SH-AWD vs. Torque Vectoring Brake
05-24-2009, 03:14 PM
#41
You dont seems to understand that when the outside wheel accelerates it is compensating for balance, it overcomes normal dynamic limitations, have you ever driven the SH-AWD? Not on the SH system buddy, VSA allows for regulation on various vehicle components to enhance the function of the SH, before the brakes, by allocating torgue where necessary it is unlike the system in the TSX or FWD TL.
05-24-2009, 03:16 PM
#42
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Tigmd99, enjoy your 2 weeks off since you started this thing between you two again.
05-24-2009, 03:25 PM
#43
In the RL they use an acceleration device to assist the rear wheels function, but it does not come on the TL and MDX becuase they have the VSA incorporated to emulate that same function, it's called cooperative VSA or C-VSA.
http://www.motortrend.com/av/feature...ure/index.html
http://www.motortrend.com/av/feature...ure/index.html
Last edited by winstrolvtec; 05-24-2009 at 03:27 PM.
05-24-2009, 03:40 PM
#44
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Are Honda's Formula I & Indy cars SH-AWD?
05-24-2009, 04:05 PM
#45
COOPERATIVE VEHICLE STABILITY ASSIST(R) (VSA(R)) WITH TRACTION CONTROL
Cooperative Vehicle Stability Assist(R) (VSA(R)) is included as standard equipment. By continually monitoring the vehicle's operating parameters (such as road speed, throttle position, steering wheel position, accelerating, braking and cornering loads), cooperative VSA(R) anticipates if the vehicle is approaching oversteer or understeer. To help correct either of these situations, cooperative VSA(R) first acts to transfer torque bias to the axle with the most traction. This preventative measure significantly reduces the number of brake and throttle interventions. The response is so quick that the instability may be corrected even before the driver knows it's occurring. Traction Control is integrated into the cooperative VSA(R), and helps the MDX accelerate smoothly on slippery surfaces. As stated in the SH-AWD(TM) section, the cooperative VSA(R) can request the SH-AWD(TM) to adjust its torque level - thus allowing Direct Yaw Control of the MDX to maximize stability under all driving conditions.
Cooperative Vehicle Stability Assist(R) (VSA(R)) is included as standard equipment. By continually monitoring the vehicle's operating parameters (such as road speed, throttle position, steering wheel position, accelerating, braking and cornering loads), cooperative VSA(R) anticipates if the vehicle is approaching oversteer or understeer. To help correct either of these situations, cooperative VSA(R) first acts to transfer torque bias to the axle with the most traction. This preventative measure significantly reduces the number of brake and throttle interventions. The response is so quick that the instability may be corrected even before the driver knows it's occurring. Traction Control is integrated into the cooperative VSA(R), and helps the MDX accelerate smoothly on slippery surfaces. As stated in the SH-AWD(TM) section, the cooperative VSA(R) can request the SH-AWD(TM) to adjust its torque level - thus allowing Direct Yaw Control of the MDX to maximize stability under all driving conditions.
Last edited by winstrolvtec; 05-24-2009 at 04:10 PM.
05-24-2009, 06:40 PM
#46
Actually the RL acceleration device is a planetary gearset that allow (around)4-5% outside wheel overdrive. The simpler device in the TL, RDX and MDX used a fixed 1.7% overdrive.
05-24-2009, 07:02 PM
#47
Yet another version of SH-AWD was introduced in late 2008 with the fourth generation 2009 Acura TL.[14] The Acura TL implementation of SH-AWD is actually mechanically more similar to the SH-AWD layout in the Acura MDX and RDX[15] in that the rear differential is over driven at a constant 1.7% faster than the front wheels[16], unlike the Acura RL, which, since its introduction in 2004[17][18], added an acceleration device[19] which can over drive the rear wheels up to 5.7% faster than the front wheels
The Acceleration Device was first introduced in the flagship Acura RL sedan, and continues in the MMC Acura RL sedan. This more complex configuration appears to be unique among the SH-AWD equipped Acuras. This more complex RL configuration could be considered an exclusive flagship vehicle feature, and not specified for vehicles with lower price points. The later SH-AWD configuration without the Acceleration Device could just be a simpler and less sophisticated version due to vehicle dynamics and price points, or it could represent a more refined, less complex and inherently more reliable, new standard SH-AWD configuration. The rationale for the two distinct configurations has not been publicized by Acura.
05-24-2009, 07:03 PM
#48
Suzuka Master
Hey all,
Just today, i was reading Edmunds preview of the new MB S550. It now comes with "Torque Vectoring Brake." TVB is very simple...and you kinda wonder why no one thought of this much earlier. TVB lightly brakes the inside rear wheel in a corner to decrease understeer.
So, Acura SH-AWD has an extra gearset to "overdrive" the outside wheel in a corner to overcome understeer. Mercedes' TVB brakes the inside wheel to accomplish the same.
What do you guys think?? Which system is better?? For me, without knowing much about Mercedes system, i prefer the Acura's overdriving of the outside wheel, BUT prefers the Mercedes simplicity of the system (no extra gearset needed). The rear brakes on the MB would die sooner i would assume, while Acura system needs a bit more maintenance of the rear differential (fluid changes). I just don't buy into the idea of BRAKING something (MB TVB) to make you go faster...it just sounds weird.
BTW, i believe that Audi has a similar system to Mercedes??
Just today, i was reading Edmunds preview of the new MB S550. It now comes with "Torque Vectoring Brake." TVB is very simple...and you kinda wonder why no one thought of this much earlier. TVB lightly brakes the inside rear wheel in a corner to decrease understeer.
So, Acura SH-AWD has an extra gearset to "overdrive" the outside wheel in a corner to overcome understeer. Mercedes' TVB brakes the inside wheel to accomplish the same.
What do you guys think?? Which system is better?? For me, without knowing much about Mercedes system, i prefer the Acura's overdriving of the outside wheel, BUT prefers the Mercedes simplicity of the system (no extra gearset needed). The rear brakes on the MB would die sooner i would assume, while Acura system needs a bit more maintenance of the rear differential (fluid changes). I just don't buy into the idea of BRAKING something (MB TVB) to make you go faster...it just sounds weird.
BTW, i believe that Audi has a similar system to Mercedes??
I don't pretend to know much about these things, but the Acura only helps if you are accelerating, does the MB still brake the inside wheel to help control the car regardless of acceleration? And the AWD in the TL adds a bunch of weight I suspect the MB method is weight neutral.
05-24-2009, 07:06 PM
#49
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For more info on the various "torque vectoring" technologies, here is a good link: http://www.popularmechanics.com/blog...s/4225886.html
As for Mitsubishi AYC (active yaw control), here are several links:
http://www.lancerregister.com/faq/G04/g04.html (excellent explanation!)
http://www.mitsubishi-motors.com/cor...003/15E_11.pdf
http://www.lancerevoclub.com/evoclub-ayc-e.htm
Seemingly, Acura system is not a breakthrough as i once thought! Mitsubishi is apparently a leader (creator??) in torque vectoring differentials. It is probably that Acura is better at advertising it than Mitsu! Mitsubishi has been installing torque vectoring differentials since 1996...way before Acura came out with AWD system in their MDX in 2001! Thus, there have been torque vectoring differentials long before Acura came up with the idea.
As for Mitsubishi AYC (active yaw control), here are several links:
http://www.lancerregister.com/faq/G04/g04.html (excellent explanation!)
http://www.mitsubishi-motors.com/cor...003/15E_11.pdf
http://www.lancerevoclub.com/evoclub-ayc-e.htm
Seemingly, Acura system is not a breakthrough as i once thought! Mitsubishi is apparently a leader (creator??) in torque vectoring differentials. It is probably that Acura is better at advertising it than Mitsu! Mitsubishi has been installing torque vectoring differentials since 1996...way before Acura came out with AWD system in their MDX in 2001! Thus, there have been torque vectoring differentials long before Acura came up with the idea.
05-24-2009, 07:09 PM
#50
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I don't pretend to know much about these things, but the Acura only helps if you are accelerating, does the MB still brake the inside wheel to help control the car regardless of acceleration? And the AWD in the TL adds a bunch of weight I suspect the MB method is weight neutral.
05-24-2009, 07:32 PM
#51
I don't pretend to know much about these things, but the Acura only helps if you are accelerating, does the MB still brake the inside wheel to help control the car regardless of acceleration? And the AWD in the TL adds a bunch of weight I suspect the MB method is weight neutral.
As for weight gain, if the TL were RWD as so many pine for, I don't see how you can argue that it (hypothetically) adds much. A RWD TL would still need a driveshaft and rear diff. I think its safe to say that driving the rear wheels in any car with a front mounted engine will require more hardware than driving the front wheels only.
Yes, but wasn't ATTS a fully mechanical system with no overspeed capability?
05-24-2009, 07:38 PM
#52
I am sure that it is based entirely on cost. That and the 'halo' that flagship tech is supposed to cast over the rest of the product. For example, the VTEC system in the NSX and GS-R is significantly more elaborate than the VTEC used in most Hondas in the US. To many, there is no difference. They don't know that their version of SOHC VTEC has only two lobes and no exhaust side VTEC. Yet they proudly proclaim "my car has VTEC"
05-24-2009, 11:26 PM
#54
I actually drove a first gen Suzuki Samurai back in 1981. My Celica GT was in the shop for accident repair, and my dad was the distributor for Suzuki in Hi. Had it for about 2 weeks and reveled in the awesome 40 hp, 4-MT and the warning not to exceed 50 mph. I cannot comment on the torque vectoring capability cause it had no torque to vector...
05-25-2009, 07:54 AM
#55
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The SH system was designed as a performance enhancer and thus working under acceleration was the whole idea. It allows a driver to come off a corner harder and not have to worry about weight transfer (to the rear) reducing steering effectiveness. This means you can get on the throttle earlier in the corner apex.
05-25-2009, 02:42 PM
#56
So with no throttle applied does VSA kick in to reduce understeer? And in that situation does it act more live the TVB on the MB? I would suspect it does, otherwise if you take a corner too hot and release the throttle the car would develop some serious understeer mid corner.
05-25-2009, 03:55 PM
#57
So with no throttle applied does VSA kick in to reduce understeer? And in that situation does it act more live the TVB on the MB? I would suspect it does, otherwise if you take a corner too hot and release the throttle the car would develop some serious understeer mid corner.
I would imagine that VSA has to act in some sort of active phase for that very reason, not to mention SH already does what TVB will mimic, in the first place, without the brakes, then this sort of pre-stability, and then the brakes application if necessary. I can't imagine getting into an SH, accelerating though a turn then letting off the gas and nealy killing myself if not for the braking function of VSA.
05-25-2009, 05:13 PM
#58
^^ This may also be the reason why we see the extra wheel acceleration capabilities (or device) of the RL, when it first was introduced VSA was not incoporated into the SH like it is now, and that feature was there to do the same thing the VSA does now. The C-VSA was introduced on the 07' MDX, RDX and then made it's way into the TL, the RL retains that extra part of SH likely for other important purposes, but it makes me think that maybe C-VSA is not on the RL becuase of this. The power transfer should be enough to assist the vehicle around the turn but naturally they would need something in place to accelerate it in the situation described above, where you might have to let off the gas mid turn, if C-VSA was not in use.
Last edited by winstrolvtec; 05-25-2009 at 05:17 PM.
05-26-2009, 12:33 AM
#59
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The SH system was designed as a performance enhancer and thus working under acceleration was the whole idea. It allows a driver to come off a corner harder and not have to worry about weight transfer (to the rear) reducing steering effectiveness. This means you can get on the throttle earlier in the corner apex.
As for weight gain, if the TL were RWD as so many pine for, I don't see how you can argue that it (hypothetically) adds much. A RWD TL would still need a driveshaft and rear diff. I think its safe to say that driving the rear wheels in any car with a front mounted engine will require more hardware than driving the front wheels only.
Yes, but wasn't ATTS a fully mechanical system with no overspeed capability?
As for weight gain, if the TL were RWD as so many pine for, I don't see how you can argue that it (hypothetically) adds much. A RWD TL would still need a driveshaft and rear diff. I think its safe to say that driving the rear wheels in any car with a front mounted engine will require more hardware than driving the front wheels only.
Yes, but wasn't ATTS a fully mechanical system with no overspeed capability?
05-26-2009, 05:09 AM
#60
05-26-2009, 05:06 PM
#61
ATTS, was also available in 96' and allowed for more of a torque transfer than the rear differential on the EVO IV. Later in 2003 Mitsubishi released a new version called S-AYC but switched from a bevel gear to a planetary gear differential, allowing for double the amount of torque AYC was able to tranfer. Honda's ATTS was transfering up to about 80% to an individual wheel from day one, already using a planetary gear differential. The ATTS utilized 3 electric solenoids, making the clutches electromagnetically controlled, the AYC on the Mitsubishi was only hydraulic. Cadillac also had some type of system similar to these also introduced in 96', prior to that in 86', I think the Porsche 959 had another that transferred front to rear on an AWD.
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