[CR] Re: Dura-Ace brakes...

(Example: Component Manufacturers:Campagnolo)

From: <Stronglight49@aol.com>
Date: Mon, 29 Oct 2007 15:40:40 EDT
Subject: [CR] Re: Dura-Ace brakes...
To: classicrendezvous@bikelist.org


Tom Dalton noted a goof in my notes, one perhaps worth mentioning as an example of the continued R&D which Shimano poured into their products. The 10% commitment of their resources to development was noted as one factor in their defeat of Suntour.

Thanks Tom! - You're absolutely right. Good call:

The 7400 was from 1986 and it's the 7402 specs dated 8/88.

The only difference I can see between the two is the addition of a nylon or plastic cylindrical anti-friction "sleeve" on the end of the return spring for the later model - just as you'll find carried over onto the 7700 & 7800 series well into this century (perhaps even the current models, but I've not checked them).

The 7400 had similar "U" shaped inserts on the caliper arms, but these were open. I think the enclosed sleeves actually produce a "self-cleaning" effect where the others could still allow build-up of grit at these pivot points - just the same as bare alloy against the steel springs of the very oldest side-pulls had permitted. And I think the friction at this point is the main reason why single pivot side-pulls always seem to go out of adjustment and ultimately cause one pad to touch the rim slightly before the other.

The Model 7403 was issued in late 1989... these were first Shimano "Dual Pivot" style calipers.

BOB HANSON, ALBUQUERQUE, NEW MEXICO, USA

------------------------------------------------ tom_s_dalton@yahoo.com writes:

BR-7400 Brake calipers --- Last single pivot brakes [08/88]

There was a model with an improved brake pad (7401?) and then a later version with the SLR spring, called 7402, I think. That was the last single pivot. As a friend called it, "The ultimate evolution of the side-pull caliper."

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