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Drum Brake Question/Roadrace Car

Discussion in 'The Hokey Ass Message Board' started by andyleonard, Sep 1, 2010.

  1. andyleonard
    Joined: Jun 4, 2010
    Posts: 22

    andyleonard
    Member
    from topanga ca

    I'm running 11" Corvette drums on the front of my vintage roadracer. I want to replace the return springs, as I can't remember when I did it last, so at the parts store this morning they laid out the kit for a '63 Vette and there are 2 different return springs per side...one for the leading shoe and one for the trailing shoe...and they are different sizes. Same length, but different wire dimension. I'm guessing this is because the stock shoes have more lining on the leading shoe than on the rear, but since I have had Andy Porterfield reline my shoes with fancy stuff and he has relined both shoes the same, I'm also guessing that it would be a good idea to use the same heavier spring on both shoes. Make sense?

    Question 2: Does anyone know of a spring for a big Chevy 11" drum that is stronger than the purple Corvette ones? Maybe off a pickup or something?

    By the way, I learned today that the color coding has no relationship whatsoever to spring strength and is just for convenience in the parts washer. Manufacturer's tech line told me.
     
  2. JohnEvans
    Joined: Apr 13, 2008
    Posts: 4,883

    JohnEvans
    Member
    from Phoenix AZ

    Er : On normal Bendix brakes the SHORT lining goes to the front. Years ago I remember some parts catalogs for brake springs gave tension specs back in the picture section, ain't seen that usefull bit of info in ages though. I would use the stronger spring to the front shoe as in a forward stop the rear shoe is already up against the anchor pin.
     
  3. Mr48chev
    Joined: Dec 28, 2007
    Posts: 33,861

    Mr48chev
    ALLIANCE MEMBER

    On every correctly assembled set of drum brake shoes I have ever seen the short or shoe with less lining goes to the front and the the shoe with the longer lining goes to the rear. Those are the Primary = front and secondary = rear shoes. Think just like a four barrel carburetors primary and secondary barrels the smaller ones go in front.

    I believe the reason the stiffer or stronger spring goes to the front is that when the stopping inertia pulls the primary shoe away from the pin it takes more spring pressure to return it when the pedal is released while the spring on the secondary shoe doesn't need to be quite as strong to get the shoe back to the pin.
     
  4. Porterfield shoes, there is no primary and secondary shoe. The lining is the same length on all four shoes.
    I use Porterfield R4's on my racer.

    Sorry, no input on the springs.
     

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