You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!
The banners on the left side and below do not show for registered users!
If you have any problems with the registration process or your account login, please contact contact us.
Actually, a lot of things can beat a Subaru in 4WD. Let's break it down to shifting power from front to rear, and from left to right. We'll see in a bit why the left-right shift is extremely important.
Transferring power between left and right wheels Why is this important??
Most AWD systems have open differentials at the front and rear axles. This transmits power to through the path of least resistance - in other words, to the wheel that is already spinning.
In a worst case scenario where you're stuck, the additional axle with power won't be able to save you when there is a wheel on each axle with limited/no grip (on ice/snow/in the air).
Better systems will use the brakes to generate resistance in order to shift power to the other wheel. This reduces the torque available to actually move the car forward. In some scenarios, this means that you won't have enough torque left to get unstuck.
One thing that I've noticed is that a lot of older systems (-2000) offered locking front/rear differentials, and a lot of car based systems (2000-2010) with open differentials do not have brake based L/R transfer, as this relied on stability control.
Implementations Acura: Differential based system on BOTH axles. Able to transfer 100% of power to either left/right wheels.
Audi (TRANSVERSE Haldex based systems in A4+ models): Brake based system.
Audi (Longitudinal Torsen based systems in S/RS models): Electronic locking differentials [either open or 50/50 L/R]/LSD ("Sport Differential") available.
BMW xDrive: Brake based system. No LSDs except for in M models.
Mercedes: Brake based system. Subaru: Open differentials front and back. Brake based system
Subaru WRX/STI: LSD on rear axles.
Transferring power between front and rear axles Subaru (manual transmission): Viscous coupling where different front/rear axle speeds generates pressure and locks up.
Audi A3s, Volkswagens, and Volvo also use this system.
PROBLEM: Since this depends on rotational speed, tire sizes must be kept constant, making repair costs for punctures/vandalism quite high.
If the difference in pressure is too great, there would be damage. Also can't lockup.
Subaru (auto/CVT transmission):
Electronically controlled clutch engages to transfer power to the rear wheels. No center diff.
Shifts power between 60:40 and 50:50.
BMW xDrive is similar.
PROBLEM: In some systems (most notably Honda's implementation), the clutch cannot sustain prolonged or significant amounts of torque. https://www.youtube.com/watch?v=jkiv-bWbLIo
Acura SH-AWD There are a couple different versions, but let's look at the simplest (1st gen RDX/2nd gen MDXs, and last gen TL). The RL adds extra overdrive capability for more of a RWD feel.
2 differentials with planetary gearsets AND clutches in both front AND rear axles - the planetary gearsets reduce load on the clutches. 2015+ MDXs only have clutches in the front/rear diffs. Can shift up to 70% power to the rear axle.
PROBLEM: Limited to 50% power to the rear in some scenarios due to diff design. More expensive maintenance.
anyone have thoughts on the new 2016 mazda cx9? is it in the same class as a mdx?
__________________ "The guy in the CR-V meanwhile, he'll give you a haughty glare. He's responsibly trying to lessen his impact, but there you go lumbering past him with your loud V8, flouting the new reality. You may as well go do some donuts in a strawberry patch and slalom through a litter of kittens." Dan Frio, Automotive Editor, Edmunds
there is a sales promo on the mdx/rdx right now. i didn't catch the whole ad all i heard was $1k credit on the rdx and $5k on the mdx for cash purchase, and special lease rates.
__________________ "The guy in the CR-V meanwhile, he'll give you a haughty glare. He's responsibly trying to lessen his impact, but there you go lumbering past him with your loud V8, flouting the new reality. You may as well go do some donuts in a strawberry patch and slalom through a litter of kittens." Dan Frio, Automotive Editor, Edmunds
any thoughts on the 07-2010 RDX? currently in the market for one
I have a 2012 rdx, same as the 07-10 rdx. love it so far. gas has been pretty good as long as you dont mash on the pedal and spool up the turbo. it gets better gas mileage compared to the wife's rav4 v6. i get 10.4kms/100k according to the dash computer while the rav4 averages about 11.2 according to the dash computer as well. so we tend to use the rdx more on the city. with normal driving it feels like a crv just better on cornerings, just took my rdx to yakima washington last month did great on the highway specially the xm radio.
also put on k&n intake on mine which helped quite a bit with the turbo lag if i had extra cash i'd probably invest on flashpro as well.
I had the Mazda CX-9 as a rental car for a few weeks, its a good roomy solid 7-seater! But its not sporty, sure it got some zoom zoom, but it does feels heavy and bulky, its super long too so parking is a challenge, not like an Acura MDX would be. Plus the CX-9 is using a Ford Motor in it, which I don't quite like! The CX-9 is due for an all-new-redesign, so perhaps the next gen will be alot nicer!
I test drove the Acura MDX prev gen, and it was really nice, the 2010+ ones. I have mixed feelings about the all-new MDX, don't know why Honda hid the exhaust pipes on the back. I always thought he MDX was sort of a Sports SUV, and the double-exhaust on the back made it look very aggressive, but now you can't even see them and just see two marker lights instead! hmm...
I had the Mazda CX-9 as a rental car for a few weeks, its a good roomy solid 7-seater! But its not sporty, sure it got some zoom zoom, but it does feels heavy and bulky, its super long too so parking is a challenge, not like an Acura MDX would be. Plus the CX-9 is using a Ford Motor in it, which I don't quite like! The CX-9 is due for an all-new-redesign, so perhaps the next gen will be alot nicer!
I test drove the Acura MDX prev gen, and it was really nice, the 2010+ ones. I have mixed feelings about the all-new MDX, don't know why Honda hid the exhaust pipes on the back. I always thought he MDX was sort of a Sports SUV, and the double-exhaust on the back made it look very aggressive, but now you can't even see them and just see two marker lights instead! hmm...
I went for the 16 MDX because they had alot of new techy safety features and I love the heated steering wheel
i have a 2nd gen mdx and currently driving a 2016 mdx for the last week as a loaner car.
it drives much better , steering a little light, and it doesnt feel like a heavy car like the 2nd gen. but , i do not like the center console too much. not too many physical buttons.
my 2nd gen mdx is in the shop so long because they are repairing the SH-AWD. it isnt cheap! and it is one owner dealer maintained.
I went for the 16 MDX because they had alot of new techy safety features and I love the heated steering wheel
You mean the 2nd GEN MDX never had a heated steering wheel?!! I never knew that! Having a heated steering wheel at this time of year is really nice!!! So many times I've gotten into my car with frozen hands to be super relieved by the heated steering wheel, its a God sent!
i have a 2nd gen mdx and currently driving a 2016 mdx for the last week as a loaner car.
it drives much better , steering a little light, and it doesnt feel like a heavy car like the 2nd gen. but , i do not like the center console too much. not too many physical buttons.
my 2nd gen mdx is in the shop so long because they are repairing the SH-AWD. it isnt cheap! and it is one owner dealer maintained.
I never knew the 2nd gen mdx was so heavy! its like one of the heaviest suvs in its class, averaging around 4600lbs for the SH-AWD model! The 3rd GEN AWD is around 4200lbs, a reduction of 400lbs, that is very significant weight reduction while adding more features from Honda!
The STI has LSD in both the front and rear, while the center differential is a special planetary gearset with a 41:59 split.
"The Driver’s Control Centre Differential (DCCD) allows the centre differential locking of the WRX STI to be dialed in and adjust its handling. It adjusts both an electromagnetic multi-plate transfer clutch and mechanical locking of a Limited Slip Differential (LSD) to distribute torque to the front and rear wheels. Auto Mode identifies the ideal power distribution for changing conditions, whilst Auto [+] keeps more power up front for increased traction. Auto [-] transfers more power to the rear for tighter cornering, and the six-step Manual Mode locks in the driver’s favourite handling characteristics."
If you have an older 2005+ Subaru you have
Variable torque distribution AWD
"An AWD system designed exclusively for 5-speed automatic transmission, E-5AT (with manual mode) models to provide aggressive, sporty driving with increased turning abilities all while retaining the fundamental driving stability offered by the Symmetrical AWD. An uneven 45:55 front and rear torque distribution has been set for the front and rear tyres. Sending greater torque to the rear wheels can reduce understeer, a trait that plagues 4WD vehicles, when cornering for smooth and agile handling. Torque distribution is controlled automatically up to an equal 50:50 front and rear to suit road surface conditions for both sporty driving and stability."
You are currently viewing our boards as a guest which gives you limited access to view most discussions and access our other features. By joining our free community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join our community today!
The banners on the left side and below do not show for registered users!
Differential based system on BOTH axles. Able to transfer 100% of power to either left/right wheels.
