z31 chassis stiffening

[Alf]

if anyone has stengthened their z31 chassis could you please inform me on how you acheived this. i have a few ideas of my own but i thought it would be better to hear from experienced z people.

[260DET]

This is of interest to me too, the next project will be a 280ZX coupe which is very similar structurally to the Z31.

 

Other than repairing/strengthening any damaged existing structural parts, I'm thinking of adding an additional underbody rail from front to back under each sill/rocker panel. Extending as far foward as practical by angling in towards the front X member.

 

Together with this there would be a half roll cage, a good thing to have with a hatchback body design. By way of additional parts, the idea is to tie all the extras in with the existing structural components and suspension points. Eg, two of the half cage floor mounting points would tie in with the proposed sill rails.

 

I love this sort of stuff, what ideas do you have Alf?

[Alf]

well at first i was planning on a subframe conector of some sort like my 69 camaro has, but after looking at my z that really isn't posible. on the 300zx(i dont know if the 280zx is the same) there is a stamped steel brace that runs laterally under the transmition tunnel towards the rear of the car. my plan is to make some type of tubular replacement and tie the bar into the rear suspension mounting points on the outward sides of the car. then i plan on making strut tower braces for the front and back. i might make some kind of x-brace under the front seats. my car has a small block chevy in it so i figure it probably neads some structural stiffening.

[260DET]

That should work Alf, my priority is to strengthen the chassis between the front and rear suspension points, there is no one way to do that of course.

 

Strut bars would be included, as part of the half cage at the back and a U brace back to the firewall at the front. If you don't get much response here you may like to try z31 com here http://www.z31.com/ Have been some recent on topic discussions there with pics.

[David K]

Try expanding foam in your rails and door sills, etc. This is next on my list afterthe 5 lug swap, and before the v8 install. Make sure you purchase the correct foam. It must be able to cure in enclosed areas.

 

http://www.sportcompactcarweb.com/projectcars/0006scc_proj300zx/

[Alf]

wow thanks david. thats a great article i cant beleive how much effect that foam has i will deffinentally look into that. its so simple, light, and the article said it was fairly inexpensive, im sold.

[Pop N Wood]

You might want to read through some old posts on expanding foam. Do a search. There are some drawbacks to foam.