Once the restoration of my 1973 Carre/Bertin C 37 was finished, it only took until the first ride to discover that the stock OEM Mafac pads were hard, high effort and unsatisfactory, especially compared to my 1960s C 37 equipped with Mafac Competition centerpulls with aftermarket black, Kool Stop pads. The search was on to try and find some kind of workable replacement.
The Mafac LS series shoes are angled to create toe-in when the shoe is mounted on the LS caliper arm. In addition, they have a nut inside the OEM alloy brake shoe to accept the brake shoe attachment bolt which means a replacement pad has to have a notched or relieved center section to fit. See the accompanying photo on the right of the screen to view both of these features. Also problematic are the tight tolerances in the brake shoes and pads themselves. Having measured pads around the workshop like generics as well as Weinmanns, I could not find an exact dimensional match to the Mafac LS pads. Consequently, I decided to take the easy way out and simply replace the whole shoe/pad assembly.
The easy way was not easy. I ordered, on line, an inexpensive set
of YST shoes with chevron shaped braking surfaces to echo the Mafac pad shape. Once they arrived, the steel brake shoes looked comparatively poorly finished and once installed they did not toe in well or look the part of a high end brake as one might expect with such an inexpensive product. However, the pad rubber was soft and once sanded clean of mold flash, the shoes did stop the bike better than the 40 year old OEM Mafac pads. Brake feel and modulation was not great but the bike would stop and did so with less lever effort than the original pads. Faint praise.
Part 2 of the easy way was to order another shoe/pad combination set but this time from Jagwire in the Weinmann X pattern pad configuration. A big name in brake components should yield big results. Not so much. The Jagwires were better finished and cleaned up the mold lines with relatively little sanding. However, even with the LS caliper arms designed in toe, the Jagwires were still nearly parallel to the rims’ braking surfaces. The stopping was adequate, better than the OEM but not enough and they didn’t look right as mounted.
Part 3 of the easy way was an attempt to open up the Jagwire pads and extract one to test fit in a Mafac alloy shoe. The steel shoe on the Jagwires was reluctant to open which basically meant destroying the shoe to get the rubber brake pad out only to find the pad dimensions wrong for the Mafac shoe. At that point, I determined to find a pad that would fit the OEM Mafac shoe.
I searched through the technical specs for pads on the Kool Stop site but found nothing that looked close enough. While searching on the EBay USA site for Kool Stop, I came across a Scott/Mathauser ad offering Type M pads specifically for Mafac and and early Dura Ace. They could not have been for regular 4 dot Mafac centerpull brake shoes because the photos of the package clearly showed a Campyesque pad that looked quite different from the usual 4 dot Mafac pads found on Racers, Competitions and 2000s. So, I ordered a set which were quickly delivered from Ebay by Canada Post. When I opened the package, the Scott/Mathausers had a superficial look of compatibility with the Mafac LS OEM pads. Like I did with the Mafacs, I measured the Scott/Mathauser pads with my digital calipers. I found the measurements to be slightly larger but within .5 to 1 mm of the Mafacs’ measurements. The one exception was the relief area on the top of the pad which in the Scott/Matthauser pad was 15 mm long compared to the 12 mm for the Mafac.
While I waited for the Scott/Mathauser pads to arrive by mail, I had been cleaning the Mafac shoes and removing the original pads. Removing the pads entailed levering them up at the end with a straight bladed screw driver followed by using pliers to wrench the pads the rest of the way out of the shoe. The shoes were wiped down and then run through an ultrasonic cleaner with some dish soap. The result was as set of clean shoes ready for the installation of the new pads. When the pads showed up, I checked the details on the reverse side of the plastic pack before attempting a trial fit or the installation.
Once the shoes were cleaned and ready, I attempted a trial fit of the Scott/Mathausers in the Mafac LS shoes. Even with the use of dilute dish soap as a lubricant, the pads did not fit into the shoes since the angle of entry of the pad was too extreme, the pad edge hung up on the round nut within the shoe and the pad would not settle under the rear stop at the back of the shoe.
The failure of the easy fit lead me to a few conclusions: that the .5 to 1 mm oversize difference of the Scott/Mathauser pads made a difference and you might want to do a little file work on the pads; the forward edges of the new pads need to be angled or rounded off to fit over the embedded nut within the shoe and finally, the rear tab of the brake shoe must be broken off to fit the new pad.
To get the pad rounded off like the center pad in the photo to the right, use a file or 120 Grit sandpaper as seen in the photo. It is also necessary to remove the rear retention tab of the alloy Mafac brake shoes. I tried a hacksaw but the result was poor and recommend bending the tab upwards with pliers until it yields and then snaps off. Once the retention tab has snapped off, put the shoe in a bench vice with padded jaws to avoid damaging the finish and take a fine file and dress the broken end thoroughly being sure it is de-burred and smooth to avoid fouling during the pad installation.
Be sure to carefully identify which end you will remove as the shoes are directional and the forward facing arrow must go to the front with a closed end but also to permit proper toe-in in combination with the LS caliper arm design. Once the shoes have been correctly opened and cleaned up, prepare a soap and water solution to act as a lubricant when installing the new pad into the Mafac alloy shoe.
Once you have lubed the inside of the alloy shoe, add the soapy mixture to the nose of the pad and to the crease along both sides. Slide the pad on an angle over the internal nut in the shoe until it is stopped by the front of the pad holder. It will now be sitting at an angle with the rear of the pad protruding from the alloy shoe. Place the shoe/pad assembly into the padded vise jaws and slowly tighten down until the pad slips into place. (You may need to reverse the shoe in the vise to get the back section to fully seat.) Once the pad is seated, rinse the shoe to get rid of the soap solution from the installation and then follow the same procedure for the other three pad/shoe assemblies.
Having cleaned and dried the assemblies, use your 120 Grit sand paper to abrade the braking surface of the Scott/Mathauser pads until the shiny surface is removed and the surface appears dulled to the eye. Trial fit the retention screws and washers before doing an installation. The finished pad/shoe assembly should look like this:
The assemblies, once installed, should show an obvious toe-in when viewed from above. See the following photo:
Seen in profile, the installed assembly looks convincingly original and discreet except for that tell tale orange colour peeking through the brake shoes:
The Scott/Mathauser M pad is the only one that I have found that installs properly in a Mafac LS, LS 2 or LSX alloy brake shoe. The fit is tight and installation could likely be eased by a slight filing along the edges of the pads in addition to the sanding described earlier. Toe-in is stock and so is the side profile appearance. Functionally, the pads are superb. There is no squeal, stopping remains higher effort than my Mafac centerpulls, as one would expect, modulation is easy and completely linear and progressive. Braking from the hoods is comfortably possible and is very strong from the drops. I highly recommend the conversion if you have Mafac sidepulls and wish to experience a major improvement in your braking quality.
The bike has not and will not be ridden in the wet so I cannot comment on that aspect of brake performance. Before the upgrade as well as after, the Carre/Bertin C 37 was fitted with Velo Orange lined cable housing and mandrel drawn stainless steel cables.