Shine up those Mafac Racers
10-01-18, 02:02 AM
#26
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Found this home made grinder at a yard sale...
Bought some cloth wheels at Canadian Tire, and some polishing sticks to do the job...
Not including filing of gouges or factory forge marks, it takes me about five to ten minutes to go from this (WARNING - always wear a filter mask, when doing this or even when fine dry sanding alloy components)...
to this...
Bought some cloth wheels at Canadian Tire, and some polishing sticks to do the job...
Not including filing of gouges or factory forge marks, it takes me about five to ten minutes to go from this (WARNING - always wear a filter mask, when doing this or even when fine dry sanding alloy components)...
to this...
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10-01-18, 05:00 AM
#27
Mike J
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I start with 120 grit on the edges where the forging marks are the worst, you almost have to treat it like you're using a rough file on it. I did try a file, but the countours of the calipers don't lend themselves to being filed with a flat file without much too heavy filing marks left behind. Then down to 240, then 400, then 800, then 0000-grade steel wool with WD-40 on it, then a polishing compound.
Lots of work and lots of time, but the results are worth it. I'm sure a buffing/sanding wheel would be the way to go, but I'm retired....so...
Lots of work and lots of time, but the results are worth it. I'm sure a buffing/sanding wheel would be the way to go, but I'm retired....so...
10-01-18, 05:39 AM
#28
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Great job! For this kind of polishing, I use Micromesh cloth sanders. They last a long time, and make it easy to just work up through the grades.
https://www.amazon.com/SANDING-SHEET...o-mesh+sanding
https://www.amazon.com/SANDING-SHEET...o-mesh+sanding
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10-01-18, 06:08 AM
#29
verktyg
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Dural Forge
I wrote: " BTW.... MAFAC caliper arms were forged not cast."
I guess I forgot to add that little tidbit. I include that in another recent post.
DURAL was one name for Duralumin alloy which was developed in Germany in 1903. It was also called duraluminum, duraluminium, duralum.
MAFAC changed the name on the calipers from DURAL FORGE to MAFAC RACER about 1969-1970. The were so many of those brake sets in the French bike component pipeline that we were seeing new bikes coming through with DURAL FORGE brakes as late as 1973.
We imported a lot of French components in the 1970's. Brought in boxed sets of MAFAC Racer brakes which included front and rear calipers, levers, cables, housing plus all of the hardware. They cost us $6.00 a box!!! Since we had them shipped in the same containers as the Bertin bikes we imported, the freight costs were nil.
There wasn't much of a demand for MAFAC Racer brakes but we sold a lot of the sets wholesale to bike shops for $12.00 a box! It was a really cheap way to get MAFAC replacement parts!
BTW, I use XXXX steel wool to get a factory like luster on MAFAC brakes.
verktyg
I guess I forgot to add that little tidbit. I include that in another recent post.
DURAL was one name for Duralumin alloy which was developed in Germany in 1903. It was also called duraluminum, duraluminium, duralum.
MAFAC changed the name on the calipers from DURAL FORGE to MAFAC RACER about 1969-1970. The were so many of those brake sets in the French bike component pipeline that we were seeing new bikes coming through with DURAL FORGE brakes as late as 1973.
We imported a lot of French components in the 1970's. Brought in boxed sets of MAFAC Racer brakes which included front and rear calipers, levers, cables, housing plus all of the hardware. They cost us $6.00 a box!!! Since we had them shipped in the same containers as the Bertin bikes we imported, the freight costs were nil.
There wasn't much of a demand for MAFAC Racer brakes but we sold a lot of the sets wholesale to bike shops for $12.00 a box! It was a really cheap way to get MAFAC replacement parts!
BTW, I use XXXX steel wool to get a factory like luster on MAFAC brakes.
verktyg
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Don't believe everything you think! History is written by those who weren't there....
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Last edited by verktyg; 10-01-18 at 06:19 AM.
10-01-18, 06:41 AM
#30
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Faux anodized Racers.
10-02-18, 07:05 AM
#31
Randomhead
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I have quite a bit of polishing for my research, so I asked myself how hard it could possibly be to polish up a Racer. Then I started in on an arm and didn't seem to be making much progress. I'm impressed by your results, I guess I just have to be more patient.
10-02-18, 11:50 AM
#32
Pedal to the medal
Hats off sir for your patience. Turned out great!
and...now I'm not sure.
10-02-18, 12:29 PM
#34
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I have a bench grinder. I would use that.
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Tom Reingold, tom@noglider.com
New York City and High Falls, NY
Blogs: The Experienced Cyclist; noglider's ride blog
“When man invented the bicycle he reached the peak of his attainments.” — Elizabeth West, US author
Please email me rather than PM'ing me. Thanks.
10-06-18, 08:35 AM
#35
Overdoing projects
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Polished on the left, cleaned on the right.
Sonic cleaner > 280 grit > 600 grit > car polish > car wax
10-06-18, 08:51 AM
#36
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10-06-18, 12:46 PM
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In the early 70's there was an article in Bicycling! magazine that gave instructions for tuning the finish on brake calipers, the subject brake was a Universal center pull, I did the task on a pair of Racers, carefully tuning the surface marks, they approached Campagnolo level of finish when done. Sold long ago with the frame of which they came with. Would have been great to anodize the arms afterward, but the turnaround was 2 weeks, and I did not have another set of brakes.
10-06-18, 02:10 PM
#38
Overdoing projects
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10-06-18, 04:40 PM
#40
Overdoing projects
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I noticed something similar with a pair of quick release cable hangers:
Before
After
Perhaps older versions were chrome and newer ones nickel?
10-06-18, 08:58 PM
#41
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Had no idea MAFACs could look like this. Kudos to all the polishers, and a big thumbs up to the OP and his file. Holy crap those things look good. 
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A race bike in any era is a highly personal choice that at its "best" balances the requirements of fit, weight, handling, durability and cost tempered by the willingness to toss it and oneself down the pavement at considerable speed. ~Bandera
Last edited by Fahrenheit531; 10-06-18 at 09:41 PM.
10-07-18, 04:00 AM
#42
Mike J
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Looking back, after having gotten into French bikes and exclusively having Mafac racers, those Dia-Compe calipers had a fairly high quality of original finish compared to the Racers. 10 minutes on a Dia-Compe, 8 hours on a Racer.
10-07-18, 02:25 PM
#43
Senior Member
So impressed by this work, the results are amazing! I’ve always loved the look of Racers and this shows what they can look like!
10-07-18, 05:13 PM
#44
Junior Member
Thanks for the pics jj1091. They look great. I had no idea they could be shined up like that. My Mafac's look neglected by comparison. Thanks for the detailed description of your technique. I'll be doing some polishing next weekend.
10-08-18, 08:31 AM
#45
Mike J
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Thanks. Also, I saw that you'd recently come back into Bikeforums, and had moved to Japan in 2010. Welcome back. When you get them all shined up, and get 10 posts, you can post some photos here, maybe pics of your (Peugeot?) bike.
10-11-18, 02:29 PM
#46
Junior Member
Your welcome. I'll gladly post a photo of my polishing results and my bike after I make it to ten posts. Just a few more posts to go.
10-17-18, 07:16 PM
#47
Junior Member
Got a chance this weekend to do some polishing. A garage sale buffer wheel was a great time saver, but other parts still needed to be done by hand.
Did not quite reach the bar set by jj1091, but they do shine more than when I started. (photo will be in post no. 11).
Did not quite reach the bar set by jj1091, but they do shine more than when I started. (photo will be in post no. 11).
10-17-18, 07:19 PM
#48
Junior Member
More lustre than Evapo-Rust can give. And in the right lighting, they do shine a bit.
10-18-18, 03:09 PM
#50
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I was in the Army back in the “black shoe” and “brass medals” days- back when it took hours to get your uniform looking good. I’m ok with spending time and elbow grease polishing parts with cotton balls and such.
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