12.691 1/4 Mile Run
12-17-14, 07:41 AM
#46
im sorry man...the TVD is an accessory for tracking the car. it will help straight line speed coming out of a corner but it is little to no benefit over a limited slip diff on the type of surfaces where acceleration tests are run.
its not conjecture...its the very definition of what the unit does.
its not conjecture...its the very definition of what the unit does.
I think you just described a torsen/limited slip differential. Only difference that the torsen doesn't use a computer to monitor it. So no...i don't think its worth 2-3 tenths over a regular LSD. Why would it? Especially since it's adding weight.
It's main purpose is for stability in turns and to enhance the cornering capability of the car. I know your intent is to speak to benefits of the added technology. However, you would make a more compelling case if you understood what that technology is actually for...
It's main purpose is for stability in turns and to enhance the cornering capability of the car. I know your intent is to speak to benefits of the added technology. However, you would make a more compelling case if you understood what that technology is actually for...
More on both aspects of TVD:
"During straight forward acceleration, torque biasing differential can produce close to ideal 50/50 power split to both drive wheels, resulting in improved traction over a conventional open differential. In cornering, while accelerating out of a turn, a torque biasing differential can bias engine power to the outside wheel, minimizing or eliminating spinning of the inside wheel, thereby allowing earlier acceleration in the curve and exiting the corner at a higher speed."
I understand the cornering application. Appreciate the link.
The statement you provided was part of the introduction which provides the reader some informational differences between an open differential and a torque biased differential:
"An ordinary open differential, standard on most vehicles, can lose traction by spinning one wheel during acceleration or cornering because the open differential shifts power to the wheel with less grip. A torque biasing differential system, however, is designed to sense which wheel has the better grip, and biases the power to that wheel, while maintaining some lesser power to the other wheel. During straight forward acceleration, torque biasing differential can produce close to ideal 50/50 power split to both drive wheels, resulting in improved traction over a conventional open differential. In cornering, while accelerating out of a turn, a torque biasing differential can bias engine power to the outside wheel, minimizing or eliminating spinning of the inside wheel, thereby allowing earlier acceleration in the curve and exiting the corner at a higher speed."
The statement regarding the 50/50 split has nothing to do with the specific features of the TVD; it applies specifically to torque-biased differentials (such as Quaife, Torsen, etc).
Last edited by redspencer; 12-17-14 at 09:53 AM.
12-17-14, 08:59 AM
#49
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12-17-14, 01:02 PM
#50
You are correct with your assessment. A limited slip differential will help straight-line performance vs an open differential but it is unlikely that a higher-end TVD would offer better 0-60 performance than a Torsen/torque biased differential since both offer near 50:50 split between the drive wheels for straight-line acceleration (unless traction conditions are abysmal which is where a clutch-type LSD would be better). The more noticeable difference with how the torque is being distributed between a Torsen and TVD would be in the corners.
I did some research on the quote you had posted in regards to the TVD. The source came from a generic patent for a hydraulic torque vectoring differential: http://www.google.com/patents/EP1514039A2?cl=en
The statement you provided was part of the introduction which provides the reader some informational differences between an open differential and a torque biased differential:
"An ordinary open differential, standard on most vehicles, can lose traction by spinning one wheel during acceleration or cornering because the open differential shifts power to the wheel with less grip. A torque biasing differential system, however, is designed to sense which wheel has the better grip, and biases the power to that wheel, while maintaining some lesser power to the other wheel. During straight forward acceleration, torque biasing differential can produce close to ideal 50/50 power split to both drive wheels, resulting in improved traction over a conventional open differential. In cornering, while accelerating out of a turn, a torque biasing differential can bias engine power to the outside wheel, minimizing or eliminating spinning of the inside wheel, thereby allowing earlier acceleration in the curve and exiting the corner at a higher speed."
The statement regarding the 50/50 split has nothing to do with the specific features of the TVD; it applies specifically to torque-biased differentials (such as Quaife, Torsen, etc).
I did some research on the quote you had posted in regards to the TVD. The source came from a generic patent for a hydraulic torque vectoring differential: http://www.google.com/patents/EP1514039A2?cl=en
The statement you provided was part of the introduction which provides the reader some informational differences between an open differential and a torque biased differential:
"An ordinary open differential, standard on most vehicles, can lose traction by spinning one wheel during acceleration or cornering because the open differential shifts power to the wheel with less grip. A torque biasing differential system, however, is designed to sense which wheel has the better grip, and biases the power to that wheel, while maintaining some lesser power to the other wheel. During straight forward acceleration, torque biasing differential can produce close to ideal 50/50 power split to both drive wheels, resulting in improved traction over a conventional open differential. In cornering, while accelerating out of a turn, a torque biasing differential can bias engine power to the outside wheel, minimizing or eliminating spinning of the inside wheel, thereby allowing earlier acceleration in the curve and exiting the corner at a higher speed."
The statement regarding the 50/50 split has nothing to do with the specific features of the TVD; it applies specifically to torque-biased differentials (such as Quaife, Torsen, etc).
Are you saying the TVD is not capable of making a 50/50 split to balance power output?
Are you contending that straight-line acceleration is not enhanced by torque vectoring through improved grip and balanced distribution of torque/hp under abrupt starts?
Are you contending this has NO impact on starts? I am hard pressed to believe it does not.
Last edited by ISF001; 12-17-14 at 01:08 PM.
12-17-14, 01:25 PM
#51
Yes, I researched the patent.
Are you saying the TVD is not capable of making a 50/50 split to balance power output?
Are you contending that straight-line acceleration is not enhanced by torque vectoring through improved grip and balanced distribution of torque/hp under abrupt starts?
Are you contending this has NO impact on starts? I am hard pressed to believe it does not.
Are you saying the TVD is not capable of making a 50/50 split to balance power output?
Are you contending that straight-line acceleration is not enhanced by torque vectoring through improved grip and balanced distribution of torque/hp under abrupt starts?
Are you contending this has NO impact on starts? I am hard pressed to believe it does not.
someone can correct me if im wrong...but the difference between what lexus is offering and the patent that you looked are the computer monitoring/motors controlling the attitude of the torque distribution on the lexus unit. that is what separates it from products like quaife differentials (which you can purchase in the aftermarket). without those motors you wouldnt be able to select between standard, slalom and track. you also wouldnt have the extra weight, either...
so in the end...its seems like the TVD is a torsen diff with motors controlling it.
Last edited by DrRick; 12-17-14 at 01:36 PM.
12-17-14, 01:29 PM
#52
I was agreeing with DrRick that the TVD is not likely to provide the RC-F with a better 0-60 time than an RC-F equipped with a Torsen (based on stock power levels and 275 width PSS rear tires which should be adequate for the Torsen to handle). A clutch-type LSD (like the TVD used in the RC-F) would deliver more consistent launches from the power delivery since I'm assuming it's capable of providing a 100% lock on both wheels (unlike a Torsen).
Last edited by redspencer; 12-17-14 at 01:38 PM.
12-17-14, 02:34 PM
#53
Driver School Candidate
Don't waste your time. Let people think the carbon TVD will make a difference. Any proof you provide won't be enough.
A stock M3 ran an 11.66 quarter. Maybe someone can take their car to the track and get a low 12 soon.
A stock M3 ran an 11.66 quarter. Maybe someone can take their car to the track and get a low 12 soon.
12-17-14, 03:16 PM
#54
That Atco track where this particular M ran always gets fast numbers according to the thread where this video originates. Appears to be a high grip track. Try repeating this 11.66 at any other location. Mags have been able to squeeze low 12s consistently. Did he run with an empty/full gas tank? These results are not typical. Yes M3/4 is faster in quarter but not a full second faster
12-17-14, 04:09 PM
#55
Driver School Candidate
That Atco track where this particular M ran always gets fast numbers according to the thread where this video originates. Appears to be a high grip track. Try repeating this 11.66 at any other location. Mags have been able to squeeze low 12s consistently. Did he run with an empty/full gas tank? These results are not typical. Yes M3/4 is faster in quarter but not a full second faster
It won't matter what results we see one can always pick any variable and blame The results on it. I just get bored when people debate "theoretically" when real world data is available.
OT: does anyone know how to stay logged in from your phone?
12-17-14, 09:40 PM
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I was agreeing with DrRick that the TVD is not likely to provide the RC-F with a better 0-60 time than an RC-F equipped with a Torsen (based on stock power levels and 275 width PSS rear tires which should be adequate for the Torsen to handle). A clutch-type LSD (like the TVD used in the RC-F) would deliver more consistent launches from the power delivery since I'm assuming it's capable of providing a 100% lock on both wheels (unlike a Torsen).
The heart of the TVD is actually an open differential (because an open differential will naturally provide a 50/50 torque split). The ring gear drives both the differential carrier, and two pairs of planetary gearsets. These gearsets then overdrive two clutch packs (one per side, same overdrive ratio). The axles meanwhile are driven by the differential sun gears (normal for an open differential), but they also connect to the clutch packs (half of the clutch plates are over-driven off of the planetary gearsets, half are connected to the axle). This means in normal, straight-line operation, the clutches are kept open, and the vehicle has a 50/50 torque split as determined by the open differential. When the vehicle needs to vector torque, an electronic actuator progressively places pressure a clutch pack; this results in the over-driven plates trying to accelerate the plates connected to the axle. This in turn vectors torque to that axle, and removes an equivalent amount of torque from the axle on the other side of the vehicle.
It is difficult to compare this type of differential to a standard clutch type because the TVD unit can never fully lock the two axles together at the same speed... This would cause the unit to bind (because you would be trying to overdrive each axle relative to the other), and no torque would be transmitted to the wheels. Rather, this differential is more similar to a Torsen unit, but with the ability to actively (electronically) adjust the torque bias ratio.
It is an extremely impressive piece of engineering, whether or not it can help 0-60 timing.
TK
12-18-14, 04:33 AM
#58
That Atco track where this particular M ran always gets fast numbers according to the thread where this video originates. Appears to be a high grip track. Try repeating this 11.66 at any other location. Mags have been able to squeeze low 12s consistently. Did he run with an empty/full gas tank? These results are not typical. Yes M3/4 is faster in quarter but not a full second faster
Many say ATCO is the fastest dragway in the nation, in addition to Rt 66 in Chicago. Allegedly, they both have unique air density several months throughout year.
Those of you near Houston HRP allegedly have a great track with similar conditions.
12-18-14, 05:27 AM
#59
Just wanted to add a bit of information on the TVD...
The heart of the TVD is actually an open differential (because an open differential will naturally provide a 50/50 torque split). The ring gear drives both the differential carrier, and two pairs of planetary gearsets. These gearsets then overdrive two clutch packs (one per side, same overdrive ratio). The axles meanwhile are driven by the differential sun gears (normal for an open differential), but they also connect to the clutch packs (half of the clutch plates are over-driven off of the planetary gearsets, half are connected to the axle). This means in normal, straight-line operation, the clutches are kept open, and the vehicle has a 50/50 torque split as determined by the open differential. When the vehicle needs to vector torque, an electronic actuator progressively places pressure a clutch pack; this results in the over-driven plates trying to accelerate the plates connected to the axle. This in turn vectors torque to that axle, and removes an equivalent amount of torque from the axle on the other side of the vehicle.
It is difficult to compare this type of differential to a standard clutch type because the TVD unit can never fully lock the two axles together at the same speed... This would cause the unit to bind (because you would be trying to overdrive each axle relative to the other), and no torque would be transmitted to the wheels. Rather, this differential is more similar to a Torsen unit, but with the ability to actively (electronically) adjust the torque bias ratio.
It is an extremely impressive piece of engineering, whether or not it can help 0-60 timing.
TK
The heart of the TVD is actually an open differential (because an open differential will naturally provide a 50/50 torque split). The ring gear drives both the differential carrier, and two pairs of planetary gearsets. These gearsets then overdrive two clutch packs (one per side, same overdrive ratio). The axles meanwhile are driven by the differential sun gears (normal for an open differential), but they also connect to the clutch packs (half of the clutch plates are over-driven off of the planetary gearsets, half are connected to the axle). This means in normal, straight-line operation, the clutches are kept open, and the vehicle has a 50/50 torque split as determined by the open differential. When the vehicle needs to vector torque, an electronic actuator progressively places pressure a clutch pack; this results in the over-driven plates trying to accelerate the plates connected to the axle. This in turn vectors torque to that axle, and removes an equivalent amount of torque from the axle on the other side of the vehicle.
It is difficult to compare this type of differential to a standard clutch type because the TVD unit can never fully lock the two axles together at the same speed... This would cause the unit to bind (because you would be trying to overdrive each axle relative to the other), and no torque would be transmitted to the wheels. Rather, this differential is more similar to a Torsen unit, but with the ability to actively (electronically) adjust the torque bias ratio.
It is an extremely impressive piece of engineering, whether or not it can help 0-60 timing.
TK
Even though the TVD has clutch packs, it sounds like it's not a true clutch-type LSD but it is more of a hybrid of different differential technologies working in unison to get the power to the ground.
I still recommend all RC-F owners to invest in a trick-differential like the TVD, regardless if the owner has no plans on ever taking the car to the track. Even a simple drive around town can be much more entertaining when you can use the pedal to steer yourself around corners. Ask me how I know...
12-18-14, 01:54 PM
#60
Instructor
ATCO is easily within driving distance from where I live in central PA.
Many say ATCO is the fastest dragway in the nation, in addition to Rt 66 in Chicago. Allegedly, they both have unique air density several months throughout year.
Those of you near Houston HRP allegedly have a great track with similar conditions.
Many say ATCO is the fastest dragway in the nation, in addition to Rt 66 in Chicago. Allegedly, they both have unique air density several months throughout year.
Those of you near Houston HRP allegedly have a great track with similar conditions.
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