Ed Higginbotham Associate Editor
Dec. 26, 2016 10:53 a.m.

https://www.youtube.com/embed/JEiSTzK-A2A

The wizardry that makes your driving wheels rotate together may not be as complicated as you think. Here's a good explanation.

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NickD Dork
Dec. 26, 2016 10:55 a.m.

Watched this same exact video when I bought the Torsen swap for my C/SP '90 Miata. Pretty cool tech, although they take a little getting used

Vracer111 Reader
Dec. 26, 2016 11:56 a.m.

I've been looking at videos for stuff on a truck I'm looking to get soon and came across this differential video I think is pretty good:

Differential locker comparison

Love the torsen in my FR-S, probably will go with a Torsen in the truck as well. The mechanical selectable OX Locker is something I would like for offroad capability, but its either an open or a locked spool...and I'm not looking to do crazy offroad stuff in a 2WD truck, just some prerunner capable handling when in Arizona/Utah unpaved roads/deserts.

CLH Reader
Dec. 26, 2016 11:57 a.m.

Good explanation. It took me three watchings to wrap my head around how it works with a wheel-speed differential (as when cornering), but I finally got it. I kept wondering how it doesn't just lock in that situation, but I eventually got the point about equal but opposite speed change (+20% and -20% in the example). Ingenious. I do wish it would have talked about what happens when one wheel lifts. I'm still not clear on why a Torsen would go "open" in that situation.

Ransom PowerDork
Dec. 26, 2016 7:50 p.m.

In reply to CLH:

That's a good question. I wonder if for some low level of load, the spur gear can drive the worm gear. I imagine it comes down to the angles involved.

But even if I grasp it a bit better now, I wouldn't say I have a solid, intuitive sense of the action. I wouldn't be at all surprised to find out that guess is in left field.

Ransom PowerDork
Dec. 26, 2016 7:51 p.m.
NickD wrote: Pretty cool tech, although they take a little getting used

How so? I'm sure the Internet can tell me some stuff about how they drive differently to a clutch type LSD, but as long as you're mentioning it...

Knurled MegaDork
Dec. 26, 2016 8:28 p.m.

"You can't backdrive a worm gear."

There ya be.

Torsens are nothing more than using worm gears for the side gears in an open diff. An axle can easily overdrive the diff if there is differential speed, so it still has all the benefits of an open bevel diff.

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