How SH-AWD works: Acura's AWD system explained
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- เผยแพร่เมื่อ 29 มิ.ย. 2014
- Have you been wondering how the Acura SH-AWD system differs from other "Haldex style" AWD systems? In this video I explain how Super Handling All Wheel Drive differs from Audi's Quattro, BMW's x-Drive and the other transverse AWD systems on the market.
Aside from the fact that Honda/Acura doesn't have a RWD drivetrain to borrow, the benefit main benefit to a transverse engine layout is improved interior packaging.
"Super Handling All Wheel Drive" may not have been the best name for the system, but it is arguably the best AWD system you can tack onto a transverse FWD platform. The systems used by Infiniti, Lexus, Volvo, Lincoln and just about everyone out there that had an AWD system tacked onto a transaxle has no center differential. Instead the power flows from the final gearset of the transmission to the front diff and the rear diff via gears at a fixed 1:1 ratio. Between this gear arrangement and the rear diff is a clutch pack that allows the car to connect, disconnect or have a varied connection between the transmission and rear axles. When fully connected the power is split 50/50 assuming all wheels have traction.
SH-AWD also uses the same arrangement but adds a unique differential unit in the rear that does two things. First, it has a gearset to "speed up" the rear wheels so that when they are connected, they spin 1.7% faster than the fronts. (The old RL used a variable ratio system but it is no longer used.) Next it has a torque vectoring unit that is capable of slitting power 100:0/0:100 left to right. In a straight line, "overdriving" the rear wheels gives the MDX a more RWD feel than otherwise possible and in corners the system is capable of sending up to 70% of the power to the outside rear wheel helping the MDX's cornering manners and masking the "plowing" tendencies normal in a front heavy car. For 2014 Acura took this a step further and uses a system to brake wheels selectively to improve neutral handling. This is beyond stability control because the system is always active rather than active only when things are going pear-shaped.
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The SH-AWD is no joke. My 2012 MDX demolishes corners. And it actually off roads really well too. Catch me wheeling with the Jeeps at Hollister or going double the speed limit with the BMW's on highway 35. (CA)
YOU ARE A GREAT PILOT 👍👍👍👍👍👍👍👍
@@armandoperez2484 well I try not to ever get air but when I do I wish the MDX featured a joystick
@@MCMinerHQ Thanks for that, I’m sure you drive fast but my question is how I have better traction for snow places? Should I drive in S sport mode or D regular mode to have more traction when is snowing 🌨? Thanks 🙏🏻 to all of you guys!!!
@@armandoperez2484 Drive modes should not effect the sh-awd much.
@@MCMinerHQ Perfect and thanks 🙏🏻 so much. I’m just learning and exploring with the new toy!!!
We, the automotive enthusiast community, love your work Sir. Thank you so much for such videos. They are truly informative & genuine!
Agree!!!
hear hear..
I've been working on cars too long because I understand everything that this man is talking about.
This was an excellent video! Just a couple of clarifications.
1.- The only car to use an acceleration unit is the RL.. That unit allowed it to have different ratios but it was specific to the RL because of its long wheelbase, It needed the extra ratio of the acceleration unit in order to prevent binding from a sharp low speed turn.
2.- There is no "Center Clutch" the way the quasi "Center Clutch" happens in a SH-AWD vehicle is carefully controlled by the application of the rear torque vectoring axles clutches. Which leads me to point 3.
3.- The system is FULL TIME AWD it cant never be 100% FWD Biased unless the car is shut off.. The Torque Vectoring system works by having a set of planetary and sun gears to overdrive the rear wheels at all times, In the RL the Acceleration Unit added torque multiplication allowed it to have a higher ratio than the fixed torque vectoring system allowed.. The RL was the only car to be fitted with it due to its abnormal wheelbase and Torque Vectoring overdrive limitations at the time.
How does it work:
1.- The front differential has an extra ring gear which sends power to a dedicated fixed ratio transfer case located in the transmission, Not in the transmission diff output like some other manufacturers (ex. Ford).
2.- The transfer case sends 1:1 power to the rear SH-AWD differential.
X.- Exclusive to the RL the Prop Shaft connects to an Acceleration unit which is basically a dedicated set of extra planetary gears sets that overdrives the power from the propshaft to the Torque Vectoring system. This Acceleration unit has a dedicated clutch pack and electro magnet that limits the turning of the ring gear in the planetary gear set which allow it to get different ratios, This clutch pack cant never be disengaged because SH-AWD is a Full Time AWD System.. If the clutch were to disengage there will be a total loss of rear axle power.
3.- The Torque Vectoring unit has a fixed ratio pinion and ring which sends power to both sides of the axle evenly (There is no mechanical differential in the SH-AWD unit). The fixed ring outputs connects to a sun gear which turns the planetary set that drives each axle. In order to send power to the axle a wet clutch system holds the ring gear at different ratios using electro magnets for precision accuracy the minimum being 1:1 a fully locked wet clutch will send either 1.5 or 1.7% overdrive to each wheel (Depends on the car).
How the "Center Diff" works then? by applying full lock to the wet clutches in the Torque Vectoring system the car can in fact start at a 1.5-1.7% from a dead stop.. This means it can send up to 70% of the power to the Rear.. In the special case of the RL with the acceleration unit fully locked in can overdrive the rear wheels up to 5.7% which in turn means up to 90% of the power to the rear wheels... By carefully applying the clutch packs to hold the ring gear the car can distribute different amount of power evenly through the rear and front wheels. By applying different ratios to each independent rear wheel then Torque Vectoring can happen only under full power and in turn the SH-AWD diff is allowed to send up to 90% of the power to 1 rear wheel but it cant never disengage the entire rear axle to become 100% FWD at highway speeds, The minimum is 10% of power to the rear wheels at highway speeds or at Torque Vectoring.
Hope this explanation and the awesome video by Alex can help you understand SH-AWD at its full potential.
And yes if the car is turned off the rear wheels are not connected to anything, You can jack up the car and turn each individual rear wheel by hand..
I essentially agree with your description and agree that Alex was confusing a few important details by stating there is an "acceleration unit" in the MDX (there isn't one) and by stating there is a central clutch that behaves like a "central differential" (there isn't one). In a SHAWD system, the rear axle does not contain a differential at all. Instead, as you mentioned, there is a wet clutch on the axle shafts going to each rear wheel and the SHAWD's computer controls each clutch.
As you mentioned, with the MDX the "acceleration unit" is simply built into the rear ring and pinion gear ratio ("angle gears" using Alex's terminology) and the independent wet clutches on the left and right rear axle are able to fully disconnect each axle so Accura doesn't need a central clutch (the drive shaft and ring and pinion gears spin freely).
One thing that most discussion's get wrong is how they talk about power splitting through a differential. Power equals Torque X RPM and most people don't realize this or don't think about how differentials direct power. A regular "open" differential is actually a 50:50 torque splitter. Open differentials don't care what the rpm on each side is, they always take whatever torque is applied, split it, and an equal amount goes to each side of the differential.
The RPM input to an open differential is actually averaged between the outputs, but that isn't critical to this discussion (outputRPM1 + outputRPM2 = 2 X inputRPM).
When stuck with only one wheel spinning, this means that only the spinning wheel gets "Power", while both wheels actually still get the same "Torque" (just the one with grip doesn't turn so its zero RPM equals zero power and the other wheel spins like mad, wasting the power). Note there are differentials that by design split torque non equally such that one side will always get more torque than the other (say 60:40 for example), but most common differentials perform an equal 50:50 torque split.
A locked differential or clutch based differential that is engaged or when both SHAWD rear clutches are engaged, this results in the outputs (or left and right wheels) being locked in RPM, regardless of torque or wheel grip. This allows a wheel with no grip to not spin wildly and all of the torque to go to the wheel with grip. Once enough torque is applied to get the vehicle to start moving using the wheel with grip, effectively all of the power goes to the wheel with grip (because RPM is equal and all of the torque goes to the wheel with grip; remember Power equals Torque X RPM).
Getting back to discussing the MDX SHAWD system, when both rear axle wet clutches are disconnected, the system becomes effectively a front wheel drive system. This is how the MDX behaves while cruising on the highway at a constant speed (with both rear clutches disconnected, resulting in front wheel drive only). Due to the 1.7% overdrive gear ratio in the rear, there would be a small amount of "binding" occurring all the time if the rear clutches were engaged while cruising down the highway and this would result in horrible fuel economy and increased wear and tear on the drive system.
If you take an MDX and get it stuck in the snow you will notice that both rear wheels plus one front wheel will be spinning initially. Then the front brake on the spinning front wheel gets applied by the computer, which increases the torque going to the other front wheel (remember open differential results in equal torque to each wheel regardless of RPM and there is an open differential in the front of the MDX) and eventually you'll end up with all 4 wheels spinning. In reality an MDX with 3 wheels on ice (so an ultra-tiny amount of torque will make them spin) plus one wheel on pavement will always drive forwards. If it is a rear wheel with grip it drives essentially right away (because the computer controlling the SHAWD engages the rear clutches initially when you start to accelerate from a stop). If it is a front wheel with grip the other 3 will spin, then the computer applies the brake to the front spinning wheel, then once there is enough torque going to the front axles, the front wheel with grip will make the car to move. This makes the SHAWD MDX exceptionally good at getting through snow and being driven on slippery roads.
Overall Honda's SHAWD system is an impressive approach to a vehicle's drivetrain. By disconnecting both rear axle clutches the vehicle becomes a fuel efficient front wheel drive. The reason for the small reduction in highway fuel economy compared to an only front wheel drive system is due to the differentials and drive shaft spinning freely (small amounts of friction loss), plus the small amount of extra weight. By eliminating the central and rear differentials found in most 4wd systems Honda is able to save money and put some of it back into high quality wet clutches on each rear axle. By using clutches at the rear and an overdriven rear gear ratio, Honda can provide greater the 50% power to the rear when desired plus provide computer controlled torque vectoring (while accelerating).
The only downside I've experienced is if towing a large trailer on slippery roads the rear clutches keep getting applied partially at highway speeds and it doesn't take long for the SHAWD overheat light to turn on. When this happens the system reverts back to a front wheel drive system until the clutches cool back down again. When it reverts to FWD you really notice how much you miss the excellent handling that the SHAWD system provides.
SHAWD works very well for an advanced light duty all wheel drive system.
@@Slider68 i've got a question (i keep asking people who seem to know what they talk about in drivetrains but i never got a real answere for this one): You mentioned the disconnection of the real wheels which makes it a "fuel efficient FWD" with the addition of " small friction loss" due to the spinning drive shafts" (no differential in the back as you mentioned). With all the disconnecting awd systems manufacturers claim to have a better the fuel effiiency than with permanent awd systems due to beeing able to "switch off" one of the driven axles. My take on this is that this doesn't save any fuel because the "switched off" parts are still driven, just not by the engine directly but over the detour of front tires ground and rear tires. Maybe a bad description... (english isn't my native language) I mean the engine power goes to the front wheels and still to the prop shaft that goes back to the clutches and the "angle gears", and as the car is driving the rear wheels turn and wiht them their drive shafts and the parts of the clutch connected those drive shaftstoo. So basically the same parts have to be moved by the power of the engine, no matter if directly or indirect which should have almost the same loss. Why should this save fuel? I mean you could say that the SHAWD saves fuel compared to a permanent awd system by not having a center and rear diff so less loss and less weight. But are two wet clutches lighter? Is moving the fluid in the wet clutches (i guess the fluid will be moved by the turning clutch parts) causing less loss? And is a half closed clutch less loss? I suspect that the fuel efficiency argument by the manufacturers for any part time or disconnecting awd system is just an argument to be able to sell cheaper awd systems. (They do admit that it is cheaper to have them instead of having center diffs with some form of locking clutch ect.)
@@nirfz Sorry for the late reply, I too question how much fuel is actually saved in an AWD system when only a clutch disconnects one piece of an AWD or 4WD system.
Back in the 60's to 80+'s North American manufacturers of full sized 4WD trucks offered systems with a center differential that could disconnect the front axle from inside the vehicle. The owners manual even stated that without also disconnecting the front hubs (little dials you could turn on the front hubs outside the vehicle) that you wouldn't save any fuel because the entire front axle assembly would still be turning, driven by the wheels.
Over time the inconvenience of turning the front hubs led manufacturers to first try automatic hubs that after reversing would disconnect until the center diff engaged the front axle again, and to later just leave the front hubs engaged all the time. Personally I do tend to leave the front hubs engaged with my older 4WD truck (especially in winter), even when in 2wd due to the convenience of switching from 4 to 2wd from inside at any time and without having to stop.
Then during the 90's to 2000's manufacturers started to add electric disconnects for one of the front axles as well as the center disconnect which stopped the ring and pinion and front driveshaft from turning to save fuel (but left the internal differential spinning wildly).
Now, most recently we are seeing vehicles like some Honda's that just disconnect the axle shafts but leave the ring and pinion spinning and they claim this still saves fuel.
Compared to a true disconnect system where components actually stop spinning I'm sure they are not as efficient. Some new vehicles do include this ability but not all, yet they all claim, even with a single point disconnect, that fuel is saved...
I suspect that they are doing things like running very light oil and light duty components where they are only engaged when AWD is required so they are saving some fuel over a heavy duty system that is capable of being used full time when using the same single disconnect. With the ring and pinions plus drive shafts still spinning I too find it difficult to believe they are saving as much as a fully disconnected system.
I think this is also the reason that vehicles with AWD do get fuel economy ratings significantly worse than 2WD vehicles these days. For example the Ford Fusion with AWD gets at least 10% worse fuel economy, even on the highway, than the 2WD version, even though power to the rear wheels only occurs from time to time. Just carrying the extra 50lbs in the trunk of the 2WD version would only lose about 1-3%in fuel economy so the AWD system isn't very efficient.
Ultimately it depends on the vehicle and the AWD/4WD system used as far as how much efficiency is lost compared to a 2WD version. Some of the very latest systems are exceptionally good at saving fuel. One AWD system that I'm impressed with is an optional one Toyota and a few others offer in their latest midsize SUVs. With it they add an ultra efficient electric motor to each rear wheel (and a battery/power controller). With the system off, the rear wheels spin freely, but it can not only add power when needed but also perform regenerative braking to store energy normally wasted.
These electric systems are very simple, durable, have minimal maintenance required, and actually save fuel compared to the 2WD version of the same vehicle. Most (all?) of them also add a larger generator to the engine to enable regenerative braking with the front wheels and to electrically transfer power to the rear wheels when needed for longer than just what you'd get from the rear wheel regeneration.
@@Slider68 Many thanks for the thorough and informative reply! I have to add something regarding the electrical powered rear axle: if there is no clutch to disconnect the electric motor, it might not save that much fuel, because an electrical motor that is turned works as an alternator -> regenerating. Like the dynamo on a bicycle if it is always on. So if you just cut the electric power to the motor, the wheels are driven because the vehicle moves in FWD you are generating drag by generating electricity. What you save in any case with the electrical rear axle in my opinion is the loss from the mechanical power distribution front to back and the differentials and their weight.
@@nirfz I can't say for certain they all do this, but a few years ago I read an article about one of the Japanese companies electric drive solutions for normally idling wheels. Instead of using a regular brushed DC or brushless DC motor with permanent magnets, they used a special type of induction motor. Both the armature and rotor consisted entirely of windings and to power the rotor's windings additional windings working like a transformer were used. The article explained that a primary advantage to this configuration is that when no power is supplied to both the armature and rotor, the wheel freewheels with no resistance to rotation. All of this was built into the hub, just inside of where the brake rotor is. It sounded like a very good solution because it not only provided this freewheeling capability, but it also had the ability to generate very high amounts of torque (far more than any permanent magnet solution could) from a small physical size.
One of the big European truck manufacturers was also using this technology in their experimental front wheel drive power adders. In this case the rear of the truck was a regular heavy duty tandem axle drive system with locking differentials but in the front it had these normally completely shut down specialized induction motors. The front normally cruised around with essentially no impact on fuel economy, but when the truck was driving in conditions where all wheel drive was required, by pressing a button in the cab the front wheels would receive electrical power and turn into a powered axle proportional to how much throttle the drive gave it. This particular system was only able to generate high torque at low rpms, but that may have been a limitation of the power source as I believe the electrical power came from a regular alternator (a big one, but not enormous).
There was another system that I read about many years ago (like 20) that uses electrically powered clutches to engage the electric motors.
Off topic, but that same truck manufacturer (I believe) also had an interesting air powered cam based front wheel drive system they were experimenting with. With it shut off the air cylinders would retract away from the cam and provide no torque to the wheel as well as zero drag. When it needed front wheel drive added, the air cylinders would fire at the right time to push on the multi-lobe cam and add torque to the front wheels. It could generate enough torque to spin the wheels when fully loaded .
I'm on my second MDX. The first was a 2007 (2nd Gen) and its replacement is a 2011 (2nd Gen Repress).
For anyone wanting to know about safety, I have to credit my 2007 MDX Sport for saving my life. Sitting at a stop light, in the protected left turn lane, a late model minivan heading in the opposite direction drifted in to the oncoming lanes, hitting my vehicle nearly head on at approx 45 MPH. Steering wheel airbag deployed. I walked away, as did my 2 year old who was sitting behind me strapped in to a front facing car seat.
Addressing the video - this info is so helpful when explaining to others who are considering an MDX or its competitors, just why the Acura's handling makes such a big difference.
rtrumble glad okay
Ok thank you!
I can't belive the manufacturers can't do this. Long live Alex
WOW what an excellent explanation, I drive to Northern California up PCH last summer and the MDX handled the curves perfectly.
More concise and informative to the point than any engineerimg explained video I've ever watched, and i just found this guy and have been watching EE for years
This is one of the best and most concise explanations I’ve seen. Great video! I will hit subscribe next!
Great explanation of Acuras AWD system
I was researching performance sedans and decided to purchase a 2014 TL SH-AWD with advanced package.
This video made me feel more confident I made the right choice.
Oh! Thanks you so much Alex. I've been looking for the information of this system for my whole life and now I can die peacefully.
Excellent explanation! I've heard others attempt to explain this but not nearly as clear and concise as this! I feel informed now!!
Exceptional Video. I was surprised someone could break the subject down so easily and illustrative. Amazing job 👍🏼
Just picked up a 2011 MDX from family member, who kept the car in really good shape, and discovered it had the SH package. Bonus!
Thanks for the explanation on how SH works, well done.
You're an excellent communicator, Alex. Great stuff. Thanks!
Alex you seriously are the man. Videos like this is exactly why I subscribed and watch your videos all the time. You take the time out to go into detail and explain things that auto manufacturers fail to explain. I appreciate it.
Would you happen to know when the around view camera system will be available on the mdx? It is already available in canada!
dude. that was just awesome. i do a lot of whiteboards in my line of work, and your explanation has shed a lot of light into areas i needed an explanation on.
Greetings. I appreciate your detailed yet completely understandable explanations. In under ten minutes, I learned not only how SH-awd works but also how other awd systems work and how they compare. Brilliant! Thank you.
Having problems with my 2011 MDX, been a great car, about 2 years ago we discovered problems,we though alternator, something was draining the battery, found DVD was running when not in use, friend discovered this when placing new alternator in and just disconnected that system, no more problems till now, was low on oil, had oil changed, new filter, checked all fluids,only one low was antifreeze and when checking air filter 3 screws broke when taking them out so decided to leave as is. Today , drove it about 2 blocks and check engine light came on, flashing, and then showed SH-AWD and car started to shimmy and ride rough, so drove it back home, not sure what is going on, also flashed twice about pulling trailer check and we were not and never have. Do you have the slightest idea what is going on because I love my car and want to keep it and prefer not to spend a fortune. Thanks for your time
@@cynthiamcalexander8101My 06 tsx had the same exact problems
Awesome video. I use to work for Acura and the explanation was on point. The drawings were simple but we're again to the point.
This is a VERY good explanation of SH-AWD! I will be sending my Acura Clients to your video! Thank you very much!
I have a 2023 Acura tlx type s and I can attest that everything this man said is 💯 best car I’ve ever owned. The sh-AWD is real and works very well in the wild
Thanks for explaing SH-AWD. Wish I knew more about it before :)
Very informative having just purchased a UK Honda Legend. Good work.
Alright, that was thorough and actually informative.
Great teaching approach. My man knows his stuff. Much appreciated.
Been a while ..hi old Alex .. current Alex is doing great and have come along nicely made new friends and has become a staple of go too guys for solid info .
Keep on enjoying your day bro .
Awesome Alex! Great as always
This was decently executed! Thank you for doing things like this. "Conventional" SH-AWD is limited by the requirement that it has to be receiving power to vector the car. This means that if you're on the track with something like a 4G TL 6-6, you'll have to be careful in a carousel situation. You have to allow yourself the time to settle between corners, or you could end up going into the third corner of a carousel a little too quickly. Once you get the hang of the perfect steady state throttle through a particular carousel, it's fine...but if you don't know your car well, you can get into a little trouble in a complicated carousel. SH-AWD is clearly superior to many other systems, but it's not the ultimate answer to all handling scenarios...but we're working on it. :-)
I have a 2007 acura mdx. 135k miles and going strong. I live in the cascade mountain range i have to say, there is nothing else on earth that is better in the snow and icy conditions than this vehicle. I have driven a lot of vehicles and i used to think nothing could be better than my little toyota. Japanese vehicles are on a whole different level when it comes to reliability and quality. My girlfriends 2012 ford focus makes me want to puke
U did a good job explaining this.
Just got the 2024 Ridgeline. The I-VTM4 system is an absolute beast. This plus the vtec I feel like I’m in a rally car.
very technical while remaining easy enough to understand
this is now the 5th awd explanation video ive watched today, does it ever stop being confusing? lol
I enjoyed the scribbling, however, I understood shAWD better now. Thanks
Absolutely excellent video
I have 2012 acura rdx sh-AWD it's like driving a sports car great handling and in the snow
Great video. I've read somewhere that soon we'll have torque vectoring on both front and rear. The Audi sports diff has vectoring too. Alex it would be fun for you to explain the GTR's 4 wheel drive system and I believe this is the secret sauce that make such a heavy and somewhat underpowered car go so fast AND I don't believe it even has torque vectoring! Every single test shows it has supernatural speed in the corners and it has to be due to it's magical transmission system?
Excellent Info!
Great vid! Thanks for sharing.
Very nicely explained 👍
Still an excellent video, but needs to be updated as SHAWD has changed a little, and so have others. I would love to see one because I could never explain to others what SHAWD with the ease that Alex does.
The RL actually had a 5 prevent overspeed in the rear. Later systems as in the MDX TL RDX used the simplified and lightened 1.7 percent acceleration in the rear.
Also, the RLX has departed from the mechanical system in favor of 2 electric motors that power the rear wheels independent of each other and can do some limited power distribution even in an off throttle (albeit adverse) driving condition. It complements the vehicle stability assist quite nicely.
This is by far the best explanation I have ever seen of this.
Also, do you think it's possible to get slightly better mileage in the MDX by turning off the traction control (VSA?)?
Beautiful video. Thank you.
Hmm.... This is very interesting. My 05 Subaru STi has the Driver Controlled Center Differential (DCCD) where you can adjust the clutch pack and torque split to the front and rear axles. This Super Handling AWD sounds very similar to Subaru drivetrain although adding the vector torquing components. Very cool.
Alex has this system changed since you posted this video? I'm asking about the new ivtm4 that is in the 2017 Honda Ridgeline which I've read is the old SHAWD.
Great video
Lifted this from Wikipedia :)
List of systems capable of active left-right torque vectoring
Audi's quattro with Sport Differential
BMW's xDrive with Dynamic Performance Control
Honda's SH-AWD
Kia's Dynamax™ AWD
Land Rover's All New Range Rover Sport HSE and Autobiography Dynamics models [9]
Mercedes-Benz's SLS AMG Electric Drive combined with active front-back torque vectoring
Mitsubishi's Active Yaw Control
Nissan Juke
Saab's XWD
Ford on several models
Porsche on several models, when torque vectoring added as an option
Subaru's AWD on 2015 WRX
Holden Special Vehicles Gen-F GTS[10]
6:33 i was gonna say that's what amazed me the most i just bought the 2012 and i'm very pleased with it!
40km/h turn (i don't recommend this i was testing on empty roads lol) ate it a 100km/h max but at 80km/h it was a dream. and thats where you'll eat these little souped brz , g35's, and 3 series acting hard lol
Wow that was an awesome video
I was driving in a snow storm with 2021 Acura awd and was wondering why everyone is driving so slow at 35 mph on the highway while I was driving at 60. Super handling all wheel drive is a very smoooooth rain and snow driving car.
Because everyone else on the road is smarter than you?
Nice video, I think you missed to explain why the SH-AWD has no classical rear diff, but a planetary gear at each back wheel (inside of the clutch packs) though (~8:40 in the Honda video)
Thank you for this Alex. can you do one on the AWD system in Ford Edge Sport ? specially in snow situation.
Hello Alex, I need advise, I got the acura tl 2012, in my Country, we have extremely shirty bad road, how well will it fair and is it good for off-road use cuz that's the best description for our roads.
Would love to find out how the ATESSA AWD from Nissan/Infiniti works!?
I am a little confused by the remarks about BMW X5M. Is there a benefit one system over the other or are the differences nullified by simply being the better solution for the platforms they are used on? I am attempting to flesh out the better AWD system for use on vehicles that were never born with them as a mental exercise. I am down to the symmetrical system in the Subaru STI and SH-AWD in the RL but have failed to consider the BMW X platforms.
Great video 👍
Preciate just grabbed a acura rl with this
Good video! Damn, that whiteboard work was rough though.
I would ask, isn't the newest Audi A5, a direct competitor to this vehicle, also using torque vectoring in this recent generation? And the engine mount is probably same as the RDX? Can you confirm?
Well explained. Ty.
I have an 08 RDX Tech with +195,000 miles and 11 MDX Adv with +150,000 miles and the sh-awd has worked flawlessly over the years in all 4 seasons. Mainly purchased for the sporty handling living in the southwest and I've haven't been disappointed over the years. I handed down my 08 RDX to family and upgraded to 18 RLX hybrid and 19 MDX hybrid with rear electric motor sh-awd. The hybrid sh-awd works even better than the mechanical sh-awd because it can engage tq vectoring/regen braking on or off engine power. The hybrid rear electric motors can regen brake the inside wheel and over drive the outside wheel to rotate the MDX even more in a corner. The hybrid sh-awd works equally as well up and down the mountain switchbacks.
Jason from Engineering Explained wants his whiteboard back. :P :)
I know this is an old video, but the clutches in the rear diff, can they/do they need to be rebuilt over time? Or do you have to just get a new rear differential?
Good work
First of all great video
Thanks you for an excellent explanation. I do wonder about the long term reliability of all of these components in the SH-AWD.
SH-AWD has been very reliable and seems to be well built. The downside and the reason that Acura has been moving away from it somewhat in the RDX and in the RLX is weight and cost. SH-AWD is expensive to make and it is heavier than a less sophisticated AWD setup.
considering the above response was 4 years ago, and we have even more history of it holding up, i guess its not too bad. im buying one today and probably picking up a few spare parts to keep it going over the years, before the only parts i can find are unreliable aftermarket, or high mileage used.
@@seanb9436 _"we have even more history of it holding up...picking up a few spare parts to keep it going over the years"_
What SH-AWD spare parts specifically?
@@commenterperson4481 nothing special, and its probably unnecessary to do, but I keep my cars for 10+ years at a time. picking up a rear diff, transfer case, and shaft next time i spot one available at a pick and pull area around here. its a lot easier to do when they're 4-6 years old as opposed to 10+, because the parts are all worn to hell and finding a low mileage unit gets far harder
@@seanb9436 I see; you seem like a long term planner.
I find that it's not easy to guess what the faulty parts will be in 10-15 years. Also, in 10-15 years, I'm not sure I'll make time to work in depth on cars...
Excellent, thanks
Seems like a lot of parts to do a simple job. I never had any issues with my older Audi quattro systems. I believe they used Torsen differentials front rear and center IIRC.
So is higher percentage in discontinued RL not as good as lower percentage ones? We just got a 2010 RL just curious why that changed.
I’ve had all 3 generations of the RDX...I fell in love with my 2009 because of how it drove and handled with the SH-AWD. The second generation one (2017) was nice and big a luxurious but I hated the way it drove...it was like driving a SUV not like driving a car. My new 2020 took the size and luxury of the 2017 and brought back the driving and the handling of the first generation one with SH-AWD and it’s better now than it ever was. My dad still drives a first generation RDX (2007) and after I got my new one I took his out for a drive to compare. Now granted we’re talking about a 13 year difference here and about a hundred or so thousand mile difference on the two cars engines but you can feel the difference. And I’m not taking about ride quality or anything like that because of course the 2020 is gonna ride better. I’m talking about taking a corner at speed, the new one literally hugs the corner where the only one lags a little. I think now that 90% to a single wheel in the back is 100% to a single wheel in the back and it ends up with a real rear wheel bias around corners. I don’t know all the specifics of these things...I’m not a mechanic and don’t know a lot about how cars work and stuff but what I do know is feel and from driving both ( I had my 2009 with SH-AWD for 7 years) I can tell you that they took an amazing design and made it even better with the new RDX. If you’re going to get a new Acura no matter which one it is...spend the extra 2000 and get SH-AWD it’s worth every penny and turns that car from great to absolutely amazing.
I still own a 2007 RDX, and am interested in changing it to the new MDX MY22, and hence appreciate your comments regarding the new RDX. Was interested in how the SHAWD has changed over the years. My 07 RDX have crossed the US twice, and I still remember how it teared through the slopes near Lake Tahoe in Norcal. The RDX continues to put smile on my face whenever I drive it (my significant other drives it now), and in some ways are better than my ‘18 Genesis G70. I look forward to getting the new MDX, and hence your observations are very helpful. Thanks again for sharing!
I just picked up a used 2015, love it. Way faster than my 07 MDX. The 07 went through snow with snow tires on, felt like you were on dry pavement
hi i have a question can i change my fwd 2014 acura mdx to a awd what do i need to replace thank's
Alex I been watching your videos and I Decide to buy a MDX 2014 thanks of you. I have one question for you, now with the winter time and all the snow, do I have to drive in S mode or D regular mode? Thanks 🙏🏻 for all your hard work.
You can use either, s mode is a sport mode, so you can use the paddle shifters.
@@alexandermueller4115 Thanks 🙏🏻 for your help 👍
Please talk about the fifth gen Prelude SH/Type S! The original which Acura's was based off! Active Torque Transferring System, or ATTS, is what made the SH and Type S shine
Alex, can you do a video on Lexus Ls, Mercedes S class and Audi A8 AWD system comparison?
Acura actually has a (in my opinion) AWD system than most of its more expensive European competitors, and that's very beneficial in Canada where 90% of BMWs, Mercedes & Lexus are sold with AWD. Heck SH-AWD is actually better than Audi's famed Quattro & Subaru's Symmetrical AWD as they don't have torque vectoring capability (via mechanical means).
Unfortunately their marketing division really needs to get its act together and actually sell some cars. Acura sales trail almost all other luxury nameplates in North America & only marginally beats out Lincoln; Cadillac isn't far behind & with their ever growing strong lineup of desirable products, it will soon surpass Acura.
+Trades46 Exactly, their SH-AWD doesn't get the recognition it deserves. It's actually quite an advanced system but held back by it's dumb name. It needs a more catchy name...
Subaru does have torque vectoring on rear axle of some models and in fact on both axles of wrx sti
+Ankur Sharma it is brake based torque vectoring, which is garbage compared to Mitsubishi and Acura implementation.
+Vlican Unfortunately I have not experienced a mechanical torque vectoring system, I only experienced brake vectoring.
Audi has mechanical torque vectoring on some models. They call it Sport Diff. It can overdrive either of the rear wheels by up to 10%.
Sory you probably explain, but I'm not very good in english
I would like To know if the car are lifted completely in the air and the hand brake are on. Does the 2 fronts wheels are suppose To spin ???
Thanks for your time and hope you Will understand my question ;) !!
So I might wonder 🤔 would this work for a TypeR with manual 🤔 and still be light enough to be just as good as it is now
Acura TL woooow !!! No problem !
You should use animations to explain it. very good.
Great video but from what I understand back in the days say 20 or more years ago Front wheel drive was way better than rear wheel drive. Since front wheel drive pulled you around the comers and rear wheel would push you through the corners. So in theory, Rear wheel would push you off the road when going to fast or fish tail. Front wheel drive would just pull you around the corner.
Also in snow having front wheel drive and the engine on top of the wheels gave you better traction. Please corset me if I am wrong.
Still, I did not understand how much% of the total engine power can get one rear wheel?
In other words, what is the maximum torque a gearbox can withstand on one axis?
Thanks!
Well done lad.
I've read quickly through all the comments, and no one is mentionning anything about the AWD systems that only works under 18mph. So if you drive slow, the awd systems might be good, but it has no use on a normal speed road or highway. That is why we still have Subaru that still works for these cases. I'm looking for a bigger SUV to replace my Tribeca, but can't find anything that has a full time AWD, except trucks.
i have 2017 MDX the SH-AWD light is on sometimes why what is causing this?Please let me know do i have to go the Acura technician
Hello Alex, Please I have 2008 MDX and my SH-AWD light and battery lights are on. please what does that mean or what do I need to look for.
I want to know how to solve SH-AWD problem when the rear wheels are disconnected from the system
Just curious, to activate the SH-AWD system, I have to floor it during a turn? or just accelerate through the turn? I have a 2008 Acura RL Technology package...
SH-AWD is always active in some capacity. Even at low throttle inputs the system will torque vector the power going to the rear. So even if the front wheels are getting 70-80% of the power, when you enter a corner the rear differential unit will direct the 20-30% power primarily to the outside rear wheel.
Is SH-AWD still available on on new TLX, heard they are discontinuing it in future
I have a 2009 acura tl sh-awd and when I’m coasting the rpm will jump 2-300 rpm and no one has a clue. No lights on dash and no codes. Did spark plugs and coil packs. Cleaned egr and carbon clean. Still same problem
Any idea??
Check out again the engine positions..
For RWD (like BMW) the engine sits it the middle of the axle. Same for the X5 (for Xdrive)
Omar El-Mohri Very interesting. I am learning that this must be part of what they refer to as chasis tuning
The Mitsubishi Asx diesel has something similar. Put it in 4WD lock mode and it will send more power to the rears at higher rpm or when theb computer thinks it needs it
I am experiencing drive problem with2008 mdx only have front wheel drive and have changed all 3 drive fluids ??can you help me out.
Ernie Lang
I have a 2012 Acura tl with a 3.5 the sh-AWD light is on but the car doesn't have the sh-awd module .and it's not 4 wheel drive but the sh-awd orange light is on.
video on the tlx I haven't seen it yet it seem like am the only one that contact you on it.
The way you explain the all wheel drive his understandable the front engine and the tm his in one line with the front wheel.
Still would like a review of the tlx Acura I like.
The TLX will actually be in my hands today with a video live in about 2 weeks.
Hi Alex, I wonder how Honda Prelude SH differs in terms of handling since it doesn't have SH-AWD.
It might be able to send more power to either the front left or right wheels rather than all the wheels.
So is the SH-AWD system's primary benefit for turning and cornering rather than for slippage during inclement weather? Or does the system also aid with slippage?
It has all the benefits of a traditional AWD system in poor weather and the front/rear and rear side/side torque vectoring for performance.
Advantages and Disadvantages of AWD front main drive and AWD rear wheel drive. Things being equal a normal AWD system is better when rear wheels are the main drive. CR-V and RDX, both having a basic AWD system, would be better with rear wheel drive AWD system especially when driving up slopes/hills.
Compared to rear-wheel drive, front-wheel drive reduces weight and
production cost, improves fuel economy and typically delivers better
traction. That's because the weight of the engine and transmission is
directly over the driven wheels.
Rear-wheel drive offers better initial acceleration than does FWD
when a quick start is of the essence. That's because weight is
transferred to the rear of the car upon accelerating, thus boosting
traction. Additionally, by keeping part of the drivetrain in the rear, RWD
cars usually have weight distribution closer to the optimal 50 percent
front/50 percent rear than can be achieved with a FWD system: Equal
weight distribution improves a vehicle's overall balance and handling.
How does engaging VSA off impact this discussion?
Bravo!