[AK Mule]

We are getting ready to buy a 2017 Limited, and I was trying to figure out what rear differential it has. The brochures show that some models have limited slip rear differential and some models have locking rear differential. Cool, I know what those are and the differences.

Under the Limited model, it doesn't say at all and focuses on the Torsen center differential. Cool, I know what that is and how it works.

It also talks about A-TRAC and TRAC and how it applies braking to help with wheel slip. Again, I know what that is and how it works.

But I can not find what differential is on the rear of a 2017 Limited. Is is open, limited slip, or locking?

Thank you,

[NuclearN8]

Center is locking on the limited. Rear is slip.

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[3wbdriver]

The rear diff on the Limited and the SR5 is open. The Trail (2017 TRD Off Road) and the TRD Pro are the only models that have a locking rear differential.

[gundrted+t4r]

There is a trak that uses the breaks to simulate a rear locker. I've never tried it on mine.

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[AK Mule]

Originally Posted by 3wbdriver

The rear diff on the Limited and the SR5 is open. The Trail (2017 TRD Off Road) and the TRD Pro are the only models that have a locking rear differential.

Thank you. The brochure says that the SR5 has an automatic limited slip rear differential in 4x2 only. Don't see why Toyota has so many different axles on one truck.

[Bevo]

Originally Posted by AK Mule

Thank you. The brochure says that the SR5 has an automatic limited slip rear differential in 4x2 only. Don't see why Toyota has so many different axles on one truck.

They only have two. One with the e-locker(Pro and Trail) and one without(SR5 and Limited). That doesn't seem like a lot to me.

[e60ral]

Originally Posted by AK Mule

Thank you. The brochure says that the SR5 has an automatic limited slip rear differential in 4x2 only. Don't see why Toyota has so many different axles on one truck.

Auto LSD is an open diff, it just uses traction control to act like a limited slip diff

[vjack]

There are a lot of drivetrain permutations:


In all 2WD models, the 4Runner has an "Auto LSD" which uses the brakes to simulate a rear limited slip differential.

In 4WD Limited and SR5 models, the 4Runner has open diffs front and rear but includes A-TRAC which simulates front and rear lockers by braking selectively. This is surprisingly effective.

In TRD models (4WD only) the 4Runner has a physical locker on the rear diff and also A-TRAC to simulate a locker on the front diff.

In 4WD SR5 and TRD models, the center diff (EDIT: it's not a differential on these models, just a transfer case) is either disengaged (2WD mode) or locked (4x4 mode). These are part-time 4x4 systems that must only be engaged on loose surfaces (dirt, sand, etc).

In 4WD Limited models, the center diff is a locking Torsen which is full-time AWD (basically a limited slip center diff) AND can be locked into the same 4x4 mode that the other 4WD models can be.

If you want a detailed breakdown of exactly what hardware comes with each trim level, I suggest checking out the 2017 4Runner PDF brochure (scroll to the bottom for a feature comparison matrix).

[Engineer]

Originally Posted by vjack

In 4WD SR5 and TRD models, the center diff is either disengaged (2WD mode) or locked (4x4 mode). These are part-time 4x4 systems that must only be engaged on loose surfaces (dirt, sand, etc).

.

There is no center differential in the SR5 or TRD/Trail trim lines on the 5th gen 4Runner

[Irikumi]

These traction control systems are quite effective, my R51 Pathfinder had open differentials on both ends but would use the ABS brake system to apply brake pressure to the wheels slipping. It makes for a psydo limited slip system. It's not as good as lockers, but pretty damn good. Toyota A-TRAC system seems to be more aggressive then Nissan's making it even more effective. Subaru does a similar thing with there AWD system, and is quite effective too. This technology has been around for a long time, some versions of it are better then others. Toyota's A-TRAC actually has to be engaged in 4L mode. It seems to be better by far then a traditional clutch style limited slip differential, but not as good as a true locker. These Offroad edition trucks seem to have maybe a more sophisticated type of A-TRAC system with the terrain modes and all that, plus a true locking differential. I like these systems better then old school clutch style limited slips, it is a lot easier to put new brake pads on a truck then tear apart a differential to replace those clutchs. But, a true locker is king for offroad.

[AK Mule]

Thank you all for the help. Much better than the brochures, which are vague (even the matrix part).

We are going to get a Limited this summer, and living on a dirt road at altitude in Alaska, we wanted to make sure there was a good system for getting power to all the wheels. Seems the open diff with electronic aids should work for us.

Thank you, again!

[3wbdriver]

Originally Posted by AK Mule

Thank you. The brochure says that the SR5 has an automatic limited slip rear differential in 4x2 only. Don't see why Toyota has so many different axles on one truck.

This is the rear drive only version of A-Trac. My 2011 2wd Tundra had it and it was actually quite good at getting me out of a couple muddy oilfield locations. The nice thing is you don't have to push any buttons. It's fully automatic even though it only works at lower speeds. A dash light actually starts blinking at you when it activates.

[vjack]

Originally Posted by AK Mule

Thank you all for the help. Much better than the brochures, which are vague (even the matrix part).

We are going to get a Limited this summer, and living on a dirt road at altitude in Alaska, we wanted to make sure there was a good system for getting power to all the wheels. Seems the open diff with electronic aids should work for us.

Thank you, again!

I think the Limited will suit you well. I drive on dirt roads regularly and the Limited's full-time AWD is awesome. I doubt you will have to engage the A-TRAC system. Plus IMO it is the best drivetrain option for driving in winter conditions.

[AK Mule]

Thank you for all the help. Picked it up yesterday. No running boards because of the snow depth. All I need is a second set of wheels and tires for the winter, and how to set the TPMS on those.

[Jetboy]

IMO - with a limited - it's unlikely that you'd ever have a reason to use auto LSD. It's generally only for 2wd mode on most 4runners and other Toyota vehicles. In a limited that's always in awd - I'd guess ATRAC (which is the same thing for all 4 tires) will be used a lot more often.

It works - really well. But ATRAC is even better most of the time. The only time I use it is to go spin doughnuts on icy parking lots.