Suspension Guru's - Rear Shock Question

Suspension guys - most of the time in drag race applications the shocks are placed behind the axle - is that done for a performance reason, or just better packaging. My Spirit has basicly a stock rear suspension - leaf springs moved inside frame rails, slapper bars, stock shocks. Due to packaging, with the shocks behind the axle, they lean forward pretty hard at the top and are probably in a slight bind. Car hooks pretty well - 1.50-1.55 60's running 11.30 at 120MPH. Simply moving them in front of the axle clears up all kinds of fitment issues. Plenty of room for exhaust, etc. I don't have the room to put in a crossbar to move the top of the shocks back. So the "Q" is - is it a performance disadvantage to have he shocks in front of the axle? Mostly street car- about 20% race.

The farther forward the shock is the stronger it has
to be to control due to leverage... other than that
its a packaging thing

The front segments are clamped and the slapper bars are slightly preloaded, so the front is fairly stiff. There is aluminum bushings in the front spring eyes, and there are no clamps on the rear segments, so they are free to separate (and do) on the launch. I only use 3 leafs to support the car so it's fairly soft to bounce the rear without the shocks, and the bars keep the springs from wrapping up. I think I may just buy some gas shocks to try and then upgrade to adjustables as necessary.
Thanks, Raff

I feel theres better axel control in the rear.

Mounted in the rear, the shock feels the axel dropping along with the rotational drop from the pinion rising in the front and the shocks rear mount lowering. So the shock is feeling downward movement only at the hit.

Mounted in front, the axel will be lowering but the shock mount will be twisting up. Momentarily canceling each others movment out. So there will be little shock control at that point.

I feel there best mounted in the rear, because of that.

I'd totally agree if I didn't run the slapper bars and the springs the way I do. The bars aren't the cheap universals - they take the place of the shock mount plate and I lengthened them to put the bumper under the spring eye. The front is pretty stiff and there is pretty much no spring wrap-up. Car has had 1.50 60' times on a 26x9" slick so it works pretty good. Right now I'm trying to improve the packaging without killing the leave.
Thanks for the reply.

Well if your pretty stiff with the front segments with clamps and slapper bars that should take most of the rotation out of the equation, if not all depending how stiff you got it.

Then it goes back the Leverage issue that Raff referred to. The shock will have less control at the front. But if you need it there , im sure you can make it work. You will just need some stronger shocks.



With my tests with the front segments made solid with bars, the front segment was to stiff and violent reacting at similer ets.

I ran my Challenger the way I got it in 1999 with the shocks mounted in front of the axle..ladder bars, with a cheap coil-over kit set-up, worked fine. Later I put good QA-1's on behind the axle, was more forgiving on junk tracks, but not noticeably different. 100% track, big tires!

You can get any set up to work.. The more of a lean the shocks have there will be side load put on the shaft bearing or seal head which will create an unwanted damping force.. this is what is called stiction.. in my opinion mounted in front or back really does not matter the straighter you can get them up and down so that that there is no stiction the better... whenever we dyno shocks we dyno them straight up and down

With my tests with the front segments made solid with bars, the front segment was to stiff and violent reacting at similer ets.

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Your just making it more like a ladder bar when its
solid... I did this YEARS ago and it worked great...
just using truck shocks