How does the transaxle/transmission function?

There is a torque tube plus drive shaft that connects the engine and clutch to the transaxle (gear + diff) in the rear. Better weight distribution but more rotating mass.

 

As I recall, that is also how the Vette is set up.

 

Been that way on Ferraris since 1958 or so I believe.

 

Not weird and has been in use for decades. Allows use of only two motor mounts and transaxle mounts. Improves weight distribution and saves weight over separate transmission and rear end. Closed torque tube with center bearing less susceptible to wear and corrosion than an open drive shaft.

Tranaxle does warm more slowly than a transmission attached to the engine, but location means no engine heat into transmission when everything is hot. Longer path for shift rods or cables is one disadvantage.

 

A picture is worth...

Cheers,

Geo

 

The 275gtb had this arrangement and if I recall accurately, a 48/52 weight distribution. Rear mounted gb increases the polar moment but generally preferred as the handling can be made more predictable. Cool huh?

And neat photo of the Vette.

 

If torque tube is not in that automotive text, time to get a new one. A torque tube is an enclosed drive shaft with solid coupling between the engine and transaxle. Can only be done with IRS or you would need a universal joint on the driveshaft, like most earlier American front engine and transmission cars with live rear axles. Early Ferrari 275 GTB/GTS models had an open driveshaft with central bearing that worked on the same principle and evolved into a full torque tube. The torque tube resists bending and imparting loads to the engine and transaxle. That is why you only need two motor mounts because the entire drivetrain is a relatively solid unit.

 

There is no u-joint in a torque tube, usually just a center bearing to keep the drive shaft from flexing. Live rear axles move up and down with the wheels, so the drive shaft needs a u-joint (constant velocity joint) to allow for that motion. Otherwise it would provide a huge bending load into the engine and transmission unit.

Gear shift linkages work exactly the same way as front transmissions except the linkage goes backwards instead of forward and the rods/cablesare generally a bit longer.

Go to ferraridatabase.com and you can download workshop manuals for transaxle equipped Ferraris for free. They have good descriptions and images of transaxles and gearshift linkages.

 

Not arguing with your statement in general; however, the term "torque tube" is commonly used in a much more generic sense to mean (no surprise) simply a tube which transmits torque. Ailerons, in simple aircraft for example, can be driven by a pair of pull cables, a push/pull tube, or a torque tube, depending on the designers wishes.

The shaft between your steering wheel and the steering rack is a "torque tube" unless it's a solid shaft. Perhaps the term is so generic that the referenced automotive text didn't include it since "torque tube" is not restricted to the way a Corvette, for example, is built.

So, while a typical front engined car with a rear mounted trans-axle may use a "torque tube" to connect the two major drive train components, that configuration doesn't narrowly define the term.

And while I'm picking nits I can say that the (admittedly unusual) di Dion suspension is not IRS, but it has been used in a front engine rear transmission configuration, most notably by Alfa.

The rear trans-axle was also used by Pontiac in their lowly Tempest but without a "torque tube" because the engine and transmission were connected by a solid shaft which actually bowed down three inches in the middle. The idea was to gain some passenger head room. If you think speedometer drive cable, you'll get the idea. They called it "rope drive" and it did NOT catch on as a great idea.

 

By the same logic, would the "springs" on an e-type qualify as a torque tube?

 

In side the tube is a drive shaft supported by usually three bearings. The shifter control could be either rod or cables. These would run over top of the tube, and then to the transmission shift linkage where ever the manufacturer decided to put it. Have a close look at the picture of the vette set-up posted. You can see the shifter assembly about half way down the tube, with the control rod attached.

 

I'm not sure I understand your question, especially since you put the word springs in quotation marks. Do you mean the coil springs associated with the E-type suspension? If so, then I would say no.

I'm no Jag expert, that's for sure, but as far as I know the E type uses conventional springs and dampers in what is known as a coil-over configuration. And, as far as I know, these coil springs are quite normal; i.e. they are not hollow. If they aren't hollow, they're not tubes; therefore, they would not be torque tubes, assuming you mean to use the words "torque tube" in the generic sense of a tube which transmits torque.

But perhaps I misunderstand what you're asking. Or, perhaps there are surprising things about the Jaguar E-type springs of which I'm not aware.

 

SN- Look at the photo of the Vette chassis you posted and you will see the manual gearshift lever in the middle. You will then see a large tube extending back from the gear shift lever. The shifter cables are inside that tube. Those cables move back and forth with the shift lever motions and move the actuators on the transmission portion of the transaxle. If you want more info, download one of those workshop manuals I told you how to find.

 

Sorry, i was not trying to pose an esoteric question on an obscure British suspension design. The e-type used torsion bars to suspend the car and provide "spring", where the bar (perhaps 12 or 14 inches in length) was twisted along its length. The torsion bars ran longitudinally, one at each wheel, one end being attached to the chassis / frame, the other to the control arm. Quite clever in design as they reduced unsprung weight. Uprated springing was provided by thicker bars. The downfall (i think) was the inability to tune corner heights (weights). Anyway, I don't know if they were hollow but suspect they were not and perhaps that answers my own question.

Philip

 

Philip- Torsion bars were used on early Porsches, too. My 356A had them and they were hollow. But they did not transfer torque like a torque tube, which contains a drive shaft, they just acted as a spring by resisting bending like a coil spring resists compression. Chrysler was also big on torsion bars in the olden days.

Ferrari tried open drive shafts on transaxles, with a center bearing, on the 275 GTS and early 275 GTBs, but the torque tube surrounding the drive shaft on the later 275s and all subsequent street front engine, rear transaxle layouts, provided extra stiffness to the entire drivetrain, better stabilized the drive-shaft and center bearing, and was the eventual preferred solution.

 

Terry, so in sum, one provides stiffness, the other springing. The Miata uses (or at least used) a ladder framework to tie the engine to the rear end to manage stiffness too so there are obviously multiple solutions to achieve the same end.
Philip

 

The Alfetta, if memory does not fail me, was one.

 

The Miata has the transmission bolted directly to the engine for cost reasons. The ladder framework, as you point out, is to provide stiffness, but it's not as good as an engine/torque tube/transaxle setup which also provides much better weight distribution. i.e. they're making up for not having the budget to really setup the drivetrain with 100% the best setup from a performance perspective.

To go back a few posts... the C5/C6 Corvettes use a shift rod instead of shift cables. A rod provides a more direct shift feel and can handle more abuse - two criteria that the GM guys required from the get got of the project when moving away from the front-mounted setup in the C4. It's a pretty slick setup, especially on the C6.

 

Bret- Thanks, I did not remember whether the Vettes used cables or a rod.