Who makes the best subframe connectors for a 67 small block?
And, are there any pros vs cons of the bolts in vs weld in?
Just looking around online and the selection has every variety under the sun.
Thanks,
Robert
IMO, Maier Racing subframe connectors are the best. Cons: They are more expensive than the GW or TCP. Pros: They are longer (they go all the way up to the torque boxes) and they connect in more places. They have a Cougar specific design and fit really well. Because they next to the front frame rails, they don’t change your ground clearance at all.
GW - 1-5/8" diameter 1/8" Wall DOM
Maier - 2" diameter 1/8" Wall DOM.
I don’t have a good picture of mine, but here is a Mustang that had them installed.
You are only going to do this one. Do it right.
I made my own from some 2" square tube and welded them in. They fit inside the front framerail and are much stronger than most any other weld on type because of this. Square tube is also stonger than round for the purposes of a connector.
Weld in is much stronger than bolt in. The bolt in style can become ineffective after they are torqued on by the chassis. Plus, overtighteneing, or retightening of the bolts can cause week points by bending the metal.
If you have a round tube and a square tube made of the same material and the same pounds per foot, the round tube will always be stronger.
When putting pressure on the ends, yes, but not twist or putting pressure on the tube. If the connector were to take a hit from the bottom and get dented, the round tube would be much weaker.
Unless removal is a priority, weld them to the car in as many places as possible. Also be sure they tie into the torque boxes. The front frame rails from that point back really just hold up the floor pans. The “frame” of the car is the body itself.
A 2.5" dia 1/8" wall round tube is used to make a 2"x2" 1/8" wall square tube which means they have the same weight per foot. According to the Steel Tube Institute, the torsional stiffness constant of the round tube is 55% higher than the square tube and the torsional sheer is 21% higher.
Here are the equations for torsional stiffness constants.
J_circle = Pi/2 (OD^4 - ID^4)
J_square = 2.25 (A^4 - B^4) Where A is the outside dimension and B is the inside dimension.
Using the dimension above, the ratio between torsional stiffness constant is
J_circle/J_square = 1.50
Source: http://www.steeltubeinstitute.org/pdf/brochures/dimension_brochure.pdf
http://en.wikipedia.org/wiki/Torsion_constant
I was looking at the Maier ones with the extra tabs for fastening along the length. Where do the extra tabs attach? At first I thought it might be the body seam, but after looking at your pic, they are too far in to do that.
I didn’t want to start the “which is ultimate” debate. Yeah, the round tubes are stronger, but I thing the skid plate factor of the square tubes would be more helpful with the roads around New Orleans. I don’t plan on taking the car trans am racing or anything. I just want to help it not start cracking apart at the seams over time.
I could always get the Maier full kit with the X brace and if they take a beating, cut a lenth of square tubing down the middle and make two C channels to weld to the bottom of them as skid plates.
Between my brother and I, we have almost the full amateur machine shop covered, so I’m not afraid of cutting, welding, bending, etc to make what I need.
Ok, you win Adam.
I still think that square is more than strong enough, especially if a C-channel full of holes is strong enough to keep my 6500 pound truck that pulls 12,000 lbs from folding up.
I guess I should have really phrased it differently. Its not the tubing I have a problem with, it the “what if” that I have a problem with. A square tube could take more impact from underneath without damage than a round tube can. If a round tube gets dinged, all stuctural integrity is gone.
Another thing is the placement of welds. Even on my square tube bars, I added multiple extra welds. Just a short three inch weld at the front and back are not near enough for the Maier type bars. They should be welded at the ends of the front frame rails as well, and a plate cut and welded in to attach the bars to the rear frame rail near the spring mount. Afterall, the majority of the twist caused is from the front spring mount.
I like the one from Maier too.
Their stuff is pretty hard to beat for mail order parts.
Square it up before you start welding steel into the frame.
They weld to the frame rails and rear torque boxes. I hope this helps.
Okay, seeing that pic and the pic on their site side by side, that makes a lot more sense.
Thanks!!!
Have you seen this?
Do they make these type of bolt ons for 69’ verts as well or just for 67-68?
Yeah, I have seen those torque arm suspensions. They look nice, but I don’t think I need that quite yet. I’m going to see how far a mostly stock suspension can take me. Considering they took Cougars Trans Am racing with off the shelf parts, I think that should work for me. I think between the subframe connectors, X brace, and building something similar to their one piece shock tower brace, the car will be plenty stiff.
I also have the weld in sheet metal divider to go behind the rear seat and the trunk sitting at the house. I read that one piece does A LOT for stiffening up the car.
Read that too; in a thread “on another Forum” by a guy who used his stripped Mustang shell as a quasi ‘test mule’ to see what stiffener options actually worked as much as they cost. First time I’d heard of the dividers helping in THAT respect.
Thinking about cutting up some sheetmetal to make one for a '73 now. My gas tank is under the trunk, not acting as the trunk floor; so I wouldn’t necessarily think about the divider’s effectivness in keeping fuel out of the back seat.
As I recall the mustang guy concluded that the rear seat divider (or similar cross brace) was the single most effective structural brace you could add to a vintage mustang. That explains why the convertible rear seat panels are so beefy.
I read that same article with mustang being supported at 3 corners and a weight being applied to the 4th to check the flex of the whole car.
http://www.stangnet.com/mustang-forums/threads/torsional-rigidity-test-67-coupe.723029/
Yup, that’s the one - and that’s the Forum. I already mentioned StangNet once today, wasn’t going to bring it up again 
And fordblue you’re from southern LA, huh? You didn’t by chance have an older (compared to your '06) Ranger with a 331 under the hood, didja? 
Nope, just the 2000. I had a 99 before that and it got totaled by a woman running a red light.
I’ll add the divider to the list of stuff to do when the major tear down happens to do cowl repairs and headliner install.