Last post on Aug 21, 2013 at 5:16 PM
You are in the Toyota Sequoia
What is this discussion about?
Toyota Sequoia, Toyota Highlander, Toyota 4Runner, Toyota Land Cruiser, Toyota RAV4, Toyota Tacoma, Truck, SUV
Aug 08, 2002 (4:32 pm)
First off, you lost me on your first few paragraphs. All i was saying is that the "thumb blah blah" is what you learn when off-roading...i have NEVER seen it in any other context! Unsuspecting soccer mom?? Did the '99 RX300 with LSD have that in their manual??
Why would you want LSD on front AND also have VSC for a family car (RX300)?? I believe, for cost benefit, Lexus did away with that LSD feature. There was simply no need for it. I am sure that Lexus did not sell many RX300 with LSD in the first place.
If you are right, why did Toyota do away with the electronic locker on the rear axle when they incorporated the ATRAC/VSC in 2001??? E-locker, in theory, should NOT cause much problem for ATRAC, since ATRAC senses difference in speed/slippage. With E-locker, there is no difference, thus, ATRAC should not care. So, back to the original question, why did Toyota do away with the E-locker when they incorporated ATRAC?? BECAUSE it is NOT needed (from a cost $$$ view)...ATRAC does a very good job. A few 4Runner owners are actually trying to retrofit the locker onto a 2001+ 4Runner.
Aug 08, 2002 (4:53 pm)
I have never wanted nor championed front LSD, real or virtual. I have only tried to put into words my thoughts about why it doesn't exist and shouldn't exist, period. But most especially not in a FWD or AWD vehicle with FWD torque bias.
The 99 RX300 only had REAR LSD as an option. Rear LSD will not cause feedback to the steering wheel, thus no "warning" was necessary.
Hey, I'm on your side here, over on the GS thread at CL there seems to be TONS of boy-racers putting mechanical LSDs in their VSC/Trac equipped GS's. Unless they can figure a way to disable the GS's Trac the LSD will never wear out!
Again we seem to be talking at cross purposes. I am campaigning for Lexus to scrap the VC in the RX300 in favor of implementing the Sequoia's virtual AWD system, a clone of the ML's but who really cares
#573 of 2493 Excuse my ignorance...
Aug 08, 2002 (7:26 pm)
What is the definition of :
1. Virtual LSD
2. Virtual AWD
given : LSD = limited slip differential & AWD = all wheel drive
#574 of 2493 virtual vs real
Aug 08, 2002 (9:10 pm)
First we had actual mechanical LSDs, Limited slip differentials. And now we have virtual LSDs, devices that do not actually exist but yet serve as functional equivalents. Lexus Trac and Porsche's PSM have LSDs implemented in "firmware", using the rear brakes in a differential manner as a substitute for a mechanical LSD.
Virtual AWD, uses three open differentials which work fine to evenly distribute torque as long as all four tires have roughly equivalent roadbed traction. Once any wheel loses traction then the torque available at all wheels is equal to the amount needed to freely spin the tractionless tire. Except the virtual aspect then steps in and applies moderate braking to the tractionless wheel thus increasing the level of torque available to all four wheels.
"Virtual" substitution for center diff'l lock and front and rear LSDs.
Also see our company home page regarding "virtualization of legacy computer peripherals"
#575 of 2493 virtual lsd requires abs right?
Aug 09, 2002 (2:57 am)
So if you are going to off-road or be in other situations where you don't want ABS you don't have nothing but open diffs. I have and know several others who pull the ABS system when wheeling. I think you guys are talking about on-road stuff, although I've done some neat tricks in gravel with ABS too. Really shouldn't work under 25mph in my book. From that point to dead stop you aren't going to lose control by skidding. I've gone right into a couple slippery intersections because ABS decided I really didn't want to stop as fast as I was telling it to. Would you rather skid 5' or roll 10'?
Aug 09, 2002 (7:33 am)
Yes, these features make use of the ABS' hydraulic pump. And I would imagine not just a few people pull the pump fuse to disable ABS when off-roading. That will probably be less common as/if more vehicles like the Sequoia, ML, X5, etc, arrive on the scene.
And I have long contented that ABS contributes to as many accidents as it prevents, and recent studies and reports are now bearing that out.
On my 92 Jeep I would always pull the ABS fuse except during the winter months.
Now that VSC and PSM systems are becoming more common I fully expect that some manufacturer, sooner than later, will figure out that ABS could ALWAYS remain passive unless the "VSC" system indicates impending loss of directional control.
Also, there seems to be an accelerometer, AND a yaw sensor, in my 01 RX. A longitudinal accelerometer could be used to detect braking effectness in "real time", actually detect whether or not ABS should come online or remain passive for each and every braking application.
Aug 10, 2002 (8:22 am)
"...that VSC and PSM systems are becoming more common I fully expect that some manufacturer, sooner than later, will figure out that ABS could ALWAYS remain passive unless the "VSC" system indicates impending loss of directional control.
I've been holding back for a while, but have to say, I would suggest that you participate in an advanced driving course! :-p
Here's a good one, if you're willing to drive up to Vancouver.:
In all of the ones that I've attended, ABS was regarded as one of the most significant advances in braking. The problem is that most people don't know how to use it in a panic situation. In all of the panic stops exercises that we did, all of the ABS cars had far longer stopping distances than those with ABS. The reason was that threshold braking and modulation had to be utilised, which is basically what ABS does; pumping the brakes is an incorrect method, especially now that all cars have power assisted brakes.
It is nonsense that a car will stop faster with locked brakes than with ABS activated. When a tire stops rotating, it loses 30% of its traction versus one that is at its tractive limit. ABS keeps the tires at the tractive limit, albeit there are wide variations in the systems out there. Some are obviously far more advanced than others; the maximum traction point of a tire is when it is revolving at 15% slower than it would be if it were freely rolling over the surface. The more advanced anti-lock braking systems are better at balancing the brakes to this sweet spot. Additionally, without ABS, when one is on a split-mu surface, the tires on the side of the vehicle with less traction will lock up first, causing the vehicle to spin.
Watch this video clip:
ABS is not as good on loose surfaces such as gravel or sand, simply because locked front wheels will create a buildup in front of the wheels, which will help to slow the vehicle down. The MB M-class, for example, has a special ABS mode in low range which allows the front wheels to lock up cyclically which ABS remains active for the rear wheels. In low range, the ABS algorithm is also different from the normal ABS mode, allowing the system to remain useful in off-road situations.
#578 of 2493 Even easier...
Aug 10, 2002 (11:31 am)
Just look at all the car magazines. Whenever they test a vehicle with ABS and one without, you will always see one thing...the one with ABS stops significantly shorter (on dry land).
In addition, not just MB, but more and more SUVs nowadays are putting in different ABS modes for on-road and off-road driving. Toyota Land Cruiser has had one since 1999. I believe the '02 4Runner has one too. Nissan has one in it's Pathfinder.
BTW, MB's 4wd system is POS! You cannot turn off the stability system's "cut-engine-power" function. In the 4Runner, all you need to do is LOCK the center diff! Same goes for the Land Cruiser. So, please no more comparing our system with that of Mercedes...it is not fair for Mercedes!
Aug 10, 2002 (12:40 pm)
That's completely incorrect. There is an "ESP off" switch which turns off the torque reduction feature altogether. Unlike Toyota's system, the torque reduction isn't so sensitive. There is no need for any locking differentials in the ML since the traction control takes care of everything. The added benefit of this is that low range can be used for towing on dry surfaces, for example. Very beneficial for towing up hills.
MB's special low range ABS feature has been on all MLs since 1997, and it works only when you're off-roading at low speeds. Nissan/Toyota have some sort of ABS sensor which is supposed to read the road surface, however, it's not the same thing as it doesn't allow the front wheels to lock up.
Heh, who do you think Toyota copied the system off of? Just as Lexus claims to have invented dual threshold airbags in their commericals :-p
Aug 10, 2002 (2:13 pm)
I don't know, but a physician I know swears that MB steals all their breakthroughs from BMW.
Also, on the Toyota, the locking diffs are in addition to the traction system. So you can use 4WD Low while towing on dry sufaces on the Toyota too.