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Robert Logan · 03-30-05, 06:30 PM

Julian,

I MUST concur with Chris on this one. I also feel that the rear chassis needs some sort of stiffening particularly as the engine / box is not a structural member in this car. I have not examined a MDA chassis up close and I am wary about commenting on NON COMPLETED stuff.

In Australia we have to take our cars through a "Torsional and Beam" set of tests. The torsional test is conducted by SECURING the chassis at three of the points of wheel centers (lets say suspension pick up) while the fourth point has a load applied to it and an allowable deflection is permitted for a given load. The allowable loads and deflections are dependant on the engine size and interestingly enough this is in CYLINDERS (ie. 4 - 6 - 8 cylinder and in my opinion should be HP and Torque related).

The beam test is where the same points are used and weights corrosponding to the seating capacity are added and the deflection of the chassis downwards to the floor is measured. A factor of safety (FOS) is used in the weights that have to be used in both tests ie. a two seater like the GT40 has the weight of FOUR people to be added for the beam test. Again allowable deflections are given for the type of car. These tests are both difficult and expensive and there are some cars (not GT40's) that have failed to reach the numbers required here in Australia. Cobra's are particularly difficult to get through these tests as many manufacturers insist on using the original "ladder" type chassis. Mistake!

I must admit that I am very suprised that the SVA does not include such a BASIC safety test (please correct me if I am wrong here).

The best way to stiffen up chassis is with WELDED sections and bolted sections are never as good but that does not say that they are at least adequate. The torsional test is realy the only way to satisfactorly test.

As a final point I must say that our chassis far exceeds the test requirements as all race cars would and it could easily be that the MDA chassis passes torsional tests and I believe it would with the brace that Chris discussed in this thread.

Best wishes,

Robert

03-30-05, 06:30 PM	#15 (permalink)
Robert Logan Roaring Forties Defunct Manufactuer - Old RF Company Join Date: Sep 2001 Location: Australia GT40: NONE Posts: 740 Rep Power: 0	Re: Ohio MDA Julian, I MUST concur with Chris on this one. I also feel that the rear chassis needs some sort of stiffening particularly as the engine / box is not a structural member in this car. I have not examined a MDA chassis up close and I am wary about commenting on NON COMPLETED stuff. In Australia we have to take our cars through a "Torsional and Beam" set of tests. The torsional test is conducted by SECURING the chassis at three of the points of wheel centers (lets say suspension pick up) while the fourth point has a load applied to it and an allowable deflection is permitted for a given load. The allowable loads and deflections are dependant on the engine size and interestingly enough this is in CYLINDERS (ie. 4 - 6 - 8 cylinder and in my opinion should be HP and Torque related). The beam test is where the same points are used and weights corrosponding to the seating capacity are added and the deflection of the chassis downwards to the floor is measured. A factor of safety (FOS) is used in the weights that have to be used in both tests ie. a two seater like the GT40 has the weight of FOUR people to be added for the beam test. Again allowable deflections are given for the type of car. These tests are both difficult and expensive and there are some cars (not GT40's) that have failed to reach the numbers required here in Australia. Cobra's are particularly difficult to get through these tests as many manufacturers insist on using the original "ladder" type chassis. Mistake! I must admit that I am very suprised that the SVA does not include such a BASIC safety test (please correct me if I am wrong here). The best way to stiffen up chassis is with WELDED sections and bolted sections are never as good but that does not say that they are at least adequate. The torsional test is realy the only way to satisfactorly test. As a final point I must say that our chassis far exceeds the test requirements as all race cars would and it could easily be that the MDA chassis passes torsional tests and I believe it would with the brace that Chris discussed in this thread. Best wishes, Robert