Join Date: Mar 2016
Location: aurora, colorado
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re 4 speed bars--more info on my combo
Hi Jim, thank you for your detailed, insightful; and thorough response. and thanks for the helpful links. after some more research on other sites i have discovered these bars go by different names, OPG calls them trailing arm mount braces and your link calls them GM A-Body Control Arm Reinforcements/Frame Braces. We always called them 4 speed bars because they came on 4 speed cars. i will continue to use my stiffened stock 4 speed bars.
i have boxed my lower control arms and i have run airbags inside my coils for years, experimenting with different pressures. they are responsible for lowering the 60 ft to its current low 1.7s -- high 1.6s. i believe now though i have maxed out that combo. i have drag shocks front and rear, the front adjusted to let the front come up, the back shocks adjusted to squat, but the car does not raise the front much nor does it plant the tires hard upon launch. i believe the air bags were interfering with this motion preventing the rear end from squatting. acting on this i removed the air bags on both sides. before i could get valid tests of this theory, i shelled the rear end. so while it is out getting rebuilt, i am using the opportunity to examine the rear suspension. i have urethane bushings in the front and rear suspension and have been told, i need to "loosen up" the front to let it rise. i understand this to mean to loosen all suspension bolts in the front so there is no bind in the movement.
i also have considered drag coil springs front and rear. presently i have NAPA replacement springs front and rear. i do not know what my pinion angle is, but once the rebuilt rear end is re installed i will check that.
i do not have wheel hop, thank goodness.
my next move is a rear sway bar, though i hate adding weight to the car.
traction at the strip is a challenge. i run hoosier quick time pros, DOTs, 11.50 X 15, 26 inch tall on weld 8" X 15" wheels, which is about all i can get under the car, as, you no doubt know, there is precious little room under the rear of early A-bodies. i have about 10 inches of rubber on the ground.
anyway, thanks again Jim, for your detailed response, and if anyone else out there has suggestions, i would love to hear them...