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nacha

Is Rx300 "awd" A Scam?

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i just returned from lake tahoe( in our trusty 4wd suburan) and i noticed something interesting. I saw several ( at least 4 ) rx300s with rear tire chains. I never saw a subaru awd, or an audi awd, or a volvo awd, or a honda crx, or a x5, or a ML with chains. only the rx300s.it made an impression on me because before our trip, WWEST on another thread posted the comment that" a awd rx300 is a figment of Lexus' marketing imangination". so my question is, is a "awd" rx 300 a scam?

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I would say it is not a scam. I guess it would have been easier to ask the owners why they felt tehy needed to have tehm .As that would have given the best answer possible,

The awd is not constant as i am sure you know and like most systems it only comes on when needed for the rear wheels if there is enough slip or loss of traction ,that it needs to be used.

Personally i would have the awd which is much better than a 2 wd if needed which is highly unlikely in an urban enviorment.

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I have driven a lot in the snow at Tahoe in my rx300 awd for the last two years with no problems. Never saw an awd with chains. I have 18"rims with m+s Toyos. A lot better than my old 4x4 Chev Blazer with m+s on stock rims.

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"rx300s with rear tire chains......"

Four of them yet!

Are you really sure those were RX300s??

Both the 00 and the 01 RX300 owners manual designate that tire chains should be used ONLY on the FRONT. According to Lexus that is also true of the new RX330. There is not enough space in the rear between the strut and the tire to fit ANY tire chain safely.

Knowing how hazardous FWD is in these conditions anyway, and especially so with extraordinary traction on the front vs the rear (front tire chains ONLY) I added 1.2" wheel spacers all around to fit 17X8 wheels/tires so I can use tire chains ONLY on the rear.

The only truly safe configuration.

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Tire chains....

I can't even begin to recount the number of times I have seen the many kinds and types of AWD & 4WD vehicles stuck on slight inclines in hard packed and icy ski area parking lots.

Around here you see lots of vehicles going to the ski slopes without chains but a lot more coming back down with chains.

I always carry chains in ALL my vehicles during the winter months. Don't often have to use them, probably 4 or 5 times since Dec 90, but they're worth their weight in gold at times.

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AWD RX300 a marketing scam....

Let's let Lexus vote on that one.

Lexus: "for 2004 the viscous clutch used in previous versions of the RX has been completely discarded in favor of just the open center differential and the use of Trac, brake modulation, to apportion engine torque only when required."

Paraphrased but literal.

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My experience with my 2001 RX300 in snow has been very positive. I do not have access to a dynanometer, but I do have my 91 LS400 for comparison.

Both the RX300 and the LS400 have snow tires on all 4 wheels. When driving the LS400 (i.e. rear wheel drive) I experimented with turning the traction control on and off. I found I could get a lot more traction/acceleration by turning the traction control off and accepting a little wheel spin.

One Saturday I took the LS400 for a drive in the snow. I then returned home and took the RX300 out. Comparing the two, I feel that the RX300 has 6 - 8 times the traction of the LS400. I do not know how Lexus splits the power front to back, but whatever they are doing they are doing it correctly. I never get stuck in the snow, have no problems with traction and the vehicle is very stable and secure.

Incidently, do these RX300 owners who are using chains have all season tires or winter tires on their vehicles? If they have all season tires, I can understand why they need chains. If they have snow tires (on all 4 wheels) there are very few circumstances where they would need chains (maybe I would put them on for mountain roads).

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tds,

re the type of tires, i was able to see two rear chained(cables actually) rx's at alpine meadows where we were skiing. both had all season type tires - the integrity. the original tire with the car.

wwest - yep, im sure they were rx 300's. dont know much about them, but i know one when i see it. yes they had cables on the rear tires, not the front ones.

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I'm interested in the comment "FWD is inherently unsafe in these conditions" FWD unsafe in snow? I don't buy that...

You have to bear in mind a couple things.

One, the RX is a FWD vehicle, and its AWD is front biased meaning it transfers power to the rear when there is slippage. So, If it were a scam, I see no point in putting chains on the car...

Also, the RX being a car based AWD system without locking diffs is never going to be as stable in the snow as something like your Yukon. Its just how it is, the vehicle is more of a compromise between the good aspects of a car and the good aspects of an SUV. So in a way yeah, the AWD system is "fake 4WD".

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Darn....

Now I find myself needing to defend the RX300 AWD system.

So, with snowchains only on the rear there is a definite difference in driveline rotational rates F/R, so the VC stiffens UP.

75/25???

But the BMW X3 is certainly feeling much more attractive than the RX330.

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Eh...

What I find more attractive than the RX330 on a whole is the FX35, but I'd get an RX330 over the X3 or X5 anyday.

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i just returned from lake tahoe( in our trusty 4wd suburan) and i noticed something interesting. I saw several ( at least 4 ) rx300s with rear tire chains. I never saw a subaru awd, or an audi awd, or a volvo awd, or a honda crx, or a x5, or a ML with chains. only the rx300s.it made an impression on me because before our trip, WWEST on another thread posted the comment that" a awd rx300 is a figment of Lexus' marketing imangination". so my question is, is a "awd" rx 300 a scam?

Ok, guys---- I'm out in the opposite end of the US, in Massachusetts, in

the high hilly country. I've only had my 2001 RX-300 since November, and

it's a AWD. Actually, it handles the snow AND the ice nicely. I haven't seen

any need for chains, except on my snowblower! I know Tahoe is definitely

higher than us, but so far, this drives far superior to all the cars I've had.

Owned a pickup, many moons ago, swore I would never buy another one.

PharmGuy

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Interesting thread, to a degree.

FWIW, given what I've seen when people are trusted to do 'smart' thing with cars, I'm rarely surprised by some of the bona-fide stupid things I've seen. Chains on the rear of this vehicle would fall, IMNSHO, in this category.

Last week, Portland, Mor(on)egon had some of the frozen precipitation. I had -0- problem with FWD in a ten-year-old Dodge Intrepid on tires which say "don't use in snow".

For grins, I took my wife and her '02 AWD RX300 out for a spin in a local ice rink of a parking lot, trying to make it do 'odd' things. To my dismay, and surprise, it was actually hard to get this vehicle to misbehave. Cut the wheel hard, goose it, hoping for some sideways action...nothing. The VSC kicks in and keeps the vehicle mostly on course. Though, there are some things which just can't be done in the ice, like instantaneous turns.

This is on the, IMO, ultra-cheesy Headstone tires, which, when on my Suzuki Grand Vitara, I couldn't replace fast enough.

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My ES300 is dead solid in the snow and its FWD, so the RX must be fine. RWD Lexus are another story...

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It looks like many RX300/RX330 owners are using all season tires in the snow. I believe this is a mistake and borders on dangerous. All season tires are a compromise between hot summer temperatures and cold winter temperatures. They are good at neither. Snow tires are formulated to have a softer rubber at cold temperatures which helps the tire grip better (remember that there are many days with cold temperatures and no snow). As well they have sipes in the tire to help grip ice and an agressive tread pattern for snow.

If you check out the Consumers Reports December 2002 page 61, they run through some comparison tests of all season tires vs winter tires for AWD and FWD vehicles. They measure the distance it takes to accelerate on packed snow from 5 mph to 20 mph. Here are the results:

1. FWD with all season tires: 95 feet

2. FWD with winter tires: 63 feet

3. AWD with all season tires: 42 feet

As you can see by the numbers, winter tires increase snow traction by approx 33%.

If you use winter tires on an AWD, the 42 foot distance should reduce to 28 feet. This is exactly my experience! I have 4 Michelin Artic Alpine snow tires on my RX300 and the traction is terrific. The traction control rarely kicks in due to wheel spin, even at significant throttle in the snow. Stopping and road holding is terrific.

Please remember that tires do three main things on your vehicle:

1. They provide traction to accelerate (this is where the AWD is an advantage since you now have 4 tires accelerating the vehicle)

2. They provide traction to brake (your AWD has no advantage in braking over any other vehicle...since all vehicles have 4 wheels for braking, they are all the same and depend only on tire traction).

3. They provide traction required to prevent your vehicle from sliding off the road during a turn or curve and again your AWD has no advantage over any other car on the road as they all have 4 wheels.

To summarize then, every car should have winter tires for winter driving and installing 4 winter tires on your RX300/RX330 will provide outstanding winter traction (and safety).

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Excuse me, BUT....

Screw the distance to accelerate to some specific speed!

In adverse roadbed conditions what's really important is what is needed to save or preserve your life!

And yes, on rare instances that might involve acceleration.

But in the clear majority of instances the time it takes to bring the vehicle to a stop or to change directions of the vehicle's motion is what is most important.

If you have any doubts at all about what might be under that layer of snow then use (drag) chains on the rear first and add front chains only if really needed.

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I don't buy it, the type of drive makes no difference in the stopping ability of the car. Sure, all season vs. winter will make a difference, but AWD vs FWD? Shouldn't. You agree with this fact, but your data shows otherwise, I don't get it...

As for winter tires, sure I agree that if you live somewhere that gets a lot of snow, then yeah winter tires are worth it. But if you get snow even just on a monthly basis, in all honesty all season are better. You talk about the minuses of all season tires in the snow, but what about the minuses of winter tires in the wet or the dry? Dry traction is radically reduced with winter tires (this is getting less so) and rolling resistance is dramatically increased. If you have no snow more days than snow, then I reccomend you stick with all seasons.

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wwest, you are missing the point. The distance required to accelerate to speed is a measure of the comparative traction of different types of tires on different types of vehicles. All the data shows is that winter tires have far more traction on hard packed snow. More traction = more safety any way you look at it.

You are correct when you say that the most important instances are braking and changing the vehicles motion, however sometimes you may also have to accelerate out of the way, so that is important too.

SW03ES, the data I show is for acceleration only. In this case AWD has a major advantage over FWD (and winter tires over all season tires) and this is what the data shows. You are correct and we agree that the type of drive has no effect on the braking ability of a car.

When any car is braking, the traction on all 4 wheels transfers the braking force down into the pavement, and this is what stops the car. For braking, the type of drive (i.e. AWD or FWD) is out of the equation and the only thing that counts is the traction provided by the 4 tires (brakes are assumed to be in good condition).

Incidently, this is why the first vehicles you see in the ditch every winter are 4 wheel drive. When a 4 wheel drive (or AWD) accelerates, they have such great traction due to all wheels being driven, that they have no clue how slippery it really is. Consequently, they overdrive the vehicle for the current conditions. When they try and stop, or go round a curve they find out how really slippery it is and slide off into the ditch, because their stopping and steering traction is no better than any other vehicle on the road (tire type excepted).

Winter tires and all season tires have equivalent traction on bare pavement at 9 deg C. The reason that winter tires have more traction at cold temperatures (wet or dry) is because the rubber compound is specifically formulated to be softer at cold temperatures. They also have sipes that flex and grab the pavement better. I agree that the rolling resistance and noise level increases but this is a small price to pay for extra safety.

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Ah okay, I misunderstood your figures, they make sense now.

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Back to AWD being a "scam," I just looked in my 2004 RX330 brochure and under drivetrain it specifically states:

"Type: Front-wheel drive (FWD) or full-time all-wheel drive (AWD)."

I also checked this on Lexus.com and it also says that the AWD is full-time. I keep reading on this forum that the AWD system is not constant... but it certainly states on the website and brochure that it is full-time. When talking AWD, are you guys talking about models before 04'?

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Well, "full time" only means that the system is always active, when in normal operating mode the RX330 is basically a FWD vehicle, which is best for fuel economy, then the system modulates power to the rear wheels when stability or traction is needed.

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RX330............AWD.........

The 04 RX uses an OPEN center diff'l and different final drive ratios F/R to bias the engine torque to the front by a rather large factor, say 98/2 F/R**. AWD engine torque apportioning is provided by braking any slipping wheel(S). With the front wheels "natively" achieving such a large portion of the torque AND having to handle the lateral torque during turning it is extremely unlikely that the rear wheels will have encounter a slipping condition.

What that means to you is that the ONLY time any significant level of torque is routed to the rear wheels is upon Trac braking application (to limit slippage) at the front followed fairly quickly by engine dethrottling if the driver doesn't react quickly and lift the foot feed.

** The RX300 used less desparate F/R final drive ratios (~3.12/2.98) than the RX330 (~3.48/2.92) and had 95/5 F/R torque biasing (actual 4WD dyno measurement) so I would assume the RX330 is closer to ~98/2)

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Soooo...... back to simple english for us less educated in this area of physics and automotive technology, is it really that important that front/rear power and torque is not 50/50? is it possible that the car might perform and handle better as an awd vehicle with the power distribution as lexus has done it?

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Well I'm starting to see what wwest is saying. No, it doesnt matter that the torque split isn't 50/50, few to no AWD vehicles are. 50/50 torque split requires a locking differential, something nowadays only found in "real" suvs with a selectable 4WD system. He's saying that because there is such a strong bias towards the front you'd be so unlikely to experience slippage in the rear that you'd never see any appreciable power diversion to the rear. When you look at it like that, you could make a case for the RX's AWD system being a "scam"

The only way really to know for certain is to drive two of them in the snow back to back and see if theres an appreciable difference.

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My old ’89 4WD Subaru had a LOCKable center diff, which was dangerous to use over dry pavement. It was a FrontWD or 4WD.

I always believed that my ’99 RX300 had a “ALL THE TIME” AWD compared to a PART TIME AWD. I almost purchased a Nissan Murano, but when I found out what it really is: FWD until front looses traction, then AWD! This means that the car must loose traction before the AWD system engages. I don’t want that!

What I understood is the early RX300s (’99 ’00) were mechanical AWD: center diff splits torque 50/50 front/rear, ALL THE TIME; when one end looses traction, the other gets more. Simple! The more recent RX300s have too much electronics for my liking.

I used to drive a ’92 Nissan 240SX with rear LSDiff. Lots of fun in winter! No fun with the RX300! I was hoping that the RX300 would also have a rear LSDiff, but not mine.

Nothing ever felt as solid as my old ’89 Subaru. But this RX300, with Bridgestone Dueler DM-Z2 is pretty rock-solid in snow and on ice. And we got plenty of both this year.

I wish that a mechanics from Lexus could clarify a bunch of “beliefs”!

FWIW, I drive a G20t with winter tires in winter and high performance summer tires in summer. Since my first set of Blizzaks in ‘93, I never drove a winter without them.

Be safe in snow

JB

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