69 impala chassis stiffening

[dgrown]

hey all i'm trying to figure out what a good start point is on this i'm trying to build my car into a street able car that on occations could be auto crossed current setup is hotchkis rear setup with dual upper control arms, hotchkis panhard bar, hotchkis front and rear sway bar set, pol tubular upper and lower front control arms ( not a fan of the stock setup want to front half the car in a few years over to a C5/C6 setup so i went cheap).

what my question is where do i start on chassis cross bracing? i see lots of cars that everything is triangulated and it looks amazing but i think that for mainly a street car i dont need to go to those extremes. how much do i need to stiffen up the center section keeping in mind that it will be front halfed in a few years?

thanks
Dave

[exwestracer]

Dave,
One of the tough things about bracing up a perimeter frame is the floorpan sits down over the rails. We did a 70 Impala at the school a couple of years ago and faced this same dilemma. If you really want the car low, you are going to give up a ton of ground clearance with all the bracing running under the floor.

If the body is solid and you don't mind some vibration, solid body mounts will help a lot. So would a cage, but that might be a little more extreme than you a looking to go.

[dgrown]

yeah as of right now i lowered the front 4"s and the rear 2"s so looks like fabing up all custom floor might be in my future which i dont mind but my question now dumb as it may be is with custom "flat" floors how do you get the structural rigity at mounting points of seats and body chassis contact?

[exwestracer]

yeah as of right now i lowered the front 4"s and the rear 2"s so looks like fabing up all custom floor might be in my future which i dont mind but my question now dumb as it may be is with custom "flat" floors how do you get the structural rigity at mounting points of seats and body chassis contact?

At that point you are going to have to design the cross bracing (X members, whatever) to pass through the areas where you need the mounts. A perfect example is designing an X member so that the trans mount falls at the center of the X... The body mounts usually don't have to be altered, as they sit over the top of the rails in most cases.

[dgrown]

okay makes sense thanks for the input after spending an hour looking at it scratching my head i think the best route maybe a cage like you said