Dawes-man

To bump, or not to bump, that is the question...

Well, I figure that it's as well to keep related info here for future searchers. I found this thread while wondering what to do about a pair of Racer calipers (marked DURAL FORGE) from around 1953 that I want to use on my 1975 Peugeot PX60. I'd fitted a pair of NOS Competition calipers but discovered, through the knowledge of fellow C&V'ers in this thread, that they were short-reach and too short for my bike. The longer reach Racers I want to use have the same wear/play in the bushings that this thread is about.

In the very informative Classic Lightweights pages on the history of MAFAC brakes it states, in part 2 under the heading "Design Weaknesses", that "Bronze bushing on the dural forge once worn cannot be replaced. One advantage of the plastic bushing on the 'Racer' is that they can be replaced." The writer obviously hasn't heard of the likes of our very own PDXaero or tux Having read that, I was very pleased to find this thread.

However, I have neither the equipment nor skill to attempt to replace the bushings on these Racers myself so yesterday I took them to a long-established engineering works a 15 minute ride away. I was going there anyway about having some BMW boxer heads worked on. It's great talking to an experienced machinist... I explained what I wanted and he said, 'Okay, I understand.' I'll post pics here when I get them back.

But I'm not just posting about that. There's a guy in Israel selling replacement washers for MAFAC calipers on eBay for 12 bucks including postage to Japan and I was wondering if anyone had tried them. If you have, any good?

noglider 

Thanks for reopening, Dawes-man.

ColonelJLloyd 

I don't understand the aversion of some to continuing a worthwhile thread, Dawes-man. So, thanks for posting pertinent content. I've seen the washers from the seller to which you refer and am currently working to make a complete pair of MAFAC Competitions from two incomplete pairs. I look forward to hearing from someone who has purchased said washers or hardware that upgrades the brakes from another source.

rootboy 

Yes. VERY interesting thread. I love stuff like this. Tinkering with an re-engineering old parts to make them serviceable again.
Much like Dawes-Man's thread about fixing his trashed old pedals.

Road Fan

They have a good reach, are more adjustable than about anything in terms of making the shoe mate with the rim, with Kool stops and good straddle length have good power and modulation (imo), and are vintage.

I think the point of new bushings is to reduce play in the pivots, not to restore smoothness. Great work on smoothing and lubing, but that just says you didn't need bushings.

Road Fan

Sorry, this was redundant - occupational hazard with zombie threads.

Road Fan

Worked in - you wore off some aluminum and need to keep it greased to make sure the bore fit remains stable.

jimmuller 

Would you (or someone) mind (re-)posting a source for these pieces?

I'm also interested in those brass washers from Israel. I may check them out and report. Wouldn't want to be paying big bucks for redundant parts though.

Thanks!

Grand Bois

Which pieces?

Road Fan

I saw a listing on Ebay for the brass washers, but not for the bushings. It's a current listing, with lots of days before it closes.

We need to talk about your project.

Road Fan

So Justin, the current Ebay seller of washers is also the former seller of bushings? Maybe he can be convinced to offer the bushings again.

Road Fan

I don't know if you've bought and installed all this stuff yet, but if I look in between the arms and the bolts on my Mafacs, I don't see a distance anywhere near 1/16 inch. If those are actually 1/16, they are way too thick. The bolts will not get seated right, and might back out as you ride. I would set those thick ones aside and go for the Ebay washers (search for Mafac Washer?). The listing gives the thickness as 0.6 mm, which sounds about right based on looking at my Racers.

I'd not use those thick plastic washers.

Road Fan

/

What I read (can't recall where) is that the Dural Forge model began, and it had bronze bushings and brass washers. Durability was good but not great. Around 1967 the Racer was begotten, same arms and castings as the DF. Around that time the bronze/brass were exchanged for the Delrin parts, and the name was changed to Racer. That's how I heard it. The Delrins would be more manufacturable - faster assembly, lower labor cost, no honing.

BTW those bushings have a 1 mm wall thickness, not 2.

jimmuller 

Thanks. I had seen the washer listing and added it to a watch list already. I was curious about the bushings. But I'm also thinking that $10 + $2 shipping = $12 is a bit steep for 4 washers. Or maybe not if they are all that special.

Dawes-man

GULP, is what I did when the machinist told me how much the bill for the new brass bushes in my MAFAC calipers came to... ¥12,600 which actually doesn't sound as bad as the US $ equivalent, $162 - the yen is very high now. I thought it would be a 'bit' expensive at around ¥8,000, or $100. Well, at least they should work like new now. (Voices singing in the background... Look on the bright side of life...)

Road Fan

Well, the seller has presumably sourced them from something like McMaster Carr. Why not just order the same thing from them? Should be cheaper. They aren't cheap, but one middleman is eliminated.

Special just means the right size and right material in this case. If you can find this at your local hardware store, go for it.

Road Fan

My experience from rebuilding my old air-cooled VW suspensions (all held together with steel pins running in precisely fit brass bushings) is that there may be precision fitting to insert the bushing in the arm, to size the inner bore properly, finish it with an etched surface (holds an oil film better than a mirror finish), and smooth the post surface to match. The lubing is really important because aluminum is so soft. Some VW bushing kits actually had a gap taken out of the bushing (it was not a complete circle) to allow it to spring into place as you press it in - that minimizes the need to machine the hole in the arm, where the bushing will be pressed in. And your Mafac parts must not get ruined, he has no spares. Any machine setups on his part must be double-checked. It can end up being a lot of skilled labor. At about $100/hour, your machinist's price is not so bad.

Dawes-man

Thanks for the insight. The shop has an excellent reputation and is used by at least one BMW motorcycle dealer, itself know for its race preparation. I'm picking the calipers up next Tuesday and expect a superb job.

ColonelJLloyd 

Looking forward to pics of the end result, Dawes-man.

Captain Blight

Your straddles are WAY too long. Look at some photos of the Comps to get an idea of how long Racer straddles should be.

lotek 

Amir (the seller in Israel) has both the bushings and washers. I'm rebuilding a pair of 2000's (later competitions)
so this is very on topic for me. You can also contact him via the CR list. There are a few posts about his stuff
and all the results were favorable.
Another CR list member has repop Competition straddle cables here:
https://sdbicyclegarage.com/French.html

Now all I need to do is find the last version that the 2000 and Competition used.

oh, anybody got any extra Mafac brake shoes?

Marty

Dawes-man

You're absolutely right, of course. If you can find the washers somewhere, in the right dimensions, they will do the job and be cheaper. How much can a couple of brass washers cost?

What we don't know is if the seller has modified the washers in any way. Another consideration is that, while the seller might have struck lucky and come across washers that worked first time, he might have had to do a lot of testing before he found the right ones. Personally, had I simply stumbled on ones that worked, I would just broadcast the source here and there for the benefit of fellow MAFAC'ers.

I came across some red plastic washers at Hasegawa's a while back, when I was building my PX60, and I thought I'd found an old-stock MAFAC source but Mr Hasegawa told me they were some left over from someone's attempt (don't remember if it was his) to copy the originals but that they didn't work. I should ask him if anyone had come up with a substitute. What with them being the traditional brake for the big randonneur scene in Japan, the tendency for the bushes and washers to wear over time, Japanese fastidiousness and their propensity for tinkering, there might be a bit of wisdom to be found out. Next time I'm there I'll ask.

Bianchigirll 

I have a 'kit' at home but have not had the chance to install them as yet, so it is just sitting on my bookcase with a neat pair of Sprint Carriers

Dawes-man

Do you mean the holders or the blocks?

If the latter, when I was last over at Mr Hasegawa's, he sitting with a cardboard box full of brand new holders and blocks next to him and a couple of buckets between his leg, prising the blocks out with a screwdriver, the blocks going in one bucket and the holders in the other. I said, 'Ah, MAFAC!' and he explained they were the tandem type, with 5 circles instead of 4. He was going to cut them down and sell them for normal bicycle use.

I did suggest they might be good to use 'as is' on a normal bike, and provide even better braking, but he said they interfered with... something, I don't remember what, as they were too long. I don't know but if you're looking for the holders maybe they could be cut down to size too. It depends if they are longer both sides of the pin or just on the open ended side.

Let me know if you are interested and I'll find out more.

Dawes-man

I've just got back from the engineering works, Kondo Nainenki, where I had the bushes done. I am very pleased The shop (as with any of these photos, clicking on one will take you to the album of photos - there are many of the inside of the shop in the album):
[IMG]
IMG_7856 by Dawes-man, on Flickr[/IMG]

These are the calipers, with new bushes fitted:
[IMG]
IMG_7858 by Dawes-man, on Flickr[/IMG]

One of the new bushes:
[IMG]
IMG_7860 by Dawes-man, on Flickr[/IMG]

And the old bushes - you can plainly see wear on the inside of the bush on the right:
[IMG]
IMG_7868 by Dawes-man, on Flickr[/IMG]

He told me he'd made the a bit tight and that they will loosen up with a bit of use. The main thing is that the play has gone. No more brakes walking when applied!

He then hit me with a couple of other things he produced from the plastic bag with all the bits in - a couple of spare bushes that he said were in 'case I ever needed them'. What a nice gesture!:
[IMG]
IMG_7871 by Dawes-man, on Flickr[/IMG]

But then, just as I was admiring these 2 little gems, thinking, 'Hmm, 4 would've been better - I have another pair of old MAFACs at home ' he hit me with this:
[IMG]
IMG_7873 by Dawes-man, on Flickr[/IMG]

He said, 'It's a drift for removing and replacing bushes... I made it for you in case you ever need it in the future.' At this, I started feeling rather emotional and nearly cried. I could feel my eyes wetting up. How incredibly kind!!

The tool in one of the new bushes:

IMG_7874 by Dawes-man, on Flickr

Comparing it to the fit on one of the old bushes, it's far more snug. So, I've had a great day so far...