Worth getting new bushings for MAFAC Racer

[mboro1876]

Hello there,

My Mafac Racers do an okay job but as part of a rebuild I'm looking for something similar in style with less flex and play (pads riding up the rim when applied, etc.), allen keys, easier adjustment... So I'm mostly looking at the spendy Paul Racers or Dia-Compe Gran Compe 610s. However, I'm intrigued by the idea of replacing the bushings with this brass set:
https://www.renehersecycles.com/shop/co ... ll-brakes/

Clearly it's going to be a little steep unless I can find an EU source. So:
-- am I right to think that the main source of serious play in these brakes is from the bushings, so that these bushings might make a big difference?
-- know anywhere better to get them from?
-- depending on the first two answers, do you have experience of the Mafacs versus GC610, Paul Racers, or whatever else? Feel free to suggest deep drop sidepulls (I need 60+mm drop) but I really dislike the looks of most of them...

Cheers!

[Brucey]

'racer' mafacs are quite flexy. Brass bushings will help but they won't miraculously make the brake caliper stiff. Someone competent with a lathe can make you bushings for your brakes.

Velo Orange calipers (not cheap) are stiff and good looking, but have a maximum drop of 57 or 59mm depending on who you believe.

FWIW if your brake calipers are flexy, you need to allow for the flex when setting the brake blocks up.

An inexpensive option is to use weinmann vainqueur 610 brakes. These have a maximum reach of 61mm. These work best with wider rims; with narrow rims they work best if you can space the brake blocks about 5mm further away from the brake arms. Obviously you need to use high MA brake levers with these calipers; many modern STIs won't do well at all.

cheers

[scottg]

The Pauls and Mafacs are great when used with brazed on pivots.
Compass sells the Mafac pivots, the Pauls use cantilever pivots.
If you don't have center mount braze ons, use the TRP or Velo Orange dual pivots.
better than single bolt mounted MAFACS.

[mboro1876]

Nice one Brucey. I have to say I wouldn't know where to look for someone lathe-competent or where to find the specs for the bushings, but it's a tempting idea to look into it. I guess at the moment I do account for the flex when setting up, so that the pads start tilted one way then the flex brings them into a more proper alignment. But the sheer amount of movement on these Mafacs doesn't inspire a lot of confidence and makes the 'correct adjustment' zone rather small.

Thanks for the tip on the Weinmanns. For what it's worth, I picked up Dia-Compe Gran Compe 202Q non-aero levers to replace the extremely floppy originals. They feel great in hand, really high quality and should have the correct characteristics for whichever the centrepull brakes I end up with!

Cheers

[mboro1876]

The Pauls and Mafacs are great when used with brazed on pivots.
Compass sells the Mafac pivots, the Pauls use cantilever pivots.
If you don't have center mount braze ons, use the TRP or Velo Orange dual pivots.
better than single bolt mounted MAFACS.

racer_gallery_5.jpg

Cheers Scott. I don't have braze-ons of any type although I would really love to add them to the front forks for this frame. Braze-on'd centre pulls would really be great! Do you know how the Mafac and Paul compare when *not* braze-on mounted?

[Brucey]

the backplate on the Mafacs is kind of flexy and this is (I think) where much of the flex comes from in a standard caliper. Braze-on mounts usually make the front brake stiffer but not the rear so much; in most frames the seat stays are not super stiff in the same way as the fork crown is.

If you make a front plate for a centre pull brake this will stiffen a standard caliper somewhat; much of the flex you feel comes from the pivot bolts splaying under load. This doesn't make much difference to the (forwards) flex in the arms that causes the brake blocks to swing into the tyre though.

cheers

[Brucey]

these are some common boss dimensions for centre-pull calipers


IIRC the standard Dia Compe 610/750 models are dimensionally similar to the weinmann ones, and the same back plate is used with both lengths.

cheers

[mboro1876]

wonderful! Thanks. The rebuild is coming together gradually now, in case anyone is interested I will write the parts list here and then update with pics when it's done...

Frame: 60cm 1984 Galaxy -- it survived scot-free a recent, relatively minor side-on collision, which knocked the bike out of the way and me up in the air, precipitating the compensation that's paying for this build. I've thoroughly inspected it and will have a trusted shop do the same, but it seems in fine shape. Worst case, an excuse for a Bob Reynolds order to replace it
Stem and bars: Nitto Randonneur and Technomic, replacing the old bars and non-original stem. I'm more antsy about these due to the collision, and in any case the Nittos are a lovely upgrade.
Seatpost and saddle: SR Laprade and Turbo already owned
Levers: Dia-Compe Gran Compe 202Q
Brakes: We'll see, as per this thread
Rear Derailleur: Suntour VX GT already owned
Front Derailleur: Suntour AR already owned
Shifters: Suntour Ratcheting already owned
Crankset: Spa Compact Double (TD-2 based) in 44/28. Down the line I may add a big ring for a triple, but not yet.
Bottom bracket: whatever gets the right chainline.
Wheelset: Open Sport on Shimano 600 hubs, 126mm spacing already owned
Freewheel: 14-28 Shimano 6 speed for now, giving a very low 26-84" gear range. I'm heading toward a cassette rear-wheel and cold-setting the frame, at which point the bike will top out at 90-95".
Racks: Blackburn rear rack already owned. May add a Blackburn front rack which I have to hand as well.
Mudguards: SKS Chromoplastic

Exciting times ahead for this beloved bike. My mum used it when she and my dad toured France, and still has the receipt .

[Brucey]

IIRC the 1984 galaxy would have come with weinmann centre pull brakes originally; 610 at the front, 750 at the rear. Check this to be sure but the 610 model is probably not long enough to reach the rear wheel.

https://dawescycles.files.wordpress.com/2019/03/1984-dawes-cat-vcc-library.pdf

the catalogue photo shows the brake blocks set mid-slot in both front and rear calipers, suggesting ~55mm reach at the front, and ~68mm reach at the rear

cheers

[mboro1876]

IIRC the 1984 galaxy would have come with weinmann centre pull brakes originally; 610 at the front, 750 at the rear. Check this to be sure but the 610 model is probably not long enough to reach the rear wheel.

https://dawescycles.files.wordpress.com/2019/03/1984-dawes-cat-vcc-library.pdf

the catalogue photo shows the brake blocks set mid-slot in both front and rear calipers, suggesting ~55mm reach at the front, and ~68mm reach at the rear

cheers

That's a great website which I didn't know of, though I have seen that manual before. In fact the stock brakes on mine were a pair of identical Weinmann's with the strange 'solid metal' straddle. Not amazing brakes but quite an interesting design. With 700c wheels they both don't reach, though by substantially more in the rear than the front as you correctly suggest!

[Brucey]

if (esp with a narrow rim) you space the brake blocks away from the arm with the weinmann CP brakes, you get

a) a touch more reach and
b) a higher MA

The solid straddle weinmanns were the 'last gasp' for their CP model. I think they are known as Model 737



IIRC they don't have the centring 'nub' of the previous version.



cheers

[rjb]

I like those brakes, have often thought you could fabricate a cover and turn them into Delta lookalikes.

[Brucey]

I've often wondered why weinmann gave up on their CP model. I now think it is because they thought they had come up with something better, the 'HP Turbo', truly a child of the 1980s






so if you like the look of maguras, but don't revel in the prospect of fluid possibly weeing out, you have (had) an alternative. I have never seen a set of these in the flesh.

cheers

Brucey

[Brucey]

BTW weinmann did their own delta short reach aero brake BITD




cheers

[mboro1876]

great to finally know what the model 737 is called!

the hp turbo is amazing.... truly horrendous . There is room for everything in the world of bikes but... yeesh.

meanwhile I'm eyeing up the Thorn Audax Mk3 frames in case there turns out to be an issue with mine. Doubt it though and hope not, but it's fun to imagine putting this mish mash of vintage and quasi-vintage parts onto a newer Thorn frame.