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Comments
Excellent choice for future on your conversions. Kudo's for that.
I personnally don't believe studded tires are needed most places either and actually hurt traction in many conditions which is why I don't normally recommend them to anyone. I don't know which part of the country your in but for those inquiring on benefits of snow tires and drive options they are obviously in an area that they have a concern and should be addressed as such not just works what works best for you in your area. The guy in FL. doesn't care much of anything about this whole thng unless he has to take a trip way north mid winter.
I also don't consider winter tires to be a band-aid for a non existent wound. I consider them more like Mechanix gloves, Goretex clothing, etc. Enough skinned knuckles and sudden rains and better to be prepared ahead of time to prevent problems. When I used to go out and it's 0 degrees and I had my all season tires on that rode like solid rubber and slid on dry corners it was time for other options. Toss the endless flurries into it and anyone would be crazy to do different (which is why most cars in the area had winter tires on it).
Steve, Host
"...sudden rains and better be prepared..."
By that measure "The guy in Fl (Al, MS, etc.)" should always run on winter tires.
Second-Wwest,
Your area is listed as a milder climate with little snow. When it does it doesn't stay around very long, not much below freezing temps. What works for you in your area doesn't relate to those who get a lot of snow that stays for months so you should help them respectively not just preach your ideal.
By that measure "The guy in Fl (Al, MS, etc.)" should always run on winter tires.
Another RIDICULOUS, uninformative, useless comment that is just typical of many of your posts. Not cold, no snow, no need. Proper info for those in the area they are asking for help on.
As MANY stated prior. "let's agree to disagree" trying to provide proper information with somebody like you is futile.
By the way, Thanks Steve! Hopefully others reading these threads will put all of mine and WWEST's comments into proper perspective. Maybe some of my links will provide useful info for them as opposed to "summer tires with no siping will always provide better traction even on pure ice" :confuse: that others provide.
If you read back in this thread you will gain some valuable info for the different systems (and some not so, actually more confusing). You really need to decide more on what fits your need. A larger, heavier SUV has advantages at times (if you need towing capability, off road ability, extra mass to hopefully protect you in an accident) and many cons (extra weight for poor fuel economy, on snow/ice once out of control a lot more mass to try and regain control, parking, High center of gravity = greater rollover risk, plus others).
Most manufacturers will describe their systems as this:
AWD (all wheel drive)- the center differential (or something similar) does NOT lock and allows the front axle/wheels to move at a different speed from the rear axle/wheels. This allows you to use it in all conditions (dry, wet, snow, mud) and normally at all speeds. All of them have a different percentage for how much torque is applied to which axle and at what times. All wheels have an opportunity to provide traction but limited to how the front and rear differentials decide which side gets power. some use limited slip that utilize clutch packs that heat up as one wheel spins and start to transfer torque to the other wheel to help gain traction, others utilize the ABS system to apply brakes to only the spinning wheel for the same reason, some have mechanical methods that lock the 2 sides together once one spins, some of the new jeeps control all the differentials electronically and can vary anywhere in between based on sensor input.
4WD (four wheel drive) the center differential or transfer case LOCKS and links the front and rear axles together. Since locked both receive the same amount of torque. Still limited to which wheel gets power based on the same front and rear differential info from above. Having the front axle locked to the rear requires that the tires be allowed to slip on a lower friction surface (snow/ice/mud/gravel) when you go around turns. On dry road and sharper turns (parking lots etc.) the surface has a high friction and does not let them slip. The whole driveline binds up until something gives (which will probably be a very expensive of the driveline). Most of the 4WD systems also have a low range gear option as part of the transfer case to allow those that have the need, the ability to provide a LOT more torque to the wheels for off road, towing heavy things, getting things unstuck (provided your tires have enough of a traction surface)
2WD, FWD, RWD drive only one of the axles and still limited to which wheel on that particular axle gets power based on the differential on that axle.
By the way the Sequoia has all of the above. Rear wheel drive normally, all wheel drive (because the center differential has an option of whether you decide to lock or not) and 4WD when you decide to lock the center diff and a separate transfer case that provides a low range gear. I do not know what the GX470 has for options but should be listed on the websites and/or go check at dealer. Another option to check is Subaru. They have a great proven history for their full time AWD drive systems, some (Forester, Outback) have more ground clearance than regular cars and better than some SUV's, and have pretty good room while getting very good fuel mileage. Only downside is if you need towing capacity for trailers or boats.
You had alluded to being prepared for sudden rains by having winter tires and I have been on FL (AL, MS, LA, etc.) interstates with "sudden rains" where hydroplaning was clearly the rule.
The Daytona 24 hour race was halted in 2004 due to HEAVY rainfall after Paul Newman spun out three times in a row in the exact same spot.
You had alluded to being prepared for sudden rains by having winter tires and I have been on FL (AL, MS, LA, etc.) interstates with "sudden rains" where hydroplaning was clearly the rule.
Do you mean this comment from #1870 "I also don't consider winter tires to be a band-aid for a non existent wound. I consider them more like Mechanix gloves, Goretex clothing, etc. Enough skinned knuckles and sudden rains and better to be prepared ahead of time to prevent problems."
Mechanix gloves for the skinned knuckles, Goretex clothing/jackets for the sudden rains! Winter tires for the consistent cold with snow/ice in my area that lasts for months. Not Winter tires for rain in the south, winter tires to be prepared for snow/ice that accumulates here during WINTER while I'm at work and need to get home, or sleeping/woken up at 3AM, 5 degrees outside, and need to get to the firehouse to drive the ambulance for the fool that wrapped his summer tire equipped car around a tree with an inch of a snow on the ground.
The 4WD HL has a full-time 4WD system, meaning it's always in 4WD; there's no way to switch it out of 4WD mode. It's designed for the non-sophisticated four-wheeler who just wants good traction in snow and perhaps does some light off-roading occasionally. But if you feel you need it, buy a replacement switch from an auto parts store for a 4WD vehicle that allows switching between 2WD and 4WD modes, and glue it somewhere in the HL's instrument cluster so your friends will think your HL can switch between 2WD and 4WD. You can even pretend to switch it and tell your friends that it shifts very smoothly between 2WD and 4WD, and ask them whether they can feel it shift...
The 4WD HL is actually a FWD vehicle unless you encounter a circumstance where the front wheels (both) develop some roadslip/wheelspin. When both front tires lose traction with the roadbed while under engine driving torque that will result in the brakes being applied to the slipping/spinning wheels and that will quickly re-route engine torque to the rear via the open center differential. Meantime the engine will have been almost completely dethrottled to prevent further wheelslip/spin which would require even more braking.
Face it, you own a FWD, 2 drive wheels ONLY vehicle.
tidester, host
Nice layman's summary of the differences between AWD/4WD/2WD. I bet that'll be useful to more than one reader of this board.
That makes the front tires much more likely to slip, spin, first and then braking is used to "force" engine torque to the rear. Note that both front tires must slip in order for this to happen since with only one slipping the virtual front LSD comes into play, only the slipping front wheel is braked, forcing torque to the opposite side.
Obviously if this braking were to continue for an extended period with the engine output fairly high the brake rotors would quickly overheat. So at the initial onset of Trac (AWD mode) braking the engine is also quickly dethrottled.
Like the Trac system on my 1992 LS400, in most cases you can make more headway turning these systems off and managing the gas pedal in a more sensitive way. But be sure and learn where the 60 Amp ABS pumpmotor fuse is in preparation for the day you will need to remove it to get unstuck or continue forward movement up a slightly slippery incline.
I read the post about tapping the brakes to get it to engage. That works somtimes.
My big concern in that when I start out my long hilly drive in the morning (if there is heavy snow) I won't be able to get into 4wd.
Do others have similar symptoms - or hints? Maybe shifting to neutral ?
That said, I have had issues while driving and you need to engage it then slow down some. YES, you can use neutral while in your driveway. The way I do it and have never had an issue with it not engaging instantly is, start the truck place in drive, engage 4WD, place in neutral then back to drive. I forget if it engages when I go to neutral or back to drive but it always was engaged when I started to drive.
IMO, if you even think you'll need 4WD, have it locked in before you need it.
Simply come to a full stop, back up a few yards until the locking diff'l engages, now GO!
I don't see it myself, sound a bit like hocus-pocus, but I was also told, in writing, that the center and front diff'ls are "beefed up" beyond that of the rear diff'l in order to handle the additional drive torque.
And keep in mind that the instant Trac applies the brakes to simulate a partially locked diff'l, front, center, or rear, the engine will also be instantly dethrottled so the brake rotors don't overheat (and later warp) due to continuous use should the engine be left to produce high torque.
Personally I think Toyota and Lexus have now learned a hard lesson and the HL, Sienna, and RX will soon have the RAV4's new AWD system.
And by the way as of the 04 model year the drive ratios are 3.48:1 and 2.92:1 for what it's worth.
You seem to be saying that the transfer unit drives BOTH the front axle and rear drivelines with a common ratio and I don't see how that would "equal out" the differing F/R rear final drive rations.
And I assume by "transfer unit" you mean the gearset from the transmission section into the center diff'l.
On the Highlander power comes from the transmission to the center differential, then splits left to the front differential, and right to the transfer unit which is a gear unit which drives the front .341 to the rears 1 turn. The transfer unit is after the center differential, actually next to it. The transfer unit connects the front axle and the propeller shaft which drives the rear. It does not matter what the final ratios are because the wheels are turning at the same speed. This means that torque is delivered equal to each axle and wheel until there is wheel slip.This is when trac steps in and slows any spinning wheel. The ratios are different because they have to fit everything, while keeping it compact and lightweight. Three open differentials are used front, center, and rear. Open diffs always send power equal unless there is wheel slip, and then trac makes it equal once again.
Because the front to rear final drive ratios are not equal turning the front wheel exactly 360 degrees will result in the rear wheel turning, again possibly the opposite direction, but plus or minus the ratio difference.
The lone fact that you're considering a 4X4 indicates you should op for VSC/Trac.
TRACS and VSC can be disabled very easily but then you are running a plain open diff with power to the wheel with least traction.
When $$ are available I will be adding a regular mechanical LSD to the Sequoia for those times. On the Sequoia with the center diff locked VSC and TRACS is off anyway and you then have open diffs anyway.
And even if you added a mechanical LSD how would you prevent the "virtual" LSD from reacting more quickly?
"As before, the RAV4 will be available in both front- and four-wheel-drive versions, though a part-time on-demand 4WD system replaces the former full-time viscous-clutch all-wheel-drive system. 4WD versions now have a system that reverts to front-wheel-drive when there are no outstanding traction demands, for the most economical operation, though the system uses an electronic-controlled viscous coupling that sends torque (up to 45 percent) to the back wheels as needed. There's also a 4WD Lock setting that allows a set amount of torque (55/45 front/back) to be sent to all four wheels, up to 25 mph, where the Auto setting overrides it. The RAV4 has never been a serious off-roader, and the 4WD will still offer off-road performance good enough to get owners to most remote campsites and trailheads. Front-wheel-drive models come with a limited-slip differential to help aid grip in limited-traction situations."
Come on Toyota - the Canadian universal health care system is good but not that good, and even if it were, no one yet knows how to unmangle a brain.
What is your message here Toyota? The heads of those who can't muster the extra few thousand loonies are unworthy of protection. Now that is an elitism that I can't stomach.
I was on the prowl for a new vehicle this year and until now, the RAV4 was on my list. No longer! Get with it Toyota!
I'm not sure what hard lesson you are referring to. I thought the hard lesson was learned before the 2004 model; i.e. the reaction time of VC system . . . hence the open differential solution that comes with RX and Highlander of 2004 vintage or later. Not sure what's so great about the new RAV4 system; isn't "OnDemand" just a market-speak for "low-cost"? What is the reaction time for it? AFAIK, the MDX OnDemand system exhibits significant delay; that's why I got the 04 Highlander.
Dethrottling is something the Vehicle Stability Control program would do any way under slippery conditions.