LexusLs400

Im considering buying a Rx3 and I would like to know about rollovers? Does the Vsc really help out? Is it easy to roll this SUV over? Whats the fastest turn you've made without flipping it over? Like freeway off ramps? etc.
This is going to be my first SUV.

Thank you!!!

SeaDooHHI

We owned a 1999 RX 300 until June of this year when we bought a 2001 4Runner. The 4Runner feels less likely to roll and you feel less body roll. However, the RX 300 is a stable vehicle, although it is a bit "quirky"

The VSC is much like the ESP system that most Mercedes have. Back in December or so, they tested this system with it turned both on and off on a Mercedes ML320. The vehicle lifted off the ground in an emergency lane change with the ESP turned off. When they did the emergency lane change again with ESP turned on, the SUV stayed sure footed. These systems really do nothing more than sense understeer and oversteer and correct it. These systems do help with stability in emergency situations. I can't recall if the RX 300 has TRAC or not, and if it does, I do not know if the one we had did have TRAC. I think all Toyota SUVs (including the RX 300, possibly the LX 470) except for the Highlander and RAV4 have VSC, TRAC, and Brake Assist.

Good luck with your purchase, you'll enjoy the vehicle.

BTW, the RX 300 just isn't us...too much like a minivan, which is one reason why we allowed the other company to buy it off of us.

wwest

First SUV purchase..

Really bothersome set of questions.

Why would anyone owning an SUV push it to the limits except in emergency manuvering situations?

Any vehicle with a high(er) center of gravity, that is descriptive of all SUVs, will be more subject to rollover than more "normal" vehicles.

I think many of , maybe even most, buy (AWD) SUVs for their wintertime performance on adverse roadbed conditions.

Some buy them for comfort, luxury, quietness, and reliability as their top priorities, those are almost exclusively RX300 customers.

The 99 and 00 RX300 had three open differentials so unless you optioned the LSD you bought a OWD vehicle. The Chrysler T&C AWD minivan would likely out-perform these in adverse roadbed conditions.

The 2001 RX300 included TRAC and VSC when should bring the RX up to par with the MDX but Lexus for some reason has been reluctant to use the famous ML series "test" to prove it so.

If you are buying an SUV primarily for performance in wintertime conditions stick to the ML or X5.

salimshah

VSC and TRAC relate to skid (traction of wheels on the road) while roll over has to do more with ceter of gravity, wheel base, weight and suspension. Some of the factors are dynamic ... based on speed of the vehicle.

At posted speed and NORMAL driving the roll over is virtually impossible for RX. Under quick avoidance conditions, I personally have not rolled over

I agree that there is more body roll and it can be attributed to the soft ride. IF it bothers you, test out the X5 sport.

SUV are NOT suitable for high speed maneuvers. For normal driving, I have not heard of any RX stories such as Explorer/FireStone or Suzuki Samori (sp?)

Please get a car if you intened to do sharp turns. Even those roll over if pushed beyond safe limits.

PHYSICS rules!


Salim

mooretorque

Willard, is it me, or are you grumpy today?

Ls400, it's not EASY to roll any SUV, though I'm sure you can if you try. Trip any car going sideways on, say, a curb, and you'll likely roll as well as peel the suspension off the side that contacts first. If you want something to rally with (or pretend you are), try the Subaru WRX.

What it really comes down to is, what do you want the vehicle for? Different car/trucks have different designs for a reason. Give us more specifics and we can give you a better answer....

LexusLs400

Sorry guys. what I would like to know is how is it in emergency handling? Can it handle a hard turn if I need to, to avoid accident. Thank you!

wwest

The only reliable source for that type of information is the agency that actually performs rollover tests on various vehicles. You can come up with "static" calculations but those don't have any allowance for differences in vehicle suspensions.

The first thing I did when I bought my 2001 RX was upgrade to 17" wheels/tires, plus 1, and that required spacers all around. So my RX ended up with about a 3" wider stance, more stability due to narrower sidewalls, and more rubber on the road.

And I doubt if any of us will ever take the time, during an emergency manuver, to check our speed.

Mooretorque is right, any SUV will be "difficult" to roll over, but my advice would be to do you absolute best not to go there. Defensive and careful driving is your best way to avoid rollovers regardless.

Don't push it...

RX300TC

How come nobody can just answer the poor guy's question?

Yes, it's emergency handling is great because of the VSC. Consumer Reports will have tests on this. The system is similar to ESP on the MB. Here is a great story on the subject http://more.abcnews.go.com/sections/...r_feature.html

The full-time 4wd is great... I usually take curves faster than I can do in my sedans. If it wasn't for the body lean, I could probably go faster. And that's with the less than optimal GY Integrity tires. Switching to a better brand like Michelin should increase handling even better.

Test drive for yourself and decide. Good Luck.

willard west

Full-time AWD is great...

You have four wheels on the ground.... four points of contact with the roadbed. Assume equal size tires, inflation etc, and equal weight distribution. For absolute maximum corning (this is an emergency, remember?) it is NEVER desireable to divide the traction of the front wheels by using them partially for turning and partially for "driving". An AWD has the very same problem in this respect as a FWD, unless you get off the gas and shift into neutral (to avoid engine braking to the front wheels) in a "hard" turn, part of the front tires' adhesion with the roadbed is dedicated to longitudinal forces.

This is one of the primary reasons most FWD "stock" cars are converted to RWD for racing. It is also the reason an AWD/4Wd with rear wheel torque bias has better "marginal traction" value.

ObiDon

Willard. when are you going to come out of the closet and get that Dodge minivan AWD and go to their form? Also were you like this before the rats bit you?

willard west

VSC

How hard was it for you to learn to steer into a skid?

The rear end of the car is coming around, skidding, toward a brick wall, and now you have to turn your car in that direction. Scary, Huh?

That's part of what VSC will do for you, just as soon as the yaw sensor detects that the car's movement is out of "whack" with the desired path, it goes to work to help re-align the car with the desired path. This will normally happen long before your "seat of the pants" yaw detector senses anything.

The effect I described above is called over-steering. Since the RX300 is predominantly FWD, a 70/30 front/rear torque bias at best, it is extremely unlikely that the RX300 could ever experience this effect. The only way this might happen in the RX300 is as a result of engine braking of the front wheels, the rear end might want to "pivot" around them. Lexus prevents most cases of this, engine braking predominantly to the front wheels, by shifting the transmission to over-drive immediately upon detecting a throttle lift to idle.

VSC is also supposed to help prevent under-steering, "plowing". Personally I can't see how VSC could be used very effectively to do this in a FWD vehicle.

willard west

Recently you submitted a question to the Lexus Customer Satisfaction Department.

Subject:
AWD


At 10/17/2001 07:49 AM we wrote -

Dear Mr. West:

Thank you for contacting the Lexus Customer Satisfaction Department. We appreciate your enthusiasm in our product. I apologize that our department is not designed as a technical center. We rely on our Lexus dealers for technical information since they have been trained on the systems and components of our vehicles. Please contact your Lexus dealer for answers to your questions. I am sorry that I am unable to be of further assistance to you regarding technical questions.

Your Question:
I have both a 2000 Chrysler Town & Country AWD MiniVan and a 2001 AWD RX300. Both of these, as near as I can tell, have virtually the same mechanical driveline setup for AWD. Other than the addition of TRAC on the RX, the only real difference is that the Chrysler has an over-running clutch, used to bypass the viscous clutch in circumstances of severe braking.

Chrysler tells me that even in a normal braking circumstance the front wheels, with 80% of the "braking" "duty", turn slower than the rears. Without the over-running clutch to bypass the viscous clutch, even at the the nominal "low" coupling coefficient, the rear wheels might lock-up. If the viscous clutch coupling happened to be fully "firmed up" in this circumstance it would be certain the rear wheels would lock-up and turn in virtual synchronization with the fronts.

Chrysler says that the extra clutch is put there primarily as a safety measure to help in preventing the rear wheels from locking up and causing the vehicle to skid, or over-steer. Additionally, without the over-running clutch to bypass the nominal, or in some instances potentially quite firm, viscous clutch coupling to the front wheels the overall integrity of the entire drivetrain would be compromised.

I have seen nothing in the Lexus literature indicating an awareness of what appears to be, potentially, an extremely hazardous condition or circumstance, one which most RX300 owners could expect to encounter fairly often.

Should I be concerned for my safety and that of my passengers?

Or is there something different about the RX300 AWD design that alleviates the need for uncoupling the front and rear axles in these ("firmed up" viscous clutch and severe braking) circumstances?

Willard West



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RX300TC

Everybody in the world (Lexus and the automotive press) says the 2001 RX300 is a 50/50 torque split under normal driving conditions. I guess you are smarter than everybody else who writes about cars for a living? Who've presented no hard facts other than your opinion that the 4WD (that's what it says on my invoice sticker, not AWD) is anything but what Lexus says it is.

Stop it with the 99 and 00 references. Nobody is talking about those models other than you.

You've posted your messages all over every discussion here about your perceived defficiencies in the drive train, air conditioning, and anything else your little ego wants to spew forward. We've all heard your message over and over. When do you stop? Can you give us a hint?

Please go out and buy whatever vehicle you perceive to be better than the present RX300. Then go bother those poor folks with your opinions.

willard west

TC..

Like I have said before, when I see something from Lexus itself, in writing, that disputes my position, then I'll back off. As you well know, and somewhat due to prompting by yourself, I have tried many times and many ways to get Lexus to "come out of the closet" and actually define the nature of the RX300's "full-time" AWD/4WD, so far with no success whatsoever.

In the meantime when someone asks a question such as the one on this thread I will continue to respond and allow the reader to judge just how valuable the information is.

"50/50 split under NORMAL driving conditions"

As I have also said before I DO NOT disagree with this statement.

I don't think you would deny, or anyone else for that matter, that Lexus uses a viscous clutch between the front axle and the rear axle. They do this primarily to prevent drive line "wind-up" when the front axle has a different rotation rate than the rear, as in a tight turn.

A viscous clutch is a "fluid" coupling, you can think of it as a "rubber band" belt drive that decreases its elasticity, dramatically, as you stretch it.

"Normal driving conditions" If all four wheels have equal traction then there is no stress on the "drive belt" (rubber band), so certainly, or logically, but not ethically, Lexus can say that defined in this very narrow, and totally improper, way, the RX300 has a 50/50 torque distribution.

But most of us buy SUVs for their performance in abnormal, or even slightly abnormal, driving conditions. And it is under those conditions that the RX300 becomes truly a FWD vehicle.

Why do you think it might be that the manufacturers of the MDX, the ML, the X5, the JGC, etc, make full and complete disclosures about the actual workings of their full-time AWD setup while the best Lexus will do is refer us to the dictionary definition of "viscous clutch".

RX300TC

First, you do more damage than good because you make your "facts" up. Where do get 70/30 split from? It's just your opinion and you make it sound like fact. Face it, you like the sound of your own voice.

Here's the response from Lexus, though it probably won't satisfy you (you're very predictable):

----------------------------

Dear Mr. *******

Here is the information I received from our technical support:
For the 2001 four-wheel-drive RX 300, power flows from the transmission to the wheels through three differentials. The front differential serves the front wheels, the rear differential serves the rear wheels, and the center differential serves the front and rear axles. In addition to mechanical gears, the center differential includes a viscous coupling. On limited-traction surfaces, the viscous coupling will help provide power to the axle that has more traction. Under most driving conditions, power will be delivered to all four wheels.
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