I am curious of your experience with the different brands of SFC's. I am going to go with the weld in 2 point version. I just don't know which ones to choose. Tubular or boxed? How hard is the installation? My favorite company is Spohn (great quality, and to match the color of my LCA's), but I would like to know your preferences. I am concerened with ground clearance, so I figure i would want to choose tubular. Any info will be greatly appreciated.

 

I have the tubular 2-point, weld-ins from Spohn and they made a night and day difference on the car. Plus, ground clearance wasn't effected at all. They tuck up very nicely to the point where you can barely see them. I paid 75 bucks to have them welded in.

 

I have some Don Goetz SFC's. They're a 3 point design. Definatly a stout piece. It was night and day after I installed them, and welded them up.

 

If you do a search, you will find the tubular sfc's are stronger than the boxed. With that in mind, I opted for the 3 point tubular sfc's from umi (they are the only company that makes tubular 3 point sfc's for fbodys). That and that's what umi recommended with their torque arm relocation kit that i have. Ground clearance sucks, but I'm stiff.... are you?

 

I think you have that backwards as a box is always stronger than a tube. I have the BMR tubular in Black and love them. There was a huge improvement and they're not even visable on the car unless you look underneathe it.

 

This statement is in a lot of threads about sfc's:
"Hi. If I might add something, SFCs make your car into a better car. You essentially create a whole frame from two sub-frames. Every suspension component benefits from a stronger backbone. The SFCs your link points to is made and marketed by J&M Products. I bought two sets of their tubular weld in connectors.

I was ready to buy the double diamond but was talked into the simpler weld on tubular units by the seller, who also happens to install them. They were about $87 at the time and the 3 point double diamond style that he was selling was a little less than double that price.

I was all set to buy the 3 points (from him) but he convinced me that round is inherently more rigid than square tubing and for that reason the 3 points are necessary to prevent twisting. Otherwise the square tubes would only effectively resist front to back flexing. The two point tubulars, if stitch welded along the rocker panels, will inhibit both front to back and lateral twisting like the 3 point but with more inherent strength because of the tubular design.

I was a little taken back by him advising me to buy their less expensive style but that is what I ended up doing. The tubular style tuck completely out of the way, up into the recess beside the rocker panel. The remainder of the connects are barely visible as they only add a fraction of an inch to the bottom of the front sub-frame terminal and then weld along side of the rear control arm mount for the axle.

I have to fabricate some gussets because the sfc tube does not match the contour along the rocker panel very well. It is important that there is enough contact for the stitch welding along the panel as this is where the twisting force of your car will be focused once the two points of the sub-frames are in place. If you have this done for you, it will likely add to the cost for time and materials. To me, it is worth the added installation expense. Guessing, I would say the money saved with lower cost tubular design is equaled out by more welding and fabricating. The one thing you will certainly gain by going with the tubular units is less weight by probably one third or more.

I obviously don't know what the double diamond square tube units are like but I can tell you about the appearance of the simpler tubular ones which I bought. They are very nicely powder coated and the welds are top notch. My only wish is that they would fit a little better along the rocker."

I'll take J&M's word on it...

 

Well, I like my KB DD SFC's which are 3 point. I can tie the torque arm cross member into the sub frames which makes the car more rigid, I also have a custom x-brace that ties the torque arm cross member into the transmission cross member, kind of like the convertibles have. Therefore, everything on my car is tied together and is about as rigid as can be. Now I just have to get around to installing everything.

You'd think that the boxed SFC's are stronger, but the tubular SFC's provide more torsion(twisting) resistance. I don't care cause I got a hellova deal on my KB DD SFC's.

 

I think whats giving you the bad ground clearance is the torque arm and not the SFC's, right? I have these 3-points they tuck up tight

 

correct.. yeah I guess i worded that wierd... sfc's didn't kill ground clearance, longtube tunnel brace did.

 

I've got KB DD's. They tie in rear/ front/ 3 places on the rocker, and, across mid pan. Also, they have clearance to drop the trans and driveline parts. I also installed their street cage system up top. (97SS 383 - D1)

 

Check out the Spohn ones we sell. Best bang for the buck. If you want a lighter style, they also make them in chrome moly.

 

There only the best bang for the buck because you carry them

 

Round tubing had more torsional rigidity than square with the same cross sectional area. The ONLY reason square would be stronger is because they use larger tubing.

In applications where weight matters, you'll get more rigidity/lb from a round tube than square tubing.

If square tubing was always stronger then motorcycle frames would be made of square tubing, but they can build a stronger and lighter frame using round.

Roll cages and tube chassis are two more examples of round tubing being used over boxed due to more rigidity/lb.


For the original poster. Look for SFC with large mating areas.