Aftermarket Product ReviewProvide questions and answers about aftermarket parts for the Third Generation F-Body.
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What would be stonger, a .5 inch round bar, or a 1 inch square bar?
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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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!!
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.
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.
Originally posted by BackInBlack86 round tubing is actually stronger than square tubing. ever notice nobody makes a quare tube LCA or TA? there's a reason for that.
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.
Last edited by Camaro_nut; 05-22-2004 at 02:55 PM.
Originally posted by mike graycar actually, those are alston's. they get resold by other venders under different names. i have those right there on my car and they are excellent.
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.
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.
Originally posted by 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.
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!
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...
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.
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.
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...
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.
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.
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.
Originally posted by 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.
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...
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........
Originally posted by 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?
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.
Originally posted by 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?
I would assume that they use round tube because it can be bent to follow the contours of a car.
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?
Originally posted by 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?
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.
Originally posted by 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.
Close but not quite. I read up about this subject a while ago, let's see what stuck. Mild steel's yeild strength and plastic deformation strength (I don't think thats the right term, but I think thats the right concept) are the same. That means that it can withstand repeated stresses (up to the point it breaks) indefinatly. Once you exceed that point, its broke, no going back. Chrome moly on the other hand can withstand higher stresses, but only for a certain number of cycles, then it starts to crack, and if unnoticed will lead to an untimely failure.
That is the reason that chrome moly is used in race cars you can use thinner (thus lighter, CM and MS are very close or identical densities) tubing. They can do this b/c race cars are inspected much more often and more thourghly than any street car. When you see the crew chief put 3 guys on chassis cleaning duty, its not b/c he wants it to look pretty, they're looking for stress cracks.
Think of it this way: you can put stress on a toothpick all day long, as long as you don't put enough pressure on it to crack it. On the other hand a paper clip can be bent a certain number of times, well past the point that it'll bend, then it will break suddenly.
I hope all of this made sense. Anyone who knows the correct terminology feel free to correct me.
Originally posted by V6canvas Close but not quite. I read up about this subject a while ago, let's see what stuck. Mild steel's yeild strength and plastic deformation strength (I don't think thats the right term, but I think thats the right concept) are the same. That means that it can withstand repeated stresses (up to the point it breaks) indefinatly. Once you exceed that point, its broke, no going back. Chrome moly on the other hand can withstand higher stresses, but only for a certain number of cycles, then it starts to crack, and if unnoticed will lead to an untimely failure.
That is the reason that chrome moly is used in race cars you can use thinner (thus lighter, CM and MS are very close or identical densities) tubing. They can do this b/c race cars are inspected much more often and more thourghly than any street car. When you see the crew chief put 3 guys on chassis cleaning duty, its not b/c he wants it to look pretty, they're looking for stress cracks.
Think of it this way: you can put stress on a toothpick all day long, as long as you don't put enough pressure on it to crack it. On the other hand a paper clip can be bent a certain number of times, well past the point that it'll bend, then it will break suddenly.
I hope all of this made sense. Anyone who knows the correct terminology feel free to correct me.
Thanks for the info.
Last edited by Camaro_nut; 09-14-2004 at 07:00 PM.
I have Alston SFC from Top Down Solutions. The mounting to the subframes was properly very tight and my professional welder had no problems to weld them in. My problem is that they hang low and they scrape on speed bumps. I don't know if other designs decrease the ground clearance as much which may be of concern if the car is lowered.
basically you can use 2 sets of sfc's for superior rigidness? The alston's mount in the middle of the subframe. and kenny brown and spohn both go into the outside if the subframe. So both can be used correct?
Originally posted by 87CIZ i agree with the round vs square. the circle exerts forces in round no points to break
Depends on what type of force your applying...
rectangular tubing (which btw is whats used not square) tends to have less tendancy to flex in one direction more than another... it also resists twisting better.
I think that when you examine a SFC - you should look more at the type of force being applied to it...
i think that twisting, and tension forces are the biggestones exerted on the sfc's...
in that case, rectangular tubing resists twisting far more than circular tubing does - remember what s10 blazers use for springs nithe front? a torq tube... why do u think they use square tubing for the frame on a race car?
as a side note, a friend of mine 91 formula had sphons tubulkar sfc's in... i have the hotchkiss ones... (rectangular) my car is far more solid than his... for what its worth!
Assuming constant modulus of elasticity and cross sectional area, the shape with a higher moment of inertia will have a higher resistance to bending moments, it will be stiffer.
Typically this will be the rectangular or square cross section.
The simple definition is that when a beam is subjected to pure bending the highest stress is seen at the point farthest from the neutral axis. The higher level of stress you have the higher your deformation(strain) will be.
The neutral axis is the point where no strain occurs, stress = 0, and is located at the centroid of the cross section. The material above the neutral axis is in compression and has a negative strain while the material below the neutral axis is in tension and has a positive strain. Simply, the material on top of the beam is shrinking in length and the material on the bottom is growing in length. The material in the centroid is neither shrinking or growing in length.
If you can move more material farther away from the neutral axis you will have a stiffer beam. Square tubes typically place a larger area of material farther away from the centroid than round tubes(hence they have a higher MOI), so the stress in that area is reduced and strain is reduced.
Originally posted by PCS74 Assuming constant modulus of elasticity and cross sectional area, the shape with a higher moment of inertia will have a higher resistance to bending moments, it will be stiffer.
Typically this will be the rectangular or square cross section.
The simple definition is that when a beam is subjected to pure bending the highest stress is seen at the point farthest from the neutral axis. The higher level of stress you have the higher your deformation(strain) will be.
The neutral axis is the point where no strain occurs, stress = 0, and is located at the centroid of the cross section. The material above the neutral axis is in compression and has a negative strain while the material below the neutral axis is in tension and has a positive strain. Simply, the material on top of the beam is shrinking in length and the material on the bottom is growing in length. The material in the centroid is neither shrinking or growing in length.
If you can move more material farther away from the neutral axis you will have a stiffer beam. Square tubes typically place a larger area of material farther away from the centroid than round tubes(hence they have a higher MOI), so the stress in that area is reduced and strain is reduced.
Typically when you consider the impact of torsional forces on beams it is in relation to toques about their axis. In this instance the torque is about the axis of the vehicle body. I am sure that they will be subjected to some torsional forces, but I don't believe that they will be of a magnitude that is worth considering. Mind you, I have no proof of this.
Lets say we lock down the rear subframe mounts so that they and the body from that point rearward are not free to rotate. We then observe the vehicle from the rear as it undergoes counterclockwise torsion from a load applied at the passenger side front wheel and an equal but opposite load on the driver side front wheel. This will simplify our objective by allowing us to consider the vehicle body as being in torsion. The vehicle body will twist about some axis. We do not know the exact position of this axis but we do know it is located somewhere on the vertical centerline of the body.
For this rotation to occur the passenger side of the vehicle must undergo a positive vertical movement while the driver side will undergo a negative vertical movement. There is also translation in the horizontal direction, the passenger side will move in the nagative horizontal direction while the driver side will move in the positive horizontal direction.
From experience I think we can assume the movement in the horizontal direction is much less than that in the vertical direction due to the relative distances involved from the axis of rotation and the relatively small angle of rotation, ie the car is wider than it is tall.
So, if we can disregard the horizontal translation we can look at the sfc's as if the passenger side sfc is undergoing positive vertical movement and the driver side is undergoing negative vertical movement. Since the rear mounting point of the sfc's are not free to move or rotate they are being subjected to bending forces only, in this instance.
Again this is only a simplified view. We don't have enough information to make an even somewhat analytical analysis, and completely analyzing the vehicles dynamics are well beyond my capability.
I've been reading about sfc's and trying to figure out what ones I want. I see that some people use 2 sets like alston and sphon at the same time. I see that alston makes a full subframe kit. I wanna tie the front and rear and not weld to the floor pans. So some tips on what way to go. I can't decide on Alston or Sphon or both.....HELP
Alston, I love mine. Get these first and if you feel you need more add the sphone or brown's later. You will not be dissapointed with the Alston's.-Mike
I'm doing alston down the middle and spohns down the sides, then i'm going to weld every seam i see... then i'm getting some tubing and welding the alstons to the spohns after they are both in.
could you draw a diagram of what you plan to do? i also have the alston's and the spohns ( actually keeny browns, but they're the same idea ). but i haven't connected them together. where would you do it? drawing please...
I prefer the JEGS unit as it actually filts within the floorpan sheet metal and does NOT extend bellow or reduce ground clearance. It is a bolt-in unit but I had mine welded in for improved rigidity.
Originally posted by wdigitog could you draw a diagram of what you plan to do? i also have the alston's and the spohns ( actually keeny browns, but they're the same idea ). but i haven't connected them together. where would you do it? drawing please...
I would but I don't have a scanner.
I'll try to find a picture of the underside of a camaro and do something crude with MSpaint.
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