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Mach1 Driver

Fastback inner rockers

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37 minutes ago, RPM said:

For the average Mustang owner without a lot of cash, equipment, skills or knowledge,  I think if the rear seat brace, export brace and Monte Carlo bar were installed they would have a much stiffer chassis at little cost in time and money. 

Coupe rear seat area structure on a fastback is not feasible in my opinion, coupe has a lot of structure like the shelf etc which carry load. I think cross brace under the car like TCP X-brace and export brace are best bang for the buck with little cost in time and money.

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I understand the energy absorption thing, but wouldn't you want the cabin to stay intact, and let the front and rear structures absorb the impact? Seems to me the early Mustang was deigned with the cabin as the crumple zone. I've been wrong before. 

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19 minutes ago, aslanefe said:

If a part is not bending and deforming, it is just tranfering the energy, not absorbing it.

True. But in a crash, we are talking about kinetic energy. It will dissipate by taking other forms like heat or sound. It's not like the impact (force) of the crash bounces around like in a pinball machine until it can bend or break something to bleed off energy. Crash force is one thing, it is what it is. The energy in that force is another. But we are getting off topic here. 

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4 minutes ago, RPM said:

I understand the energy absorption thing, but wouldn't you want the cabin to stay intact, and let the front and rear structures absorb the impact? Seems to me the early Mustang was deigned with the cabin as the crumple zone. I've been wrong before. 

Well, on a head on collusion the energy that will go to the rear structure has to pass through the cabin right? People sitting in the cabin will be subject to that. You want the energy absorbed before it reaches the passenger.

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I can see the floor support attached to the SFC keeping the front from pushing back ,i just cant see it keeping the front from flexing upward ,just not a strong enough piece . I would be willing to bet with a colision like you had it would bend right in front of the SFC. 

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4 hours ago, fvike said:

True. But in a crash, we are talking about kinetic energy. It will dissipate by taking other forms like heat or sound. It's not like the impact (force) of the crash bounces around like in a pinball machine until it can bend or break something to bleed off energy. Crash force is one thing, it is what it is. The energy in that force is another. But we are getting off topic here. 

Did you see the car latoracing posted on this tread? Looks real stiff.  I think that car may bounce like a pinball in a crash if it hits something very heavy.

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On 1/13/2019 at 3:01 PM, fvike said:

That is impressive. My car did not do that. But it's been known for a long time that drag racers prefers the coupe over the fastback due their stronger construction. I'd like to see this on a stock fastback.

My fastback is all stock, a southern California car with 77k on the odometer and no rust. I tried picking it up from the drivers front torque box. The front passenger tire stayed on the ground but the suspension unwound, same with the rear drivers tire. So three down one up. Just out of curiosity I'll have to see what goes on with the coupes construction (behind the rear seat?) that stiffens it up.

I wonder if I could get three in the air if I put in an export brace and a solid plate behind the rear seat. From the torsion test the export brace gives a 25% improvement, and a rear seat divider is 11%. A Monte Carlo bar does 0%- it just keeps the towers separated. Welded-in SFCs without cross bracing give 0%. 

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3 hours ago, Mach1 Driver said:

My fastback is all stock, a southern California car with 77k on the odometer and no rust. I tried picking it up from the drivers front torque box. The front passenger tire stayed on the ground but the suspension unwound, same with the rear drivers tire. So three down one up. Just out of curiosity I'll have to see what goes on with the coupes construction (behind the rear seat?) that stiffens it up.

I wonder if I could get three in the air if I put in an export brace and a solid plate behind the rear seat. From the torsion test the export brace gives a 25% improvement, and a rear seat divider is 11%. A Monte Carlo bar does 0%- it just keeps the towers separated. Welded-in SFCs without cross bracing give 0%. 

Try jacking of up the rear tire. Use the factory jack point on the rocker or the area just front of the leaf spring attach point and let's what happens. You can see where the lift pad is on my car in one of the pictures I posted.

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