Center Diff Lock?
Center Diff Lock?
On the Toyota trucks there is usually a 4WD lock.
Can you tell me why it's a bad idea to drive it on the pavement with it on? I understand it could be ok moving in straight line, but steering could be stiff?
It is supposed lock the front and rear power distribution 50/50. But the left and right wheels on the front or rear end are running on open diffs. So it's not like you cannot turn in an arc like a welded diff e.g. drift car. Or am I misunderstanding something.
Can you tell me why it's a bad idea to drive it on the pavement with it on? I understand it could be ok moving in straight line, but steering could be stiff?
It is supposed lock the front and rear power distribution 50/50. But the left and right wheels on the front or rear end are running on open diffs. So it's not like you cannot turn in an arc like a welded diff e.g. drift car. Or am I misunderstanding something.
Lexus Fanatic
Joined: Oct 2003
Posts: 94,574
Likes: 265
From: Virginia/D.C. suburbs
That is correct,....and there is also the factor that, in a turn, the two outside wheels roll faster around the greater-radius of the turn than the two inner wheels. If the differential(s) are locked on dry pavement, all four wheels will try and rotate at the same RPM on a non-slip surface, which means tire-scrubbing, unnecessary stress on drivetrain parts, and, in some cases, actual damage to the parts.
That only applies, of course, to dry pavement (or pavement that is part-dry/part-wet. On continuously-slippery pavement, or in off-road conditions where the tires can slip, no problem. That's what the locking-diffs are for...to maintain at least some traction during high-slip conditions.
That only applies, of course, to dry pavement (or pavement that is part-dry/part-wet. On continuously-slippery pavement, or in off-road conditions where the tires can slip, no problem. That's what the locking-diffs are for...to maintain at least some traction during high-slip conditions.
That is correct,....and there is also the factor that, in a turn, the two outside wheels roll faster around the greater-radius of the turn than the two inner wheels. If the differential(s) are locked on dry pavement, all four wheels will try and rotate at the same RPM on a non-slip surface, which means tire-scrubbing, unnecessary stress on drivetrain parts, and, in some cases, actual damage to the parts.
That only applies, of course, to dry pavement (or pavement that is part-dry/part-wet. On continuously-slippery pavement, or in off-road conditions where the tires can slip, no problem. That's what the locking-diffs are for...to maintain at least some traction during high-slip conditions.
That only applies, of course, to dry pavement (or pavement that is part-dry/part-wet. On continuously-slippery pavement, or in off-road conditions where the tires can slip, no problem. That's what the locking-diffs are for...to maintain at least some traction during high-slip conditions.
But the left vs right wheel RPM on the same end of vehicle, should be dictated by the diff of that end. They should be able to move at different RPM, there are no actuator in the front and rear diff to lock the left and right wheels, Am I correct?
Lexus Fanatic
Joined: Oct 2003
Posts: 94,574
Likes: 265
From: Virginia/D.C. suburbs
That was what I am wondering, the center diff (or transfer case?) locks the driveshafts so seems like the 2 drive shafts would spin at the same RPM, I get that.
But the left vs right wheel RPM on the same end of vehicle, should be dictated by the diff of that end. They should be able to move at different RPM, there are no actuator in the front and rear diff to lock the left and right wheels, Am I correct?
But the left vs right wheel RPM on the same end of vehicle, should be dictated by the diff of that end. They should be able to move at different RPM, there are no actuator in the front and rear diff to lock the left and right wheels, Am I correct?
Generally correct. Different vehicles have different locking-differential hardware. Some lock the center diff, some the rear diff, and, some, like hard-core off-roaders, all three. As you note, the more of them lock up, the more potential problems there will be on dry pavement.
So for Lexus, is it really necessary to switch to 4 LO and press the center diff lock to "exercise" them once in a while, even if you don't move the vehicle in those modes? 4 LO can drive forward and back a little.
Most Lexus SUVs that are used as mall crawlers and I think some have gone by 10-20 years have not been used. Yet when you go to sell them, everyone wants a demo of it working.
Most Lexus SUVs that are used as mall crawlers and I think some have gone by 10-20 years have not been used. Yet when you go to sell them, everyone wants a demo of it working.
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Lexus Fanatic
Joined: Oct 2003
Posts: 94,574
Likes: 265
From: Virginia/D.C. suburbs
So for Lexus, is it really necessary to switch to 4 LO and press the center diff lock to "exercise" them once in a while, even if you don't move the vehicle in those modes? 4 LO can drive forward and back a little.
Most Lexus SUVs that are used as mall crawlers and I think some have gone by 10-20 years have not been used. Yet when you go to sell them, everyone wants a demo of it working.
Most Lexus SUVs that are used as mall crawlers and I think some have gone by 10-20 years have not been used. Yet when you go to sell them, everyone wants a demo of it working.
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