Howdy, Stranger!

It looks like you're new here. If you want to get involved, click one of these buttons!





Toyota Highlander Hybrid Transmission Questions

2

Comments

  • terry92270terry92270 Posts: 1,247
    In 4 Wheel drive, like the old Jeeps, etc....you actually had to get out, lock the hubs on the axle, to get it. It was equally divided among the four feels.

    AWD is, or was, generally capable of four wheel drive, wherein the computer and sensors transferred power to all four wheels, on demand, as needed, in various percentages.

    Most other descriptors are merely marketing ploys, and not technology. ;)

    It could have better been presented to the public as On Demand 4 Wheel Drive, not "just" AWD.
  • cdptrapcdptrap Posts: 485
    I wish whoever invented these terms were more careful. This is how I see the differences after years of driving 4x4 or 4WD as it was originally defined.

    4WD or 4x4 normally has a locking differential, solid axles and springs and shocks that gives a lot of room for the tires to "extend". Such a car can put power to all 4 wheels and also has tranmission gearing that offers 4 High and 4 Low.

    Locking differential, when locked (manually), allows all four wheels to turn at the same speed with absolutely no chance of any wheel spinning free. When it is not locked, one wheel can often turn faster or slower than another wheel depending on terrain and driving condition. This allows spinning to occur. Spinning, at least in my experience, causes problems because when a tire spins on a smooth surface (boulder, rock, sand), it is not helping my truck to move along the trail. While the wheel on the other side of the spinning wheel can still work if it has traction, it now has actually less power to use to move things along. Spinning also causes jerks and slips and slides, all very very bad on rough terrain that requires precise control. With a fully locked diff, the tires must move at the same speed. So the tire with less traction still must move at the same rate as the tire with traction. It really keeps my truck moving nicely especially when I am a bit tilted and having to drive on the side of a rock (off-camber?). I used to do a lot of work on farms and ranches, so we learnt these things from old-hands who passed along their knowledge.

    This is why in demanding off-road condition, we prefer fully locked differential, not the popular "Llimited Slip Differential" which still allows the wheels to move at different speed. With power into all 4 wheels and the locker, the car can really do some crawling with authority.

    4 High in general refers to the normal gearing we use for everyday on-road driving. 4 Low is the low speed, high torque gearing we use when we have to haul a really heavy load or when we have to negotiate really nasty terrain at low speed. We will lock the differential, shift into 4-Low and work our way through rocks, deep ruts, sometimes mud (not always) or deep snow and so on at low speed.

    Run-of-the-mill AWD in general does not offer locker, does not offer solid axles and does not offer 4-low. While it still powers all 4 wheels, it is not capable of heavy duty hauling or demanding off-road work. Such AWD system is either part-time automatic or full-time requiring no driver input. That means you do not have to jump out to lock the hubs. On paved surface, this capability does make the car safer especially when integrated with modern Traction Control; so everyone is selling some form of AWD for on-road use.

    Another way to see this is that while 4x4 uses a locking differential and low gear to provide "Traction Control" and eliminate wheel spin, AWD uses power-reduction and Anti-lock brakes to eliminate spin in a wheel.

    New generation AWD (Lexus, Mercedes, Land Rover, Ford, Jeep, etc) now offers some form of low-gearing in some of their AWD models. I recall seeing a SUV in the 80's (Ford Explorer?) that had switches on the dash that switched between 4Hi and 4Lo.

    Amidst all these confusing marketing terms, I now use the terms "4 by 4" or "4x4" to mean the real-life old style truck that offers locker, 4Lo. Everything else is some form of AWD. When talking to salesman, I ask very specific question to be sure we are talking about the same thing. It is pays to actually see the car and actually ask where is the 4Lo? Where are the hubs?

    The 4WD-i HH is definitely not a full-time AWD or 4WD or 4x4. It is a FWD first and automatic on-demand AWD second.
  • wwestwwest Posts: 10,706
    Is that AWD never requires driver intervention, should really be referred to as AAWD, Automatic All Wheel Drive.

    And sorry, there can never be, WILL never be, an otherwise satisfactory definition of AWD, 'way to many variations in the design methods for impleenting AWD, SH-AWD likely being at the top of the list insofar as functionality, and those with a simple open center differential with brakes used to apportion engine torque being at the bottom.
  • stevedebistevedebi LAPosts: 3,719
    "The more "conventional" CVT uses a dual pulley belt drive wherein the ratio of one pulley vs the other is continuously variable."

    Close, but no cigar. The good quality CVTs use a chain, not a belt.
  • wwestwwest Posts: 10,706
    Sorry, can't agree, exactly, it IS a metal "belt", metal to metal friction drive, not a metal "chain".

    I don't exactly disagree with calling it a metal chain, just that it conveys the wrong impression for most readers.
  • stevedebistevedebi LAPosts: 3,719
    "I don't exactly disagree with calling it a metal chain, just that it conveys the wrong impression for most readers."

    Well, the word "belt" conjures up the image of a timing or pully belt in the engine compartment. That is a lot less durable than high strength steel.
  • wwestwwest Posts: 10,706
    Ooops....

    Age differences have struck again.

    To me, belt, when used in an automotive context, relates to fan belt or serpentine belt, completely over-looked the ribbed or cogged timing belt.
  • Don't try driving your HH AWDi on ice. We ahve a big hill near our house and unless you get a running start, the HH will quit 1/2 way up and slide uncontrollable backwards. The AWDi/traction control just stops work when all the wheels start slipping. Since there is no "low" gear, the transmission just wants to accelerate and cuts off when it sense the RPMs are too high and there is not traction.

    Being the cynic I am, I think this was done so Toyota will not have electric motor/transmission problem that would be covered in their 100,000 mile electrical drivetrain warranty. Sheetmetal and structural damage is covered by the owner!
  • cdptrapcdptrap Posts: 485
    Wow, you hit a worst case scenario where all four tires lose all traction. THANKS for sharing the experience. Do you have snow tires on your HH? I am just wondering if good snow tires will make a difference. We got our set of four snow tires but we have not put them onto our HH. Sounds like I have better do it.

    I believe when there is a total loss of traction, not even a HUMMER can do much but slide. We have had some interesting experience in our 4x4 V8 Chevy on tall wet grass. 4x4 or not, low gear or not, once the 4 tires lose all traction, the truck will slowly but surely slide backward. We used to have a 4x4 Jeep with a rear mount post-hole digger (used car purchase) for digging fence posts. After that thing slipped and slid down a steep grassy slope, we ended up calling the pros. They came in with a tracked vehicle. I guess when the "HUMMER" cannot do it, it is time for the M-1's :).
  • stevedebistevedebi LAPosts: 3,719
    "Don't try driving your HH AWDi on ice. We ahve a big hill near our house and unless you get a running start, the HH will quit 1/2 way up and slide uncontrollable backwards. The AWDi/traction control just stops work when all the wheels start slipping. Since there is no "low" gear, the transmission just wants to accelerate and cuts off when it sense the RPMs are too high and there is not traction."

    I suppose it is on another HH topic, but this has been discussed recently. The TC will stop the wheels from moving; overheating the AWD electric rear motors will stop the AWD from working.

    Yes, Toyota is preventing the components from burning out. The HH AWD is not meant for anything resembling off-road use, which I guess also includes your icy climb.
  • wwestwwest Posts: 10,706
    Sounds like a circumstance wherein my Jeep Cherokee Limited would have needed all four tire chains....

    Even the non-hybrid AWD RX300 VSC/Trac system will time out to protect the ABS pumpmotor after about 45 seconds. That is if you don't first get a CEL & VSc fault due to vehicle speed sensor, P0500, faulting.
  • gowhittengowhitten Posts: 11
    An update from last winter: On that same icy hill, if I go up in REVERSE, the AWDi (read - stupid) does not react the same and I do not have problems with the ICE shuting down the electric motors.

    Reminds of when I was growing up in Cleveland and we lived on steep brick hill. We drive our RWD drive car up the hill in reverse - and scrape the curb for added traction.

    BTW - Chains would have solved the problem - but what a pain for a such a short hill. My neighbor's FEH does not have any problems.
  • stevedebistevedebi LAPosts: 3,719
    "An update from last winter: On that same icy hill, if I go up in REVERSE, the AWDi (read - stupid) does not react the same and I do not have problems with the ICE shuting down the electric motors. "

    Oh, my. I hope Toyota isn't reading these forums. Apparently they forgot to put in the TC systems in reverse!
  • gvurgvur Posts: 2
    I think they maybe purposely provided us with means to "backout" of a bad situation will preventing continue forward movement into potentially more trouble...
  • rogcurtisrogcurtis Posts: 3
    This is required every 15,000 miles. How many are they? Where do I find them? What is the Torque? Does a safety cap/pin need to be removed? Has anyone done this?
  • wwestwwest Posts: 10,706
    Huh...??!!

    I think that only applies to the F/awd HL since the F/awd HH doesn't have a drive shaft.
  • rogcurtisrogcurtis Posts: 3
    I got the information to re-torque drive shaft bolt on the Highlander Hybrid from the website "toyotapartsandservice.com"
  • rodonnellrodonnell Posts: 37
    I believe the answer is.....220 FT LBS. I found this spec on the ALL DATA website for the 2007 Toyota Highlander Hybrid. Apparantly this refers to the 4 (Four) driveshafts that extend from the electric motors to the wheel assemblies. They are attached with a 35MM nut at the axle end and are hammered over to prevent loosening.

    I posted a note on this subject long ago with no replies, only turned into a read only thread. I had asked the Toyota dealer about this and got very vague responses.

    My 07 has 102,000 miles on it now, and I have never actually retorqued the bolts, rather I only visually check to make sure none of the nuts have moved off the hammered over spots. I do this when I rotate the tires.

    In my experience, whenever these axle nuts are taken off, on any make or model of automobile, they should be replaced, not simply put back on. Makes no sense to me to loosten then retighten the nuts.

    Just my 2 cents.
  • rogcurtisrogcurtis Posts: 3
    Thanks for the excellent information. The hammered over is very obvious when the wheels are removed. Yours is the only information I have on this subject. Thanks again.
  • wwestwwest Posts: 10,706
    220 FT LBS....That is one HUGE number and cannot possibly be correct. 220 INCH LBS might be closer.
2
Sign In or Register to comment.