capnjonny 

does anyone have a scale drawing of the after market stiffener that supposedly makes these brakes less prone to squeal. If so could you post it. I would like to ake a set for my '58 Follis.

John Nolan 

Don't have a drawing, but in case some haven't seen them, there are images of them here.

Cynikal 

I would think that your first step with these brakes is to get new bushings. The brass bushings, or even new delrin bushings, eliminate the vibration that causes the noise.

Velo Mule

I made one once when I was younger and far less sophisticated. Oh, wait, that implies that I am sophisticated now and that is not true. I just took a piece of aluminum, about an 1/8" thick and placed the center-pull bracket over it. Then I marked the position of the first screw hole, drilled the hole. I then put a bolt through the first hole and used a drill to mark the position of the second hole. Once the center point was marked I can drill the hole without the possibility of messing up the bracket. Now the two holes had the proper center to center distance. Then marked out the curve of the bracket and cut it with a jigsaw.

Nowadays, I'd use transfer punches and a band saw. It is still the same process with better tools.

tiger1964 

If you are talking about the aftermarket kit that came in a poly-bag that boxed-in the calipers forward of the pivot bolts... I have ONE, not a complete set. What's your address, I'll send it to you! That said, I bought them in the early 1970's, so if there is a period-correct 1950's product -- I don't have a clue.

scarlson 

Spence Wolf made them, so I'd imagine whenever he was around they would have been available. But it's hardly an original idea, I'm sure others have also made them! I have an original Spence Wolf one and I could make a dxf drawing if you nagged me enough.

cudak888 

Anyone have the basic measurements for these? I bet I could have a set laser cut and deburred.

-Kurt

scarlson 

You musta replied right as I did. I can draw the dxf file from my original spence wolf specimen if that's what you need. Maybe extrapolate and make one for Raids too?! Drawing dxf files is easy.

tiger1964 

Yeah, that's what I have here.

Better still if you could substitute a MAFAC logo for the three center holes. "Yeah, this is the rare MAFAC Model 377 calipers, I paid a fortune for them on eBay".

cudak888 

Exactly my thoughts. This is doable.

This is also doable.

-Kurt

markk900

Curiosity here: the spencer wolf thing just stabilizes the pivots a bit, right? So the actual load transferred between pivots is relatively small? If so could the majority of the brace be slotted?

bulgie 

The only critical dimension is the post-to-post spacing, and even that has some tolerance because you can enlarge the holes if it won't bolt on, or "customize" (ovalize) one or both holes with a round file as necessary to get it to fit. The holes are nominal 6 mm but you can drill them with a 1/4" drill, slightly OS but it won't hurt the function any. Once the screws are tight, the brake can't tell what size the holes are — to a point. The plate has to tighten against the end of the pivot boss, which is 8 mm (5/16"), so don't let your hole get that big!

I don't think the plates are a panacea against squealing, but they can help and they're unlikely to make it worse. Their main effect is to reduce the "lost motion" at the hand lever caused by flex in the arch with the pivot posts, what Mafac called the etrier. Gives a firmer or less mushy feel, especially good if you were in danger of bottoming out the lever on the handlebar.

But that same flex in the etrier can allow the pads to twist into an anti-toed position under hard braking (especially in front), so reducing it is likely to help with squealing. I still recommend a little toe-in, but you can get by with less with a stiffener.

juvela

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ironic that it is only a five km or so hop from capnjonny's location to the Spence Wolf Randy Lane location...

​​​​​​

advert of fifty yar back, March 1973


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cudak888 

I have a pair of Racers I can measure. Anyone have the CTC for the Comps and RAIDs, by chance?

Going to try something later this week.

-Kurt

bulgie 

Racer, Comp, 2000 and some others are 62. Raid = 75
Oh Rueda Tropical sez the Racers/Comps with the adjustable etrier were 63 mm. I can't confirm that at the moment.

Here we go, from a Mafac catalog:

tiger1964 

...and matching the arc of the base plate, presuming you want fender clearance.

bulgie 

Sure, but I wouldn't call that a 'critical' dimension. If you miss it by say an eighth of an inch in either direction it'll still work OK.

Ooh straight across from boss to boss (sounds fun to say) would be the stiffest, if you're using tiny enough tires! <jk>

79pmooney

But there's plenty of room to fudge. As long as there is enough material up high, too shallow an arc doesn't matter. Drill the holes, lay it in place over the bolts and see if fender clearance is an issue. Yes? Cut or grind. (You may see upon trial fit that there is a s**ier curve than a boring arc .

Now, if you have the tooling to do a machined perfect arc, get it right the first time! But the band and jig saw folk don't have that issue/privilege.

tiger1964 

Well, it wouldn't be critical for me either -- but I have not seen the OP's bike.

mhespenheide 

Would these be roughly the same dimension for cantilever brakes from the 90's, such that you could use the add-on aftermarket bridges that were designed to stiffen suspension forks on mountain bikes?

zukahn1 

Not really since there is about 5mm difference in the mounting points.

scarlson 

Furthermore, the cantilever stiffening plates arch way up high, which isn't necessary for a center pull. It would look funny and not be as strong.

cudak888 

Got it.

Just ordered a run of five 62mm laser-cut bridges out of 5052 aluminum. Should be interesting to see how they perform.

-Kurt

scarlson 

@cudak888 how much does that cost, roughly, to get that done?

My OG Spence Wolf plate measures 0.1" thick (2.55mm or probably 10ga if my chart is right). It is obviously done in inches, so I'll describe it in inches. It has the two 1/4" holes for the brake pivot posts plus 3 more 1/4" holes (one centered in the center, one centered 1/2" outboard on either side). The plate is 0.55" wide. The arc its centerline inscribes peaks at 3/4" up from the level of the posts. So it's a radius of 4.4" on the centerline, or 4.125" minor radius and 4.675" major radius.

Aw heck is this information even useful if you've ordered them already? Should I make a drawing for the Raids?

cudak888 

Depends on quantity. Also depends on the amount of time the part takes to cut and engrave; there's a stylized "M" laser burned into the design which ramps up the price a bit.

A drawing for the Raids would help, though Mike Terraferma might have one I can borrow. A straight-on photograph of a Raid with the arms at their normal spot when resting (with the cable set) might help more than anything else.

-Kurt