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What about benefits under braking?

In the air cooled 911 world the plate type LSD supposedly are really great on the track under threshold braking. Where the torsion style dont help under braking but, of course help with traction on corner out.

Do mid engine cars get an advantage from a plate type under braking or is that unique to the rear engine config?
 

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Do you know what was the problem? Was it ever fixed?
From what I heard, it was a problem with the initial design damaging the differential output shafts. They did try to revise the design, but it was too costly to put into production, so some sport 300 didn't even get the LSD, due to the issues, and some have broken theirs and had them replaced with a standard open diff, or a Quaife over time.
 

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Just a clarifying question, and a personal observation:

1. So who here has first-hand experience with the OEM torque-bias diff, and the Quaife torque-bias diff? First hand, as in, you....yourself....hands-on....you. Are we just speculating in the dark, or can somebody comment from actual experience?

2. Personally, my first hand experience has been that the plate style LSD works better in many sports cars than the TB style, particularly for aggressive street driving and track. That assumes a properly functioning plate pack....in other words, not worn out. When the plate pack is worn out then they operate essentially like an open diff as they're really not doing what they're supposed to be doing. Lots of people are driving around with worn out plate packs, and complaining the LSD doesn't feel right.

With regard to the OEM TB diff v. the Quaife TB diff, I don't have first hand experience with that in an Esprit so I can't really comment. However, what I can say (based upon first hand experience) is that the Quaife TB diff did not exhibit the right characteristics I was hoping for in one of my other sports cars, and I was left a little disappointed. I just recently installed a plate style LSD in my Esprit but have not yet driven it so can't comment on that either. I suspect it will not be helpful with the understeer.
 

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Discussion Starter #25

From what I heard, it was a problem with the initial design damaging the differential output shafts. They did try to revise the design, but it was too costly to put into production, so some sport 300 didn't even get the LSD, due to the issues, and some have broken theirs and had them replaced with a standard open diff, or a Quaife over time.
Thanks Travis.
It would help if they avoided stress raisers. Splines could/should be cut without the clearance groove.
 

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Having used the Quaife and the TRD that was offered by lotus in the Elige(not sure if that is the same as the Sport300), I can say that the Quaife works a bit better. It is a bit more aggressive to lockup and functions as if it have a bit more pre-load, those these diffs don't really have pre-load. Quaife also have a lifetime warranty. We sell them, but they have been hard to get recently.

MachineGunKelly, You're right about the diff being designed for each specific car and the Quaife was. The TRD might just be a recycled Celica diff, however, Helical diffs are very tolerant and I would argue that a helical diff for the wrong model would still be better than no diff in most cases.

EricL, depends on the clutch-type differential. You can set them up to behave differently on corner entry. Our BWR-Spec OSGiken fixes the corner entry problems that diff had in the Lotus and corner exit is the best there is, full stop. OSGiken uses many plates so lockup is strong, but smooth and progressive. You don't have to use Diff adder in the trans fluid because it is so smooth. The grip is so good coming out of corners it can be tough on transmissions, but when you want the very best.....

For 90% of owners the Helical is the way to go.
 

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Discussion Starter #29
LSD problems: Loss of drive during zero or near-zero axle-load conditions.

The problem: :facepalm Loss of drive during zero or near-zero axle-load conditions.

Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions. Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drive train, when one drive wheel is nearly or completely lifted (often in aggressive cornering). It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground.

Here’s how that loss of drive hurts you:

1) If you lift a wheel, all gear diffs, will NOT power the other wheel.

2) During the transition from accel to decel, all gear diffs, do nothing.

Why does this happen?

All gear LSDs (including Torsen®, Truetrac®, Quaife®, Peloquin, OBX, etc.) work in basically the same manner: they divide the drive torque between the two axles, applying drive to each side, up to the available grip of each tire. The amount of drive torque one wheel can get over the other is described as the bias ratio, a measure of the torque split across the axle.

Standard, open differentials have a bias ratio of 1:1. They can only apply as much drive torque as there is available traction at one wheel. When one wheel loses grip, the total available drive is lost as well (at a 1:1 ratio). All your power goes out the slipping wheel - along the path of least resistance.

Torque biasing differentials offer increased bias ratios over open differentials. For example, if a diff has a bias ratio of 2.5:1, then it can apply drive torque to the wheel with the most traction (gripping wheel) at 2.5 times the traction limit of the wheel with the least traction (slipping wheel). This is a significant improvement over an open differential, well... most of the time.

The problem is that when one tire has LITTLE or NO grip (zero axle-load), the other wheel gets ZERO DRIVE, because (basic math here): 2.5 x 0 = 0.

Lift a wheel (or substantially unload a wheel) and you get zero axle-load on that side - that means that during the time the wheel is unloaded, the typical diff will NOT power the wheel that’s still on the ground. No matter how high the bias ratio, you get no power to the ground.

During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over. While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction (delay) time in the drive line.
 

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This is one of the reasons many cars went to all wheel drive with computerized traction control. You cannot solve this problem with pure mechanics. Because it is a rare and unusual condition, most automakers tend to ignore it but in racing even a tiny problem can mean the difference between winning and losing. It is good that you point out that it doesn't matter if you have an LSD or an open diff. Only a locked diff will not have this problem but they have a whole host of other issues instead.
David Teitelbaum
 

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Less is Better
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The problem: :facepalm Loss of drive during zero or near-zero axle-load conditions.

Zero axle-load is a condition that occurs during normal driving, but creates the most noticeable problems when driving in extreme conditions. Zero or near-zero axle-load is the condition that exists when there is ‘no-load’ applied through the drive train, when one drive wheel is nearly or completely lifted (often in aggressive cornering). It also occurs during the transition from engine driving a vehicle to engine braking and back, even with both drive wheels firmly on the ground.

Here’s how that loss of drive hurts you:

1) If you lift a wheel, all gear diffs, will NOT power the other wheel.

2) During the transition from accel to decel, all gear diffs, do nothing.

Why does this happen?

All gear LSDs (including Torsen®, Truetrac®, Quaife®, Peloquin, OBX, etc.) work in basically the same manner: they divide the drive torque between the two axles, applying drive to each side, up to the available grip of each tire. The amount of drive torque one wheel can get over the other is described as the bias ratio, a measure of the torque split across the axle.

Standard, open differentials have a bias ratio of 1:1. They can only apply as much drive torque as there is available traction at one wheel. When one wheel loses grip, the total available drive is lost as well (at a 1:1 ratio). All your power goes out the slipping wheel - along the path of least resistance.

Torque biasing differentials offer increased bias ratios over open differentials. For example, if a diff has a bias ratio of 2.5:1, then it can apply drive torque to the wheel with the most traction (gripping wheel) at 2.5 times the traction limit of the wheel with the least traction (slipping wheel). This is a significant improvement over an open differential, well... most of the time.

The problem is that when one tire has LITTLE or NO grip (zero axle-load), the other wheel gets ZERO DRIVE, because (basic math here): 2.5 x 0 = 0.

Lift a wheel (or substantially unload a wheel) and you get zero axle-load on that side - that means that during the time the wheel is unloaded, the typical diff will NOT power the wheel that’s still on the ground. No matter how high the bias ratio, you get no power to the ground.

During the transition from accel to decel, where you have near zero torque on the axle, even if the wheels are on the ground, the typical diff is unable to begin applying drive torque until AFTER the zero torque condition is over. While this condition is generally short-lived, the fact that most diffs can do nothing during that time means that there will be a delay once the zero torque condition stops - creating a reaction (delay) time in the drive line.
Really interesting that this description is basically lifted from the web page of a product that does not suffer from the phenomenon but mention of the Wavetrac is completely missing.

Wavetrac® Differential - A torque biasing differential with a difference
 

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Discussion Starter #32 (Edited)
Really interesting that this description is basically lifted from the web page of a product that does not suffer from the phenomenon but mention of the Wavetrac is completely missing.

Wavetrac® Differential - A torque biasing differential with a difference
You are stating the fact. It is a very good description of the lost traction phenomenon. Isn't it?:grin2:

1. VT does not provide a unit bespoke to Lotus
2. I don't own one, nor have any past experience with their product.
3. I tried to avoid my posting being misconstrued as an endorsement.
4. Combining #2 and my notoriety on this and other websites, I'd prefer to do a DD first.
5. Their website is in Public Domain and the content is not Copyrighted.
 

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Their website content is not Copyrighted.
Yeah, no offense, but it does seem a bit deceptive to just put in the info without speaking of a reference, especially when it's verbatim. I believe copyright does apply to web site content, even if there is no actual symbol.
 

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Discussion Starter #34
Correction

Yeah, no offense, but it does seem a bit deceptive to just put in the info without speaking of a reference, especially when it's verbatim. I believe copyright does apply to web site content, even if there is no actual symbol.
My Friend, I would refrain from using words not knowing their exact and true meaning...

Here is a quote from Merriam-Webster Dictionary:
Definition of deceptive
: tending or having power to cause someone to accept as true or valid what is false or invalid : tending or having power to deceive

It has been verified, that my previous messages did not contain any false or invalid content.
Case closed.
 

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Yeah, no offense, but it does seem a bit deceptive to just put in the info without speaking of a reference, especially when it's verbatim. I believe copyright does apply to web site content, even if there is no actual symbol.
My Friend, I would refrain from using words not knowing their exact and true meaning...

Here is a quote from Merriam-Webster Dictionary:
Definition of deceptive
: tending or having power to cause someone to accept as true or valid what is false or invalid : tending or having power to deceive

It has been verified, that my previous messages did not contain any false or invalid content.
Case closed.
Ah, there, you see how quoting the source works. Excellent.

I was trying not to use the most direct word for it to be polite but it's called plagerism.

Deceptive is absolutely appropriate in reference to someone making a statement as if it were their own but it indeed is not. See how attempting to make people believe words written by someone else are yours is deceptive?
 

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Discussion Starter #36
Ah, there, you see how quoting the source works. Excellent.

I was trying not to use the most direct word for it to be polite but it's called plagerism.

Deceptive is absolutely appropriate in reference to someone making a statement as if it were their own but it indeed is not. See how attempting to make people believe words written by someone else are yours is deceptive?


Get a life!
 

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Ah, there, you see how quoting the source works. Excellent.

I was trying not to use the most direct word for it to be polite but it's called plagerism.

Deceptive is absolutely appropriate in reference to someone making a statement as if it were their own but it indeed is not. See how attempting to make people believe words written by someone else are yours is deceptive?


Get a life!
Well that devolved quickly :)
 

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