Ask the Car People.SM


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 215 of 249

#2137 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by hdfatboy

Jan 15, 2008 (9:36 pm)

Replying to: 2toyotas (Jan 15, 2008 6:38 pm)
"In 2005 the Sequoia began using the VF4AM transfer case which was already used in the V6 4Runner since 2003. It has a torsen center differential. I get my info from techinfo.toyota.com. It will cost you 10.00 to view, or you can just trust me."
 
Actually the VF4AM transfer case with a Torsen-C center differential is new for 2008 in the Sequoia, LC, LX570. The addition of the Torsen-C center differential is what makes it unique from past applications in the Sequoia. The VF4AM has been used in the v6 4Runner since 2003.
http://www.toyota120.com/GenDocs/2003_4Runner.pdf
 
The v8 4Runner used the VF4BM transfer case. More details in the article below.
http://www.vibratesoftware.com/html_help/html/Toyota/Toyota_Transfer_Units.htm
 
Here's additional information on the older style VF4BM transfer case that was used in the previous gen Sequoia and 4Runner.
http://youronlinemechanic.com/2007/09/28/vf4bm-transfer-with-torque-sensing-type- /

#2138 of 2487 Re: RAV4 .vs. Subaru AWD [hdfatboy] by 2toyotas

Jan 15, 2008 (10:22 pm)

Replying to: hdfatboy (Jan 15, 2008 9:36 pm)
You keep giving the wrong info, and I will keep correcting you. The VF4AM is used on the V6 4Runner and 05 - 07 Sequoia. The VF4BM is used on V8 4Runner and FJ Cruiser with a manual transmission. The 08 Sequoia uses the JF3A transfer case, and the Land Cruiser/LX570 uses the JF2A transfer case. All four have a torsen center diff., the difference being that the VF4AM and the JF3A have a 2WD option.
 
You keep talking about ALSD as toyotas system. It is just a function of TRAC. You would only use ALSD if you needed rear wheel spin in 2WD when stuck, because TRAC would cut some engine power in addition to braking the spinning wheel. Once you are moving you wouldn't want ALSD on you would want TRAC on to keep stability.

#2139 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by hdfatboy

Jan 16, 2008 (8:49 am)

Replying to: 2toyotas (Jan 15, 2008 10:22 pm)
2Toyotas,
 
"You keep giving the wrong info, and I will keep correcting you. The VF4AM is used on the V6 4Runner and 05 - 07 Sequoia. The VF4BM is used on V8 4Runner and FJ Cruiser with a manual transmission. The 08 Sequoia uses the JF3A transfer case, and the Land Cruiser/LX570 uses the JF2A transfer case. All four have a torsen center diff., the difference being that the VF4AM and the JF3A have a 2WD option."
 
I'd like to recommend that you take the time to read the source information I shared before suggesting I'm wrong in my statements. The Toyota information I provided above and that I will share again clearly states that the Sequoia through 2007 used the same transfer case as the V8 4Runner...namely the VF4BM transfer design. Here's the specific link again. If you believe you are correct and Toyota is wrong, let me suggest you contact them.
http://www.vibratesoftware.com/html_help/html/Toyota/Toyota_Transfer_Units.htm
 
According to all the information available that I have read... the Sequoia, LC and LX570 drivetrains were updated to include the Torsen-C center differential in 2008. Here’s Toyota’s press release for the new LC describing the “newly developed transfer case with a Torsen center differential”. http://www.zercustoms.com/news/2008-Toyota-Land-Cruiser-in-Japan.html
 
All information prior to 2008 on the Sequoia describes an open center differential that can be locked by the driver. There is no reference anywhere I’ve searched that would show that the Sequoia had a lockable mechanical center LSD prior to 2008.
 
Its interesting how I provide resources for my comments and yet your assertions are based on "trust me because I know more". I welcome the opportunity to learn and if the information and resources I shared are incorrect, it might be best to share a source, any source, that can support your claims.
 
Please share any link that shows the Sequoia had a center Torsen LSD (4wd models obviously) prior to the new 2008 models as I've been unable to find any information that would support your claim. I'm confident that the center differential of the Sequoia is not a National Security issue and therefore if prior year models included a mechanical center LSD, it should be readily available on the internet. Perhaps I'm looking in the wrong places. I would welcome a link to any source suggesting the Sequoia had a Torsen center LSD prior to 2008.

#2141 of 2487 Re: d [hdfatboy] by trebor129

Jan 16, 2008 (9:09 am)

Replying to: hdfatboy (Jan 15, 2008 8:49 pm)
"I agree with "Limited". I agree with "Slip". I disagree that their system has anything to do with the "Differential" in LSD. If Toyota had called it "Limited Slip Drive" or "Electonic Limited Slip" or "E-LS", I'd have no issue. It just technically is not a limited slip differential and any reference to the "differential" in their terminology is incorrect at least from a design perspective. I view it as an attempt to mask the fact that the rear differential is a basic open design.
 
I disagree because the Toyota system can apply brakes to just the slipping wheel. Since there is a constant amount of torque going to both wheel, braking one wheel has the effect of sending power (power being torque * rpm) through the open diff to the non-slipping wheel. So they are using electronics to make the open diff behave as an LSD. So calling it an electronic LSD "system" is fair.
 
That being said, it has disadvantages to a mechanical LSD in that slip has to occur before it goes to action. A mechanical Torsen system can redirect power before slipping occurs. That is why a combined system, like the 1997 and newer H1, is better.

#2142 of 2487 Re: RAV4 .vs. Subaru AWD [hdfatboy] by 2toyotas

Jan 16, 2008 (10:00 am)

Replying to: hdfatboy (Jan 16, 2008 8:49 am)
http://www.tundrasolutions.com/forums/sequoia/29500-2005-sequoia-first-looks/
  
You will clearly see the transfer was changed to the VF4AM which includes the torsen. This info is directly from toyota, your page is not. How can the Sequoia have the same transfer case as the V8 4Runner? The V8 is Full Time 4WD, and the Sequoia has a 2WD option? The VF4BM does also have the torsen in the center diff though. If you spend 10.00 for a day and go on techinfo.toyota.com which is also a toyota site, you can see all the features and how they work. I am not trying to go back and forth with you, but I will make sure you post the correct info. It is not fair to give people the wrong info about a vehicle.

#2143 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by 2toyotas

Jan 16, 2008 (10:51 am)

Replying to: 2toyotas (Jan 16, 2008 10:00 am)
1. General
 The ’05 Sequoia uses the multi-mode VF4AM transfer.
 Along with the adoption of the VF4AM transfer, the transfer lever has been discontinued. Thus, in the
4WD mode, the driver operates the 4Lo switch to switch between Lo and Hi.
 The VF4AM transfer is already in use on the ’04 4Runner with the 1GR-FE engine. For details on the basic
construction and operation of the VF4AM transfer, see the ’03 4Runner NCF (Pub. NoSpecifications 
Model ’05 Sequoia ’04 Sequoia
Engine Type 2UZ-FE 
Transfer Type VF4AM VF3AM
Drive Type Multi-mode
(Part-time & Full time) 
H2 1.000 
Gear Ratio H/H4 1.000 
L/L4 2.566 
Reduction Gear Type Single Pinion Planetary 
Center Differential Gear Type TORSEN LSD*2 Double Pinion Planetary
Oil Capacity
Liters (US qts, Imp.qts) 1.4 (1.5, 1.3) 1.2 (1.3, 1.1)
Oil Viscosity SAE 75W-90 
Oil Grade API GL-5 API GL-4 or GL-5
Weight (Reference)*1 Kg (lb) 41.2 (90.8) 42.8 (94.4)
*1: Weight shows the figure with the oil fully filled.
*2: TORSEN is TOYODA-KOKI-TORSEN’s registered trademark. NCF238U

#2144 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by hdfatboy

Jan 16, 2008 (11:53 am)

Replying to: 2toyotas (Jan 16, 2008 10:00 am)
This discussion is not about fairness. It was about information and sources. I appreciate you sharing the Toyota product brochure for the 2005 Sequoia as that is the first resource of any type that depicts the Sequoia in that year having a VF4AM transfer case. Obviously the other sources were incorrect.
 
The Toyota info you shared does clear the matter up regarding the type of transfer case used in the pre-08 Sequoias. Curious that so many other sources would either be incorrect or would not have referenced that transfer case in the earlier model years.
 
Based on your access to the Toyota site can you clarify which model years the Sequoia, LC, LX470 and the 4Runner each transitioned to a Torsen center LSD from an open center differential?

#2145 of 2487 Re: e [hdfatboy] by wwest

Jan 16, 2008 (12:05 pm)

Replying to: hdfatboy (Jan 15, 2008 8:44 pm)
"..It would make quite a racket after it fails...."
 
No, it wouldn't/doesn't. The spring pre-loaded clutch type, just as would a regular clutch in a stick shift, simply ceases to work once the friction surface has worn off. The VC type might "lock" in failure mode but since it is designed for "failsafe" operation that is rather doubtful.
 
So a driver probably wouldn't notice the failure until the moment of need arises.

#2146 of 2487 Re: RAV4 .vs. Subaru AWD [2toyotas] by wwest

Jan 16, 2008 (12:19 pm)

Replying to: 2toyotas (Jan 15, 2008 10:22 pm)
"..Once you are moving you wouldn't want ALSD (A-LSD) you would want TRAC on to keep stability.."
 
Someone, please, correct this if you have information otherwise but I think I have read documentation indicating that A-LSD is a sub-mode of TRAC. Whereas TRAC's default, always on, mode will instantly apply braking to a slipping wheel and simultaneously dethrottle the engine, if you put the system in A-LSD mode it will allow a certain level of wheelspin/slip just as one might sometimes want to get unstuck.
 
I think, also, A-LSD capability is only to be made available on RWD or R/AWD vehicles.
 
For many years now owners have complained about this aspect of TRAC, no ability to use wheelspin, say for rocking the vehicle back and forth to get unstuck, out of a mudhole, and now Toyota is offering A-LSD as a possible solution. Previously the only solution was to somehow disable VSC/TRAC altogether.
 
"..want TRAC on to keep stability."
 
Methinks you meant to say VSC.

Messages Page 215 of 249

To POST a message, please Sign In.

Advertisement

Browse by Category

Browse by Vehicle
   View All Vehicles

Browse by Board
Browse by Topic
View All Topics

Edmunds Community

Advertisement