Shine up those Mafac Racers
08-27-18, 08:32 AM
#1
Mike J
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Shine up those Mafac Racers
I love my Mafac Racers, but they never did a good job on the finish quality. Lots of casting marks and rough edges, grainy surfaces, nothing that would be called pretty. Since all the bikes I own are Peugeot's, I've gradually spent time upgrading the old Racers. Now they look fitting for the builds.
I start with a bit of filing on the worst edges where the casting marks are the heaviest, completely removing them. Then, there's about 5 levels of sanding, then a final polishing. All by hand, no buffing wheels or Dremel tool. Once I'm done, I'm a bit more happy with their quality.
Grainy surface
After
Casting marks
All gone
Under the crown
Much better
Not so pretty
Now they're bling
I start with a bit of filing on the worst edges where the casting marks are the heaviest, completely removing them. Then, there's about 5 levels of sanding, then a final polishing. All by hand, no buffing wheels or Dremel tool. Once I'm done, I'm a bit more happy with their quality.
Grainy surface
After
Casting marks
All gone
Under the crown
Much better
Not so pretty
Now they're bling
08-27-18, 09:04 AM
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Really nice job on bringing those to life. I would re polish the bolt faces to match, but beauties nonetheless.
Last edited by jwolfe; 08-27-18 at 09:20 AM.
08-27-18, 09:05 AM
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Wow, those look great! I've been gathering parts for a future build up of a Jeunet 620 and I figured a set of Mafac Racers would be the best pick for that bike.
Now I know what to do with a set once I get them.
Now I know what to do with a set once I get them.
08-27-18, 09:28 AM
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Nice work! someday I am going to have a space where I can use a buffing wheel and then stuff is going to be dangerously shiny 
08-27-18, 09:43 AM
#8
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Fantastic job! How long would you say it takes to do an entire brake caliper, wth your 5 step process? I’ve been following other threads on aluminum polishing and need to get around doing my own.
08-27-18, 09:51 AM
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Good job on those lovely old calipers. The Mafac Racer is one of my favorite stoppers. Can't recall if I did a little extra polishing on the calipers, for sure, but I think I did...
But the levers did get a few spins from my homemade polisher...
But the levers did get a few spins from my homemade polisher...
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08-27-18, 10:04 AM
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Nicely done. They look great with a shine on them! Perhaps my favorite brake for performance, looks, name, and reputation.
I’ve only rode with one set so far. I had a ‘72 UO-8 for a few months with nearly all original parts. The frame was too large so I recently sold the bike. It was a real challenge to not swap the Racers out before selling it, but I wanted to respect the integrity of the bike.
I’m thinking of putting Racers on a ‘72 Super Course build, unless I can find a complete set of GB 66’s at an affordable price!
I’ve only rode with one set so far. I had a ‘72 UO-8 for a few months with nearly all original parts. The frame was too large so I recently sold the bike. It was a real challenge to not swap the Racers out before selling it, but I wanted to respect the integrity of the bike.
I’m thinking of putting Racers on a ‘72 Super Course build, unless I can find a complete set of GB 66’s at an affordable price!
Last edited by deux jambes; 08-27-18 at 10:09 AM.
08-27-18, 11:38 AM
#11
Mike J
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So far, I've done 4 sets, each taking 2 whole days per set.
08-27-18, 11:43 AM
#12
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Looks great! Can I send you mine?
08-27-18, 12:16 PM
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Those look fantastic, and having started that job on a single set, I’m aware of the intricacies and time required. BTW, I elected to get the Compass upgrade kit, which saved the effort of the little parts. In the end, I decided to keep my Gran Compe on brazed on posts.
If anyone is interested in a single Racer brake set (one “caliper”) with those upgrades, the beginning of a polish job, and four new 4-dot salmon pads (not in holders), please send me a PM.
If anyone is interested in a single Racer brake set (one “caliper”) with those upgrades, the beginning of a polish job, and four new 4-dot salmon pads (not in holders), please send me a PM.
08-27-18, 12:30 PM
#14
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Those look fantastic!!
EDIT ^what he said!^
EDIT ^what he said!^
08-27-18, 12:34 PM
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Well done, sir, and good to know it can be done well!
(I have a set I've contemplated addressing, but was unsure how rewarding that effort might be.)
Shiny!
(I have a set I've contemplated addressing, but was unsure how rewarding that effort might be.)
Shiny!
08-27-18, 12:53 PM
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Looks great! 
BTW.... MAFAC caliper arms were forged not cast.
verktyg
BTW.... MAFAC caliper arms were forged not cast.
verktyg
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09-30-18, 06:23 PM
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I love my Mafac Racers, but they never did a good job on the finish quality. Lots of casting marks and rough edges, grainy surfaces, nothing that would be called pretty. Since all the bikes I own are Peugeot's, I've gradually spent time upgrading the old Racers. Now they look fitting for the builds.
09-30-18, 06:47 PM
#18
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Great job! Makes me want to break out the file, even with a great polish those ridges always bother me.
09-30-18, 08:12 PM
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Hence the term "Dural Forge" on the earlier versions.
09-30-18, 08:30 PM
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09-30-18, 08:39 PM
#21
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First time I ever did any aluminium polishing, it was on a set of ‘79 mafac competitions. Filing and sanding the forging seams is always a rite pain in the ass, but so worth it in the end. Mine were clear anodised, and I first stripped the anodising off, chemically. I would have been sanding for days otherwise. Going from 80 all the way to 2500, including wet sanding, I probably went overkill, but I was learning as I went, completely inexperienced. The most work I ever did was stripping and polishing a campy gran sport 3arm fluted crankset and chainring. I don’t have any photos because I’m not keen on documenting my work, and lord knows raw aluminium scratches up quick. Without professional tools, like a bench polisher, it’s a lot of work and I don’t know that I’d ever want to do it again. Gives me even more appreciation for all the work that goes into metal fabrication, especially steel bicycle frame building.
09-30-18, 09:14 PM
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I've been hanging out here for a while now and never have I seen Mafacs look that nice. So any old Mafac Racers can look like that? If I can do that, I might ride my Peugeot at Eroica CA.
09-30-18, 11:23 PM
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Yes! Just add elbow grease. RAID's can be done like this as well.
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10-01-18, 01:21 AM
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Just received a pair of Mafac racers for cheap and I was thinking of polishing them as well. But you have certainly taken it to the next level here.
10-01-18, 01:46 AM
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Nice work! Now I associate Mafac Racers with cheap UO-8s and almost every rain/'winter/city bike I have ever set up and the idea of polishing them is completely beyond my comprehension! What I did do (with far less work) was a take a near NOS set and with a bolt from a hardware store turn the rear into a front. Did the same with a set of Schwinn approved Weinmanns(?), turning the front into a rear. Took these mixed sets and installed them of my two current rain/winter/city bikes. Real stoppers! Don't ride close and fail to tell me you are there. (I love how going to the Weinmanns in back stiffens them up so after the long cable and housing run, they feel like the Mafacs in front, but being Weinmanns, have the pwer knocked down so lockup is much less of an issue. In the hands, front and rear feel the same and operate the same. Only difference is stopping power. Drawback - it flunks C & V,
Ben
Ben