Question about locking center diff
- Thread starter gsrthomas
- Start date
JB.
New member
An understatement.
One causes all sorts of confusion and the other is a perfect description.
CJ3Flyr
Super Moderator
JB.
New member
x2 or is it x3
Scottm has it, M1911 and JB are correct.
Unsure of the tone of your post but if it was suggesting overkill I would submit that the OP's question has long been answered and that in the ocean of confusion created by "50/50 torque split" a few drops are at least as good as one.
CJ3Flyr
Super Moderator
Tone is good!
I was adding a vote/opinion agreeing with you guys. If anything I was/am 'overkilling' it. I totally agree about 'confusion' about this and other aspects of 4wd especially the 4th gen system. It seems this topic is tough one for folks to get their arms around. The other interesting thing, to me, about this system is once the proverbial light turns in someones head they've "got it" 100%, no looking back. People either get Torsen, center diff-lock ATRAC, VSC etc or they don't. It's such a great system and even better when the end-user fully understands it (that's why I like threads like this). The more people know the better they can use/enjoy the expensive, cool equipment they've chosen to own:bigok:
The only reason I chimed in was to add 'support' in the hopes next person with this question discovers this thread in their search AND when they're done reading it they're less confused rather than more confused.
:cheers:
JB.
New member
Tone is good!
It seems this topic is tough one for folks to get their arms around. The other interesting thing, to me, about this system is once the proverbial light turns in someones head they've "got it" 100%, no looking back. People either get Torsen, center diff-lock ATRAC, VSC etc or they don't. It's such a great system and even better when the end-user fully understands it (that's why I like threads like this). The more people know the better they can use/enjoy the expensive, cool equipment they've chosen to own:bigok:
The only reason I chimed in was to add 'support' in the hopes next person with this question discovers this thread in their search AND when they're done reading it they're less confused rather than more confused.
:cheers:
OK, now it's overkill. :bigok:
OK I get it, thanks. Looks like this won't be an issue for me as my beach driving is right along the water to get around flooded areas on trails. No dunes, but nice to know.
My biggest challenge is mud, would you suggest locking the diff would help there??
So which one is it? People are giving 2 different answers on this. Some have said each wheel gets 25% of power regardless if it has traction or not. Others said that if 3 wheels are off the ground then the wheel with traction get 100% of the power which is hard to believe. Because why would they have offered a TE for 2009 with ATRAC.
If each wheel gets 25% of the power than this is not enough power to pull the rig up hill with just on wheel.
If each wheel gets 25% of the power than this is not enough power to pull the rig up hill with just on wheel.
Doozi
New member
All of the confusion is basically around the semantics of this discussion... people with true knowledge of physics will agree that if a tire is in the air, it can do no work as it is not appying force. Maybe a different explaination will help... without worrying about what percentage of "power" is going where.
If a differential is "locked", regardless of where your wheels are, both sides of that differential will rotate at the same speed... whether it's your front, center, or rear differential. Think of "locking" as physically connecting the two shafts the differential is connected to. When speaking of an "open" differential, you could say that the "power" will go to the wheel with the least amount of resistance. Ever turn a corner and punch it in a rear wheel drive car and have the inside tire break free and spin? Ever try climbing a gravel hill (in a vehicle without A-TRAC) and have the tire that starts to come off the ground break free, spin, and leave you stuck in that position? That's an open differential sending "power" through the path of least resistance. A locked differential will keep both sides rotating at the same speed... if one tire comes off the ground, it can't spin any faster than the other tire (same axle, of course) that's on the ground. Our 4Runners have "open" differentials, but utilize the vehicle's brake system to grab the slipping tire and force "power" across the differential to the tire with more traction.
I recommend experimenting with your 4Runner in an off-road situation and watch some real rock-crawlers for an understanding of what it means to "lock" a differential.
I'd say, "Now that's overkill", but I wanted to try and offer an explanation in different words... hopefully, it will help.
~Doozi
If a differential is "locked", regardless of where your wheels are, both sides of that differential will rotate at the same speed... whether it's your front, center, or rear differential. Think of "locking" as physically connecting the two shafts the differential is connected to. When speaking of an "open" differential, you could say that the "power" will go to the wheel with the least amount of resistance. Ever turn a corner and punch it in a rear wheel drive car and have the inside tire break free and spin? Ever try climbing a gravel hill (in a vehicle without A-TRAC) and have the tire that starts to come off the ground break free, spin, and leave you stuck in that position? That's an open differential sending "power" through the path of least resistance. A locked differential will keep both sides rotating at the same speed... if one tire comes off the ground, it can't spin any faster than the other tire (same axle, of course) that's on the ground. Our 4Runners have "open" differentials, but utilize the vehicle's brake system to grab the slipping tire and force "power" across the differential to the tire with more traction.
I recommend experimenting with your 4Runner in an off-road situation and watch some real rock-crawlers for an understanding of what it means to "lock" a differential.
I'd say, "Now that's overkill", but I wanted to try and offer an explanation in different words... hopefully, it will help.
~Doozi
eskimochaos
Banned
Tires on the ground dont do any work either. The velocity between the tire and the road surface while moving is 0. W = F*d. d=0, work = 0.
JB.
New member
Part of the confusion is because the word power gets used in two different ways.
Grab a pencil. The pencil shaft is the axle and the eraser is a wheel. If there were an eraser (wheel) on the other end they would have to rotate together like two wheels on a locked axle. Press the eraser end into a surface while keeping the pencil almost parallel but keep the other end up. Twist. The eraser end is the only point of resistance and gets 100 percent (virtually) of the twisting force (torque). The other end is rotating, ready to receive power when traction appears.
So, in every day speak, the raised end is receiving power. In a physics sense, it's not, because there is no resistance.
ATRAC adds resistance to make open diffs start to act like locked diffs but since it uses the brakes, it subtracts some overall engine power. With low ranges gears, though, it's probably nearly impossible to be in a situation without enough overall vehicle power.
A minor quibble: on a 4th gen, the front and rear diffs are open (except for the very rare 2009 TE which has a lockable rear diff). The center diff is a lockable, limited slip Torsen, and thus not "open". I know that's what you meant, but I just wanted to clarify for others.
Doozi
New member
Don't forget about the angle between the force and the displacement vector. W= F*d*cos(theta). The tire may not be moving the road surface (although I have seen that), but there is a vectored force applied and your vehicle moves as a result.
Anyway... this isn't a physics lesson... I'm mearly trying to offer an alternative explanation.
~Doozi
CJ3Flyr
Super Moderator
4runherpow
New member
Sorry to bring up an old thread, but is there a workaround to get my fifth generation limited to have four wheel low unlocked? I can't see a reason why it couldn't be modified to do so? I mean, it stays unlocked in four wheel high, why can't I install something that selects it to unlock when I put it into low4?
Anyone?