BackInBlack86

to be honest, i'm not sure. i've seen plenty of circle track cars with square tube cages hit the wall, and they crumple twice as bad as a round tube cage. it has something to do with the way the force is exerted on it.

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rp_guy

in a circle the force is distributed evenly..there are no sharp points for pressure..

B4Ctom1

these are home made?

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92 zzz28

Yes, they are...

Yeah, I know the post is for commercially available connectors, but a lot of people wanted to see examples of connectors on the car so I put up my pics of mine. Hope you like!!

tilstad

But just to sum this up, is tha Alstons bad, good or what?

'Cause I was intending on getting them since I really liked the service that topdown solutions supply.

But I wont if they really suck. I havent really seen an installed picture of the alstons against the spohns. Is it a really big difference?

Another thing that would be a plus for me is being able to bolt them in at first, then welding them up at a later time when I have thye oppurtunity to do so.

ckjoshz28

i recently bolted up a pair of competition engineering sfc's. I ordered them through a speedmart and they ordered the wrong pair so it didn't clear my y pipe at all. But i didn't start this until a sunday afternoon so i had to drive it for a week with open headers. So the following weekend i bent the y pipe around them for some back pressure for a quick fix until i figure out what im going to do to run a new y to the back.
But the pieces are excellent, very thick, square, nice black powdercoat, work as great jacking points, and there is a major difference in handeling /even without welding.
The only problem with comp eng. is the price tag, i don't have the summit/jegs mag in front of me but i think its something like $240/$250usd(plus s&h) for bolts ins like mine which i paid $340usd over the counter from the shop.

Camaro_nut

You are wrong.

BMR have square (boxed) shaped LCAs. Other
companies as well. I am sure that they are perfect
for the application.

And I also think that having square tubed subframe
connectors are fine. The ones I bought claim to be
60% stronger than the others. They are also bigger
and thicker than the most others. And most car
manufacturers make "boxed" or square shaped frames
anyways. I haven't seen any round shaped frames,
either full framed or subframed.

84 1LE

Ill say.Those are the exact ones i have.Of all the people to sell these.I bought mine from saleen(yes mustangs) some 12 years ago.Back when he was just in long beach by the 405 Fwy.They sold them under the name AERO CAMARO.All that said i like mine.They really hug the floor boards & also clear the dual cat set-ups.Plus round tube is generaly stronger then square tubes.

Nocturnall

I would think round is better then square because round doesn't have points where stress builds but I'm not all that bright and just ate lead paint for 7hrs so who knows....stupid house.

Camaro_nut

Yeah, the round tubing may be stronger, but how much
stronger? Is it marginal or a big difference? Also, I hope
you wore a face mask or something for that job!

92 zzz28

Rectangular and square tubing tend to be very rigid in beam strength. Think of an I beam used in building a skyscraper or the frame of you full size pickup trucks/SUVs. Round tubing tends to be very rigid with torsional strength, twisting resistance. Not to mention it is easy to work with. Remember all these companies are in business to make money! They choose strong, suitable materials, but also look for materials that are easy to work with and make installation easy for the average joe.

When you think about the stresses that are car, especially an F body, goes through with driving, you could hypothesize that either rect/squ or round tubing would work equally well. I would say that round has an advantage to quelling chassis twist problems many drag cars have problems with. At that same time, having a full chassis that is tuned to a certain application works very well.

I think that anyone would be happy with any of the SFC available from Spohn, BMR, Alston, etc...

They really should have been a factory option!!!

wdigitog

i ended up using two sfc's...first, i put in the kenny browns, but the driver's side end piece isn't connected to anything..just the floor pan. i then welded in the alston's along with the kenny browns.......boy, that chassis don't move now!!! feels as firm as a full frame car! i really recommend the alston's first...then you can brace the rocker sides with a sfc like the kenny browns.

Camaro_nut

I am thinking about buying some 2" round tubing and
"reinforcing" my existing square tubed SFCs. I want to
make it look like the way Spohn has them set up. Where
you have the tubes coming from the middle of the SFCs,
then it goes to the sides of the body, next to trans. area.
I will go a step further and use 2 tubes for each side, instead
of one for each side. But where do I buy good quality round
tubing from? I have no problem with having them mocked up
to fit then welded. Just don't know where to buy the stock
from.

92 zzz28

Try a local welding or racing shop. They may not have any materials there, but I bet they could point you towards a distributor. Or check your yellow pages for steel. Make sure you get tubing and not pipe. I suppose you could use a schedule 80 or 40 or whatever that crap is but I WOULD NOT. Use mild steel round tubing. Ask for roll cage tubing and a local steel wholesaler should know what you want. Good luck...

Mike89GTA

I've had the Alston SFC"s for about 5 years. They made a huge difference. They're getting pretty rusty, I guess the powdercoat doesn't last forever

theonly350z28

Kenny Brown are the best if you are push some serious hores power if you not push that much go for the spohn they are great.:yourock:

Larry Dunlap

On the round vs. square, consider this. I work for a company that makes a machine that is basically a vibrating screen. We made a shaker that had two drive motors, basically electric motors with counterweights attached to them, mounted on a frame, connected by a round support between two motors, one on each side. The round support had persistent cracking problems and was replaced by the design group with a square one. No problems after that. The stresses here would be vibrational stresses up to a force of 6 Gs or so. For what it is worth.

Attached Images

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wdigitog

well, larry, all race car frames are made from tubular steel as well as all roll cages ......do they know something we don't know?

Larry Dunlap

It may be that there is an insignificant difference in square and round for the type of stresses encountered in auto racing, it may be that the round is possible to bend into smooth curve type shapes and the square is not, it may be that the type of stresses on the shaker are completely different than the type of stresses with auto racing, I really don't know. I just know that in the case of this shaker that the square tube worked better for the type of stresses encountered using that machine.

wdigitog

perhaps the round cross/section can absorb a certain amount of stress before it breaks....nascar frames are all tubular and they can absorb a lot of stress before they deform. they will have a certain amount of give..perhaps your machine does not want any energy absorbtion.

fb305svs

Saying something is tubular doesnt necesarily mean its round or square or rectangular - nascar frames use rectangular frame rails, with round tubular stock for the rest of the chassis.

on the other hand, at the stress levels our sfc's see, your not going to break them.... i would think that any strength diff would be negliable in doing there job...

toecutterv8

The best subframe connectors are made at home,hire a pipe bender,get some 1 3/4 inch tubing,some 6inch wide 1/8 thick plate to prefab the mounting points,and some 1 inch tube for smaller pick up points.This is quite easy to do and you will achieve far better results than going out and buying a set,once you have your main tubes in you can then brace to other main areas of stress,i ran tubes down from the cage onto the main subframe connector tubes,and brace onto the sill boxsections as well,the result is a very stiff,and very strong chassis,you can then run a tube striaght across the car,for the forward mounting of the torque arm,this is a great improvement of the torque arm mounting,removing it totally from the gearbox.I could post pictures if anyone is interested.......If you Aint breakin nothing,you aint making no power........

JDF-Z28

And yet another vote for Spohn. Fit and finish were unmatched.

iroczrockz

Hey, have you ever seen a Nascar Race Car? They have rectangle tubing for the frames and round tubing for the roll cages. Got to look at Earnhardt's car close up one time.

IROCFAST

I would assume that they use round tube because it can be bent to follow the contours of a car.

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leeperryracing

I love my spohn sfc!!

87Formula356

what the difference between using mild steel, or ording one made of chrom-moly?

and have any of you with true dual setups had a problem with clearence? im getting true dual done soon and i don't want anything to get in the way, accually what i hear is u can get Sfc's then take out the tourqe arm (is that what runs from front ot back along the DS?) with the torque arm out you should have np running true dual down the mid section with keeping your ground clearence.

i know i asked a few questions in there lol but does anyone know the answers?

Camaro_nut

Mild steel is a weaker metal than chrome moly. Chrome moly
is also lighter. That's why chrome moly steel is more expensive.

For a stock or near stock car, mild steel is fine. But more
any full out street or drag car, chrome moly would be a
better choice, both for strength and lighter weight.

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