Rear Frame Z questions

i'm making a custom 2x3 tube frame for my late 20s desoto roadster. 32" wide, 6" Z in front and 15"Z in back, though i cant decide how far in front of my rear axle to kick the frame up. i havent settled on what suspension setup to use on my rear end, but its lookin like a 4bar+panhard or a triangulated 4 bar wiht coilovers. this is my frist all out custom roadster project and i jsut need to know how far i should kick the frame up forward of my rearend to have enough room for my rear bars.
thanks
Pax

 

hm... noithin?

 

From what I've read while building... a parallel will go in anything whereas the triangulated will have to have a more particular "Z" placement. where do you put a 15" rear Z in a roadster? You can put the panhard high or low but the uppers need to be in the "right" spot. my .02 BTW I bought the parallel setup

 

I made bars out of 2" square, 18" from the pivot to the axle, which was u-bolted to the bar. This was a simple setup, although a 4-link would have lots of adjustment, that's why they are popular with drag racers. Don't use a panhard, use a "track locator", also popular with drag racers. It is simpler, and takes up less space.

 

with a standard 4link, the longer the arms on the 4link the better it works, so id put the kick as tight up to the seat back as possible.

but, with a tri-4bar, your top links need to be at 90deg. to each other. that means their length is dictated by the width of your frame. the bar length will be the hypotenuse of half the frame width. so, triganometry dictates you need the kick to be at least as long as half your frame width to fit them in. your bottom links will then be half your frame width long, to keep the operation length of both the same.
hope this helps.

Cheers
DEZ

 

That's awesome! That's a smooth, simple setup!

 

thers one good reason that setup isnt really used often on the street.

articulation.

 

point taken. Although I wouldn't be rockcrawling with it, driveways would suck.