o4 6 basic , cd in dash, roof rack, side air bags(hard to find in basic) , moon roof, JBL stereo upgrade, remote key, illum vanity mirrors, power seat, alloy wheels, privacy glass and probably some other stuff for $27,714 which included the $300 south carolina sales tax (capped at $300 in south carolina)
added a hidden hitch off the web for $145 and harness for $44. 10 min install.
I need an honest opinion. I am shopping for a new vehicle. I live in Baltimore, MD and the last 2 winters were very snowy. To get to my house I have to climb about 200 yards driveway that is about 25-30 degrees steep and when it was covered with snow and ice, I had a tough time getting up with my front wd Highlander. Snow would melt during the day and refreeze in the afternoon. I don't go off road and my only concern is to make it to my house. Is 4WD Highlander would be sufficient or should I buy 4 Runner? Thanks for your comments.
The highlander is AWD but beyond that it is predominantly front wheel drive even in AWD dress. FWD, and/or front biased AWD vehicles can become very hazardous in the circumstances you describe. When engine torque application results in loss of driving traction you will also have a loss of directional control.
But I suspect that under the conditions you describe not even the 4runner would be satisfactory absent the use of snowchains. And if snowchains are required in any case then the HL can be workable with wheel spacers at the rear to make room for snowchains.
I can't remember where I read it, but the AWD '04 HL has a 50/50, front/rear axel distribution. Maybe the earlier models are a higher distribution front to rear.
I was really hoping they would offer this in the '04 as I am getting ready to purchase one. I would wait for the '05 (since I already own an '02) but my dilema is to take advantage of the still low interest rates and incentives.
Memory seats, that's one feature I will pay for too. I am sure a lot of you guys out there share your car with your wife/husband and every time after he/she drove it, we will have to re-adjust the seat. What a pain in the butt.
Personally, I don't see this feature will be offered under any HL. Even a more expensive car, it's still hard to find they have memory seats.
I can vouch - my Highlander is AWD with about 50/50 split. And no - its not only when there is good traction.
I was parked on soft dirt and accelerated hard - I left 4 equal sized scooped out divets in the dirt. To me - that shows that both front and rear axles getting equal torque. Its not a controlled experiment - but it doesn't explain the theory of 90/10 torque split.
I may be wrong but wwest doesn't own a Highlander - but an RX300?
For the last few years, I have been reading wwest comments about the Highlander not being AWD but 90% front wheel drive / 10% rear.
All I know - my rear wheels can dig out just as much dirt as the front ones do. Never been stuck never have a problem.
The following is a quote from Edmunds 2003 review:
"The Toyota's full-time all-wheel-drive system is always on, splitting power 50/50 front and rear via a viscous-coupled center differential. The system overcame every limited traction scenario we encountered without difficulty. Judging by its performance, we believe the Highlander could easily handle a rutted or snowy road to a vacation home, trailhead or remote beach. Ask more of it than that and you may be calling for roadside assistance."
It is my understanding that with the advent of the 04 MY the Toyota Sienna, HL, and the RX330 all share the same AWD system. For 04 the viscous clutch has been eliminated entirely in favor of s simple open center diff'l and the use of the brakes to apportion engine torque when necessary.
The brake apportioning system will not activate unless the ABS wheelspeed sensors indicate one wheel or wheels is turning, spinning, faster than others.
Note that wheelspin must occur before the torque apportioning system comes on-line. A clear indication that the instant a wheel looses traction the 50/50, 25/25/25/25, torque distribution "rule" becomes "null".
The same is true of VC use in prior years.
Prior to 04 the HL and RX shared the same AWD system using a viscous clutch ACROSS the open center diff'l to eliminate extended periods of disparate front/rear rotational rates.
And pardon me, but I don't think any automotive magazine writer knows "beans" about the actual design and/or implementation of any of the modern day systems, ALL inclusive, they generally just parrot the propaganda put out by the factories.
And yes, it is a 2001 AWD RX300 I have.
And now to those four divots....
Wouldn't you agree that any FWD or RWD vehicle would have driven away from that spot just as quickly as you did?
Assuming your experience was with a MY prior to 04 and ignoring the VC for the moment the center differential in the Toyota AWD system will act exactly like the normal rear or front open differential as long as the effort required to turn both of the differentials output shafts are roughly equal.
How many times have you seen a RWD or FWD non-turning vehicle spin a wheel on one side and not the other when the roadbed is NOT slippery. Sand and loose dirt and "fine", pea gravel surfaces DO NOT constitute a slippery roadbed.
By it's very design the VC cannot come into play and provide any substantial level of locking of the center diff'l in a constant or instantaneous manner. To do so would result in long term damage to the driveline each and every time you turn a corner, especially so for accelerating tight turns.
The "viscous" fluid is formulated to have a very high volumetric expansion ratio with temperature. When the two output shafts of the center diff'l start to turn at disparate rates the fluid between the tightly spaced interspersed clutch plates is rapidly heated by the shearing forces and since the volume of the hermetically sealed VC container is FIXED the pressure between the clutch plates increases dramatically thereby increasing the coupling coefficient between the clutch plates.
We're talking about hundreds of milliseconds for the VC to reach even a low lock level and several seconds for it to reach a locking level of any real benefit. As one can readily see, it cannot sustain anything close to 100% locking of the center diff'l, thus the 70/30 measurement I obtained with sustained "slippage" on a 4 wheel dyno.
One of the things I discovered during the winter snowstorm this past year was that my RX's Trac system dethrottles the engine long before the VC has an opportunity to react to wheelspin. That's very likely the reason the VC was eliminated, the Trac system made it useless anyway.
The only Toyota vehicle available with memory seats is the Avalon XLS and even then only with the optional "Premium Luxury Package". Maybe this will become more main-stream one day, but Toyota needs to keep these luxury distinctions between HL & RX to justify the price gradient.
Not sure how many know why the center diff'l MUST "initially" be OPEN for AWD systems. These are basically systems which automatically add some level of locking to the center diff'l during extended periods of wheelspin.
When you enter a turn the front wheels turn at a different rate than the rear, the tighter the turn the greater the difference in F/R rotational rates will be.
Anyone who has driven a 4WD "part-time" system while actually engaged on a high traction surface can describe the effect. With the center diff'l locked (RIDGID mechanical coupling/linkage) the front and rear drivelines MUST turn at equal rates. With no slippery roadbed surface to provide the "give" or "slack" while turning, the driveline winds up until the windup torque exceeds the tires' traction coefficient, and then the tires "scrub", slip, to release the mechanical windup.
Probably not just a few busted fingers and knuckles as a result of the feedback to the steering wheel during this effect. 4WD owners are taught, or else quickly learn, to keep fingers on the outside of the steering wheel when the 4WD system is engaged.
So, the problem for automotive design engineers was how to provide an "automatically" engaging all wheel drive system. A system that ONLY engaged with actual wheelspin, and not the apparent wheelspin resulting from simply entering a tight turn.
I admit that I'm a bit surprised that some enterprising young engineer hasn't come to the realization that steering wheel position "off-center" could be used as an indicator to disengage the center diff'l "lock".
You can probably get a good idea of how effective a VC implemented AWD system is, how quickly it comes "on-line" and how ridgid it becomes, by driving your vehicle on a high traction surface in a tight circle as fast as your comfort level allows. But be sure and keep your fingers on the outside of the steering wheel since a good system will quickly begin to scrub the tires and just might jerk the steering wheel from your grasp.
I understand all about VC. But have you considered that in the HL the engine output drives both sides of the drivetrain simultaneously through the automatic transmission?
In your scenario - the engine drives the front axle, while the rear axle is connected to the front by a center VC. This is not the case. Both front and rear axles are connected to the VC which is part of the automatic transmission. This is how they can get each side to be 50/50 split and it doesn't rely upon the front drive train to drive the rear through a slipping center VC
You can say whatever - the HL is 50/50 split front rear.
the 00 and/or 01 AWD RX300 Lexus shop manuals (I have both), tranny volume:
The transmission (not "technically" transaxle)output directly drives the input to the center diff'l (drives the center diff'l outer case in actuality) then one output "shaft" of the center differential drives the front differential and the other the rear driveline and thereby the rear differential.
The two input shafts of the VC are connected, one each, to an output shaft of the center diff'l. There is NO locking of the center diff'l unless or until the viscous fluid can react to differential turning rates of the two output shafts of the center diff'l.
Think about it, seriously, if the system had full time or instantaneous 50/50 coupling that would be an exact equivalent to an engaged 4WD part-time system and the driveline would be destroyed in short order due to the continual windup stress during turns.
According to all the public information - the HL is AWD with 50/50 split.
And NO - the drive line would not wind-up as I said - front and rear are connected through a VC in parallel to the automatic transmission (not in series). I have the 03 Highlander shop manuals - which describes the HL drive line better than the RX300 shop manual (which is a different vehicle.
Let's take a part-time 4WD system and put it in 4WD mode wherein the front driveshaft is solidly locked to the rear driveshaft. 100% of the available engine torque is delivered to that "single" driveline. Both the front and rear wheels have good traction so the split is truly 50% front and 50% rear, or just as you state, a 50/50 F/R torque distribution ratio.
And that all works perfectly fine as long as I'm carefully going STRAIGHT down the road. But now suppose I come to a curve in the road. Wouldn't you agreed that something has to "GIVE"?
In rounding the curve the front wheels will undoubtedly cut a larger radius than the rear wheels. That means the rear wheels will be turning slower than the front wheels and therefore if something doesn't "give" the driveline will eventually fail. Unless, that is, the tires are scrubbing so much that they quickly overheat and blow out.
All of the above is really for naught since everything I have said so far has been published and taken as absolute gospel for many many years.
You cannot drive a vehicle with a locked center diff'l, (forced) 50/50 torque split, on our highway tractive surfaces without doing serious damage to the driveline.
Now, it should be obvious that if one could come up with a way to automatically disengage the 50/50 split mechanism (of whatever ilk) upon entering even a slight turn there would be NO problem.
Or in the alternative what if one came up with a way to only engage the 50/50 torque split if a wheel or wheels began to slip?.
And that latter approach is exactly how the VC works.
Take any 2WD vehicle that doesn't have any type of LSD, real or virtual. With both wheels/tires firmly on a tractive sirface the left and right axles will each deliver 50% of the engine drive torque. Now lift one of those wheels off the ground, or encounter a patch of ice at one side of the roadbed, and suddenly the available engine torque is reduced to almost zero because the tire with no traction doesn't take much torque to spin it freely.
But is the torque distribution still 50/50??
YES, ABSOLUTELY!
That why Toyota or Lexus, or whomsoever, can make the 50/50 torque split statement truthfully.
But now, does the fact that the system still has a 50/50 torque split do you any good?
ABSOLUTELY NOT!!
With one wheel spinning freely it is extremely unlikely that the 50% torque level still being delivered to the other end of the open diff'l will move the vehicle off dead center.
The very same is true if we now place the open diff'l at the center, absent an LSD somewhere, one wheel loosing traction results in your being STUCK.
The VC contains a fluid which under extended front vs rear wheelspin will "stiffen" and steadily increase the center diff'l locking factor as long as the disparate f/r rotational rate persists or the greater the rotational difference is.
There is one other circumstance wherein the front driveline should not be locked to the rear driveline. And that is during moderate to heavy braking. Many modern day AWD/4WD systems automatically disable the Antilock braking system when in "locked mode". Some of the newer systems only allow locked mode in low range, granny-grunt low, for the same reason. At the higher speeds attainable in locked 4-hi the potential for loss of vehicle control due to rear over-braking is too great.
An open differential always delivers a 50/50 torque split, and its advantage is that by default it instantly causes the total available torque to be reduced to only twice that required to turn the output shaft with the lowest resistance.
The design problem is to maintain those open differential advantages while at the same time finding ways to keep the total available torque at a fairly high level.
The new 04 models, HL, RX, and Sienna, and I think the 4-hi mode of the Sequoia and possibly others, use the brakes to apportion and maintain a high level of engine torque if a wheel or wheels begin to spin, basically a "virtual", or simulated LSD.
If you choose to call that traction control then find by me.
The actual traction control firmware only comes into play if the use of the virtual LSD capability doesn't fairly quickly result in eliminating wheelspin, and then only to dethrottle the engine to prevent rotor warpage from overheating.
your description of traction control is absolutely correct for 2WD vehicles, front or rear drive. In that case if any driven wheel slips then the brakes are applied (moderately??) to both driven wheels and here again if that doesn't quickly result in restoring traction then the engine is dethrottled.
Ask any Sequoia owner who has tried to use engine revs, spinning wheels, to get unstuck from a mudhole while in 4-hi (AWD for you, except the Sequoia has definite rear torque bias). The engine dethrottling prevents any serious wheelspin, and about 45 seconds later the entire ABS/BA/VSC/Trac system BAILS to prevent the ABS pumpmotor from overheating and failing.
an 04 Limited 4x4 White... not sure how I feel yet. Not as comfortable as I expected. NOISY..don't open the back windows! Feels "small" in the front...leather seats seem skimpy and are not comfortable to me. Purchased in Tidewater Virginia. Paid under edmonds recommended price but still seemed high for the car. I was also considering an MDX and worry that I screwed up. Sister got a Limited 4Runner and that's NICE...but it seemed TOO big to me...I sound like Red Riding Hood, don't I! I think running boards might improve appearance. Any thoughts?
Sounds like normal second guessing most of us go through after a big ticket purchase - enjoy the ride for a few weeks and see how you like it. And fiddle with the seats some to find the sweet spot.
Congrats on the new ride!
Steve, Host (If you do decide to move on, at least you purchased one of the better SUVs from a depreciation standpoint).
I'm sure over time that you will be able to get past these issues. Did you notice any of these "problems" during your test drive? My wife drove a Highlander, Pilot, and Murano back to back and that made it clear that the Highlander was best for her.
I think others have given good advise, but I will add one comment: You mentioned that running boards might improve the appearance. Appearance is a matter of personal taste, but I once had running boards (92 Ford Exporer) and they were not useful for getting in and out, and in bad weather, they always got my pants dirty. Something to think about.
I have only seen a couple HLs with running boards and I thought they detracted from the appearance. They look OK on big truck-based SUVs but I think they look silly and out of place on the car-based models. YMMV.
Comparing 1994 Camry with 2004 Highlander (I like my Highlander a lot, but I think Toyota has cheapened the product)– build differences to me are:
1. Factory Front Floor mats – weigh 3.5 pounds each in the 94. Weigh 2.25 pounds in the 04 – very thin in the 04. 2. Rear view mirror is on a metal post on the 94. It is glued onto the W/S in the 04. Will probably fall off in 5 years. 3. Gas cap only has two lugs on it such that to put it in the door holder, you have to line up the two lugs with the holder(dumb) the 1994 gas cap fits in the holder any which way. Toyota probably saved all of 10 cents on this one. 4. Fuel release lever is 1/2 the size of the 94 (smaller on 2040) 5. Passenger side window switches are smaller. 6. I did not have a keyless remote in the 1994 but the 2004 remote is very sensitive, when I put it in my pocket it frequently beeps the lock or unlock function. Toyota screwed that up – very little button movement will set it off. My mom’s Buick you have to push it down almost 1/8 inch. Least the Toy has a chirp noise – the Buick and most Fords blow the horn. Bad in a city.
You're right, cars have been cost reduced in the last 10 years. It's a fact of automotive life that if you don't keep your costs under control, you go out of business. Toyota still builds a Camry that hasn't been cost reduced. They call it a Lexus ES330.
Does anyone know why the change interval for the Front Differential oil is much longer than that for the Rear Differential and Transfer Case. I had those changed yesterday and was thinking of having the Front's done too, but decided to stick with what is in the Maintenance booklet. Any thoughts, WWest? Thanks.
I always suspected that, since introducing their Lexus line, Toyota has transitioned the Toyota line to more of a plain, economy-style look to better differentiate the lexus line from the Toyota line. My impression is that Toyotas of old were more refined and detailed.
I agree that running boards are just for appearance (and that is subject to debate), and are out of place on the Highlander. I have seen RAV-4s with running boards - talk about ridiculous. If you can't get in the vehicle, perhaps you shouldn't be driving it?
Have any of you noticed a rattling or clanking sound coming from the front of your highlander? I recently noticed that if I drove over those plastic reflectors on the roads at 35mph with the windows down I hear a clanking sound. I hear it when I drove over the bumps with both the left or right tire, but it noise goes away when I press the brakes. I took my car to my dealer and they said that it was the brake pads. The Tech explained it was normal for highlanders and that the pads float inside the calipers so when you run over a bump, the pads rattle inside the calipers. He said he test drove at least 4 cars that made the sound. But my parent's cars all have disc brakes and they don't make the noise. Also, is it possible to get my car replaced under the lemon law if I bought my car in VA last year, but I now live in CA? Would I have to go through the dealer I bought my car from or can I go to my local dealer?
The "cheapening" of the Camry began in 1995 (my son still has my old 1994 LE). That's the year the Avalon was introduced. The Camry was Toyota's flagship vehicle during the transition between the Cressida and the Avalon. This and the intro of the Lexus line (as stated) contributed to the "decontenting" of the Camry. I recall reading an article in a business magazine concerning this issue. The then president of Toyota stated that the Camry was not a luxury car and should not be manufactured as one.
I wrote to Toyota a couple times complaining about the removed features and how the post 1994 models felt cheaper and less classy than previous models (I also had a 1986 LE). I guess they figured that other manufacturers were doing it so why shouldn't they. The result is more money in their pocket they aren’t the richest car company in the world for nothing. The balance is giving customers what they want in a respectable package (hiding the cost cutting measures). Incidentally, the current Camry LE lists for about the same as my 1994 did. With the recent sales records they are achieving they must be doing something right.
My 2002 started clattering as well, so I pulled the wheels and found the anti rattle spring clips were loose and one almost had completely come loose. I replaced and they are keeping the pads from rattling now...
I traded a '94 Corolla on an '04 Highlander. Not everything is cheaper on the '04. The Highlander doors and body panels don't ding and scratch like the '94 Corolla did whenever someone opens a car door into them.
Thanks for the reply. I'm curious to know if the extended warranty that you purchased is specifically the platinum 7 year / 100,000 mile warranty with a zero deductible. Please let me know.
I have a 2003 Highlander - with the same noise. Front brakes rattle going over lane divider bumps Please see message 662 in the Highlander problems and solutions section....
2003 AWD V6 Limited, 8,600 miles
I noticed a rattle coming from the front wheel (brake). When my drivers window is down, and I change lanes, the lane marker bumps (here in California) cause a clunking sound from the front wheel (which I can hear over the tire noise).
If I apply the brakes gently, the clunking noise stops.
The normal sound of the tires going over the lane markers is a "whump - whump" sound. In my case - I hear the "whump - whump" and also the clunk clunk. Light brake pressure stops the clunk.
I figured it may be the caliper or the pads. I took the wheel off, looked at the caliper and pads. Everything seems OK. The Caliper has more play than I expected, and this may be the noise I am hearing.
One other observation - the front rotors are really thick. I can't believe people are having trouble with warping.
Overall I really like the highlander - but there are a couple of annoying issues I don't like - especially on a $35K vehicle.
1) Front struts make a loud thunk at full extension (when front end is light going over the crest of a bump)
2) The "loose" front calipers and pads which make a cheap clanking sound going over lane marker bumps
3) Misc dash and seat rattles (seems a little cheap)
05 4cylinder Highlander will come with a 5 speed automatic tranny? The 05 Camry 4 cylinder does but will the 05 HL? If so any EPA mileage estmates? I think the 04 is rated at 22/27. Also any increase in power hopefully closer to 170/180hp?
Although I have enjoyed our Highlander for eight months, the delayed acceleration or hesitation has become unbearable. Search the board and you will find others who experience the same problem. I finally took it in to the dealership to see what they can do. I was surprised when they acknowledged that there is a hesitation! However, it is a design issue since other Highlanders do it. Below is what is delineated on my work order.
Concern: Customer states vehicle hesitates on acceleration check and advise. Cause: Verified concern with customer Correction: Delay response verified with customer road test. Compared with STK ##### compared the same.
Since there is no way to repair the vehicle, service department gives my Toyotas phone number to start the arbitration process. This took me to a meeting with the district service and parts manager from Toyota. I thought he was very nice and professional. He acknowledges that this problem exists with the Highlander and Solara. Toyota engineers are at the beginning stages of finding a way to rectify the issue. However, he did not know how far along in the process they are in finding a solution. Below is his write up on the work order from him:
Concern: Customer states vehicle has hesitation or delayed acceleration while driving. Cause: 0 Correction: Had factory rep inspect – see notes Tech Notes: Test drove vehicle with customer; there is a hesitation while accelerating. Advised that Toyota is aware of complaint. Advised that dealership will complete an MDT report including their feeling.
They will not acknowledge that it is a design defect or a safety issue. Therefore, any manufacture buy back will have to be ordered through arbitration. Today, I applied for arbitration.
I try not to be too materialistic and dwell over things that really have no meaning to my life. However, when you pay over $30k for a vehicle and you have no recourse, it can be upsetting. Anyway, I thought I would post this to help others who may need the info.
Below is some important information I left out from my original post:
My HL is a 2004 V6 AWD with approx. 9k miles on it. The factory rep said it applies to those vehicles with “fly” or “fly wire” acceleration. I cannot recall the exact verbiage he said (I will need to know for arbitration).
Test: Drive 30/40 miles an hour and imagine a large truck pulling in front of you. You slow down quickly to about 10-15 miles an hour. While slowing down you look over your shoulder to see it the lane is clear to go around the truck. You have a nice gap to accelerate into in the next lane and you “punch” the gas to shoot the gap. I will always get a very significant delay while doing it. Please note that you do not need to floor it. Another test is just imaging merging onto traffic.
On several occasions I thought my vehicle would stall. I can create the delay at anytime, however, the severity of it is hard to create. I feel it is a very serious safety issue. I have seen the delay the near two second mark.
Comments
added a hidden hitch off the web for $145 and harness for $44. 10 min install.
But I suspect that under the conditions you describe not even the 4runner would be satisfactory absent the use of snowchains. And if snowchains are required in any case then the HL can be workable with wheel spacers at the rear to make room for snowchains.
I was really hoping they would offer this in the '04 as I am getting ready to purchase one. I would wait for the '05 (since I already own an '02) but my dilema is to take advantage of the still low interest rates and incentives.
Any suggestions?
Thanks.
Personally, I don't see this feature will be offered under any HL. Even a more expensive car, it's still hard to find they have memory seats.
You need to move into Lexus to get memory seats. It's one of those "luxury" features.
And no - its not only when there is good traction.
I was parked on soft dirt and accelerated hard - I left 4 equal sized scooped out divets in the dirt.
To me - that shows that both front and rear axles getting equal torque. Its not a controlled experiment - but it doesn't explain the theory of 90/10 torque split.
I may be wrong but wwest doesn't own a Highlander - but an RX300?
For the last few years, I have been reading wwest comments about the Highlander not being AWD but 90% front wheel drive / 10% rear.
All I know - my rear wheels can dig out just as much dirt as the front ones do. Never been stuck never have a problem.
"The Toyota's full-time all-wheel-drive system is always on, splitting power 50/50 front and rear via a viscous-coupled center differential. The system overcame every limited traction scenario we encountered without difficulty. Judging by its performance, we believe the Highlander could easily handle a rutted or snowy road to a vacation home, trailhead or remote beach. Ask more of it than that and you may be calling for roadside assistance."
The brake apportioning system will not activate unless the ABS wheelspeed sensors indicate one wheel or wheels is turning, spinning, faster than others.
Note that wheelspin must occur before the torque apportioning system comes on-line. A clear indication that the instant a wheel looses traction the 50/50, 25/25/25/25, torque distribution "rule" becomes "null".
The same is true of VC use in prior years.
Prior to 04 the HL and RX shared the same AWD system using a viscous clutch ACROSS the open center diff'l to eliminate extended periods of disparate front/rear rotational rates.
And pardon me, but I don't think any automotive magazine writer knows "beans" about the actual design and/or implementation of any of the modern day systems, ALL inclusive, they generally just parrot the propaganda put out by the factories.
And yes, it is a 2001 AWD RX300 I have.
And now to those four divots....
Wouldn't you agree that any FWD or RWD vehicle would have driven away from that spot just as quickly as you did?
Assuming your experience was with a MY prior to 04 and ignoring the VC for the moment the center differential in the Toyota AWD system will act exactly like the normal rear or front open differential as long as the effort required to turn both of the differentials output shafts are roughly equal.
How many times have you seen a RWD or FWD non-turning vehicle spin a wheel on one side and not the other when the roadbed is NOT slippery. Sand and loose dirt and "fine", pea gravel surfaces DO NOT constitute a slippery roadbed.
By it's very design the VC cannot come into play and provide any substantial level of locking of the center diff'l in a constant or instantaneous manner. To do so would result in long term damage to the driveline each and every time you turn a corner, especially so for accelerating tight turns.
The "viscous" fluid is formulated to have a very high volumetric expansion ratio with temperature. When the two output shafts of the center diff'l start to turn at disparate rates the fluid between the tightly spaced interspersed clutch plates is rapidly heated by the shearing forces and since the volume of the hermetically sealed VC container is FIXED the pressure between the clutch plates increases dramatically thereby increasing the coupling coefficient between the clutch plates.
We're talking about hundreds of milliseconds for the VC to reach even a low lock level and several seconds for it to reach a locking level of any real benefit. As one can readily see, it cannot sustain anything close to 100% locking of the center diff'l, thus the 70/30 measurement I obtained with sustained "slippage" on a 4 wheel dyno.
One of the things I discovered during the winter snowstorm this past year was that my RX's Trac system dethrottles the engine long before the VC has an opportunity to react to wheelspin. That's very likely the reason the VC was eliminated, the Trac system made it useless anyway.
When you enter a turn the front wheels turn at a different rate than the rear, the tighter the turn the greater the difference in F/R rotational rates will be.
Anyone who has driven a 4WD "part-time" system while actually engaged on a high traction surface can describe the effect. With the center diff'l locked (RIDGID mechanical coupling/linkage) the front and rear drivelines MUST turn at equal rates. With no slippery roadbed surface to provide the "give" or "slack" while turning, the driveline winds up until the windup torque exceeds the tires' traction coefficient, and then the tires "scrub", slip, to release the mechanical windup.
Probably not just a few busted fingers and knuckles as a result of the feedback to the steering wheel during this effect. 4WD owners are taught, or else quickly learn, to keep fingers on the outside of the steering wheel when the 4WD system is engaged.
So, the problem for automotive design engineers was how to provide an "automatically" engaging all wheel drive system. A system that ONLY engaged with actual wheelspin, and not the apparent wheelspin resulting from simply entering a tight turn.
I admit that I'm a bit surprised that some enterprising young engineer hasn't come to the realization that steering wheel position "off-center" could be used as an indicator to disengage the center diff'l "lock".
You can probably get a good idea of how effective a VC implemented AWD system is, how quickly it comes "on-line" and how ridgid it becomes, by driving your vehicle on a high traction surface in a tight circle as fast as your comfort level allows. But be sure and keep your fingers on the outside of the steering wheel since a good system will quickly begin to scrub the tires and just might jerk the steering wheel from your grasp.
But have you considered that in the HL the engine output drives both sides of the drivetrain simultaneously through the automatic transmission?
In your scenario - the engine drives the front axle, while the rear axle is connected to the front by a center VC. This is not the case.
Both front and rear axles are connected to the VC which is part of the automatic transmission. This is how they can get each side to be 50/50 split and it doesn't rely upon the front drive train to drive the rear through a slipping center VC
You can say whatever - the HL is 50/50 split front rear.
The transmission (not "technically" transaxle)output directly drives the input to the center diff'l (drives the center diff'l outer case in actuality) then one output "shaft" of the center differential drives the front differential and the other the rear driveline and thereby the rear differential.
The two input shafts of the VC are connected, one each, to an output shaft of the center diff'l. There is NO locking of the center diff'l unless or until the viscous fluid can react to differential turning rates of the two output shafts of the center diff'l.
Think about it, seriously, if the system had full time or instantaneous 50/50 coupling that would be an exact equivalent to an engaged 4WD part-time system and the driveline would be destroyed in short order due to the continual windup stress during turns.
And NO - the drive line would not wind-up as I said - front and rear are connected through a VC in parallel to the automatic transmission (not in series).
I have the 03 Highlander shop manuals - which describes the HL drive line better than the RX300 shop manual (which is a different vehicle.
And please, don't mention front window fog-up to Willard!
Let's take a part-time 4WD system and put it in 4WD mode wherein the front driveshaft is solidly locked to the rear driveshaft. 100% of the available engine torque is delivered to that "single" driveline. Both the front and rear wheels have good traction so the split is truly 50% front and 50% rear, or just as you state, a 50/50 F/R torque distribution ratio.
And that all works perfectly fine as long as I'm carefully going STRAIGHT down the road. But now suppose I come to a curve in the road. Wouldn't you agreed that something has to "GIVE"?
In rounding the curve the front wheels will undoubtedly cut a larger radius than the rear wheels. That means the rear wheels will be turning slower than the front wheels and therefore if something doesn't "give" the driveline will eventually fail. Unless, that is, the tires are scrubbing so much that they quickly overheat and blow out.
All of the above is really for naught since everything I have said so far has been published and taken as absolute gospel for many many years.
You cannot drive a vehicle with a locked center diff'l, (forced) 50/50 torque split, on our highway tractive surfaces without doing serious damage to the driveline.
Now, it should be obvious that if one could come up with a way to automatically disengage the 50/50 split mechanism (of whatever ilk) upon entering even a slight turn there would be NO problem.
Or in the alternative what if one came up with a way to only engage the 50/50 torque split if a wheel or wheels began to slip?.
And that latter approach is exactly how the VC works.
Take any 2WD vehicle that doesn't have any type of LSD, real or virtual. With both wheels/tires firmly on a tractive sirface the left and right axles will each deliver 50% of the engine drive torque. Now lift one of those wheels off the ground, or encounter a patch of ice at one side of the roadbed, and suddenly the available engine torque is reduced to almost zero because the tire with no traction doesn't take much torque to spin it freely.
But is the torque distribution still 50/50??
YES, ABSOLUTELY!
That why Toyota or Lexus, or whomsoever, can make the 50/50 torque split statement truthfully.
But now, does the fact that the system still has a 50/50 torque split do you any good?
ABSOLUTELY NOT!!
With one wheel spinning freely it is extremely unlikely that the 50% torque level still being delivered to the other end of the open diff'l will move the vehicle off dead center.
The very same is true if we now place the open diff'l at the center, absent an LSD somewhere, one wheel loosing traction results in your being STUCK.
The VC contains a fluid which under extended front vs rear wheelspin will "stiffen" and steadily increase the center diff'l locking factor as long as the disparate f/r rotational rate persists or the greater the rotational difference is.
There is one other circumstance wherein the front driveline should not be locked to the rear driveline. And that is during moderate to heavy braking. Many modern day AWD/4WD systems automatically disable the Antilock braking system when in "locked mode". Some of the newer systems only allow locked mode in low range, granny-grunt low, for the same reason. At the higher speeds attainable in locked 4-hi the potential for loss of vehicle control due to rear over-braking is too great.
The design problem is to maintain those open differential advantages while at the same time finding ways to keep the total available torque at a fairly high level.
I don't really mind if you think my AWD is 100/0 front to rear.
Does my AWD work (ie do I experience improved traction / handling) YES.
Have I ever been stuck - NO
Do I need to know what the actual ratio is - NO.
And to answer your point about one wheel spinning - Its called "Traction Control"
Thats why they don't use LSD in the AWD Highlander.
If you choose to call that traction control then find by me.
The actual traction control firmware only comes into play if the use of the virtual LSD capability doesn't fairly quickly result in eliminating wheelspin, and then only to dethrottle the engine to prevent rotor warpage from overheating.
Ask any Sequoia owner who has tried to use engine revs, spinning wheels, to get unstuck from a mudhole while in 4-hi (AWD for you, except the Sequoia has definite rear torque bias). The engine dethrottling prevents any serious wheelspin, and about 45 seconds later the entire ABS/BA/VSC/Trac system BAILS to prevent the ABS pumpmotor from overheating and failing.
Congrats on the new ride!
Steve, Host
(If you do decide to move on, at least you purchased one of the better SUVs from a depreciation standpoint).
Good luck.
Highlander is supposed to be a smooth SUV, running board? You pay for it but never get to actally use it unless you are really really short?
And yes, it will always get your jeans dirty when it rains
1. Factory Front Floor mats – weigh 3.5 pounds each in the 94. Weigh 2.25 pounds in the 04 – very thin in the 04.
2. Rear view mirror is on a metal post on the 94. It is glued onto the W/S in the 04. Will probably fall off in 5 years.
3. Gas cap only has two lugs on it such that to put it in the door holder, you have to line up the two lugs with the holder(dumb) the 1994 gas cap fits in the holder any which way. Toyota probably saved all of 10 cents on this one.
4. Fuel release lever is 1/2 the size of the 94 (smaller on 2040)
5. Passenger side window switches are smaller.
6. I did not have a keyless remote in the 1994 but the 2004 remote is very sensitive, when I put it in my pocket it frequently beeps the lock or unlock function. Toyota screwed that up – very little button movement will set it off. My mom’s Buick you have to push it down almost 1/8 inch. Least the Toy has a chirp noise – the Buick and most Fords blow the horn. Bad in a city.
Also, is it possible to get my car replaced under the lemon law if I bought my car in VA last year, but I now live in CA? Would I have to go through the dealer I bought my car from or can I go to my local dealer?
I wrote to Toyota a couple times complaining about the removed features and how the post 1994 models felt cheaper and less classy than previous models (I also had a 1986 LE). I guess they figured that other manufacturers were doing it so why shouldn't they. The result is more money in their pocket they aren’t the richest car company in the world for nothing. The balance is giving customers what they want in a respectable package (hiding the cost cutting measures). Incidentally, the current Camry LE lists for about the same as my 1994 did. With the recent sales records they are achieving they must be doing something right.
Front brakes rattle going over lane divider bumps
Please see message 662 in the Highlander problems and solutions section....
2003 AWD V6 Limited, 8,600 miles
I noticed a rattle coming from the front wheel (brake). When my drivers window is down, and I change lanes, the lane marker bumps (here in California) cause a clunking sound from the front wheel (which I can hear over the tire noise).
If I apply the brakes gently, the clunking noise stops.
The normal sound of the tires going over the lane markers is a "whump - whump" sound. In my case - I hear the "whump - whump" and also the clunk clunk. Light brake pressure stops the clunk.
I figured it may be the caliper or the pads.
I took the wheel off, looked at the caliper and pads. Everything seems OK. The Caliper has more play than I expected, and this may be the noise I am hearing.
One other observation - the front rotors are really thick. I can't believe people are having trouble with warping.
Overall I really like the highlander - but there are a couple of annoying issues I don't like - especially on a $35K vehicle.
1) Front struts make a loud thunk at full extension (when front end is light going over the crest of a bump)
2) The "loose" front calipers and pads which make a cheap clanking sound going over lane marker bumps
3) Misc dash and seat rattles (seems a little cheap)
Although I have enjoyed our Highlander for eight months, the delayed acceleration or hesitation has become unbearable. Search the board and you will find others who experience the same problem. I finally took it in to the dealership to see what they can do. I was surprised when they acknowledged that there is a hesitation! However, it is a design issue since other Highlanders do it. Below is what is delineated on my work order.
Concern: Customer states vehicle hesitates on acceleration check and advise.
Cause: Verified concern with customer
Correction: Delay response verified with customer road test. Compared with STK ##### compared the same.
Since there is no way to repair the vehicle, service department gives my Toyotas phone number to start the arbitration process. This took me to a meeting with the district service and parts manager from Toyota. I thought he was very nice and professional. He acknowledges that this problem exists with the Highlander and Solara. Toyota engineers are at the beginning stages of finding a way to rectify the issue. However, he did not know how far along in the process they are in finding a solution. Below is his write up on the work order from him:
Concern: Customer states vehicle has hesitation or delayed acceleration while driving.
Cause: 0
Correction: Had factory rep inspect – see notes
Tech Notes: Test drove vehicle with customer; there is a hesitation while accelerating. Advised that Toyota is aware of complaint. Advised that dealership will complete an MDT report including their feeling.
They will not acknowledge that it is a design defect or a safety issue. Therefore, any manufacture buy back will have to be ordered through arbitration. Today, I applied for arbitration.
I try not to be too materialistic and dwell over things that really have no meaning to my life. However, when you pay over $30k for a vehicle and you have no recourse, it can be upsetting. Anyway, I thought I would post this to help others who may need the info.
My HL is a 2004 V6 AWD with approx. 9k miles on it. The factory rep said it applies to those vehicles with “fly” or “fly wire” acceleration. I cannot recall the exact verbiage he said (I will need to know for arbitration).
Test: Drive 30/40 miles an hour and imagine a large truck pulling in front of you. You slow down quickly to about 10-15 miles an hour. While slowing down you look over your shoulder to see it the lane is clear to go around the truck. You have a nice gap to accelerate into in the next lane and you “punch” the gas to shoot the gap. I will always get a very significant delay while doing it. Please note that you do not need to floor it. Another test is just imaging merging onto traffic.
On several occasions I thought my vehicle would stall. I can create the delay at anytime, however, the severity of it is hard to create. I feel it is a very serious safety issue. I have seen the delay the near two second mark.
Hope this helps.