Learn me: Torque tube set up front engine rear transmission

I know of several cars that use different methods to get power from a front engine to a rear transaxle. The Porsche 924/44 using a rigid tube, The Alfa GTV using a regular ujointed axle, and the Miata with it's PPF.

Each has it's advantages and disadvantages.

The Porsche Setup is nearly bulletproof and maintenance free. Aside from pulling it to remove some serious part of the drivetrain (engine, Transaxle, or the tube itself) there is little to do with it.

The Mazda setup is more or less the same as any front engine/ rear drive car. The U-joints require the usual maintenance, but are easy to get at.

the Alfa set up.. is just wrong. It requires the usual maintenance, but to replace a joint, you basically need to replace the whole shaft (or get it balanced) as there is no way to simply replace a joint without destroying it's balance.

Remember, all these systems are older than the one in the current Vette, so that is apples to oranges to compare. I think that Porsche looked at Alfa's system, saw that it gave the car great balance, but it raised some eyebrows about how fragile the whole system is, thus the torque tube was born

A Torque Tube is sometimes not a Torque Arm

In reply to FlightService: True. I wasn't implying cost.

Porsche uses a torque tube because the clutch is mounted on the engine while the trans is at the rear. To reduce the loads of the driveshaft on the transmission synchronizers a drive shaft of minimum inertial was used, but that means a flexible driveshaft, so the torque tube has 2 bearings in it to support the driveshaft.

Alfa (and Corvette) transaxles have the clutch at the transmission, so the drive shaft imposes no additional loads on the synchronizers and is made from the familiar large diameter tubing. The Alfa drive shaft uses 2 rubber flex joints and one cross type u-joint. There no service issues with such an arrangement, and replacing either joint does not affect balance- it didn't the many times I have done it in anycase.

Miata u-joints are sealed and not servicable nor are they replaceable with normal shop equipment. But they do last a long time.