Increase Chassis Stiffness without Off-Road Compromise | Steeda Bronco Strut Tower Brace

[Bronco1971]

Two point brace? The only thing it could possibly stiffen is the distance between the tops of the strut towers. Even in that, there's no triangulation, so is this a moment resisting member? There is near zero added stiffness torsionally and none fore aft, and none vertically. In addition the lever arm from the UCA pickups to the top of the bend on this part is rather large. So, I'm curious, what is the measured dimensional change in the distance between the tops of the strut towers under load that this part is designed to resist, and does it in fact make a significant change.

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[Valhalla]

What he said... looks like fluff

 

[Sparkherd]

L-U-V your spare(s) setup!!!

 

[BigMeatsBronco]

I'm all for a strut bar, (and a engine torque bar too) as it is very helpful for vehicles with tall coilover perches and NO crossmember between the perches, like the Bronco....the tall coilovers mounts allow extra leverage and a twisting motion to the frame rail, especially when the bump stop is built in to the coilovers. Additionally, the way the tops of the coilovers are splayed inwards, means under extreme compression the force is transferred inward at the top of the frame. While this is happening, the lower control arms are being effectively stretched apart as the suspension bottoms out. This further exaggerates the frame twisting forces. Luckily the bottom of the frame has crossmembers located at the LCA mounts for this exact reason. So then the forces are transfered to the coilovers bucket pushing it upwards and also inwardly...so a crossover brace could help here. ALOT.

HOWEVER, the design of the one pictured above doesn't offer much structure or stiffness especially in compression. The structure needs to be much bigger tube and /or double tube all the way. With braces at those bends. Do these improvements and get rid of the ugly logo and I'll buy one.
While your at it Incorporate passenger side engine adjustable torque rod as well (with bushings at each end) and I'll buy 2 of them.

 

[Bronco1971]

I'm all for a strut bar, (and a engine torque bar too) as it is very helpful for vehicles with tall coilover perches and NO crossmember between the perches, like the Bronco....the tall coilovers mounts allow extra leverage and a twisting motion to the frame rail, especially when the bump stop is built in to the coilovers. Additionally, the way the tops of the coilovers are splayed inwards, means under extreme compression the force is transferred inward at the top of the frame. While this is happening, the lower control arms are being effectively stretched apart as the suspension bottoms out. This further exaggerates the frame twisting forces. Luckily the bottom of the frame has crossmembers located at the LCA mounts for this exact reason. So then the forces are transfered to the coilovers bucket pushing it upwards and also inwardly...so a crossover brace could help here. ALOT.

HOWEVER, the design of the one pictured above doesn't offer much structure or stiffness especially in compression. The structure needs to be much bigger tube and /or double tube all the way. With braces at those bends. Do these improvements and get rid of the ugly logo and I'll buy one.
While your at it Incorporate passenger side engine adjustable torque rod as well (with bushings at each end) and I'll buy 2 of them.

I agree that stiffening the chassis is rarely a bad thing. However, as you note, there are engineering considerations that need to be taken into account. If, as in this case, the brace were made as a rigid moment frame the connections on either end become critical. IOWs I doubt an unmodified sheet metal strut mount would have the ability to manage the stresses without severe damage. The factory designed load cases don't seem to leave room for it. There's a lot of legitimate questions here and I'd like Steeda to show their work. I don't question it one bit as a dress up part, or even a beer shelf, but describing it as a chassis improvement begs a lot more. Real chassis dynamics, not inverse kinematics.*

*Bonus points for the origin of that one.

FWIW, I had a Steeda STB and TriAx shifter in my track day Mustang. That STB had a far less severe angle across the engine and had a rather substantial firewall mount for triangulation. That part only worked in the X and Z axis, no effect in the Y. There is some debate as to whether or not that added weight was of any use, but, I think it allowed for slightly better camber and caster control at high loads.

ETA, the Bronco has massively more chassis rigidity than an SN95 Mustang. Massively more. A fuck ton more rigidity. Implication being how much improvement is plausible?

 

[ScorpydJim]

IMO, just a dress up item, like fancy underwear.

 

[69351windsor]

Two point brace? The only thing it could possibly stiffen is the distance between the tops of the strut towers. Even in that, there's no triangulation, so is this a moment resisting member? There is near zero added stiffness torsionally and none fore aft, and none vertically. In addition the lever arm from the UCA pickups to the top of the bend on this part is rather large. So, I'm curious, what is the measured dimensional change in the distance between the tops of the strut towers under load that this part is designed to resist, and does it in fact make a significant change.

Exactly what I was thinking -- even stock the chassis was engineered to function with suspension dong it's "job" & if your chassis is flexing THAT much - geeze something might be wrong....

 

[Bronco1971]

Exactly what I was thinking -- even stock the chassis was engineered to function with suspension dong it's "job" & if your chassis is flexing THAT much - geeze something might be wrong....

In all fairness to Steeda, the Fox and SN95 Mustangs were very floppy from the factory. Laughably so. IMO the strut tower brace did serve a function on those two closely related derivatives of the Fairlane. Particularly if you were wanting to have 10/10ths performance. Steeda did (still does?) make a good STB for those chassis. I seem to recall (though I could be wrong) that it was good enough that JR Granatelli copied it and sold it as his own, like he did with the MM K-member.

There are NO modern chassis that have anywhere near the uncontrolled flexibility that the Fox bod has. With Bronco, the proof is in the driving. There is no way that a short wheelbase, wide, tall, truck sitting on 35" tires is going to be as stable as the Bronco is at 90mph if there is any significant uncontrolled movement in the suspension system.

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