That is my thought also. I am planning to go with the max range and would add the solid tonneau cover. I need enough payload to handle my travel trailer that has 950# tongue weight.

Brian

 

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.

 

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

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

 

Interesting that 5th wheel trailers are not allowed. I say this because people on this forum made a HUGE deal about the bed wings on the Cybertruck preventing 5th wheel trailers from being used. I guess that was pretty short-sighted criticism since GM disallows them anyway!

 

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.

 

What did you see that made you think the active damping only functions near the end of the stroke?

It would make more sense for the damping valve to have an effect over the entire travel of the suspension. That way it could better adjust for heavy and light loads and different air spring rates.

 

These are pretty impressive specs for the price.

 

I think these may be the same Nokians if your's are Outpost nAT? I originally put the stock size Nokians on but traded those right back in for 285's

 

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.

 

You want it on the rears first because when climbing hills more weight will be transferred to the rear wheels than the front, it will transfer more weight, traction and drive to the rear wheels to help push you up.

 

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.

 

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

 

https://www.reddit.com/r/HummerEV/s/M2T9uP1lvX

And this 3X SUV doesn't have the Off-road package.

 

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

 

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.

 

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

 

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

 

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.

 

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 😅

 

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.

 

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.

 

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.

 

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.

 

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 👀

 

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.

 

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.

 

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 …

 

Silverado Rear, Hummer Front/Silverado Front, Hummer Rear

Front Motor teardown:

 

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.

 

Why does this spec list show Trail Boss turning circle as 42 ft (same as RST/Denali) where another set of specs showed the AT4 at 39? Unlikely TB/AT4 would be different. Or is it that the shorter turning circle is only in Terrain Mode?

Am really impatient to have real world reviews so these sorts of inconsistencies get cleared up.

 

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.

 

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.

 

Super Cruise:

1. Included and only available with (SW4) Premium Package.

 

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.

Sorry guys, I know this is repetitive. 😒

 

Great product. Could be my next truck. Max 478mi is amazing, but honestly if the cost savings is there, that 410 is getting close to my current 440, I think I'd be comfortable sacrificing 30mi of ranch of $5-10k in savings.

The issue I'm having, and picked up from looking into the LT's, is that there will surely be some kind of package you'll be forced into for the Super Cruise which is a must for me. That means that it will still be $80k, and not enough savings to come off my Sierra EV. Just need SuperCruise/Lane Center on a $72k or less pickup. With Tax credit, only Ford and Tesla offer this at the expense of range. My Whack-A-Mole game for the perfect truck continues.

 

I think around 520 was the record going 100% to zero but with a lot of 70 mph. I actually think getting - who knows - 530+ should be possible with under 60 and a bit of hypermiling. I don't know why the YouTubers aren't trying this, seeing how high they can get, it would make a great video. They just run and gun. The first one to get 550 miles would be a big splash.

 

Not a youtuber but have 35" and willing to go for that drive!