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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 Land Cruiser Forum.

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

Messages Page 4 of 249

#31 of 2487 Thank you Cliffy1! by kmh

Jul 06, 2001 (5:54 pm)

Sorry if I mislead you on the second question.
 
What I was wondering was what sort of maintenance considerations should I take into account for my AWD with the LSD? Is there any special needs for maintenance at 60,000 miles because of the AWD and LSD?
 
Many thanks!

#32 of 2487 KMH by cliffy1

Jul 07, 2001 (6:21 am)

As you noted, the rear LSD does need maintenance. The clutches can and do wear out and will eventually need to be replaced. When they do wear out, you will not notice anything drastic. They will just stop transferring power to the side with the most traction. It literally reverts to an open differential.

#33 of 2487 4wd low on Sequoia by gratefuldad

Jul 15, 2001 (8:15 am)

cliffy 1,
 
Thanks again for all the informative postings. My question, which by implication you may have already answered, is whether the sequoia's transmission must be in "L" to engage 4wd low? The reason I ask is that you imply that 4wd low is essentially designed only to extricate the vehicle from a bad situation. My experience with 4wd was with a 76 LC, the ultimate in conventional 4wd as you say, in Colorado, and I rarely ventured off road without 4wd low engaged simply for the ability to handle steep grades. I rarely got stuck, but I was always going uphill. I love the idea of the 3 open miff's saving wear and tear with the tracs computer easing any potential bog downs, but can it work in 4wd low. (trans in "D" ?) Thanks for any info.

#34 of 2487 gratefuldad by cliffy1

Jul 15, 2001 (10:10 am)

The low gear range operates in all gears. If you shift the transmission into "L", the center differential is also locked and the TRACS system is disengaged. This means that as long as you don't have the transmission in "L", you have the low gear range plus the TRACS and open differentials working for you.
 
Great user name by the way.

#35 of 2487 HL Center Diff by llofgren

Jul 16, 2001 (4:49 pm)

Cliffy1,
Thanks for your excellent explanations on these systems. You mentioned that the HL center diff maintains (with the transfer case) a 50-50 split between front and rear. If there is Front slip then the viscous coupling thickens and routes more power to the rear.
Two questions: 1) Can the opposite happen? That is, if there is rear wheel slippage, can power be transfered to the front so that the front wheels are getting more than 50%?
2)Does the system work when the transmission is placed in Reverse?
Thanks!

#36 of 2487 llofgren by cliffy1

Jul 17, 2001 (6:50 am)

The answer to number 1 is yes.
 
I'm not positive on the answer to number 2, but I don't see why it wouldn't. The viscous coupling center differential is pretty simple and if one drive shaft begins to spin more than the other, power is transferred. I don't see why direction would impact that.

#37 of 2487 Allow me to understand this by kmh

Jul 18, 2001 (7:55 am)

Say I'm going along and my front wheels begin to slip in my RX 300. Power is transmitted to the rear tires, correct?
 
Everything is going along with power to the front and rear wheels until one of the rear wheels begins to slip... Does the power then move forward to the front wheels?
 
At what point does the transfer stop? When there's no longer any wheel slippage?
 
I apologize if I sound completely ignorant on this, but I am in a way and merely want to understand what my RX is doing in conditions when the transfer occurs. Thanks!

#38 of 2487 kmh by cliffy1

Jul 18, 2001 (8:01 am)

You've got it! The power equalized when traction is equalized.

#39 of 2487 cliffy1 by brillmtb

Jul 19, 2001 (9:52 pm)

cliffy,
 
Good job on helping folks out on the Toyota systems. I found that the dealers couldnt even explain it and they go to the training.
 
I would disagree on something you said in an earlier post. It is not the unibody that would limit the HL. It is suspension design, one aspect of which is the ground clearence you mention.
 
Then again, I hope nobody is considering much off roading in the HL anyway. So my point is, the highlander should do fine for its intended purpose just as the whole line of Toyota products seem to do.
 
The trick is to figure out what you want to do then find the SUV to match it.

#40 of 2487 4 Runner Roll Over by ggoodwin22

Jul 25, 2001 (3:05 pm)

Cliffy,
 My wife was driving my '99 SR-5 through Kentucky on I-75 while I slept in the back. It rained hard and fast and she hit a puddle and hydroplaned at about 55 mph. I awoke and saw her turning into the skid but knew she wasn't going to be able to correct it. We ended up rolling over 3 times, landing back on the wheels. Luckily we walked away from it. She doesn't drive my truck very often and isn't familiar with it's handling. Could this have been prevented if this vehicle was equipped with VSC and in 4WD?

Messages Page 4 of 249

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