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Torsen Diffs

Old 02-26-04, 07:46 PM
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Torsen Diffs

For anyone of you guys who have torsen diffs in the back, how do you like it compare to the clutch type diff? Reason I am asking is because Torsen = torque sensing, it will load and unload depending on how much tq it sees. So say if you are in mid corner and apply throttle or let off, will it cause the diff to load/unload making the car unpredictable?

Or say if you hit an oil patch on one wheel while mid corner, in a clutch type LSD, the car would still fine, would it have a huge impact on the Torsen since at that split moment, it see's no TQ.

Last question, does anyone have the rachet type LSD in their cars? I heard it's the best LSD option rite now.

Thanks.
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Old 02-27-04, 09:34 AM
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I don't think a torsen will upset the car that way. The diff doesn't really "unload", it just moves the torque between the wheels based on what they can handle.
IMO, torsen > clutch type
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Old 02-27-04, 10:21 AM
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Torsen VS Plate VS Ratchet (sic)

I ahve raced on all 3 types. The Torsen does load and unload when going through a corner with grip/ bump variations between both tires. It feels a little snatchy (hehe he said snatchy) or jerky. The Torsen requires a very smooth throttle technique to minimize twitches. In the rain it is fantastic as both tires have very similar grip levels. Second concern with Torsens is temperature in the diff. In some applications the Torsen temperatures can sky rocket if the unit is working a lot. Some of the real Torsens, not the Mazda ones, use different gear slope angles to minimize temp rise and twitchiness in differentiated grip levels. Check on some of the race sites as to modifications that need to be made to the Mazda Torsen to get them to live in a racing environment.

The plate type causes some temp rise, however to use it to its best effect it needs to be shimmed rather tight and can cause some low speed understeer and power on oversteer. Performance deteriorates from first moment of use as the plates wear. In driving it is the most benign of the three and very consistent.

A locker or ratchet works really well with the right driving technique. In braking or de-celeration it opens up and minimizes understeer. It really helps turn in and braking. On the flip side it plants both tires under acceleration when it locks up. The only thing a locker doesn't handle is on-off-back on throttle techniques. It will jerk the back end around a ton. As a driver you need to be commited on acceleration application.

Another version that fits between a locker and a clutch type is a "KAAZ" style of locking plate diff. It uses different slope ramps to increase the wedging effect against the clutch plates under acceleration. A really neat idea, however I have not raced one to give you a drivers opinion.

I know that you didn't ask, but the best diff I have experienced was the Cobra R Hydrogyroscopic diff. It is a diff that used the speed differential between the 2 driven wheels to drive a pump that increased the lock up of the diff. It was fantastic in the wet and dry and incredibly proportional in effect. I loved it, but it did require some massive cooling to live in a racing environment. Just some of my experiences in racing a variety of different cars both front and rear wheel drive.
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Old 02-27-04, 10:27 AM
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ISC does the modifications to Mazda Torsens for cooling and lockup adjustment. I'll be sending mine off shortly though I've never used this service before.

www.iscracing.net
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