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  1. #1
    Join Date
    Jun 2006

    Default Brake pressures at calipers

    Posted the question before of what pressures should be and no one answered. Now I've got pressures so more data and would like some input please. Trying to trouble shoot if a system problem or just that different friction coef on the pads.

    Car 1981 Trans Am factory 4WD stock 1 1/8 quick take up MC, dual diaphragm booster 2 15/16" front D52 calipers, factory ratchet 2.5" rear calipers. Always braked balanced.After replacing the rear calipers when they locked up and using some organic Bendix pads with an FF rating the rears would lock first with what ever semi metallic pads the previous owner had on there. After freshening the front suspension swapped on new front calipers and Hawk HPS FF rated 614 pads that fit the D52 calipers. Rear still locks up first . Which normally those funky ratchet rear calipers barely work!

    Pressures with motor on and booster with vacuum front 1000 psi, rear 750 psi. Seems like a decent split to me and decent pressure. So I guess looking more like the pads-even though both have a FF. Not sure I have even bedded in the Hawks good enough since the rear is locking up first.

    I can sure dump the factory prop valve T it and add an adjustable in the rear, swap to a different rear pad but they are working so almost hate to do that.

    1978 Black Trans Am 455 Edelbrock heads 10.99@124.5 through mufflers on pump gas
    1981 Trans Am 400 stock type motor
    79 Camaro getting a 500" 695 hp IA2 Pontiac motor
    1965 GTO project car
    470ci/Chevy dual quad 409 604 HP 64 Impala SS project
    2004 Pulse Red GTO

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