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Dumb Q of the day, does the SH-AWD kick in only on accelaration?

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Dumb Q of the day, does the SH-AWD kick in only on accelaration?

Old 01-11-2019, 02:25 PM
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Cool Dumb Q of the day, does the SH-AWD kick in only on accelaration?

Just curious as I've been fascinated watching the SH-AWD display on the instrument panel (why Acura can't I keep this active when I restart?). Anyway I only see the SH-AWD kick in when I accelerate, but I'm assuming it also divides power between the wheels depending on the situation even if I'm not accelerating. Of course I have little technical know how on cars these days so I am not entirely sure.
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Old 01-11-2019, 02:47 PM
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Originally Posted by spinedoc777 View Post
Just curious as I've been fascinated watching the SH-AWD display on the instrument panel (why Acura can't I keep this active when I restart?). Anyway I only see the SH-AWD kick in when I accelerate, but I'm assuming it also divides power between the wheels depending on the situation even if I'm not accelerating. Of course I have little technical know how on cars these days so I am not entirely sure.
Think it through. If you are pressing on the gas, you are putting power to the wheels and you are accelerating. If you are coasting with your foot off the gas, you are not putting power to the wheels, and none of the wheels are being driven, and you show no bars.

A hard start from a stop will greatly transfer the weight back, and the back wheels may show more bars. A light acceleration on the highway may only require the fronts to pull, so you may see 2 bars on the fronts and one bar on the backs. Straight ahead, under light power (acceleration) you will see an even number of bars, front to back. Nail it on a curve or hard sweeper, and the outside rear will show the most bars as you are pushed around the curve.

Practice on an empty, uphill sweeper to a highway.

One of the quirks is that some of the settings you make are not persistent and you must select them again for each driving session.
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Old 01-11-2019, 04:35 PM
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Originally Posted by Madd Dog View Post


Think it through. If you are pressing on the gas, you are putting power to the wheels and you are accelerating. If you are coasting with your foot off the gas, you are not putting power to the wheels, and none of the wheels are being driven, and you show no bars.

A hard start from a stop will greatly transfer the weight back, and the back wheels may show more bars. A light acceleration on the highway may only require the fronts to pull, so you may see 2 bars on the fronts and one bar on the backs. Straight ahead, under light power (acceleration) you will see an even number of bars, front to back. Nail it on a curve or hard sweeper, and the outside rear will show the most bars as you are pushed around the curve.

Practice on an empty, uphill sweeper to a highway.

One of the quirks is that some of the settings you make are not persistent and you must select them again for each driving session.
Yeah I know it definitely makes sense, so it seems you actually have more traction if you are accelerating versus coasting into a curve. I've always been taught to slow down BEFORE the curve and accelerate out of the turn. Which of course still applies, but maybe with earlier acceleration to take advantage of the SH-AWD.
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Old 01-11-2019, 04:36 PM
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Just to add, what I was wondering was if the SH-AWD had the ability to brake one or more of the wheels when NOT accelerating in order to increase traction.
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Old 01-11-2019, 06:45 PM
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Originally Posted by spinedoc777 View Post
Yeah I know it definitely makes sense, so it seems you actually have more traction if you are accelerating versus coasting into a curve. I've always been taught to slow down BEFORE the curve and accelerate out of the turn. Which of course still applies, but maybe with earlier acceleration to take advantage of the SH-AWD.
That's the crux of SH-AWD. More traction while power is on vs when it's off. It's common nature to take your foot off when turning but with SH-AWD you want to actually keep your foot going or push more to rotate the rear.

Originally Posted by spinedoc777 View Post
Just to add, what I was wondering was if the SH-AWD had the ability to brake one or more of the wheels when NOT accelerating in order to increase traction.
The traction control system does that not the SH-AWD system. However on hybrid Acuras, SH-AWD can cause one of the rear wheels to spin in the opposite direction without your foot on the pedal in order to increase traction on curves and pivot you inwards. Very cool system both in hybrid and non-hybrid forms
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Old 01-11-2019, 07:02 PM
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Originally Posted by spinedoc777 View Post
Yeah I know it definitely makes sense, so it seems you actually have more traction if you are accelerating versus coasting into a curve. I've always been taught to slow down BEFORE the curve and accelerate out of the turn. Which of course still applies, but maybe with earlier acceleration to take advantage of the SH-AWD.
it's way more complicated when turns are involved. You'll have more grip if you go slow into a turn. More acceleration can get you through the turn quicker but you'll have less grip.
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Old 01-11-2019, 10:14 PM
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Vehicle Stability Assist works its magic with individual brakes to try to keep your car going in the direction you intend, whether you are accelerating, coasting, braking, or brushing your teeth. Agile Handling Assist gets into the game when you are cornering intentionally.

The Sport Hybrid system will NOT cause a wheel to spin in the opposite direction ( that would be a mess ), but it will apply regenerative braking ( running an electric motor as a generator ) to alter the yaw moment of the vehicle as appropriate. The Agile Handling Assist system in 2019 RDX will apply individual friction brakes in a similar fashion, to achieve a similar result. A unique feature of the Sport Hybrid system is that it can "charge the battery" with regenerative braking on the inside rear wheel and send the juice to the electric motor on the outside rear wheel in hard cornering. That way minimal net power is lost to friction braking.

The torque vectoring capability of mechanical SH-AWD, as in 2019 RDX, does allow it to send extra torque to the outside rear wheel in corning, but any braking applied to the inside rear wheel needs to come from the Agile Handling Assist system.

Brake BEFORE the curve, no matter what you're driving. With SH-AWD, accelerate gently through the curve to control understeer. Try to resist the urge to lift off the throttle in the middle of the curve. Or if you have the traction, punch it and grin ear-to-ear.

Last edited by Wander; 01-11-2019 at 10:22 PM.
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Old 01-11-2019, 10:37 PM
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Let’s not even talk about trail braking, as it is not appropriate for driving on public roads.

Except in, like, an emergency situation....

Last edited by Madd Dog; 01-11-2019 at 10:42 PM.
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Old 01-11-2019, 10:52 PM
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Well, when we say to accelerate through the turn, we're assuming there's nothing in front of you that would respond unfavorably to that.
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Old 01-11-2019, 11:55 PM
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Originally Posted by Wander View Post
Vehicle Stability Assist works its magic with individual brakes to try to keep your car going in the direction you intend, whether you are accelerating, coasting, braking, or brushing your teeth. Agile Handling Assist gets into the game when you are cornering intentionally.

The Sport Hybrid system will NOT cause a wheel to spin in the opposite direction ( that would be a mess ), but it will apply regenerative braking ( running an electric motor as a generator ) to alter the yaw moment of the vehicle as appropriate. The Agile Handling Assist system in 2019 RDX will apply individual friction brakes in a similar fashion, to achieve a similar result. A unique feature of the Sport Hybrid system is that it can "charge the battery" with regenerative braking on the inside rear wheel and send the juice to the electric motor on the outside rear wheel in hard cornering. That way minimal net power is lost to friction braking.

The torque vectoring capability of mechanical SH-AWD, as in 2019 RDX, does allow it to send extra torque to the outside rear wheel in corning, but any braking applied to the inside rear wheel needs to come from the Agile Handling Assist system.

Brake BEFORE the curve, no matter what you're driving. With SH-AWD, accelerate gently through the curve to control understeer. Try to resist the urge to lift off the throttle in the middle of the curve. Or if you have the traction, punch it and grin ear-to-ear.
This is correct, sorry I was thinking regenerative braking and the MID showing reverse arrows and wrote that it spins backwards
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Old 01-12-2019, 11:37 AM
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Originally Posted by Wander View Post
Vehicle Stability Assist works its magic with individual brakes to try to keep your car going in the direction you intend, whether you are accelerating, coasting, braking, or brushing your teeth. Agile Handling Assist gets into the game when you are cornering intentionally.

The Sport Hybrid system will NOT cause a wheel to spin in the opposite direction ( that would be a mess ), but it will apply regenerative braking ( running an electric motor as a generator ) to alter the yaw moment of the vehicle as appropriate. The Agile Handling Assist system in 2019 RDX will apply individual friction brakes in a similar fashion, to achieve a similar result. A unique feature of the Sport Hybrid system is that it can "charge the battery" with regenerative braking on the inside rear wheel and send the juice to the electric motor on the outside rear wheel in hard cornering. That way minimal net power is lost to friction braking.

The torque vectoring capability of mechanical SH-AWD, as in 2019 RDX, does allow it to send extra torque to the outside rear wheel in corning, but any braking applied to the inside rear wheel needs to come from the Agile Handling Assist system.

Brake BEFORE the curve, no matter what you're driving. With SH-AWD, accelerate gently through the curve to control understeer. Try to resist the urge to lift off the throttle in the middle of the curve. Or if you have the traction, punch it and grin ear-to-ear.
This makes a lot of sense, thank you. What I'm getting at is if I go into a turn too quickly with SH-AWD am I better off letting up on the throttle, or am I better off lightly applying throttle, which you answered. I suppose it also depends on when the tires let go, but I'd rather not test those limits. So far I've been impressed with the SH-AWD system. As sloppy as I feel the handling is overall, it's really nice to rocket off an exit ramp and that's when the handling feels really nice.
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Old 01-12-2019, 11:58 AM
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Originally Posted by spinedoc777 View Post
This makes a lot of sense, thank you. What I'm getting at is if I go into a turn too quickly with SH-AWD am I better off letting up on the throttle, or am I better off lightly applying throttle, which you answered. I suppose it also depends on when the tires let go, but I'd rather not test those limits. So far I've been impressed with the SH-AWD system. As sloppy as I feel the handling is overall, it's really nice to rocket off an exit ramp and that's when the handling feels really nice.
That depends where you are at the turn. You always want to accelerate out of the turn, regardless of AWD. The SH AWD will adjust the differential of wheels traction, giving you more confidence and stability to pull through a turn, without you slowing and and braking to compensate.

It's awesome tech but it wont automatically make you a better driver tho 😅
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Old 01-12-2019, 12:17 PM
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Silly me . Read the post wrong. I blame on my tiny phone screen . Wander already provided a much detailed and professional answer
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Old 01-12-2019, 02:59 PM
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But I still danced around the central question. Lifting off the throttle in the middle of a turn is likely to induce an abrupt transition in the cars attitude, and with AWD it's somewhat unpredictable which way that transition will go.

For one thing, it depends upon whether the AWD is front-drive biased or rear-drive biased. Honda/Acura AWD systems are front-drive biased ( with the exception of NSX ), so they will tend to transition toward understeer off-throttle.

SH-AWD helps control understeer, but only when you stay on-throttle. So if you're accelerating through a turn, using SH-AWD to push the car around the turn, and you suddenly lift, things can get "interesting". Other systems, like VSA, will kick in to try to save your silly a$$, but it will be exciting.

In general, if you really need to adjust mid-turn, be gentle about it.

Last edited by Wander; 01-12-2019 at 03:05 PM.
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Old 01-12-2019, 09:35 PM
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Originally Posted by Wander View Post
But I still danced around the central question. Lifting off the throttle in the middle of a turn is likely to induce an abrupt transition in the cars attitude, and with AWD it's somewhat unpredictable which way that transition will go.

For one thing, it depends upon whether the AWD is front-drive biased or rear-drive biased. Honda/Acura AWD systems are front-drive biased ( with the exception of NSX ), so they will tend to transition toward understeer off-throttle.

SH-AWD helps control understeer, but only when you stay on-throttle. So if you're accelerating through a turn, using SH-AWD to push the car around the turn, and you suddenly lift, things can get "interesting". Other systems, like VSA, will kick in to try to save your silly a$$, but it will be exciting.

In general, if you really need to adjust mid-turn, be gentle about it.
Great info, that's exactly what I was wondering about.
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Old 01-14-2019, 10:19 AM
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I'll add a couple of things that I didn't see addressed specifically (unless I overlooked them)...

1. Agile Handling Assist brakes only the front inside wheel on FWD models and both inside wheels on AWD models during cornering.

2. This version of SH-AWD constantly overdrives the rear axle by 2.7%. When accelerating through a corner, more power is sent to the outside rear wheel. This helps create a yaw moment. The rear wheels are never completely locked - there's always a small amount of clutch slip occurring which is one of the reasons behind the relatively frequent fluid changes compared to traditional differentials. This version of SH-AWD is virtually identical to the iVTM-4 system used on the Pilot, Ridgeline, and Passport, but with different software that allows for a bit more torque vectoring.
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Old 01-14-2019, 02:21 PM
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I think only the sport hybrid sh-awd can provide sh-awd off throttle on a curve. No sh-awd without engine power for the rest of us on a tight curve. I've learned to drive my 08 RDX and 11 MDX a little differently because of sh-awd AND having a +2 ton top heavy SUV weight in a curve. It helps to have a 5AT or 6AT and use the paddles to downshift to engine brake before a curve. This allows me to stay off the brake in a curve, raise the engine rpms for faster response from the RDX turbo, I keep my foot on the gas to slowly accelerate out the curve, and this engages the awd or sh-awd to help rotate out depending on the amount of lateral G-Forces.

I have Progress RSB+Eibach lowering springs+Ultra high performance tires with my 08 RDX along with Hondata+ETS intercooler and that gives me a higher entry/exit speeds compared to OEM set-up. My 11 MDX has ADS magnetic suspension, larger front/rear stabilizer bars, and 20" ultra high performance tires for improved handling. Having sh-awd is only half the story. Having an upgraded suspension set-up will give you better handling before, during, and after a curve with or without sh-awd engine engagement.
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Old 01-14-2019, 10:23 PM
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Originally Posted by mrgold35 View Post
I think only the sport hybrid sh-awd can provide sh-awd off throttle on a curve. No sh-awd without engine power for the rest of us on a tight curve. I've learned to drive my 08 RDX and 11 MDX a little differently because of sh-awd AND having a +2 ton top heavy SUV weight in a curve. It helps to have a 5AT or 6AT and use the paddles to downshift to engine brake before a curve. This allows me to stay off the brake in a curve, raise the engine rpms for faster response from the RDX turbo, I keep my foot on the gas to slowly accelerate out the curve, and this engages the awd or sh-awd to help rotate out depending on the amount of lateral G-Forces.

I have Progress RSB+Eibach lowering springs+Ultra high performance tires with my 08 RDX along with Hondata+ETS intercooler and that gives me a higher entry/exit speeds compared to OEM set-up. My 11 MDX has ADS magnetic suspension, larger front/rear stabilizer bars, and 20" ultra high performance tires for improved handling. Having sh-awd is only half the story. Having an upgraded suspension set-up will give you better handling before, during, and after a curve with or without sh-awd engine engagement.
I would definitely consider a suspension upgrade if it wasn't a lease vehicle. Would love to see how this drives with substantial suspension work. Now that I've gotten over the fear of accelerating (lightly) through the curve I'm really impressed, you can actually feel the vehicle being pushed to the center.

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Old 01-14-2019, 10:32 PM
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True. AWD can't push the go pedal for you.
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Old 01-14-2019, 10:32 PM
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Computer controlled motors are different.
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