Guide to Rear Shocks for Ladder Bar Drag Car (Pro Street)

gregsdart said

Think of it in terms of slowing the motion of the rear housing. I am on my fourth set of shocks in back, ending up with Afco BigGun shocks which are able to handle 926 hp, a 11.17 SLR, a 30 inch ladderbar and 10.5x33 Hoosiers plus transbrake.
To see how brutal things can get, hear is the math; engine torque x 2 (converter)1500 x SLR (low gear x rear gear) 11.17= 16,600 ft lbs at the hit trying to swing the rear housing down. With a 30 inch ladderbar (2.5 feet)= about 6500 lbs of torque is what those shocks have to control to slow down the housing at the hit.

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Exactly. You have to control the motion of the axle. Ladder bars, by their nature are very violent and because you can’t lower the Instant Center (IC) and move it forward you have to have a shock capable of dealing with that violence.

If you don’t get control of it you’ll just beat the tire to death.

As an example, on my best stuff I was at least 200 HP down from Greg’s stuff, and for my gearing, tire size, torque output and curve my IC was 104 inches out and 4 inches off the ground.

If I had a ladder bar I would have been limited to whatever the length of the bar is (usually 32 inches) and whatever the the height of the holes are from the ground.

Clutches and ladder bars HATE each other. BTDT. I’ve seen downloads from stick cars and ladder bars and the shock speeds were so fast that at that time one of the few remedies was to move the shocks to the front of the axle.