Big difference?
I've done a little chassis/suspension tuning on formula SAE cars before. And one thing that can/should always be modified on a stock car is chassis rigidity. The stiffer the chassis is, the more accurate the suspension/steering can be. And almsot just as beneficial is the increased ride quality by essentially making the suspension take up the deflection, instead of the chassis, and in turn, you. So that's why I started with a "backbone". I didn't want to spend what DDM was charging for an aluminium plate. So I went to a local metal stock supplier and bought myself a plate of 3/8" cold rolled steel.
The following was part of a post I made after I had put it in
I was concerned the aluminum to steel contact, especially on a daily driver that sees winter would be a BAD idea in terms of corrosion.
I think one reason all the braces are made of aluminum is because at 3/8" plate steel, it's not easy to work with. I'd never mechanically cut it. If I didn't have a plasma cutter, I definitely would have gone with aluminum. Cutting and drilling the 3/8" was a pain the a** unless it was with the plasma cutter.
Plus I was afraid of going with a 1/2" plate because I was worried the increased thickness would pose a problem for threading of the bolts. And I'm glad I did. If anyone intends on using a 1/2" plate, they'd better get longer bolts.
So I got the best of both worlds, stronger strength with 3/8" steel then with 1/2" aluminium. And a thin enough plate to still be able to do use the stock bolts. And no need to worry about constant steel/aluminium contact.
It definitely did a lot. In terms of ride quality, the car feels more like it was forged from a single piece now. Less chassis "chatter" if you will. And it used to feel like I had to load up the chassis before it would generate high g's, as though there were a slight delay between steering input and stressing the entire chassis and turning, whereas now that delay seems to be gone, or atleast significantly reduced.
I'd say the only drawback is now it's made obvious just how unrigid the rear feels. I believe you said you had the rebar/probeam (can't remember which) done at the same time as the back bone correct? Now I can feel how the rear end could use more rigidity.
I painted it with high temp black paint. Let's see if the tech notices it at the dealership.
After that, I bought a probeam from opjohn from the solstice forum. Before putting the probeam on, if accelerating hard, particularly in tighter turns or on not perfect pavement, at the limits of adhesion while accelerating in that turn, you almost felt axle hop basically. Lots of juttering of the rear wheels. With the probeam on, now it's a progressive load up, breaks away smooth, catches smooth, and allows you to really get the power down coming out of a turn at the limits of grip.
Basically, anything you can put on your car that will make significant changes to stiffening of the chassis is going to improve handling and ride. It's part of the reason why high end cars are so heavy, and ride so well even with pretty stiff suspensions.
