New commercial mount for 2004R transmission

Thanks FABO folks for the positive and constructive commentary. Jeff is a very involved customer and researches much before any decision on his Dart.

We engineered the new cross-member to replace the factory center section of the torsion bar cross-member, provide clearance for the transmission (and the speedo sending unit!) and be stronger when installed.

I enjoy the debate about strength, angles, locations, material thickness. We did consider an awful lot of factors in the design including the prior work we have done installing 518 OD units in Mopar's and the Viper T56 we did in an E-Body.

A note about strength (please skip if this gets boring, thrills me to pieces but not everyone's cup-o-tea). Strength comes from the structure more than the material thickness. Think Cardboard tube. Rolled into a circle - pretty strong. Cut so it is just a rectangle of cardboard - pretty flimsy. Same engineering concept goes into the torsion cross-member, we engineered a structure to provide the strength needed to support the torsion bar rear mounts and be an integral component of the factory unibody monocoque construction.

If you study the strength of a structure, it is seen that the size of the structure adds more strength than the thickness of the material. The box is stronger than a 4"wide piece of 1/4 plate formed to follow the floor tunnel contour. The torsion cross-member replacement becomes a box when it is seam welded to the floor. Wicked strong ? - you betcha.

While Jeff is running the Coil-over from RMS, we built this to work on a standard, torsion bar in place, Mopar front end. When you consider how the rotational (twisting) force is transmitted to the cross-member, the U-shaped dog-leg angles do not have a negative impact at all. I get the bridge analogy, except bridges are designed for a force from above (vehicles traveling over them) or weather hitting them (wind etc.) and they are self supported in the middle - just hanging in space.

The replacement cross-member has a twisting force from the ends (torsion bar sockets) and the entire cross-member is supported along its entire length by virtue of being welded to the uni-body. It is a substantial component of the monocoque, has a force applied that is perpendicular to the bridge force analogy and is pretty darn strong when installed.

That was a major concern as we designed the piece and why it is a complete box (much harder to manufacture/fabricate) than just a thick steel plate. Sometimes I wish we could just use the plate method; we have a CNC press brake and could form up a 4"wide 1/4 (or 3/8") plate to follow the floor/tunnel contour in pretty short order. Just would not be strong enough though.

I can see from the responses that folks care about strength, and so do we. Please keep asking questions and challenging assumptions, that is how innovation starts.

Chris has been awfully busy in the shop but we do expect this product to ship in the coming week. We are always happy to help folks get this to fit a unique application and if slotted holes or multiple transmission mounts make that happen, we are happy to make the modifications for you.

Best Regards,