?Chassis Re-inforcement?

[eddiec]

so the plan is to reinforce the chassis of an s13. i have read a little here and there about using rivets along seams, also welding the seams, and the use of foam (which i will not use here).

however the pix and writeups i have seen only involve other makes of cars, bmw, porsche, etc. I was curious if anybody else has pics or can get them of a reinforced s13. if also you have suggestion for major areas to reinforce then put it here.

initially i will start in the area under the fr fenders. in this area the strut towers/door jamb/ firewall all come together. several seams present themselves to be riveted. and others look better to lay a bead. eventually i want to reinforce the rear shock area and subframe connections. i know there are pre-fab bars for several areas of the chassis out there to be purchased, but i want to do all the work myself and dont want to rely on bolt on reinforcement. if anyone has done this i'd like to know your methods and the areas you worked on. thanks

[Nismo_Freak]

Weld about 1" apart, and completely trace the factory pinch weld regions. This will solidify the tub so to speak.

You will notice factory weld areas / adhesive glue crap all over the chassis. This is a guide of where you should concentrate on solidifying the joints.

However solid steel bars... ala roll cage are the best beginning.

One thing the S13/14 chassis has a big issue with, moreso on the S13s, is mid chassis flex. The relatively long door openings aid in creating a flexable region in the middle of the car. I noticed this greatly when I was jacking up my car and noticed the chassis was creaking from the roll bar not allowing it to flex. Upon further inspection I noticed a slight difference in angle between the front and rear. This eludes to the fact that I need forward lateral support (ie. 6-pt.)

[Onizuka]

There are also floor support bars that bolt on underneath the cabin that run length-wise. Do-Luck makes a set, there are others too.

[eddiec]

yeah i noticed the "frame rails" are not one continuous piece front to back. theres a seam or several of them along its lenght.

Nismo_Freak: what type of cage do you have, custom or autopower?

[Hijacker]

I noticed this greatly when I was jacking up my car and noticed the chassis was creaking from the roll bar not allowing it to flex. Upon further inspection I noticed a slight difference in angle between the front and rear. This eludes to the fact that I need forward lateral support (ie. 6-pt.)

Hmm...I don't have that issue.

As much as you don't want to rely on bolt on reinforcement, they help the most on our chassis. Roll bars and ladder bar help reinforce the torsional regidity of the car.

If you want, I would take some steel and go through the undercarriage and make the frame rails one continuous piece. ASC did that on the convertibles, and I have no problems with front to rear flexing. Also, if you go into the convertibles forum (http://www.nicoclub.com/zerothread?id=77984), you can see all the extra reinforcing Nissan and ASC did to the vert, and it may give you ideas on what you want to do.

One other thing I can say to do is to plug weld major seams along the underside of the chassis. Every inch or so, you would drill a hole in the seam and then fill it with weld. This is one of the best things you can do when you have two overlapping pieces of sheetmetal.

EDIT: If you're starting with a hatch, you're already one step back from having the slightly more flexible S13 chassis.

[Exar-Kun]

l;adder bars..thbbbt...

I have one thing to say to you:

Triangulation.

Learn it, love it. Find the wakest stops and figure out how to use a triangle frame to reinforce it (or make a triangle out of the rails already there)...

extra ladder bars won't help your torsional rigidity much, since the member can still flex back and forth.....

-Chet

[eddiec]

thanks for the ideas all. the vert fsm section was nice.

[deezlins]

Learn it, love it. Find the wakest stops and figure out how to use a triangle frame to reinforce it (or make a triangle out of the rails already there)...

what are wakest stops?

[eddiec]

my engrish trantation = weakest spots.

[Dori Dori]

what are wakest stops?

Only Chet knows...

[Nismo_Freak]

Hmm...I don't have that issue. .

You do, you just don't notice it.

If my caged and gutted S14 coupe chassis does it then a convertable full weight S13 chassis sure the hell will.

[chmercer]

Nismo_Freak: what type of cage do you have, custom or autopower?

kirkracing http://www.kirkracing.com

[eddiec]

chmercer: thanks i hadn't seen them beofre.

[Exar-Kun]

yeah..spots..

sorry that was a post typed hastily pre-FL trip for the last few days...

bleh.-Chet

Weakest spots are like the front frame rails, doors/transmission tunnel...etc.

[sixxdeuce]

heres some pics of a fully seam welded and custom welded caged S13. Maybe it can give u some ideas.



I am planning to start stitch welding my chasis since i can do it for free, and later on get a welded cage, but nothing as extreme as the one pictured. Maybe weld in seperate support bars from the strut towers to the frame rails, but not all tied together passing through strut towers and firewal like the G-dimensions car.

[eddiec]

hey thanks for the pics. i'd like to see how your seam welding turns out. i got a welder laying around collecting dust as well. lie to put it to use once it warms up.