leaf spring question/traction

[OneslowZ28]

I was wondering with moving in a set of leaf springs what kind of loss of stability I will have. im looking at moving my springs in to the other side of the frame on my 78 camaro approx. 4"-5" in I believe. I also plan on running 345's in the rear. hopefully someone can give me a simple answer im still a little slow in the terminology dept. Thanks!

[Norm Peterson]

Sounds like the desire for 345's is driving a need for moving the springs. Both of those mods will increase the tendency to "push", assuming that your new spring brackets, shackles, extra structure, etc., are at least as rigid as what's there now and that the various spring and shackle pivots are kept in the same positions relative to the axle and the ground as OE. If anything, that's greater straightline stability, and you'll probably end up wanting to re-tune the suspension to get things back in better balance. Otherwise, you might not just get less than you could out of the 345's - it's even possible to end up with less than before.

When you move the springs inward and don't also increase their rate, you'll end up with slightly more roll during any given turn, the front tires have to resist more of that roll, and they'll consequently run at poorer camber and higher slip angles (and will reach their ultimate grip sooner).

Depending on the details, those huge rear tires will make it possible for the rear to run at lower slip angles, and to have greater ultimate grip. There's a thread or two in this forum already that discusses large difference in front:rear tire sizes, including a current one.

Norm

[OneslowZ28]

does anyone else have any input on this question. this info was of some help. what kind of spring rate should i be looking at? like what is stock and where should i be? (approx.) Thanks!

[David Pozzi]

When you move the springs in, the vertical ride stiffness won't change, but you will see a reduction in roll stiffness and extra lean from that. I'd guess that a slightly stiffer rear antiroll bar or softening of the front bar would be needed to get the car balanced again.

In other words, the tires will increase rear traction for cornering, the spring move will reduce rear roll stiffness reducing the cornering load they will carry, you need to increase rear bar stiffness to compensate for the loss. I wouldn't stiffen the springs because they are tuned for acceleration/ braking needs and moving them inboard doesn't change that.

We put 265's on our 73 Camaro with no spring or wheelwell changes, you should look into the detroit speed type rear shackles that move in the rear of the spring and allow the front to stay where it is. The springs are wider apart at the rear and the DSE kit moves them in at the rear only.

[jeffandre]

I may be wrong here so take this with a grain of salt. I recall that the 2nd Gen F-body has parallel springs, unlike the 1st Gen. If you move the rear eyes inward on a 2nd Gen you will also need to move the front eyes inward to regain the parallel setup. According to the leaf spring tech I have studied it is beneficial to move the front eyes in more than the rear, supposedly helps corner bite and exit speeds (or something like that). Anyway, I believe that is why the leaf spring rear eye relocation parts (DSE, Comp. Eng., and others) are listed for 1st Gens only as they can get away with moving the rear eyes a few inches inward each and end up closer to parallel.

http://www.landrumspring.com/pages/technical6.html

There were otehr links but they are not working now. Anyway, do some research on leaf spring tech to find more info.