Limited
Slip / Peg Leg Discussion Shown in order that they happened
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Message Title: Peg Leg vs. Limited Slip |
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Posted by:
Malachi on 2002-12-14 at |
Message:
Based on what I think I know
there is no difference between the two on a straight, dry, equally smooth
surface...like a drag strip.
The Limited Slip only helps when traction can vary from wheel to wheel (snow,
ice, rain, gravel, etc.) and going around curves where one wheel can spin due
to weight transfer.
Thoughts?
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Message Title: Re: Peg Leg vs. Limited Slip |
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Posted by:
rsmillar on 2002-12-14 at |
Message:
no, that's not really
accurate. An open differential will always supply the same amount of torque to
BOTH wheels - so if one wheel spins, for example due to excessive power during
a 1/4mile drag launch, it is transmitting no torque to the ground. In this
case, the OTHER wheel will also deliver no torque - think of it as being
disconnected from the driveline in this case, and the
car will go nowhere.
A limited slip differential is capable of supplying differing amounts of torque
to both wheels - in the case above both wheels will be driven regardless of
whether one is spinning. This dramatically increases the amount of torque which
can be transmitted to the ground.
So the LSD offers a very definite advantage on a drag strip.
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Message Title: Let me make sure I understand, point by point |
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Posted by:
Malachi on 2002-12-14 at |
Message:
1) If I am on a dry smoooth straight away, and the right rear is not spinning,
both wheels are getting equal power
Q) If the right rear begins to slip does the left rear get (a)the
equal amount of power that right rear is getting (considering the slip) (b)no
power at all or (c)continues to get 50% of the full power?
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Message Title: Re: Let me make sure I understand, point by point |
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Posted by:
rsmillar on 2002-12-14 at |
Message:
1. That
is correct. But don't think in terms of power - rather torque applied to the
ground.
2. As you apply more and more power to the input of the differential, it will
apply that power equally to both rear wheels. But as soon as one wheel begins
to slip, it is transmitting less and less torque to the ground. Due to the rule
that the diff will ALWAYS apply the SAME amount of torque to both wheels, the
other wheel will similarly transmit less and less torque, even if it is not
spinning! This can be observed by watching a car with open diff which is doing
a 'burn-out' - one tire will be spinning madly, while the other will be doing
nothing - it is essentially 'coasting'. Note that on dry pavement friction
makes it impossible to transmit ZERO torque.
Another way to think of it is: the wheel with the least traction limits the
amount of torque the other wheel will transmit. This is NOT true in an LSD.
Does that make any sense?
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Message Title: I think I have it, but you said one thing that is |
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Posted by:
Malachi on 2002-12-14 at |
Message:
news to me you wrote:
"Another way to think of it is: the wheel with the least traction limits
the amount of torque the other wheel will transmit."
I thought that even if the left rear was spinning the right rear would still
have 50% of the power, becasue it is the
"drive" wheel. So if the left rear had no traction, the right rear
would sill be applying 50% of the car's torque to the ground.
I thought what you wrote applied to if the right rear wheel was spinning.
Was I thinking wrong or did I misread your statement.
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Message Title: Re: I think I have it, but you said one thing that |
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Posted by:
rsmillar on 2002-12-14 at |
Message:
No - the differential doesn't
know anything about 50% of this or that. All it knows is total input power, and
max torque that can be applied to both wheels, as limited by the wheel with the
least traction.
So if you think of the input power as 100% torque, and the wheel with the least
traction as 27.5% torque (for example), the other wheel will only have 27.5%
torque, meaning only 55% of available torque is being transmitted to the ground
- the rest is wasted within the diff.
Only in cases where BOTH wheels have total grip is all power transmitted to the
ground as torque.
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Message Title: Here you go man some more info..(m) |
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Posted by:
humanoid on 2002-12-14 at |
Message:
Basically the same thing Randy
is telling you.
Copied from http://www.quaifeamerica.com
The Quaife Differential powers both drive wheels under nearly all conditions,
instead of just one. With an ordinary open differential, standard on most cars,
a lot of precious power is wasted during wheelspin
under acceleration. This happens because the open differential shifts power to
the wheel with less grip (along the path of least
resistance). The Quaife, however, does just the opposite. It senses which wheel
has the better grip, and biases the power to that wheel. It does this smoothly
and constantly, and without ever completely removing power from the other
wheel.
In drag-race style, straight-line acceleration runs, this results in a close to
ideal 50/50 power split to both drive wheels, resulting in essentially twice
the grip of an ordinary differential (they don't call open diffs
"peglegs" for nothing).
In cornering, while accelerating out of a turn, the Quaife biases power to the
outside wheel, reducing inside-wheel spin. This allows the driver to begin
accelerating earlier, exiting the corner at a higher speed.
The Quaife also controls loss of traction when the front wheels are on slippery
surfaces such as ice and snow or mud, providing the appropriate biased traction
needed to overcome these adverse conditions. The Quaife Differential provides
constant and infinitely variable drive. Power is transferred automatically
without the use of normal friction pads or plates seen in other limited-slip
designs.
The Quaife's unique design offers maximum traction,
improves handling and steering, and puts the power where it is needed most. A definite advantage whether on the track or on the street.
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Message Title: Malachi - check this out! |
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Posted by:
rsmillar on 2002-12-14 at |
Message:
I did a google
search on "how differential works" and this was the first one that
came up - take a look.
link