locking rear differential?

Bleh. Yeah. Like a broken record. You would think I knew what I'm talking about having a fully locked rig, and now one with a-trac and crawl control. The almighty David K will never let it go.

 

Toyota is all mighty... not me and why would I change if the system keeps doing great and is so good they have it on all Off Roads since 2009?
Toyota doesn't offer a front locker, so it's A-TRAC or nada.
Without spending a DIME over the purchase price, you get the A-TRAC system.
Why the complaining?
Not everyone has an extra 2 grand to add a locker.
Now, try and enjoy your truck, it wasn't cheap... unless your parents bought it for you.

 

So I am really confused about this. It's my understanding (and experience) that when in 4WD, your tires will tend to jitter around the pavement when you turn. Isn't this because the front tires are locked in 4WD? And wouldn't that cause them both to spin if one tire was lifted off the ground?

I'm just trying to understand this, as the articles I've found have not clarified things for me.

 

Yes, it is confusing...
Here is what is happening in easy words (I hope)...

When in 4WD, the front driveshaft and the rear driveshaft are locked together (at the transfer case)... and since the front tires turn more than the rear tires in a turn, if on dry pavement the scuffing is from this difference between the combined two front tires and the combined two rear tires. Use 4WD only if on a surface that will permit the tires to slip.

AWD vehicles (full time 4WD) have a third differential that allows the front and rear drive shafts to turn at different rates, so dry pavement is not an issue.

The left and right tires (front or back) also must rotate differently in a turn, this is what a differential allows. The tire that can rotate the easiest is what gets the 'action' and spins if on loose ground or in the air, while the one you need seems to do nothing. A locking differential, and to a degree a limited slip differential shares that 'power' so both tires get the same power to move you, even if one is not on firm ground.

 

A rear locker is a huge help in deep sand and mud (along with airing down a ton). If I ever open up my front pumpkin I am dropping in an ARB.

 

I hear people start breaking parts when they throw a locker in the front of an IFS truck. Might do a LSD instead... I know some people don't have a problem with front lockers, just seems like a lot of stress for IFS.

The way I figure it, if I get to a point where I feel I "need" a front locker, I'll just go ahead and throw a solid axle up front.

 

@jbrandt that is true. I have heard putting an ARB in the front makes the front diff stronger. A TrueTrac would probably work perfect for me. I don't lift tires often, more plow through deep sand.

 

The diff itself is stronger, but CVs are still the weak link... A lot of people just buy a couple extra CV assemblies and get real good and changing them in the field, lol...

A trutrac would definitely be a cheaper option than a solid axle swap... Easier install, no need to wire it up and plumb air lines, etc...

Quite honestly, a truetrac would be on my plate before a solid axle. I don't do the hard rock crawling that would justify the $6k + for a SAS...

 

@jbrandt I feel you there I think that a trutrac is a great call if you aren't doing gnarly offroad (i.e. considering a SAS).

 

I see more potential for damage having an open or LSD diff that loses traction, spins up fast, and then bites quickly when someone uses speed to overcome the traction issue. Whereas with a diff locker, you simple lock the diff, and away you go. I’ve been dual locked for a couple years now and I’ve yet to have an issue. And I off-road quite a bit and have pushed the front locker to the point where I’m surprised I didn’t snap a CV.

 

Like I said, there's plenty of people who work just fine with locked IFS. I've also heard of a lot of people who start breaking CVs when they do, enough to be a legitimate concern of mine. The wheel that gets bound up on a rock or whatever still has ALL the torque being applied to it rather than letting some of that torque go to the unbound wheel - hence, breakage.

I know this is old, but just wanted to add for the record, that TRDs and ORs aren't the only models that come with the A-track. My '17 SR5 4Runner I got off the lot has A-track and downhill assist (DAC). It doesn't have crawl control or a locker. I can turn traction control off too, but I can do that in my Carolla, too, lol.

Honestly, though, I'll take the locker in my '04 Taco and good foot control over the electronic gadgets. The DAC is mad annoying, as all it is doing is engaging the ABS so it's just a constant loud popping noise.

All the electronic gadgets make you (well, at least ME) feel less "connected" to the trail, and basically all you're doing is steering, and since Tesla has nearly perfected auto pilot, at what point do you even need to drive anymore? If I find myself needing more traction in the front (I haven't yet), I might consider an LSD as a good compromise between maximum traction and breaking bound up CVs, or just pick form my money tree and go SAS.

 

A-TRAC was available on other Toyotas and Lexus models before the Tacoma got it in 2009. The ONLY TACOMA to get it was the OFF ROAD TRD 4WD. The A-TRAC has been evolved since it was first on 4Runners and Lexus vehicles, too. In 2016, the A-TRAC became "MTS" [multi-terrain-select] (adjustable) on the automatics.

 

I’ve been running my front locker since 2016, haven’t had an issue. There’s much more damage potential to using speed and momentum to overcome the traction issue, than being able to lock the diff and crawl over obstacles.

 

I never said lockers = breaking things. All I said is I've heard from enough people that put lockers in their IFS trucks and started breaking stuff to give me pause.

My first post on this subject I even said I know there are plenty of people with IFS lockers who do just fine...

 

I think a big part of why you see front ends busting up with locked front diffs is that there are usually 35" or bigger tires on those trucks. Big heavy tires and a locked front end is at a much greater risk of breaking potential than the locked solid axle rear.

 

If you want to do the big name trails, you'll need a front locker. In my experience people who break front CVs are either binding them up or they are bouncing and or going from low traction to suddenly full traction. You want the cvs to be the weak link or you start breaking diffs. That being said I carry spare oem CVS with me at all times. But if you compare the second gen/3rd gen Tacoma ifs with that of a 1st gen you'll notice the components are much larger and robust. I just spent 2.5 days flicking the front locker on and off in all kinds of situations and would not have been able to complete the trail without it. Well actually that's a lie I'd just have to winch a hell of a lot and would probably have tons of body damage.

 

Meh, my brother did the Rubicon back in the 90's (before they bulldozed some of the hard sections) with his open diff 86 4Runner running 32 BFG M/Ts. Driver skill gets you in (and out) of a lot of places. He got yanked up in a few places, but dudes in Jeeps with $20k in mods and 37's couldn't believe he was going where he was.

I agree you want the CVs to be the weak point, as they are (relatively) easy to replace in the field.

 

Lol That's what all the buggy guys were saying to me coming up Cadillac. Still the most technical trail I've ever been on. But ya I'd rather launch a cv in than have to run back to town get a new diff and replace that on the trail. CVS, clutches, brakes they're all wear items imo

 

Would really suck to have to replace a clutch on the trail...if that'd even be possible.