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Discussion Starter #61
Paul I purchased it from Mustangs Unlimited about 1 year ago. NPD has one in their catalog, here is the link.
When I installed mine I did not use the supplied self tapping screws, I nut & bolted mine in.
Excellent! Thanks.
 

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It would still be better than before...SFCs will keep the unibody from "peaking" and "dipping" under acceleration and deceleration...but don't expect miracles from SFCs alone. Ideally you would want torque boxes, SFCs, convertible inner rockers, and convertible upper and lower seat pans(and a metal rear seat divider)
I would say Expect a modest miracle, the most common response is I noticed the difference just backing out of the driveway. I thought it was a pretty dramatic difference

I'll be following with interest. As a simple carpenter of almost 40 years I really don't see how any of these could help much. I just don't see enough vertical reinforcement being added? I autocross without even torque boxes and experienced drivers who have driven my car seem to think it does good and have never complained about a lack of structural integrity.
This would be an incorrect assumption. I've been autocrossing my car for 28 years, SFCs made a huge difference, you should definitely get a set ASAP.
Are you good with fabrication? I've been interested in trying these:

My question is would adding sub frame connectors without even having torque boxes be counterproductive? or better than before?
I fabricated mine from his plans. THey work just fine. I ran mine farther back on the rear subframes to make them look less like an add-on. If I was to do it again, I would cut the lowest part in half lengthwise, diagonally brace them internally and cap them to gain an inch of ground clearance. They were easy to make and cost about $12 to make.

THere is no good reason NOT to install SFCs. As I said above you will notice the difference backing out of the driveway. Mustangs unsupported were meant to get groceries on narrow tires. They do not even approximate the strength of aldente noodles, they have the strength of totally overcooked noodles...

What ever model you decide, put 'em in and thank us later for the heads up.
 

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Discussion Starter #63
I am well aware of the effect SFC's have from my years messing with 5.0's. It is a truly remarkable difference. When this coupe comes home, and it definitely will, they will be my first "mod".
 

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Are you good with fabrication? I've been interested in trying these:

My question is would adding sub frame connectors without even having torque boxes be counterproductive? or better than before?
IMHO it really doesn't matter... attaching anything to the front sub-frame extensions (floor supports) doesn't accomplish a heck of a lot. If you've ever held a set of sub-frame extensions in your hands you'd know what I mean... they don't transfer much, if anything, up to the cowl and out to the torque boxes.
 

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I welded in a set of Global West SFCs to my '67. I would say you can see them from the side unless you're right next to the car, they reduce your ground clearance by at least 1.5-2 inches. My options were VERY limited, I wanted an X-brace but since my car is a convertible there's nothing on the market and I'm no fabricator. I have the export brace up front, plus the Monte Carlo bar and a 4-point rollbar behind the front seats. The rear seat brace wouldn't do much for the vert either since that is already reinforced from te factory like the inner rockers, and the plates that bolt up underneath. The biggest issue I have was finding room for exhaust with those plates. I considered using spacers but that would defeat their ability to a large degree, so I had to go with 2.5 inch tubes.

My car will see track days (COTA is my plan) but only on a parade lap sort of thing, certainly some aggressive use but no racing. Main reason for considering them mandatory is the convertible chassis is very prone to flex, and while this will not eliminate that I don't want 425 ft/lbs of torque to twist it either.
 

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So it might be overkill but with all that you are talking about why not just put a frame under it ?https://www.schwartzperformance.com/chassis/1964-1973-mustang-chassis/
You bring up a great point here, because in the long run, if you're thinkin' 3 link rear or IRS, do all the front coilover and suspension, etc, then you will likely spend MORE in parts & labor than the base cost of that complete frame. Schwartz Performance, The Roadster Shop, Scott's Hot Rods, and prolly others make full replacement frames. I wonder how much WEIGHT a complete frame adds to our vm's? Just a guess it looks like it'd add 300-400 lbs?? Anyone know?

I'd like to keep my weight way down, well, my vm's weight anyways.
 

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Also, since I have been thinking about it since last night..... I figure that if the project comes home, I will most likely put the subframe connectors on it immediately. Then, further down the road, do the extra rocker support. I do have some wild daydreams about my dream coupe. So chassis support an strength are a big part of the overall plan.
I've got those wild ambitions for my car too, so I wanted to find the ultimate subframe connectors that could let me upgrade in steps to, say, an X brace with driveshaft loop, 3 link rear suspension, tie into a 6 point roll cage, etc. The ones I've seen that do this are like Griggs racing, Cortex racing, Total Cost Involved (TCI, pics 67GT Guy posted looks great), etc. Any experience on the street with these, anyone?
 

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I know you said you want square cross-sectional ones, but you might want to do a bit of research on torsional rigidity - the round (cross section) ones control flex in multiple directions better.

Anyway it is your car (or soon to be is) do whichever you like. I would vote for Global West ones, but my vote doesn't count. :)
 

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Ya know, I don't have any dog in this fight and don't care if you buy, build or even ever install subframe connectors because
I no longer sell chassis components for a living, but I will say this..... even a crappy set welded on is a noticeable improvement.
I'll go you one better- installing a trunk separator plate (behind the back seat on a coupe/sedan and PERMANENTLY
attached to the car)...... I can tell that improvement immediately. (You wouldn't think that at all from the inexpensive
nature of that modification, but it's a factual situation)
Here's another truth.... bolted-in subframe connectors are ok until they loosen up and then you're pretty much hauling
around extra weight. Believe it or not. You might as well weld the stuff in because by the time you get enough mechanical
fasteners in place to do the job right..... welding would have been way easier.

ex-Global West GM
1991-1995
 

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Nailbender said:
I'll be following with interest. As a simple carpenter of almost 40 years I really don't see how any of these could help much. I just don't see enough vertical reinforcement being added? I autocross without even torque boxes and experienced drivers who have driven my car seem to think it does good and have never complained about a lack of structural integrity.
This would be an incorrect assumption. I've been autocrossing my car for 28 years, SFCs made a huge difference, you should definitely get a set ASAP.
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So I'm planning on doing some reinforcement eventually. I'm thinking the vert rockers and torque boxes will be a better choice without putting a bunch of crap in the way of everything? I'll have my own 2 piece version of the vert rockers bent up so I can do a thousand plug welds from the top side instead of getting burn't to a crisp below. I know a guy with a big brake.
 

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You bring up a great point here, because in the long run, if you're thinkin' 3 link rear or IRS, do all the front coilover and suspension, etc, then you will likely spend MORE in parts & labor than the base cost of that complete frame. Schwartz Performance, The Roadster Shop, Scott's Hot Rods, and prolly others make full replacement frames. I wonder how much WEIGHT a complete frame adds to our vm's? Just a guess it looks like it'd add 300-400 lbs?? Anyone know?

I'd like to keep my weight way down, well, my vm's weight anyways.
Kinda what I was thinking when I mentioned it
 

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Ya know, I don't have any dog in this fight and don't care if you buy, build or even ever install subframe connectors because
I no longer sell chassis components for a living, but I will say this..... even a crappy set welded on is a noticeable improvement.
I'll go you one better- installing a trunk separator plate (behind the back seat on a coupe/sedan and PERMANENTLY
attached to the car)...... I can tell that improvement immediately. (You wouldn't think that at all from the inexpensive
nature of that modification, but it's a factual situation)
Here's another truth.... bolted-in subframe connectors are ok until they loosen up and then you're pretty much hauling
around extra weight. Believe it or not. You might as well weld the stuff in because by the time you get enough mechanical
fasteners in place to do the job right..... welding would have been way easier.

ex-Global West GM
1991-1995
This makes a lot of sense. In my research of frames and chassis stiffening, the car is basically three separate areas; firewall forward, truck divider rearward, and the section in between.

Firewall forward: We all do a great job on this with export braces transferring torque to the firewall. The firewall is basically a big vertical shear plane. Everything done up here is to keep the firewall and frame rails from twisting in relation to each other. All the bracing that can be tied from the suspension mounting points to the firewall will be benificial but, of course, some more than others. There's also a point of dimenishing returns.

Trunk divider rearward: As GT289 mentioned, the trunk divider will help tremendously, providing a vertical shear plane, just like the firewall does for the front section. This is coupled in with the rear floor section and the shock structure between the rear frame rails.

Section in between: This is the section that holds the two aforementioned sections together. For best stiffness, it needs to be built to resist twisting. A flexible center section will negate most of the improvements that are done to the front and rear sections. From better to worst; fastback, couple, then convertible. The further out you move any of the members, the easier it will resist twisting. If you think of this section as a big box and each side contributes, it would be best to add bracing to the roof, door frames, and the floor. Think of a tube chassis race car - this center section has cross bracing all over the place and it all contributes. The roof frames could use some gussets at all four corners to help and maybe these could be hidden under the headliner. The roof skin itself nicely adds in a decent amount of support though. The door openings - well, not much can be done there without adding a roll cage. However, I'm going to hide some large triangular braces between the B-piller and the rear torque boxes behind my fastback rear panels to add some bracing. I did a test with a dial indicator in this area and pushed and pulled on my car structure (minus roof and quarter panels) and the deflection at the B-pillar reduced a lot when clamping in a brace. Go look at the convertible structure, you'll see the brace that they tie into the inner rocker panel.

Then the floor comes next. This is the side of the box that can be modified the most. In fact, that's what Ford did with the rocker panels, torque boxes, seat risers and the floor itself. Obviously, the convertible uses this section entirely for torque transfer since it is missing the other three sides of the box, so a lot can be learned from this. The convertible inner rockers, one piece seat riser, lower seat bracing and bolt in section, bracing to the B-pillar, and bracing to the trunk divider. Think of a one plane ladder. How would one make that as stiff as possible? Well, you obviously need some cross supports (rungs). That gets you a decent structure to resist torsion but can be better. How? Add in as much vertical height as possible, just like the seat platform structure which adds in a lot of strength adding cross section. Next would be adding cross bracing (X's). Add in some skins across one side of the ladder and it's going to stiffen it in torsion quite a bit. Think of old airplanes and racecars that had aluminum panels riveted inbetween all the members, they all act as shear planes and resist torsion. On a standard coupe or fastback, the floor has a tunnel that is not very strong, so if gives up quite a bit of this. That's partially why the convertible ties this two sides together, to transfer forces across the tunnel.

Now on to subframe connectors (SFC's). A lot of people say they are not as good as adding convertible rockers - they are probably right since the rockers are much further out, so they have more leverage to resist twisting. That doesn't mean SFC's don't do any good. In fact, I think the main thing "most" SFC installs do is help resist up and down bending, i.e., the lengthening or shortening of the distance between the frame rail extensions and the rear torque boxes. Think of a drag car slamming down on the ground after a wheelie.

If one just took the front frame rails extensions, SFC's, and rear torque boxes and made a separate assembly, would it resist any twisting? Not too much, actually it would act like a ladder without rungs and X's. That's why I think they are there mostly to provide bending resistance (up and down) like I mentioned in the last paragraph. BUT, how do you make this simplified section resist torque, you guessed it, add as many rungs and X's as possible. If you did this, would it resist torque? Yes! Tie that Inner ladder into the outer ladder - will it help resist torque? Yes! You can do this test in your hands but just taking two pencils separate from each other and twist - you'll notice that the pencils will twist. You have to tie the two "pencils" together to resist twisting, with rungs and X's. Look at frame rail vehicles, they basically look like a ladder. The stiffest chassis' are the ones with X's added in. A lot of car manufactures did this before uni-bodies became popular.

Now here's my plan (image below). I found the image below online and added in the orange and blue lines to show my bracing plan. In some web searching, I found this image LINK, so thanks to that poster on a cougar forum!

The base of the plan is using the Maier Racing SFC's LINK. I really like these because each one uses a strong four points of connection. They are 2", 0.125" wall round tubing. They are heavy! Anyways, since they connect so well to the structure of the car, and will allow for bracing to be welded to, they were a good fit for my plan.

The orange lines represent two things, X-bracing and "rungs" that coincidentally align with the one piece seat riser I'm installing on top of the floor. They make those now for coupes and fastbacks. I don't want to add the lower convertible seat platform, so I'm going to use the orange "rungs" to build up this center section like the convertible. Not shown is the bracing I'll attach to the floor board at the seat riser perimeter. Then of course, is the orange X bracing.

I haven't yet decided if I'm adding on the blue braces, depends on available space. You'll often read about the rocker panel braces that weld in this area. These would help transfer torque from the front and rear torque boxes and rockers to the SFC's and X. If I tie the SFC's into the floor at several points, the floor itself will act like a skin to transfer torque here, so they may not be needed - BUT, you need to tie the floor into the SFC's to make the floor work that way since the tunnel takes away strengh of the floor "skin."

The goal of a stiff chassis is to not flex and turn into an undamped spring (remember suspensions control the springs with dampers!). This allows the suspension to do all the work. This can allow a car to use softer suspension. A stiff chassis should improve ride quality, not make it worse. There are many articles on this. Car manufacturers do this all the time to improve ride quality by adding all sorts of bracing in unibodies. This is also why stich welding all the joints on the unibody can help too. This is what structural adhesives do for new cars - just another way to improve ride quality goals for new cars.

Anyhow, that's all why I chose the Maier Racing SFC's for my build. I just don't think it would make much sense to do all of the X bracing if the chosen SFC's weren't able to really connect into the framerails securely and resist torque individually. In my pencil example above, if you took really small diameter tubes or used flexible material, or had weak joints connecting three sections of "pencil" together, they themselves couldn't complete the stiff X-braced ladder. In fact, the stiffest ladders out there have really nice and stiff "pencil" sections.

Well, there you go, my $0.02, for what it's worth! :)


7T02S Bracing Plan.png
 

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I made the Daze frame connectors as well (pics in my build thread). I'm a long ways from driving the car. Not to worried about the ground clearance. I do plan on fabbing and building my own X brace like the TCP set up. I thinking boxing in the uni body is a great idea and worth doing but that is just my poor opinion. I have installed front torque boxes and did so before I knew of the vert inner rocker option. I'm still on the fence about adding the vert inner rockers or not. I have even thought of just adding a 1x2 channel to the inner rocker. Input is welcome, good or bad.

I think one thing we overlook when it comes to frame connectors is just that, it connects the rear and front frame sections together. That has to account for something. Now the rear torque box has support on both the outside and inside edge of the torque box and the same can be said for the front torque box. I believe any frame connector will be more than what most of us will ever need. I went with the Daze because they fit my build and the cost was low. Plus I like making things. So I would suggest buying based on ones skill and look they prefer unless you need the absolute most out of the frame connector then buy accordingly.
 

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Ya know, I don't have any dog in this fight and don't care if you buy, build or even ever install subframe connectors because
I no longer sell chassis components for a living, but I will say this..... even a crappy set welded on is a noticeable improvement.
I'll go you one better- installing a trunk separator plate (behind the back seat on a coupe/sedan and PERMANENTLY
attached to the car)...... I can tell that improvement immediately. (You wouldn't think that at all from the inexpensive
nature of that modification, but it's a factual situation)
Here's another truth.... bolted-in subframe connectors are ok until they loosen up and then you're pretty much hauling
around extra weight. Believe it or not. You might as well weld the stuff in because by the time you get enough mechanical
fasteners in place to do the job right..... welding would have been way easier.

ex-Global West GM
1991-1995
When you say permanently attaching a seat divider, does that need to be welded? Or just bolted?


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Can anyone who has installed the ‘vert rockers comment about the differences of before and after? I think we all understand why it would be beneficial, just wondering if you would recommend it over a fine set like maier’s etc...
 

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