Don't miss my GMC Sierra, but miss the diff lock

I have a TRD Offroad with the diff lock, but I can only use it 10% of the time I normally used the diff lock in my Sierra.

The mechanical locker, aka the G80 in the Sierra automatically engages when one of the wheels spins slightly faster than the other. Was driving in partially snow packed roads today. So stop in 2WD at an intersection with one wheel on snow, the other on bare pavement. So spin, traction control kicks in, but late because it's MT and the truck confuser doesn't want to stall the engine (that's good) and eventually get going. Don't want to use 4wd because I had to make a sharp turn onto a dry road. Only the side street I was on was partially covered.

That happened frequently in the GMC that I'd feel one wheel spin a little and immediately feel the other lock and it would move. A diff lock limited to 4-low is silly. Had an Xterra Pro4x and it was the same, only available in 4 low. Even the F150 with electric locker allows it in 2wd. Not sure why the imports feel the diff lock should only be used in 4 low.

Still my favourite truck, but it does come with quirks like all the others did.

 

There was an easy electrical mod for the 3rd gen to allow 2LO. I bet someone will figure it out for the 4th gen, too.

 

Not sure if it’s the same on the 4th gen MT, but the third gen allows you to turn on the Limited slip differential with a quick press of the traction control button. It’s a simulated LSD, uses the ABS to break the wheel with less traction. It works very well and is intended for that exact scenario.

Toyota’s prefers this over allowing users to engage the locker whenever, simpleton proof. Same reasoning for no front locker, limiting it to 4low. That and their A-trac/crawl has gotten very good. Also keep in mind the new gen is making way more torque at a much lower rpm. I can see users breaking diff’s/cv’s with a heavy foot off-road in 2wd if they had the ability to turn on the locker whenever. And that with larger diffs and sturdier CV’s than previous gen’s.

I believe the 4th gen still has auto lsd, might need to turn it on.

 

That would be nice, I wonder if that also fakes it to use the diff lock in 2 hi. Will see if they make it.

I could be wrong, but when I was comparing models and debating between a diff lock (OR) or a trailer brake controller (Sport), I think I saw what the simulated LSD was available on models without the locker. I had simulated LSD on my Xterra on the front axle and didn't need to do anything to turn it on other than spin. It worked well, I was pulling a friend out of the snow and had 1 front wheel on pavement and that would wheel would chirp on and off as the ABS would do it's magic.

I'll have to experiment see if I have the simulated LSD and how to activate it. The automatic mechanical locker is still the best, engages automatically when a wheel spins, releases when there's no tension on the diff or when going over a certain speed. So can't forget it on and always there when needed.

For rock crawling, electric lock that stays locked is probably better, but it's snow and mud for me.

 

There are good reasons why you shouldn't modify the truck to go into 2wd low range. Back in the day when trucks had manual locking hubs and 3 sticks in the floor it was easy to just shift to low range while still in 2wd. But they also included labels on the dash warning drivers not to do so. I've seen guys break U-Joints who ignored the warnings. They no longer include those warnings because it's impossible to do this with new trucks unless you modify the truck

But there is no reason why Toyota should force you to be in low range to lock the diff. 2wd Tacoma's will let you lock the diff and every other truck manufacturer will do it.

Normally traction control would have kicked in and done the job in this situation. This is one of many reasons I want no part of a manual. In your case I'd have just shifted into 4X4 briefly to get moving.

 

Traction control with a manual transmission doesn't work well from a dead stop otherwise it might cause the engine to stall. I don't get stuck and still able to get moving, but it gets moving quicker when the rear locks automatically as opposed to traction control alternating the ABS from side to side to get some traction which is nice when trying to pull into traffic. Moot point when there's no traffic.

Anyway, there's no solution, an electric locker will never work like a mechanical locker and this truck came with an electric locker. It's more venting than anything.

 

Weird. It claims that the auto-LSD is only available on 2WD models. I find no reference to auto-LSD on toyota.ca, there's no 2WD in Canada, so maybe it's true.

 

They just call it something different on 4wd models (TRAC or something). I'm sure if you push that button, it will do the same thing. Edit: the button is the squiggly lines one, just turns off traction control.

What it does is removes the power cutoff, so you just get braking on the spinning wheel with full power.

 

No braking on MT from a dead stop and certainly no engine throttling to avoid stalling

 

Reread the first post, and it sounds like you got going, so the truck is working as designed. I get it, though, it seems like more work for the truck for the same end result.

A mechanical LSD would also be good in this situation (better than a locker, in my opinion).

 

Never had a mechanical LSD over, so can't comment, I'm sure it's better than open diff. I've had pretty much every other combination: 2 open diffs, 1 open diff with fake LSD with ABS/traction control, 2 electric locker (include this one) and 2 Eaton MLocker (GM G80). For daily driving, the Eaton MLocker is the best of the systems I've owned, but there could be better out there.

The locker alone is not a good reason enough to go to a GMC truck though, I just miss that feature of the GMC.

 

Best system was the Borg-Warner's in my Isuzu Axiom. Mechanical Torsen LSD was on all the time. Normally drove it in 2Hi, with just an LSD. Switching to 4Hi/TOD/Torque On Demand meant that center differential sent power to the axle with the most traction, front or rear, up to 20/80 split (IIRC). TOD could be used on ALL surfaces: dry roads, snow, ice, water, gravel. At highway speeds.
Switching to 4Low locked power distribution at 50/50 between front and rear axles.
And real LSD was on the whole time, 2Hi/TOD/4L.

It was a better vehicle for Alaska than my Taco TRD OR was.

 

Is that an actual locker or something else?

I don't think it even kicks in until one tire hits 100 RPM. I'm happy with my locker; when it is on, it's on. I've never felt a need for it in 2wd or 4 hi.

 

I don't know, but I am guessing based on my experience, that the pseudo-LSD on the TRD OR models is just "on" all the time in 2WD. Without doing all sorts of contrived stuff in simulated settings, I can't prove it. I have parked on a steep hill, with one tire on pavement and the other tire basically dangling in mud on the other side with an 18" drop. If I give the truck some gas, you feel that danging tire barely touching the ground spinning for a second until it does the atrac thing and the brakes lock on the gimpy tire and power goes through the open diff to the non spinning tire. It seemed like it just worked the several times I drove on this spot, just had to give it some mild throttle to get the loose wheel spinning.

Here's a schematic I made in MS Paint CAD, feel free to put this on a T shirt if you want.

The top was the view looking at the tailgate, the other is the view from side:

 

https://www.topspeed.com/cars/car-n...otors-g80-locking-rear-differential-ar169064/

Or a video, I think this is the good one:
https://youtu.be/RtdaBmi3ubk?feature=shared

 

So this video will explain how these differentials work. The whole video is an hour, and most people can't manage to focus for more than about 3 minutes. I've skipped to the part that will answer how these work and why they need some rotational speed to auto lock, but the entire video is very much worth your time in watching if you wish to understand how different types of differentials work.

Open diff, clutch-locked diff, air locker, welded, etc. all covered.

https://youtu.be/1a9JQC6fgXw?si=NM5TWHUF4pNrD-Q2&t=1636

 

On a good day, I'm there. Maybe two and a half.

 

Most people can't focus longer than a tic toc. I'm amazed that people don't remember what happened three months ago.

 

My 2022 OR definitely has the auto LSD option as long as I am not in 4LO

 

Need, probably not, but it's nice to have. I wouldn't not bother to turn it on on 2wd most of the time, I'd go 4wd instead. But it happened a lot with my old truck to feel it locking and improve traction, like moving in wet grass with slight incline and one wheel spins slowly, the other wheel engages and the truck moves. Without it, probably would have needed 4wd, or back up and take another run. It's rarely in the extreme situation that an automatic locker that works in 2wd comes in handy, it's just with regular driving. A mechanical LSD would have similar benefits.