Last post on Aug 21, 2013 at 5:16 PM
You are in the Toyota Sequoia
What is this discussion about?
Toyota Sequoia, Toyota Highlander, Toyota 4Runner, Toyota Land Cruiser, Toyota RAV4, Toyota Tacoma, Truck, SUV
#2144 of 2493 Re: RAV4 .vs. Subaru AWD [2toyotas]
Jan 16, 2008 (10:53 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 2493 Re: e [hdfatboy]
Jan 16, 2008 (11:05 am)
"..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 2493 Re: RAV4 .vs. Subaru AWD [2toyotas]
Jan 16, 2008 (11:19 am)
"..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.
#2147 of 2493 Re: d [trebor129]
Jan 16, 2008 (11:28 am)
"That being said, it has disadvantages to a mechanical LSD in that slip has to occur before it goes into action...."
Assuming a VC, Viscous Clutch, implemented LSD is considered "mechanical" your statement is wrong, a VC must experience a period of slippage before it will "tighten" the coupling coefficient.
"A mechanical Torsen system.."
Doesn't this add to the confusion? I have never considered the Torsen system to be in the LSD "realm", more of a torque control/distribution system rather than an LSD.
Jan 16, 2008 (11:34 am)
I was referring more to a Torsen type which would not operate seemlessly after failure.
Jan 16, 2008 (11:42 am)
Almost all references to the Torsen differential, including the manufacturer's refer to it as a LSD.
You description of the viscous liquid diff is accurate and one of the reasons its not the best mechanical design for transfer of torque under severe conditions. It can be ineffective when operating in sand for example in transferring torque from the rear to the front of an AWD vehicle. It excels however at providing a very smooth torque transition when operating on slippery road surfaces.
#2150 of 2493 Re: RAV4 .vs. Subaru AWD [hdfatboy]
Jan 16, 2008 (11:47 am)
"There is no reference anywhere I've searched that the Sequoia had a lockable mechanical center LSD prior to 2008."
I thought the Sequoia ALWAYS had a lockable mechainical center diff'l for 4WD/4X4 mode...??
And yes, while that was otherwise an "open" diff''l (or transfer case equivalent) I thought they used TRAC braking in AWD mode to effectively have a center LSD..?
And isn't that basically the same system used quite effectively on the RX330/350, the HL and the Sienna AWD systems today, the VC version of those systems having been dropped prior to the '04 model year.
#2151 of 2493 Torsen "C"
Jan 16, 2008 (11:53 am)
The way I read all of this is that Toyota has adopted the Torsen "C" center diff'l design so the engine torque to the front would/could be limited to not more that 40%. The "old" system, TRAC braking, could clearly result in 100% of the engine torque to the front driveline therefore quickly converting a reasonably beniegn handing rear torque biased AWD vehicle into a wildly uncontrollable, SCARY, FWD, F/AWD vehicle.
#2152 of 2493 2008 Highlander, what type of 4WD/AWD system ?
Jan 16, 2008 (1:48 pm)
Torsen center diff? Atrac on the front and rear diffs? I'm going from an 06 4runner which has an amazing 4wd system. I don't offroad much, but I want something thats capable in the rough weather. I knwo it wont match my runner, but I don't want to get stuck in the snow. Please advise gurus.
#2153 of 2493 Re: RAV4 .vs. Subaru AWD [wwest]
Jan 16, 2008 (1:52 pm)
"I thought the Sequoia ALWAYS had a lockable mechainical center diff'l for 4WD/4X4 mode...?? "
I thought I knew the answer until 2Toyotas shared information from the "Pay for" toyota website. While the Sequoia has always had a Lockable ctr differential, I thought the addition of the Torsen LSD (in place of an open diff) was new for 2008. He shared information describing a Torsen Ctr Diff in the 2005 model. Therefore I do not know when Toyota transitioned from an open diff to the Torsen LSD ctr diff. for the Sequoia.
I was hopeful that 2Toyotas could look at his website to determine what model year the upgrade actually took place. (As well as when the upgrade to the Torsen occurred for the LC, LX470 and 4Runner.)
Most external information sources suggest the Torsen was added to the drivetrain for these vehicles in 2008 with the 4Runner getting it earlier. These sources must be wrong based on his review of the Toyota site.