W123 blower motor brushes -- any interest? - PeachParts Mercedes-Benz Forum

Maki · #1 05-12-2004, 03:47 AM

The blower motor in my '82 300td stopped working this spring, which honked me off a bit -- after all it had only 235,000 miles on it...

Anyway, after checking the price of a new blower motor ($140-$150), I fell back on my words to live by -- when in doubt, cheap out!

Opening the motor up, I discovered the brushes were worn down to nubs. I did a web search for motor brushes and stumbled across Schunk Graphite Technologies, a division of the German-based multinational Schunk Group. Hey -- the place is in the Milwaukee area, my home town! So with the stub of one of my old motor brushes in hand, I went a-calling...

To my pleasant surprise, they agreed to duplicate my brushes for me. One catch, though -- I had to order at least $100 worth. That adds up to 24 brushes at $4.17 each.

The motor isn't exactly meant to be disassembled and reassembled repeatedly, but without exceptional difficulty, I got the replacement brushes installed and the motor back together...AND IT WORKS GREAT! I also smoothed out a groove in the commutator and oiled the bearings while I had it all apart. I've NEVER experienced a W123 climate control system with a fully functional motor, it seems...they can move some air when they're working right.

I shared my triumph with some other W123 diesel enthusiasts I corespond with, and they snapped up the brushes remaining from my order of 24 -- in fact, I had more requests than I had brushes. Someone suggested I make up some more and charge $15 for each pair.

Well, I wouldn't charge $15. $12, maybe. And I'd need to know if there's more interest in the effort than the three guys whose requests for brushes I couldn't fulfill.

Sooo...Is anybody out there interested in some replacement brushes for their W123 blower motors for $12 per pair plus shipping? If I can find a demand for nine pair I'll order up another batch. Shipping would be via priority mail, $3.85 if my local USPS clerk is to be believed.

I need commitments for six more pairs. If that happens, I can break even and will order a second run of brushes from Schunk. Otherwise...Yahoo! I brought my dead blower motor back to life!

Russ M
'82 300td
'82 300cd

whunter · #2 05-12-2004, 06:07 AM

A full DIY with pictures would have been a big help.
Do you still have the old brushes, and could you post pictures?

jas2wa · #3 05-12-2004, 10:03 AM

I just did this on my 84 300TD- had to order a set of brushes from the only place I could find them- a M-B parts guy (who has some really cool re-engineered pieces for our cars) in Texas I believe (George Murphy I think is his name, have his catalog at home). Paid more like 20-something shipped.

But, for way less than 200 bucks for a new motor, mine too works like new.

-JAS

Maki · #4 05-12-2004, 11:56 AM

Well, I didn't take any pix -- don't have a digital camera -- but I could certainly give you a written blow-by-blow if you like. It's pretty simple, really.

You take the motor/fan assembly out from under the dash, then detach the rear plastic cover. The leads come off the motor via quick-disconnect hardware -- one is male and the other female so you can't mix 'em up. motor shaft out of the fan cage with a small drift. Then you're ready for the serious part.

The rear bearing carrier, which also holds the brush retainers, is staked to the motor casing. I used a file, some small Vise Grips and a screwdriver to loosen up the joints enough to remove the carrier without bending it too much.

Now to the brushes. One has a pretty easy connection to desolder. The other lead goes into a cylindrical connector that's a bit of a pain to deal with. I ended up drilling the lead out with a small bit and a variable speed drill at very low speed for maximum control. The solder and copper drill out quite easily, of course.

From there you fit the new brushes, solder in the leads and assembly is the reverse of removal!

If the commutator is a little notched it can be cleaned up by chucking the shaft in a 1/2-inch drill and running a file over it as it turns. I finished that job with some 1000-grit paper to smooth out the commutator surface. Also, a couple drops of oil on each bearing can't hurt.

The biggest challenge in putting the thing back together is restaking the bearing carrier to the case. I opened the jaws of my bench vise to the opposite ends of the case rested on them and the end of the motor I was working on stood up vertically. Then, with the bearing carrier fitted to my satisfaction, I used a hammer and cold chisel to stake it down. You stake it at eight points. The main issue to to make sure you've straightened any bends you introduced to the bearing carrier tabs by prying it out. There are four slots in the case where the tabs should fit like factory intended before you go to whacking.

I'm thinking of overhauling the blower motor in my coupe now. I'll try to take some pix at that time.

I've heard Murphy sells the brushes -- not sure what he wants for them but $20 sounds about right. He's making a little money; like I said, I paid the factory $4.17 each. I sold the remainder of my first run for exactly what I paid for them, and people urged me to order some more.

That entails a 10-mile detour for pickup, some bookkeeping, packing and shipping and the likelihood that I'm gonna be stuck with a couple pair. Hence the markup from $8.34 to $12 a pair. I don't plan to make a boat payment on this deal.

In fact, if there isn't enough interest, I'm gonna simply refer those in need to my rep at Schunk Graphite and let *them* get into the brush business.

Russ M

leathermang · #5 05-12-2004, 12:09 PM

"1000-grit paper to smooth out the commutator surface"

For those not aware of it... one should not use wet and dry sandpaper... silicone carbide for either Points ( moot on this forum) or electical things like the commutator... one should use flint sandpaper for things like this... non reactive....
and the way to keep it as level as possible is to wrap the sandpaper around it most of the way.... covering all the copper ...

Boston Benz · #6 05-12-2004, 12:49 PM

Save yourself all of this trouble and get a replacement set from George Murphy in TN. Don't reinvent the wheel-he's already done it for you. He sells replacement parts for common failure items on MBs (such as these brushes) for a fraction of the cost of what MB charges. In fact, I don't think MB sells the brushes, you have to buy the whole unit new. George has discovered this niche market and he sells at reasonable prices. His # is 865-482-9175

Maki · #7 05-13-2004, 01:31 AM

Quote:

get a replacement set from George Murphy in TN. Don't reinvent the wheel

Hmmm...a tough call. Do business with George Murphy, or reinvent the wheel...

...Where's my spokeshave?

Seriously, I won't trash Murphy on this list. But I won't deal with him either. I'm not too happy with the way a prior transaction worked out. YMMV.

Russ M
'82 300td
'82 300cd

Maki · #8 05-13-2004, 01:36 AM

Quote:

one should not use wet and dry sandpaper

Interesting. To quote Johnny Carson, "I did not know that."

I flushed/swabbed the commutator pretty thoroughly with CRC electric contact cleaner after smoothing it out, but I wouldn't doubt that a little abrasive residue got left behind. Hope the effect turns out to be minimal.

I'll lay off the wet/dry stuff when I rebuild the blower motor in my coupe, though. Thanks!

Russ M
'82 300td
'82 300cd

81Wagon · #9 05-13-2004, 02:05 AM

I'll take a pair if you end up with enough orders :-).

wjm · #10 05-13-2004, 09:53 AM

www.**************.com has been carrying these for a while. Go to site and click on "repair manuals" on left hand side.

Look for:

123/116 Heater Motor Repair Kit
Item # MRG-123HMR

For all 123 chassis cars made from 1977 to 1985 and all 116 chassis sedans built from 1973 to 1980.

This repair guide will take you through the process of how to properly remove your heater blower motor and replace the motors two brushes. ... click for more information ...

81Wagon · #11 05-13-2004, 10:23 AM

Maki's are a lot cheaper :-)

Stevo · #12 05-13-2004, 08:57 PM

Russ

You already have me down for a couple sets..(from the other list)

I would assume the material they made them from was the same hardness as the ones you gave as samples? That would be part of duplicating yours which were original, Yes? I have used small appliance ones and they are very soft, which might be better than ones that were too hard tho.

Thanks for doing this, I have not heard good things about the other supplier either.

Maki · #13 05-14-2004, 02:45 AM

Hiya Steve,

Yep, the maker, Schunk Graphite Technology, manufactured the brushes in my first batch to duplicate the brushes that I pulled from the motor. It was a custom order -- the turnaround was about 10 days. They appear to be made of the same graphite compound that was used in the originals, judging by color, surface quality and hardness, although I confess I'm no expert on such things.

All other aspects -- dimensions, gauge of the copper pigtail, location of pigtail mounting point on the brush -- are identical to the one that came out of the motor. With the new brushes, that motor has run responsively for about four hours now at various speeds as the climate control unit functions (I commute 90 minutes every day to work and back). Seems to be doing fine.

The manufacturer has a website at www.schunkgraphite.com. Their corporate history (under the "about us" link) and product line are pretty interesting. This is a domestic branch of a German-based multinational company that specializes in motor brushes and other motor components.

These are definitely not brushes for the ol' Black & Decker!

That said, I'm afraid I'm hitting a wall when it comes to rounding up other people interested in sharing that second run. If I can't break even, Steve, I'm sorry to say I'm not going to go ahead with the order. To elaborate on a previous statement, I have no desire to go into business, and I particularly have no desire to maintain an inventory!

I would happily pass along the information I've gained in arranging my original purchase to anybody who wants it. The company is Schunk Graphite Technology, W146 N9300 Held Drive, Menomonee Falls, WI 53051. I dealt with Melinda Schall, who can be reached toll-free at 800-955-3610. I'll even provide the number of my order: C001671, which includes all necessary specs. She may describe the order as "BMW brushes." Please forgive her.

Russ M
'82 300td
'82 300cd

wjm · #14 05-14-2004, 05:26 AM

If you could verify if the same brushes will work in a W124 blower motor, I might be interested.

Maki · #15 05-14-2004, 11:13 AM

I don't know if they'd fit a W124 blower motor, Willy. I kinda doubt it.

I can tell you that the brushes measure .312x.312 inch, .750 inch long. I found a picture on Schunk's European web site that is pretty representative of the W123 brush:

http://www.schunk-automotive.com/automotive/english/0_1.htm

From there, click "Products" and then "carbon brushes." The brush labeled "carbon brushes for heating fans" is pretty much what I got from them.

Russ M.