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Discussion Starter · #1 ·
We’ve be doing a lot of water burnout only no prep racing, and have been really experimenting with different weight ballast placement in our 1970 nova. Trying different heights, amounts, forward and back movements of weight, etc… Luckily for us, the track is consistently really bad, so it doesn’t change much.

The top picture below is what we started with, and as you go down, are the more recent weight placements and percentages. It’s worlds better now than when we started, and have also learned that you can’t use anywhere near the power you can use at the track. Still have a long way to go, but it’s coming around. Just sharing what we tried and what’s been working for us. Never in a million years would I think making a 2740lb car weigh 3300 would make it go quicker and faster 🤯. We always run the fuel cell full to the brim, 15 gallons.

Starting to find that getting the weight up higher is much more meaningful than adding it low/under the chassis rails. It’s been low 1.5X 60’ with no prep/water burnout only, trying to go consistent 1.4Xs. Been a very humbling process 🤣.
Don’t get all jealous about my art skills lol.

The last weight placement we haven’t tried yet, but are going to this Saturday. Thinking it will help transfer weight more easily than having half of the ballast under the trunk floor.
 

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I moved my engine back until the distributor was barely able to wiggle past the base of the windshield. Rear percentage now varies between 53% and 57% depending on bumper weight and fuel load, 2325 race weight with no added bumper weight and 1/2 fuel load. The torque arm car almost sits almost on the bump stops, and the front springs are set up to fully unload at full extension. The last part is key as you want all the weight to transfer to the rear, but you don't want to knock the tires loose when the front runs out of travel. Smooth dead hook from a manual trans car with 275 radials on virgin chip seal surfaces.

Grant
 

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The front springs may need to be stiffer than you might think for efficient weight transfer. You want zero stored energy left in the spring when the front suspension tops out, as you don't want an excessive amount of stored spring energy helping push the front of the car up, and then suddenly losing that assist when the front suspension comes up against a stop. The higher the front gets jerked off the ground, the harder the front will come crashing back down. And when the front comes crashing back down the entire chassis is rotating, and that rotation adds torque to the rear tire's contact patch. Adding to that when the front tires touch back down, its springs start compressing again. The rear is now losing weight on its contact patches as weight is now transferring back to the front.

You want the front to come up smooth and then settle back down smooth.

Front spring rate needs to be matched to the amount of available front extension travel. With a front strut car, it's easier to ballpark the front spring rate as there's not much motion ratio involved. A 2740lb strut car with 45% static front weight (1233lbs front) and 3" of front extension travel, around 225lb/in front springs would get you in the ballpark. With 6" of extension travel, the same car would want around 112lb/in front springs. With 8" of extension travel, around 85lb/in springs.

With a stock style frontend on a '70 Nova, there is a motion ratio involved in ballparking the front spring rate.

Get the front right first, then adjust rear percentage as necessary to get all the weight transferring to the back tires. The more front extension travel you have, the less rear static weight percentage you will need to achieve full weight transfer.

Grant
 

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the farther back you can get the weight the better it will help. if you could get that 230 back & up by the 100#s would be the best.
Any weight you can take off the front will be better than adding weight to the back. Smaller radiator? Lighter wheels & tires, hood, bumper supports ect
 

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Discussion Starter · #6 · (Edited)
It’s really seeming like putting the weight at the extreme rear of the car slows the speed at which the car transfers weight, but once it’s settled in, it has more ability to hold it there. Not that it’s a bad thing, but it’s a tuning tool I guess. Big balance of ramping the timing in fast enough to keep downward force on the rear tires, but not so fast that everything gets upset, and timing it with the suspension movements. It’s definitely delicate while the fronts on the way up, and I get why you want to run the front out of spring while it’s all the way extended. We can’t get much lighter as far as front wheels/brakes without doing spindle mount stuff. I do think the R/F spring is starting to give up and sag (old moroso trick springs). We’re going to replace the springs and shocks before we go out again Saturday. Going to try and lower the front another inch to try and get another inch of extension travel. Has 4.5” of extension now, more travel will let us get the help of the front suspension for a little more time. It has strange single adjustable shocks with 240lb moroso trick springs now. Doing the QA1 double adjustable Coilover system with 250lb springs for now. Over the winter, we’re gonna do some nice long front coilovers and aluminum spindles. It’d be nice to use some 5-6” stroke shocks vs the 4” ones that fit in the stock locations. We run it with no hood, but yea, it still has a big radiator, stock radiator support, steel fenders, etc… 1 piece nose may be in the cards over the winter time, we’ll see.
 

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Discussion Starter · #9 ·
We put them in already. Gave us another 1” of travel. The Alston chassis works spindles have the upper ball joint mounting hole raised up 1.5” from stock, we’re going to swap to those spindles in the next few weeks. Should get us a little more. Not sure if we can do both the tall ball joints, and the spindles though, may not be able to get the alignment correct.
 

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We put them in already. Gave us another 1” of travel. The Alston chassis works spindles have the upper ball joint mounting hole raised up 1.5” from stock, we’re going to swap to those spindles in the next few weeks. Should get us a little more. Not sure if we can do both the tall ball joints, and the spindles though, may not be able to get the alignment correct.
True. Might work against themselves. The tall ball joints make the spindle think it is taller already. Using both may not have control arms on same plane. Not sure of right wording.
 

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It starts to really whack the camber out when they’re up that high.
Yes. With my stock spindles same as nova I think. And my plus 1/2” ball joints my travel is excellent. But for prep track. I actually limit it back with limiters in upper control arms that use factory bump stops on frame. I know I posted some photos up here on 69 skylark build thread. They work excellent.
But for no prep you need that full motion with good camber. I had 6” of travel.
 

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My car has roughly 7 inches of front end travel, it's currently limited to 4 inches. It's stock control arms, tall lower & upper ball joints, and a bump steer kit. I also took all the bump stops out that would stop upwards travel. It's on an A body but should be similar. I have viking double adjustable shocks, if I tighten compression up a lot it will be settle the front down until I hit the brakes @ the 1/8th

This pic gives an idea of how much travel it has with no limiter.

Wheel Car Tire Vehicle Hood


If I could afford the power I'd no prep race
 
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