I understand that round tubing is supposed to be better because of less stress points vs square. BUT, I am in the process of making my own STB and was following someones else's design using 12 guage 1" square steel. I guess I could have bought 12 guage round....but I had this particular design in my mind's eye and got the square.

No big deal, right?

Well....I took my project to a welder who said that I needed round tubing b/c its "10 times stronger" than square. This is the same guy who quoted me $100 for the job

Not a big deal.....Only cost me $5 for 5 feet of steel. But would it make that much of a difference?

 

in a word... NO.

in terms of strength/ weight i believe round tubing is stronger in torsion (twisting) than a square steel member of the same weight. Square steel i beiieve is stronger in terms of bending loads. As far as a strut tower brace any strength difference between round or square 1 in tubing is negligable the loads should be mostly in conpression so the straiter the better. if i were to split hairs, considering that the stb's are usually not strait i would go square to better cope with the slight bending loads that the tube will see due to the compression loads. Thats my opinion.

 

i hope not.

i just made mine out of 1" square steel...


now i just need my welder.....


btw, what design did you copy? any pics?

 

whatd be a better material to use for subframe connectors? tubular or rectangular? i see both kinds in the aftermarket.

 

i guess it depends on what you're doing....

imgoing to be using a combo..... round tube for the long sections that run along my factory vert bracing, and flat plate and square tube for the cross braces.....

im using round tube because it fits in the spot perfectly. and i know where i can get it bent just right....


kinda like this:

 

MrDude: (fellow vert owner) I'll post that pic later of the STB (posting away from home at the moment). Its a simple design and parts cost $5 plus $45 for welding/rolling.

Nice design on your SFC's. I have alstons in at the moment but will be using a design similar to yours soon. How are you going to address that little bend on the passenger side? Spohn shows installation pics of their SFC's on verts. Pretty informative. Looks like you have a thought-out design.

Laiky: Thanks for the info. I was thinking the similarly about compression/torque but my head was cloudy and needed someone to spell it out for me. Thanks.

 

for that lil bend im going to take a LONG piece of cardboard and cut it so it stays peftectly flush witht he bottom of the car..... then im going to take it and the tubing to a shop with the right bender and have them make it as cose as they can...

the pic says 1 1/2" tubing, but im probly going to run 2"- 2.5" whatever size just lines up in that groove between the floorboard and the factory bracing.

first the factory bracing is going to be welded to the floor (its only rivited stock) then the tube goes in and is welded to both the floor and the bracing....


as far as the pass side cross brace though, there are really 3 designs im choosing from.

1. 2 thin bars like the pic shows... it looks like it fits above the exhaust...

2.. use a bigger bar, but where the exhaust is, use a 4" square tube in the middle that is turned so the exhaust is run THRU it.

3 wait until i have my longtubes, then just brace that like the drivers side...

 

heh, after you said spohn has pics i just looked on his site...


yea, mine look similar to his.... except im braceing the tube agienst the subframe a lil more..


edit:

since he probly will pop in here to see this...

mr spohn, do you not add any more bracing because its not needed, or will i see a benifit from my design?

 

Any subframe connector is going to make a huge difference. One brand to another or custom...chances are you will never be able to tell the difference. Mine are custom 2 inch square tubing. Goes from the outside of the front subframe straight back to the rear subframe--right under the floor pan. Yes they hang down, but not any further down than the front suspension. The SFC's have no scrapes and I drive it all the time. The front air dam takes a beating though.

 

i just bought alstons, and since i want the best chassis strength ive been hearing running two pairs in cogneto is the best ur gonna get. so i have my alstons and i wanted to mimic a spohn type SFC. just curious as to what material would be better to use, round or square stock.

 

i would say square ones are better but usually heavier, round ones should deal with chassis twist better but will be lighter. I really don't think it makes a difference.

 

as far as square vs round, i say whatever you can make fit better and get a strong weld with is best... *shrug*


i doubt the diff would be anything we could tell without good measuring equipment... and ever then it would change from car to car..

 

ditto

 

Here is the design I used.


I had it welded in place today!! Nice diff. Very yummy.

Front end feels so much more confident. Have not really put it to the test yet.

The guys who did the work just bent the bar with the center of the curve at the center of the bar and just trimmed the ends until it was low enough to avoid hitting the hood and high enough to allow the engine movements without the intake hitting the bar.


Cost me $50.

 

Nice brace!!

 

Dude...is that yours? I couldn't remember who's design that is.

Man...it really changed up my front end feel. It feels like someone is squeezing my front end together w/ a huge set of vice-grips. Very strange. Still getting used to the new feel. Good that it really tightened it up. Bad that it had highlighted problems w/ the steering components.


Did yours make you feel similar?

 

When I first put mine on it made a huge difference. Now I need to rethink the STB because with my recent swap to HSR I don't have it and I can tell!! I am going to mess with that and see if I can make it go over the TB since I am putting on an aftermarket hood that should have much more clearance above the engine...

My design used round tubing and went across similar to yours. I also used two links from the mounting ends to the firewall...

 

Might want to consider oval tubing for clearance issues, it could net you from 1/4"-3/8" extra clearance.