pancake crossmember or Z the front chassis

[60chevyjim]

witch one would be better ?
to pancake the front crossmember 2 inches or
Z the front chassis 2 inches ?

no $$$ for porterbuilt or dropped spindles .
doing the work is not a problem .

[theastronaut]

I notched my frame rails 1.5". Less work than a Z or pancaking the crossmember. I also raised the upper bag mounts 2" to keep the bags from being compressed too much.


You can see the notches in this pic:




Assembled and on the ground:

[chevyrestoguy]

Pancaking the crossmember is easier, but it puts the steering geometry in a condition where the tie rods go slightly uphill to the spindles. In extreme situations, (notably, the suspension at medium/full compression) it can cause bump steer. You can heat and reposition the pitman arm and the tie rod eyelets on the spindles, but I'm not a real fan of doing that because you may take out some of the temper. If you decide to pancake the crossmember, don't go more than 2". If you do, it'll exaggerate the geometry and you'll have clearance issues between the frame and the steering linkage.

Z'ing the chassis is more work, but it keeps all of your suspension in the stock positions, geometrically. Cut the frame just forward of the steering box and just aft of the rear shock mounts. Everything goes up 2" as an entire assembly. The added work comes in with everything else, like the inner fenders, engine position, fan position in regards to the radiator/shroud, swaybar mounting, etc. It's a much bigger job than pancaking.

You can also explore notching the frame, like John did. I think he's running a rack, so that solves a lot of the issues concerning using the stock Chevy truck stuff.

On my '64, I wound up Z'ing the chassis. It's all documented on my build thread.

[theastronaut]

Ah, yeah forgot to mention that the rack & pinion moves up with the crossmember so it solves that issue.

[60chevyjim]

thanks for the reply's ,
astronaut
I had thought about notching the chassis as another way to do this also .
chevyrestoguy
I had checked out your whole build thread with Zing the chassis before .
that's where I got the idea from. very nice work on that .
I had even thought about doing the frame cut on a angle so it moves the wheels forward
1" at the same time .
what I do like about A 2" pancake crossmember is the ground clearance and the motor mounts stay the same .
I am going to use cut springs , no air ride .
I don't like rack n pinion , so I want to use a truck ps box.
I bought a complete 79 front crossmember with 5 lug disc's and
the 5 lug rear from the same truck with highway gears.
this way I can run 17" 96 impala SS rims that I have .
I want to notch the rear chassis for axel clearance too .
I want the truck low but using coil springs
and factory hood hinges with the springs.