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Toyota 4WD systems explained

2487 messages,  Last post on Apr 28, 2012 at 12:48 PM

You are in the Toyota Sequoia Forum.

What is this discussion about? Toyota Sequoia, Toyota Highlander, Toyota 4Runner, Toyota Land Cruiser, Toyota RAV4, Toyota Tacoma, Truck, SUV

Messages Page 217 of 250

#2156 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by hdfatboy

Jan 17, 2008 (6:54 am)

Replying to: 2toyotas (Jan 16, 2008 9:28 pm)
Very helpful summary. Thank you for the timeline info.
 
Just to summarize...the Open to Torsen conversion for the center diff of these models took place in the following years:
 
4Runner - 2003
Sequoia - 2005
LC/LX470 - 2008
 
Is there any other Toyota made 4wd vehicle with a torsen ctr diff?
 
You also shared that the Sequoia and LC/LX changed transfer cases in 2008. The Sequoia from VF4AM to a JF3A. The LC/LX from an HF2A to JF2A.
 
Do you know what the primary difference is between the previous transfer case and the Sequoia's new JF3A? Also do you know what the difference is between the JF2A and the JF3A? Is the primary difference in the transfer cases between the LC/LX and the Sequoia the new "Hill Start Control" and the new "Crawl Control" which are in the LX/LC but not in the Sequoia?

#2157 of 2487 Re: 2008 Highlander, what type of 4WD/AWD system ? [josephd05] by nedzel

Jan 18, 2008 (8:50 am)

Replying to: josephd05 (Jan 16, 2008 2:48 pm)
The 2008 Highlander will do fine on trips to the mall in the snow. I always advise snow tires (which I have on my 2003 4WD 4Runner), since AWD/4WD systems help you go but don't help you stop. Whether or not you get stuck in the snow is all up to you -- don't drive in snow that is deeper than the ground clearance, use some caution, brake and steer gently and you'll be fine. I never got my 1987 Acura Integra stuck in the snow and it was far less capable than an AWD Highlander.
 
The 2008 Highlander is significantly larger and heavier than the previous version, so don't expect to get significantly better mileage than your V6 4Runner.

#2158 of 2487 Guess what... by wwest

Feb 05, 2008 (4:24 pm)

NO torsen in the 4runner after 2003, apparently one year only...!
 
Cannot find any documentation that the torsen was used after 2003 but lots of stuff indicating TRAC was used in its place. Same for the Lexus GX & LX series.
 
Strange, very.
 
Lot of component pictures/diagrams/breakouts of the VF4AM transfer across the years and models but only the 2003 4runner shows a torsen.

#2159 of 2487 Re: Guess what... [wwest] by nedzel

Feb 06, 2008 (8:35 am)

Replying to: wwest (Feb 05, 2008 4:24 pm)
WWest: that is not correct. Go to: http://www.toyota.com/4runner/specs.html
 
Look down at drivetrain: "Multi-Mode 4-wheel drive with Torsen® [1] limited-slip center differential with locking feature" for the V6 and "Full-time 4-wheel drive with Torsen® [1] limited-slip center differential with locking feature"
 
The 4Runner drivetrain hasn't changed since 2003.

#2160 of 2487 Re: Guess what... [nedzel] by wwest

Feb 06, 2008 (10:05 am)

Replying to: nedzel (Feb 06, 2008 8:35 am)
Yes, I know what all the advertising says, hardcopy and on the internet.
 
Clearly, I may be wrong but the information at techinfo.toyota.com is pretty detailed, detailed well enough that a good mechanic could use it to overhaul the transfer system.
 
The word "torsen" is not used beyond 2003 in any of the documentation and I have no idea why that would be unless it isn't used or there is some legality involved.
 
Additionally if you read the document ion for traction control it appears that a torsen diff'l would be of no use since the TRAC system would quickly brake any wheel (and dethrottle the engine simultaneously) that exhibits spin or slip.
 
As somewhat of a parallel, I bought a 2001 AWD RX300 because it had HID VSC/TRAC and a viscous clutch across the center diff'l to provide torque to the rear driveline if front slippage occurred.
 
I quickly discovered that the VC was probably useless since the TRAC system activated at the first sign, seemingly the very instant, wheelspin developed.
 
Apparently Lexus discovered the same thing as the VC was discontinued for the RX330 series as was announced in NCF, New Car Features for the new 2004 RX330.
 
But guess what....??
 
Lexus continued to advertise, hardcopy sales brochures, on the internet, and in various PR pieces, that the RX330 had a VC, Viscous Clutch when the shop/repair manual indicated otherwise.
 
Lexus finally admitted, in writing (email), that the RX330 did not use a VC and apologized for the mis-information.
 
And now here I am arguing with Lexus as to whether or not the new(er) RX350 uses the VC. The advertising says yes but the shop/repair manuals say not and the TRAC use indicates it might be useless even if it is installed.
 
Sorta of like the issue of a torsen with TRAC in the 4runner.

#2161 of 2487 Re: Guess what... [nedzel] by wwest

Feb 06, 2008 (10:11 am)

Replying to: nedzel (Feb 06, 2008 8:35 am)
Read the material, however sparse, on TC, Traction Control, on the provided link.
 
If you have a torsen diff'l in the 4runner wouldn't you need to disable TC in order to put it to use...??

#2163 of 2487 Re: Guess what... [wwest] by green

Feb 11, 2008 (1:15 pm)

Replying to: wwest (Feb 06, 2008 10:11 am)
A torsen center diff, compared to an open center diff, enhances brake TC by multiplying the effect of a slipping, braked wheel by more than 1:1 across the axle diff to the other wheel. The amount depends on the bias ratio of the torsen.

#2164 of 2487 Re: Guess what... [green] by wwest

Feb 11, 2008 (2:15 pm)

Replying to: green (Feb 11, 2008 1:15 pm)
Yes, but doesn't that seem counter-productive...??
 
The front wheels are already slipping (abet at a rate limited by TC) an obvious indication of a slippery roadbed surface, and the Torsen will MULTIPLY the torque at the rear wheels (torque sustained via TC braking), or vice versa.
 
I would think one would want LESS torque at the opposite wheels, not MORE.

#2165 of 2487 How is F/AWD accomplished? by wwest

Feb 11, 2008 (2:18 pm)

The linked YouTube video gives certain evidence that the Highlander AWD system is quite clearly heavily biased to the front, as is probably the RX3X0 and the Sienna.
 
But how...??
 
http://youtube.com/watch?v=t09ExAUgtyE&feature=related

Messages Page 217 of 250

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