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itey said:
Jumping a car like that requires at least a rear shock absorber with tight or locked rebound that does not allow the axle to extend down after the front weight comes off the ramp. The rear axle extension causes the car to rotate around its center of gravity, pushing the rear up causes the ass-over-teakettle rotation that makes it land nose down. The rear axle needs snubber loops or chains like the jalopy derby guys uses to use to limit the motion so no suspension down travel.
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That is one opinion and it may have some merit but I'm not so sure. I've jumped cars for a couple of home movies that I made back in the late 90s. One car was a front wheel drive Geo Prizm that we mixed and poured 500 lbs of concrete into the trunk. I was just guessing but I wanted the car to land level.
This sagged the rear springs a lot so I replaced the coil springs with front springs from a V8 car. This proved to drastically OVER-spring the ass end to where the car actually DID rebound UP from the rear far more than the front. It did result in a nose down landing even given a fairly short 45 foot jump. Upon landing, the rear bounced up and down a few times while the front stayed pretty even. The problem was, I didn't know what I was doing, it was all a guess. The load of concrete was too heavy and when the rear springs sagged, I went way overboard trying to compensate with more spring rate. The extreme stiffness of the rear springs didn't allow the rear to compress much when the car hit the ramp.

Lumbergh said:
On a jump like that, with a nose-heavy car I doubt it matters much........but I'm no expert.
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It is mostly due to the front weight bias that cars do nose dive. The General Lee jumps in the Dukes of Hazzard did utilize concrete in the trunk at first but that shifted to metal cages mounted in the trunk with steel plates of various weights used to offset the weight of the engine and transmission. They had stock suspensions with new shocks but nothing fancy.

350LUV said:
I can see that… front leaves the ramp .. weight goes to basically neutral,,, the rear springs and axle unload and the tail kick starts the rotation around the center of gravity… I get it now..😁👍

So limiting straps will prevent the tail kick and allow the center of gravity to remain neutral??
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The cars are in contact with the ramp for such a short amount of time, there is not enough time for the springs to compress and react.
 
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FTRV said:
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I grew up on a dairy farm. This is written by someone who thinks milk comes from the grocery store, I grew up on raw milk, the flavor and health benefits are much better than that cooked shit. You city folks can keep your blue john, when I can find it, I'm drinking milk the way it was intended.
 
Y
Kern Dog said:
That is one opinion and it may have some merit but I'm not so sure. I've jumped cars for a couple of home movies that I made back in the late 90s. One car was a front wheel drive Geo Prizm that we mixed and poured 500 lbs of concrete into the trunk. I was just guessing but I wanted the car to land level.
This sagged the rear springs a lot so I replaced the coil springs with front springs from a V8 car. This proved to drastically OVER-spring the ass end to where the car actually DID rebound UP from the rear far more than the front. It did result in a nose down landing even given a fairly short 45 foot jump. Upon landing, the rear bounced up and down a few times while the front stayed pretty even. The problem was, I didn't know what I was doing, it was all a guess. The load of concrete was too heavy and when the rear springs sagged, I went way overboard trying to compensate with more spring rate. The extreme stiffness of the rear springs didn't allow the rear to compress much when the car hit the ramp.



It is mostly due to the front weight bias that cars do nose dive. The General Lee jumps in the Dukes of Hazzard did utilize concrete in the trunk at first but that shifted to metal cages mounted in the trunk with steel plates of various weights used to offset the weight of the engine and transmission. They had stock suspensions with new shocks but nothing fancy.



The cars are in contact with the ramp for such a short amount of time, there is not enough time for the springs to compress and react.
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Years ago I went to duke fest in Bristol where they jumped a general lee. Exactly what you said above. They used concrete in the trunk to balance the car out so didn’t nose hard. Stunt team had worked on the original set. Also had just enough gas so when it hit the ramp it ran out so no threat of fire.

After the jump they auctioned the car off and a local mom and pop bought it and had it on display out front for years. Lots of pics of it floated around internet for years. Car is still around last I heard but tucked in a building.
 
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