Rambler Marlin features cutaway

"RamblinRover Luxury-Yacht" (ramblininexile) 06/10/2015 at 09:28 • Filed to: None

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...because. Just because.

RamblinRover Luxury-Yacht > RamblinRover Luxury-Yacht 06/10/2015 at 09:28

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Meanwhile, on the Dodge side of the ludicrous fastbacks divide, I have no idea why the blonde with the flintlock. No. Idea. Something something “Dodge Rebellion”? Whatever, Dodge.

pip bip - choose Corrour > RamblinRover Luxury-Yacht 06/10/2015 at 09:32

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buy a charger or flintlock , they’re both antiques. (even when new)

Berang > RamblinRover Luxury-Yacht 06/10/2015 at 10:07

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A time-defying muffler is what I look for in a car.

RamblinRover Luxury-Yacht > Berang 06/10/2015 at 10:09

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Cheaper than a flux capacitor, and quieter.

StoneCold > Berang 06/10/2015 at 17:25

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Coated? Nah, my headers are ceramic armored

Jedidiah > RamblinRover Luxury-Yacht 06/11/2015 at 15:04

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Torque tube rather than a driveshaft? Interesting

StoneCold > Jedidiah 06/11/2015 at 15:10

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So are the axles Torque Sticks?

Jedidiah > StoneCold 06/11/2015 at 15:12

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They’re not being clever with their naming. Torque tubes are an actual thing. They are basically an enclosed driveshaft

I’m not really sure what advantage they have over a traditional driveshaft other than protecting u-joints from dirt

RamblinRover Luxury-Yacht > Jedidiah 06/11/2015 at 15:18

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They’re a way of controlling the pitch of the axle, fore and aft. You know how normally there are either two links on each side with a drag link straight axle rear, a leaf spring setup, or a fixed center diff? The diff has to have a way to keep from pitching forward and backward under driving torque, and this is how nearly every vehicle of the 20s did it.

In this case, it helps keep unsprung weight down somewhat, but not as much as a proper IRS would.

Jedidiah > RamblinRover Luxury-Yacht 06/11/2015 at 15:28

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That makes sense, otherwise you’d have to run control arms to the diff like a 3-link or 4-link setup if you wanted coils

I’m not entirely sure of the weight advantage. Some decently made controls arms can’t possibly be heavier than a huge tube?

Wouldn’t the tube also have to be large in order to accomodate for joints and shafts as strong as a traditional driveshaft making the weight dependant on the diamater of the tube?

RamblinRover Luxury-Yacht > Jedidiah 06/11/2015 at 15:40

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The weight advantage is less an ultimate weight advantage, and more seen in dynamic effects at the wheel - an individual wheel jounce is going to have less resistance offered by a tube at the center of the axle (only half of whose weight the axle supports) than by leaf spring mass, in theory. You could beat it with a second control arm per side, or doing what Range Rovers do with the control arm fixed radially to the axle, but here we have a clean-cut example of AMC Doing Their Own Thing. Probably cheaper this way and requiring less complexity of frame design. The geometry is even pretty good, the only stupid thing being that a torque tube changes the relative angle of the two U-joints, so it would be better to set up with a CV to avoid U-joint wear requiring you to take the whole thing apart, and with CV’s being newer tech and this being older tech, I don’t know if the twain have met.

Unimogs also use torque tubes, BTW. As to the strength, the bending strength of a tube goes up astronomically with tube diameter out of proportion to its weight (you can make the tube wall thinner and thinner), so while you might have to have a bigger tube for a stronger driveshaft, it doesn’t cause weight problems or anything else other than difficulty in packaging. For perspective, the strength of a tube in bending is proportional to the *fourth power* of its radius, and its weight is more or less proportional to just the radius at a given wall thickness...

Jedidiah > RamblinRover Luxury-Yacht 06/11/2015 at 15:55

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Excellent explanation.

RamblinRover Luxury-Yacht > Jedidiah 06/11/2015 at 16:03

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I did miss something in this case, though. With the Marlin, the transmission and rear axle are actually rigidly mounted to one another, while normally (or more commonly) a torque tube hinges at the transmission. This setup puts next to no wear on the driveshaft components, but as a tradeoff rides the transmission and engine around with the suspension, even if only by a few sixteenths of an inch per bounce. Which has elements of crazy, and is sure to beat the motor mounts like a rented mule. I’m not sure it even has a transmission mount, no matter how flexible.

You sometimes see a torque tube of this kind as part of a car’s “spine” and running to an independent suspension diff. Riding around with the whole rear axle? Almost never in a modern car, even by the 60s.