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Gforce · 06-09-2017, 10:59 PM

This is pretty interesting. Japanese corporate brochure but with English.

http://eb-cat.ds-navi.co.jp/enu/jtek...catd1001je.pdf

Apparently the friction involved in torque biasing of helical differentials is axial against the bore.

And this seems pretty straightforward:

https://members.rennlist.com/951_rac...84gleason.html

The worm wheel (side gear) can drive the worm gear (spider gear) but not the other way around. The carrier transfers pinion/crown gear torque equally to the worm gears and then to each of the left and right side gears. Any difference in torque reaction results in the worm gears locking together and requiring the side gears to turn at the same rpm dividing the torque proportionally to the resistance of the tire and driving the side gears at exactly the same rpm instantaneously. However, rotational forces coming the other way, from tire to differential, cause the worm wheel (side gear) to drive the worm wheel which provides constant differentiation capability regardless of torque applied at the pinion and regardless of the direction of that torque at the pinion.

Helical versions work on the same principle but the worm gears are in parallel to the worm wheels instead of at right angles, saving one set of spur gears per set of worm gears. Torque biasing capacity is higher in the T1 right angle setup.

So, Torsen diffs "lock up" immediately under torque applied between the pinion and the tire, either direction, but simultaneously remain unlocked as between each wheel. This simultaneous locked but unlocked condition is the advantage and disadvantage of the Torsen at the same time. The locking is instantaneous, under torque delivered by or to the pinion gear no differentiation is possible, however as between the two drive wheels differentiation is always possible regardless of the amount of torque applied at the pinion and regardless of whether the torque is directed from or to the pinion gear.

Under braking the Torsen is completely open. Under power or lift off the Torsen is completely locked except that as between the drive wheels it is completely open. You cannot help noting that wheel speed differences cannot cause any wear in the differential. The diff differentiates freely without any changes caused by any applied torque. No wear results from the amount of torque and normal minimal wear results from any differentiation, just as for an open diff. The torque load has no effect whatsoever on the differentiation. Brilliant and elegant engineering.

Under very hard acceleration on dry road you can feel the differentiating as the grip is alternately transferred left to right and back again. On slippery surfaces where both wheels have limited grip, wet or snow or ice, this left to right and back again squirming is very noticeable. On a drag strip this could become dangerous. On a race track not so much.

On a dry road and in a straight line you get perfect 11's every time, confirming the instant lock up capability of the Torsen.

06-09-2017, 10:59 PM	#176
Gforce Banned Join Date: Mar 2017 Drives: 2013 Subaru BRZ Location: Alberta Posts: 519 Thanks: 39 Thanked 162 Times in 109 Posts Mentioned: 5 Post(s) Tagged: 0 Thread(s)	This is pretty interesting. Japanese corporate brochure but with English. http://eb-cat.ds-navi.co.jp/enu/jtek...catd1001je.pdf Apparently the friction involved in torque biasing of helical differentials is axial against the bore. And this seems pretty straightforward: https://members.rennlist.com/951_rac...84gleason.html The worm wheel (side gear) can drive the worm gear (spider gear) but not the other way around. The carrier transfers pinion/crown gear torque equally to the worm gears and then to each of the left and right side gears. Any difference in torque reaction results in the worm gears locking together and requiring the side gears to turn at the same rpm dividing the torque proportionally to the resistance of the tire and driving the side gears at exactly the same rpm instantaneously. However, rotational forces coming the other way, from tire to differential, cause the worm wheel (side gear) to drive the worm wheel which provides constant differentiation capability regardless of torque applied at the pinion and regardless of the direction of that torque at the pinion. Helical versions work on the same principle but the worm gears are in parallel to the worm wheels instead of at right angles, saving one set of spur gears per set of worm gears. Torque biasing capacity is higher in the T1 right angle setup. So, Torsen diffs "lock up" immediately under torque applied between the pinion and the tire, either direction, but simultaneously remain unlocked as between each wheel. This simultaneous locked but unlocked condition is the advantage and disadvantage of the Torsen at the same time. The locking is instantaneous, under torque delivered by or to the pinion gear no differentiation is possible, however as between the two drive wheels differentiation is always possible regardless of the amount of torque applied at the pinion and regardless of whether the torque is directed from or to the pinion gear. Under braking the Torsen is completely open. Under power or lift off the Torsen is completely locked except that as between the drive wheels it is completely open. You cannot help noting that wheel speed differences cannot cause any wear in the differential. The diff differentiates freely without any changes caused by any applied torque. No wear results from the amount of torque and normal minimal wear results from any differentiation, just as for an open diff. The torque load has no effect whatsoever on the differentiation. Brilliant and elegant engineering. Under very hard acceleration on dry road you can feel the differentiating as the grip is alternately transferred left to right and back again. On slippery surfaces where both wheels have limited grip, wet or snow or ice, this left to right and back again squirming is very noticeable. On a drag strip this could become dangerous. On a race track not so much. On a dry road and in a straight line you get perfect 11's every time, confirming the instant lock up capability of the Torsen. Last edited by Gforce; 06-09-2017 at 11:53 PM.