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Technical Question - LSD Operation

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Gladiator
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Technical Question - LSD Operation

Postby Gladiator » December 31st, 2021, 9:41 pm

Does a clutch based LSD wear the clutch discs during normal use or only when one wheel gets stuck/spins?

kamakazi
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Re: Technical Question - LSD Operation

Postby kamakazi » December 31st, 2021, 9:43 pm

It will wear during normal use... Unless the road is straight everywhere you go . Essentially the tighter the turn and the faster you take it will cause the clutches to wear. High grip tyres might cause it to wear even faster

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Re: Technical Question - LSD Operation

Postby Gladiator » December 31st, 2021, 9:49 pm

kamakazi wrote:It will wear during normal use... Unless the road is straight everywhere you go


Thanks for the reply... does the LSD ever behave as an open diff say when taking corners etc?

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Re: Technical Question - LSD Operation

Postby kamakazi » December 31st, 2021, 9:56 pm

Clutch type LSD can potentially act like an open diff if the clutches are worn out or if they are packed with very little friction, assuming everything else is mechanically sound

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Re: Technical Question - LSD Operation

Postby Gladiator » January 1st, 2022, 3:08 pm

kamakazi wrote:Clutch type LSD can potentially act like an open diff if the clutches are worn out or if they are packed with very little friction, assuming everything else is mechanically sound


Thanks again...was doing some reading and there seems to be different variants - Type A, type B, Type AB, Positronic/Torque Vector

What would be the standard used in todays 4x4s?

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*KRONIK*
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Re: Technical Question - LSD Operation

Postby *KRONIK* » January 1st, 2022, 4:16 pm

Gladiator wrote:
kamakazi wrote:Clutch type LSD can potentially act like an open diff if the clutches are worn out or if they are packed with very little friction, assuming everything else is mechanically sound


Thanks again...was doing some reading and there seems to be different variants - Type A, type B, Type AB, Positronic/Torque Vector

What would be the standard used in todays 4x4s?



There are a few types used in commercial vehicles:

Clutch type: which uses a series of clutches to engage the axles

Viscous: which uses fluid to engage the axles

Helical: which uses mechanical gearing to engage the axles

Most new 4x4 carry either a clutch type LSD or in more recent times open diff with selectable locker

Maybe you can shed some light on what you where your questions are leading to so a better answer can be given

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Re: Technical Question - LSD Operation

Postby *KRONIK* » January 1st, 2022, 4:20 pm

See also:

https://en.m.wikipedia.org/wiki/Limited-slip_differential

Broadly speaking, there are three input torque states: load, no load, and over run. During load conditions, as previously stated, the coupling is proportional to the input torque. With no load, the coupling is reduced to the static coupling. The behavior on over run (particularly sudden throttle release) determines whether the LSD is 1 way, 1.5 way, or 2 way.
A 2-way differential will have the same limiting torque Trq d in both the forward and reverse directions. This means the differential will provide some level of limiting action under engine braking.
A 1-way differential will provide its limiting action in only one direction. When torque is applied in the opposite direction it behaves like an open differential. In the case of a FWD car it is argued to be safer than a 2-way differential.[6] The argument is if there is no additional coupling on over run, i.e. a 1-way LSD as soon as the driver lifts the throttle, the LSD unlocks and behaves somewhat like a conventional open differential. This is also the best for FWD cars, as it allows the car to turn in on throttle release, instead of ploughing forward.[6]
A 1.5-way differential refers to one where the forward and reverse limiting torques, Trq d_fwd, d_rev , are different but neither is zero as in the case of the 1-way LSD. This type of differential is common in racing cars where a strong limiting torque can aid stability under engine braking.

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Re: Technical Question - LSD Operation

Postby kamakazi » January 1st, 2022, 4:23 pm

That is a very broad question and I can't speak for all of them. For the Japanese vans that came with LSD, I think most use clutch type.

The Hilux has a loose setup and behaves like an open diff for the most part.
The older Nissan d22s had a much tighter setup.

I don't think the newer diff lock vans come with an LSD. They most likely use the stability and traction control to brake the wheel that is spinning in an attempt to send power to the other wheel on the axle when the diff lock is off; in essence mimicking what an LSD does.

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Re: Technical Question - LSD Operation

Postby Gladiator » January 2nd, 2022, 10:17 am

Thanks for the information... I am looking at getting a 4x4 and one of the specs is a clutch type LSD. Trying to determine what kind of wear the clutches will see on normal highway and road use since it will be driven like that 99% of the time. This is to gauge the maintenance required.

Some articles say the clutches only wear on off road conditions when one tire is spinning and needs to lock up, however during cornering the LSD behaves as an open diff. While I know you can get slippages on the highway or when accelerating, is it enough to wear the clutches in the LSD significantly?

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Re: Technical Question - LSD Operation

Postby *KRONIK* » January 2nd, 2022, 12:15 pm

Gladiator wrote:Thanks for the information... I am looking at getting a 4x4 and one of the specs is a clutch type LSD. Trying to determine what kind of wear the clutches will see on normal highway and road use since it will be driven like that 99% of the time. This is to gauge the maintenance required.

Some articles say the clutches only wear on off road conditions when one tire is spinning and needs to lock up, however during cornering the LSD behaves as an open diff. While I know you can get slippages on the highway or when accelerating, is it enough to wear the clutches in the LSD significantly?
Lemme put it into perspective

My hilux is 10years old
Maintained according to toyota schedule
LSD is clutch type and performs perfectly
I can predict when to throttle or let off and how to get it to lock or react quicker or less as the case may be.

A big reason for clutch pack failure and chatter is the use of the wrong type of fluids;
Clutch type LSD in pick-ups/4x4 tend to require a specific fluid with a friction modifier and different brands fluids react differently with dfferent vehicle diffs.

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Re: Technical Question - LSD Operation

Postby kamakazi » January 2nd, 2022, 7:10 pm

It shouldn't wear significantly with regular driving. Spinning up one wheel while stuck will cause it to wear faster.

Regarding servicing... Most call for a fluid change approx. every 40000kms. I don't see many people replacing clutches in worn out pickup LSDs... But I really am not looking that hard if I'm honest.

I have to say my Hilux LSD has felt like an open diff for the most part; no one on any forum has anything good to say about any Toyota LSD. It might have worked in the early days, but my antics have probably worn them out by now. It doesn't prevent the vehicle from being driven, and I probably have to get better tyres.

Would rather a helical or torsen LSD (cause they use gears instead of friction plates), but I don't think they are offered in the pickups sold locally.

Gladiator wrote:Thanks for the information... I am looking at getting a 4x4 and one of the specs is a clutch type LSD. Trying to determine what kind of wear the clutches will see on normal highway and road use since it will be driven like that 99% of the time. This is to gauge the maintenance required.

Some articles say the clutches only wear on off road conditions when one tire is spinning and needs to lock up, however during cornering the LSD behaves as an open diff. While I know you can get slippages on the highway or when accelerating, is it enough to wear the clutches in the LSD significantly?

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Re: Technical Question - LSD Operation

Postby Gladiator » January 5th, 2022, 9:51 pm

Thanks again bro...the information shared was most helpful

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Re: Technical Question - LSD Operation

Postby *KRONIK* » January 5th, 2022, 10:08 pm

So what was the decision?

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