Dia Compe 981 cantis

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seph
Posts: 165
Joined: 3 Sep 2010, 8:22pm

Dia Compe 981 cantis

Postby seph » 3 Feb 2015, 8:43pm

I've put a set of these mid 80's brakes on my tourer (80mm between posts), they havent been very good, but I think that is down to the old pads in them. They also look rather ratty. So I was going to replace them either with tektro 720s (similar wide profile which I like the look of) or shimano cx 50 or 70s (mid profile).

But then I thought maybe I could spruce them up. Whilst the canti arms are fine, their main issue is rather manky exposed springs and rusty nuts and bolts. I'm thinking about cleaning these up then galvanising them using zinc sulphate, or even copper plate them (though I suppose that would go green... ).

Does anyone use/remember these brakes?

Anyone had any success with home plating to refresh old bits and pieces?

Brucey
Posts: 43049
Joined: 4 Jan 2012, 6:25pm

Re: Dia Compe 981 cantis

Postby Brucey » 4 Feb 2015, 12:21am

like these?

Image

Much favoured by CX riders at one stage IIRC. There are also some (later) cheap copies that don't have the loopy springs but do have (pretty poor) spring covers. The pivots seem to wear a bit quickly, perhaps because the dirt can get in easily at the front and rear of the pivot with this exposed design.

I'd advise that you can replace most of the hardware with stainless steel. What you can't replace can be replated or simply painted and then given a coating of waxoyl to prevent rust. I have the wherewithal to make some new stainless steel springs for these brakes (I have a set to refurb too) but the spring temper wire I have is 2.3mm diameter rather than 2.0mm, so they won't be identical in every respect.

Like any mid-profile canti you will get more power if you run with a lower straddle. You can buy XTR-style post mount canti pads (eg clarks CP522 ones) and these will be a great update for these brakes, as they allow fitment of any 72mm V-brake pad insert.
Image

Just look out for the end of the long pad catching the tyre if your pivots are a bit worn.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

seph
Posts: 165
Joined: 3 Sep 2010, 8:22pm

Re: Dia Compe 981 cantis

Postby seph » 4 Feb 2015, 9:33pm

Thanks for a really useful reply Brucey. Mine are just like that, except missing the straddle wire pulley things. I think I'll look for some stainless cable bolts, the alloy arms have cleaned up nicely. The springs are sat in 1M ethanoic acid for tonight. If that brightens them up a bit I'll galvanise them tomorrow.
Cheers for the info on pads, I think I'll order some.

Since the spring fits in place in a little recess behind a nut (not visible on the pic) I'm sure you're right about the wire width being important, but if you ever do make any let me know :)

Brucey
Posts: 43049
Joined: 4 Jan 2012, 6:25pm

Re: Dia Compe 981 cantis

Postby Brucey » 4 Feb 2015, 11:14pm

I wouldn't worry about the pulley yokes if I were you, unless you especially like the look of them or something. They don't actually move when the brake is working properly, and you will notice that the straddle wire invariably develops a 'set' that soon inhibits any real movement anyway.

They also have a tighter radius than (say) a weinmann yoke; I've seen several DIa-Compe straddle cables start to fray at the roller where this is almost unknown in many other types of brake.

If you must have the roller yokes you can still buy Dia Compe ones at times and there are fancy ones made by VO and Compass too. They are all just as likely to knacker the straddle cable IMHO.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~