[SilverDan]

So what's the logic behind the fact that the front lockers can only be used if the back are engaged? The back do less work as they're not a steering axle for most vehicles. Except the TB/AT4 have rear steer, so both are steering axles.

 

[SilverDan]

As far as I can see it's the same approach, they both use the 'wait 5 seconds' wording. I'm guessing they'll use one of the left hand side buttons for lockers, at this point will take it as one button, long press to get both lockers.

TB and AT4 presumably will be the same, with the airbag button replaced by a single locker button with long press.

Somewhere I saw some wording around Terrain mode on those web pages, maybe that mode will automatically engage the lockers? Probably take an approach similar to the Hummer whatever that does.

 

[SilverDan]

Impressive - lockers really work even and especially for non rock climbing.

 

[SilverDan]

Taking a closer look, they just swapped "Silverado EV" for "GMC HUMMER EV", added the front/rear icons, and touched up the formatting. Obviously the Hummer was a placeholder and that was probably always the intent, they designed the help pages originally knowing lockers were coming.

For reference here's the Hummer Quick Start guide for lockers

 

[SilverDan]

I checked the Wayback Machine for this page. It's been around unchanged since 2023 with just very generic information about diffs and lockers, only the Hummer EV is mentioned and the icon is shown for the rear lockers only. The last snapshot was Feb 14 of this year with no changes. So these edits are post Feb and not captured by Wayback yet.

So somebody came into these pages in the last three months and added instructions on how to use them for the Silverado EV specifically. I'll call that practically definitive and say we're going to see dual lockers 🎉🎉🎉

before

after

 

[SilverDan]

Well well well …

How to use locking differentials

Your vehicle must be in Terrain Mode or the 4Lo transfer case setting (if equipped) to engage both the front and rear lockers. On some vehicles, such as the Chevrolet Silverado EV, the button must be held down for at least 5 seconds to engage both lockers.

This is a page about using lockers and EV’s, on the Chevy site. Could be a typo (but a really weird one?) or an inadvertent leak. Also an article about how to use Sidewinder mode

 

[SilverDan]

Except for - as I mentioned above - the EV's are more fully optioned with a smaller trim lineup than the ICE's (they already dropped the RST). To get into the TB/AT4 you're spending some serious bucks compared to the ICE versions, a locker costs nothing, dumb move IMO if they leave them off. Plus there's price compression, a ZR2 would have to be back up at $100k for what, some fabric, zippier shocks and lockers? Not even to mention the competition (CT and Rivian) already have them ...

From AI

2025 Chevrolet Silverado 1500 ZR2 starts at $70,995. The price can go up to $79,435 depending on options and trim levels. For example, the 2024 model starts at $71,895 and can go up to $80,335

Lockers, it'll have to have them or be the marketing dumb logic move of the century 😅

 

[SilverDan]

Just to drive you guys nuts, here's the locker, two plates with intermeshing ratchets, the actuator is in the lower right corner

Partially assembled, actuator is on the final drive housing, diff with ratchets on the left, you can see how the plastic alignment pins (surely with a metal pin center, the plastic is probably for wiggle) go through the housing on the right under the actuator. It presses on these to push against a spring (probably) and lock against the diff which is in that housing.

The rotational force on that ratchet must be pretty low with the diff gears taking the load, however the statics of it works.

 

[SilverDan]

Front Motor teardown:

<Munro boys>

Watching Munro videos always hurts, production wonks criticizing every weld and machining turn makes me want to cry 😅 It's like they think an engineered product is just about the lowest level of production efficiency, when it's much, much much more to consider.

Bean counters basically, it's like the food companies that say "aw damn you know cane sugar is marginally more expensive than high fructose corn, let's use the latter everywhere". Or another one they do "hey you know stopping the production lines for maintenance is costing money, but if we put more oil into the material (e.g. what you eat) then it'll naturally grease the machines and we can keep them running 24/7".

Manufactured food is such garbage in the US because of this this kind of production efficiency thinking; it's a disease and I'm thankful when I see a company like GM not succumb to it. Sure - make production as efficient as you can but don't obsess about it, make your margins other ways. This is why I have a bone to pick with Tesla - sure they produce cars cheap, big deal, but it's the same damn car year after year. Do not ever tell me that's better.

On this one I wish they did the video more like the Weber Auto channel where you can see it semi-assembled. Again a couple of wonks looking with a microscope.

 

[SilverDan]

It would be cool to be able to turn on a locker with an aux switch if we could enable on an existing truck!

In the old days at <some> company (pre fancy encryption software) we would put resistors on the board that would get clipped out to enable the paid for options. Until that is, some canny customers figured this out and clipped them off themselves. 😅 Much cheaper production to produce one widget. Drove people mad but they don't get it, they're not paying so much for a physical thing but the options that mix into the total BOM/margin price.

Now GM's customers take these things apart and are loudmouths, so my guess is they would split off a variant, just to avoid the heartache. If not then in theory you could take the whole motor apart, drill into it, access that control line and hotwire it. A heck of a lot of bother though instead of just buying a Trail Boss. Anyhow watching that Munro disassembly looks like it would be trivial to drop the components in a variant, so the only cost is the inventory (which is more than it would seem). So I think probably not.

I'm pretty confident we'll see dual lockers and I'm hoping there are physical switches on the left hand side for them; I like physical.

 

[SilverDan]

Hummer does not have physical connection between the two rear motors in spite of their common housing.

Yah, I wasn't saying so. Actually I was going to write that it looks like the two motors just butt end to end inside the housing along that centerline. Also you can see there's no diff, at least on this side. GM will probably use this motor for other exotica, such as military vehicles.

Disagree with your logic based on observations by testers. Mechanically locked single motors perform better than virtually locked dual motors.

That's a separate question and I'm not disagreeing on performance; which is what it is. What I'm saying is just the physics of it (unless I got something wrong in there), but a force diagram doesn't always translate directly to experience. In this case I think the physical works better because there's no software in-between the driver and the wheels. Virtual lockers are mitigated by a different more complicated control stack which loses that direct feel, plus it's not what people are used to on the road (simpler control stack). But a physical is the same control stack the driver is used to but they have more trail feel because of the physical connection.

Example from a different realm, bicycling. I have two e-Bikes, one is a traditional chain derailleur drive, the other is an (ridiculously expensive German) belt and hub gear. On paper the hub gear is technically better, more gears, equal or better power transmission, and the belt is what is used on performance cars. But the old style chain and derailleur feels better and (feels like it) gives me more control. That's why that's the Mountain Bike (single track), and the hub gear is an all terrain adventure bike (road/fire road). Just like with off roading cars, I depend on the feel of that chain drive (just a single waxed chain/direct gear instead of a belt and complicated gear set) to get me over technical spots and not slip or spill. When rock climbing you need visceral contact and control of that surface.

Anyhow I completely understand what they're saying about the virtual vs physical 'which is better' discussion, but I don't think you're going to explain it using a force diagram; this is in the human realm.

 

[SilverDan]

Hummer rear dual motor motor, duplicated ports for the two motors

Hummer/Silverado Front, Hummer version has a locking diff. Presumably the diff is built in like the housing? Looks like it would be on the left side output from this picture. If so then a variation.

Silverado back has a diff too, and will probably have a locker if it has any at all.

Now for the interesting question; what if the lockers are already built in but neutered? With low BOM lines like this it’s pretty common to just include dead hardware you neutered out for options, cheaper than having different variations. And would already be the case as the Hummer front uses the locker, with the non TB/AT4 SEV’s having them neutered 👀

 

[SilverDan]

With separate motors for each wheel, e-lockers mean the wheel with traction is limited to the power of that wheel's motor and can even get less as the electronics try to match power to both wheels but are limited by the one with less traction.

Had to think about this for a bit, I think there’s a problem with that logic; it’s actually backwards. With one motor and two wheels on a flat surface, each wheel gets half the total power delivered. With a motor on each wheel, in total there’s twice the power. There’s always more power with more motors.

OK so other extreme is one wheel off the ground. It’s the same for single locked diff or dual motor - there’s only one operational motors with the total power in either case. Either the in air motor is off, or the diff only delivers to the traction wheel.

So you’re talking here about some middle ground where the two motors are trying to match power somehow? Like say there’s a side with slip, so it lowers the power output to that side to keep traction. Here the motors aren’t matched, they’re deliberately using different power levels to maintain traction.

So not seeing what the idea is here …

 

[SilverDan]

on the 3X with 3 Motors it's Virtual locker in the rear and Physical in the front, on the 2X it has 2 Physical lockers one for each of the single front and rear motors.

Checking the web - so the 3X has two motors on the rear which explains the virtual locking/torque vectoring, you're controlling each wheel individually. The front axle, with one motor needs a physical locker. So the SEV's would have one or two physical lockers only (probably two).

Anybody have a schematic of the motor and axle configuration for the SEV? I'm curious how the differential comes into play. Here's the Bolt from Webers vid

Final drive goes through motor center on top, differential at end, the two axles right/left to the front wheels.

In-situ

From the video the second 'idler gear' has a 'counter gear' on it. Not sure what that is there for, maybe some gear-head can explain

So presumably the Hummer has some locker Ultium motor variation - a standard Ultium motor version but with a locking differential. Given GM's new desire to reuse parts, presumably we have two of those in the SEV.

Having worked through this it seems pretty darn likely to me.

 

[SilverDan]

Why do you suggest one e-locker? Since they are going for reduced BOM complexity and so many of the drive components are common across the different vehicles, wouldn't they be both mechanical lockers? Also, how do you define e-locker?

Sorry using the wrong term, I'm thinking of a 'Virtual Locker' (it appears to be called) on the Hummer rear, using torque vectoring. But I'm not thinking this through, the Hummer has up to three motors with physical and virtual is my understanding. Maybe somebody can step in here who knows what they're talking about 😅

 

[SilverDan]

I would be thrilled to see Magnetic Ride Control but they haven't used it on a truck to date. It offers amazing capabilities...even Ferrari is using it.

DSSV has been the go to for trucks. Very capable but not adjustable until the ASV came out. Was hoping for ASV but MRC would do the trick.

Unfortunately, base Trail Boss ICE has only had the Rancho's. To get lockers and the DSSV shocks, you either had to order the ZR2/AT4X trims or, in 2025, ZR@/AT4X became options on Trail Boss/AT4 instead of separate trim levels.

Not a whisper on lockers in anything I've seen published for the 2026 SEV Trail Boss.

In addition to simplifying the physical architecture and master Ultium BOM I have zero doubt that the Marketing side isn't doing the same - they will definitely be mirroring the simplified structure on their side and we're already seeing it. Trims and options increase complexity and cost. I think we're already seeing it, they're using battery (Std, Ext, Max) and Trim (WT, LT, TR) as the main options, in addition to judicious use of upgrade packages for those who want an Extended battery but upgraded options. Otherwise the upgrades are determined by the Battery/Trim combination.

Point being, along with the slow roll on suspension information I'm now thinking we'll see something exciting. While they might offer a boutique option or two much later (like High Country), the 'option compression' we're already seeing appears to be pointing to physical lockers (well one locker and one e-locker) plus some kind of spicy shocks. *

Will be exciting in any case!

* Note we already had a boutique trim which was the RST and all it had was every option plus some window dressing. Then they dropped the RST and you have to go Denali to get the air bags. So any High Country or specialty TB I think will be similar, maybe some token hardware feature you don't need but mostly window dressing.

 

[SilverDan]

Trailer good option but here's another option...hitch mount but has receiver for your trailer (max weight 7500 lbs). They've got other types of tire carriers as well.

I was planning that, but the trailer doesn't have much outside storage so I'm getting a 3rd party bumper storage tray/boxes which are really the treat, so the hitch isn't available. That would also cover up the license plate which might be a problem ... well so would putting a bike back there I suppose, but just not as much.

 

[SilverDan]

When was the last time you had a flat?

Agree, around the house I may keep it in the garage. But traveling my trailer has a full sized spare on board so dumb not to have one for the truck too. Getting stranded with a trailer is no fun, you can tow the truck but what about the trailer?

Presumably GM will have some kind of lockable bed mount like they did for the Hummer. Only problem is when I need to use the bed, I‘ll probably look into the possibility of small spare stored under. There’s some possibilities of storing it on the trailer too.

 

[SilverDan]

Also with those 22”/24” one concern for me is road noise, I’m not fond of the short sidewalls they have on the Bolt which gives too much road feel and noise.

You guys know from my blathering that I was long planning the Max LT, but damn if the off roadies aren’t compelling packages. Knowing the range just seals the deal. Only - the only downside for me is no underbody wheel storage. I’ll have to keep a spare in the bed. But totally worth it since the tradeoff is lots of sidewall cushion, AT and doesn’t hurt range enough to matter.

 

[SilverDan]

Not a whisper on lockers in anything I've seen published for the 2026 SEV Trail Boss.

At this point I'm getting the feeling they're holding back something to make a splash at the public reveal Andre is going to. They're carefully teasing this out, full order guide is out (except suspension), then teaser with a mysterious 'hydro suspension' (whatever), so keep your hopes up