[flyinglow]

Thanks Nebula... it's just soooooooooooooooooooooo annoying. I don't need 22's, I don't need mid-gates, etc etc... please please GM just give us the tech. If I end up in a Tesla CT, if and when they increase range, it will be because of stuff like this. Actually, the Lightning Flash package comes with Blue Cruise capability for $67k pre-tax credit; how does GM choose not compete in this space.

With the Trail Boss/Premium Pkg, you at least avoid the 22" wheels. You also get 4 wheel steering with a smaller turning circle than the Denali. That's a big deal for me.

 

[flyinglow]

Here is the door sticker/capacities of the extended range Trail Boss with Premium Package.

Towing 12,300 as reported, payload of 1,968.

 

[flyinglow]

The theory no lockers on Silverado? Maybe on AT4?

The Trail Boss and AT4 will be kissing cousins. If one doesn't have lockers, the other most likely won't. If GM follows ICE truck pattern, lockers and expensive trick shocks will be reserved for ZR2/AT4X options. Those aren't in the most recent order guide so my guess is we have to wait even longer.

 

[flyinglow]

There was a patent application a while back for interlocking the diffs on axles with motors on each wheel. For now, you are better off in off-road/limited traction situations having one motor per axle since, in that case, full power can be transferred to the wheel with traction with mechanical lockers. 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.

 

[flyinglow]

So, I've been trying to figure out what the hydraulic rebound control is that keeps getting referred to in regards the Trail Boss and AT4.

The best I can make out is that it is the equivalent of a hydraulic bump stop only on the rebound side of the shock rather than the compression side. Here is a diagram of a shock with integrated hydraulic bump stop. Note, on the right, that it is a separate hydraulic valve set that creates additional resistance as the shaft stroke approaches the end of its compression stroke. I think the hydraulic rebound control is this sort of valve, only on the top of the stroke where the wheel is at its largest droop. This makes sense for higher speed running with heavy wheels and tires where you want the suspension to follow the terrain but not hit a hard stop in the shocks when they fully extend. Most suspensions will already have some form of mechanical bump stop on the compression stroke.

Hopefully, we will know more soon.

 

[flyinglow]

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

Corresponding button on the center stack...sounds like a physical button, not just something in the UI menu.

 

[flyinglow]

Well well well …
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.

Verrrry Interesting...great catch!

Encouraging. At some point lockers should be available...but when? If it weren't on a Chevrolet site I might go with typo since the Hummers have lockers but, with this being webpages specifically about EV driving on a Chevy site I am more inclined to think it is a publication getting ahead of the vehicles being in public.

 

[flyinglow]

There’s some possibilities of storing it on the trailer too.

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.

Hitchgate Solo

Light Weight and Rock Solid Spare Tire Carrier. Fits Mid and Full-Size vehicles up to a 35" tire. Swing your tire away and have full access to the rear of your rig. Made in the USA

wilcooffroad.com

 

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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.

When was the last time you had a flat? I buy quality tires and it has been 30 years or so - lack of a spare isn't a big concern for me. With the 24s it might have been but with 35" tires on 18" wheels not really.

 

[flyinglow]

You're the shock expert not me in the slightest but I wonder if they're using this now?

General Motors Magnetic Ride Control



Been around for a while but according to AI search has not been on the TB, which instead 'features a Z71 suspensions package with factory lift and Rancho shocks".

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.

 

[flyinglow]

I was watching the dirt ride for wind tunnel aero performance, the dust giving visuals.

40s mark
You can‘t tell from the still but if you watch the sequence it sure looks like it’s reforming those air streams from the bed and the bottom. Certainly I’m not seeing much turbulence in general


35s mark
Looks like low turbulence right behind the truck which is what you want. This shot is picture perfect, that dirt stream off the back is so perfect it almost looks like an artist created it for a aniumation. Notice how much it looks like contrails, which form from the highly aerodynamic airplane wing/engine

37s mark
If you watch the sequence you see the dirt kicked up by the front tire doesn’t get sucked under the truck which would mess with that flow presumably, instead it just quietly is outside the envelope. Also clearly shows low turbulence off the back

At 57s the angle clearly shows the surface turbulence getting kicked out of the way as you’d want. And fascinatingly the kick off is pretty much the same no matter the steering toe out/in, he does some turns but it doesn’t really affect this part

The acceleration at the end shows it better as the tires dig in and kick off more dirt. Interesting in that it appears like it’s the front motor doing all the work with the back little changed 🤔
You can also see the truck rear up - notice the back well is squatting

56s mark
Dirt pulled up by the tire is in a quiet zone, it just kind of drifts off, not a lot of turbulence in that wheel well it seems which is what you want - it’s not getting turbulence from the outside

Even in the macho money shot notice all that manly dirt clouds are just from the tires banging through that loose stuff, the ambient clouds the truck is driving through are relatively undisturbed. The messy lower section is just from the impact of the tires hitting mounds of fine sifted dirt, but look at that ambient along the top - beautiful! Also I think we get a hint of the sail action

Anyhow this isn’t remotely definitive, and may not be unique to the SEV. I looked for other truck dirt videos but didn’t see anything comparable. Maybe some interesting clues though

This is without a tonneau...the benefit of the sails and roof spoiler. Would love to see something like this for the AT4.

The dust kicked up from the rears may just be hidden by what comes of the front tires. Or, as the truck pitches up the fronts slip a bit in the dirt.

As I mentioned in the other thread, it rocks in this color.

No mention of lockers.

 

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I know GM is now using SiC in the inverters.

You mean they weren't previously?

 

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The Tire looks like a Goodyear Wrangler Territory AT @flyinglow

So I believe this then is the tire, except the tread isn’t the same. Maybe an EV variant or something.

To be expected.

 

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Thank you for the door jamb specs. It is interesting that the extended range unit is 1968# vs. the specked 2100#. I am now wondering if the max range unit will have a lesser payload.

Brian

The extended range gets 2100# without the Premium Pkg but that package adds weight (midgate and MultiFlex tailgate probably accounting for most of that) which lowers the payload. I was expecting that but wanted to know how much.

 

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They use the same terminology on the Dampers for the 2024-25 Travers and Acadia off-road trims...

Tried to find something on the net that explains what it is but no luck. Any idea what it was on the Travers/Acadia? Shocks/dampers obviously control rebound hydraulicly. So, what is different from a normal shock absorber?

 

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

We can only hope. With GM's drive to simplify their Bills of Materials and the Hummer going down the same production line, wouldn't they standardize the drives for all the EV trucks. The Hummer dual motor has mechanical lockers so it should be a breeze to include lockers on the SEVs. As you say, it would be a dumb marketing move not to but the pencil pushers might want to soak us for more money as ZR2/AT4X options. Even if so, why not make those available now?

I am still scratching my head as to what "hydraulic rebound control" might be.

 

[flyinglow]

I thought the GM rep said the trailboss would have lockers a couple years ago? I think it was a TFL video with the female product manager or something.

It was the chief Silverado EV engineer Michelle Kraatz. Things change. Back then the ZR2 and AT4X were separate trim levels in the ICE range. Then they made them option on the Trail Boss/AT4.

I don't imagine the lockers add too much to the cost other than being relatively low volume. The DSSV shocks, however, as factory aftermarket kits for ICE trucks cost over $3k.

We are going to have to wait for reveals but the order guide has nothing on lockers or shock absorbers.

 

[flyinglow]

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

View attachment 5508

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.

View attachment 5509

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 👀

I am dubious that the lockers are in the truck and just need to be turned on. That is more of a Tesla strategy. Also, given the total lack of mention of lockers in the articles on the TB/AT4, I do not expect they will have them. GM will likely only offer them with ZR2/AT4X options or trim levels.

 

[flyinglow]

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 …

Hummer does not have physical connection between the two rear motors in spite of their common housing. From Hummer site: "On some electric vehicles with dual rear motors, such as select GMC HUMMER EV models, a mechanical locker is not required. The vehicle uses software to virtually lock the two motors that power the rear wheels together."

Disagree with your logic based on observations by testers. Mechanically locked single motors perform better than virtually locked dual motors. I realize visualizing it is tricky. I think of it this way. With a single motor, the wheel off the ground isn't providing resistance. It's like it isn't there. All the power is transmitted to the ground regardless of which tire has how much grip so if one wheel is in the air, the other gets all the power. If I come up with a good way of demonstrating it I will post it, but right now I am going on what I have seen in the off-road tests of various vehicles.

With virtual lockers, the traction control computer is trying to equalize both wheels rotation. It has to do that by matching the one without traction to the one with it. What seems to happen is that, if one side has less traction, that motor with traction reduces power in order to allow the side with traction to get traction. In the real world testing, this seems to result in less forward drive. Also, in general, the motors of two motor axles have less power individually than the motor of a single motor axle.

If I find the time, I will try to go back through TFL and Out of Spec off-road tests of Hummers and Cybertrucks with 2 and 3 motors. They both found the results I am referencing.

 

[flyinglow]

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. *

Hope you are right.

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?