, threaded in the new brush w/spring and insulator, then tied the copper cable into a small knot, then crimped the nub, and now will re-solder. (Call it the 'belt + suspenders + girdle' method.) Later, I'll dab some insulator-in-a-can on each nub.

Just to be sure, I'm now taking the whole shebang to an automotive electrician, who will turn the armature shaft for ~$10 to make sure it's smooth, so the new brushes don't hop and wear prematurely. He'll probably bench test the works, just in case I fried the voltage regulator, or whatever.

Who knows, maybe there's another 237,000 miles in this alternator. We'll see.

[Unregistered]

Got my alternator shaft contact rings turned on a lathe to super-smooth finish, so it won't eat up the new brushes. Bearings looked good and turn easily, but may replace them anyhow, for the sake of durability.

FWIW, I asked the guy (who has done auto electrical machine shop work for ~25 years) about the silver solder vs. rosin solder question. He flatly says rosin solder is just fine, and that if your average soldering gun will melt the solder, it probably is not really silver. Well, my soldering gun melted the solder on my brush nubs.