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2004 GMC Envoy SLT 4.2
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Some of the guys on the Jeep Forum have experience with those :
 

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2003 chevy trailblazer_ltz
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I've heard of them, although always with the alliteration "Lunch-box Locker". I think it's a silly nickname.

They cost as much as a real differential. The only savings is in the ease of installation. No gear-mesh issues 'cause you don't **** with the gear mesh adjustments.

When it was me, I bought an Eaton Truetrac; but it's not installed yet. Currently working up the ambition. Who the hell buys a K2500, puts a V-plow on the front for snow removal, and DOESN'T order the truck with a locking differential? I'm gonna fix that...someday.
 

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'05 Chevy TB EXT
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Discussion Starter · #5 ·
I sortta feel that with the axle disconnect, it should work out just fine in the front diff on our vehicles.

Maybe not so much in a straight K5-type axle with manual hubs. I drive around all winter with my hubs in LOCKED position on my K5, choosing to use 2- or 4-WD via the floor shift ... so with locked hubs and no slider, they may clunk a lot even if the transfer case is in 2 anyway.
 

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You want the locker in the front axle? I missed that the first time.

I know folks do that, but I think it's more for off-road including competition than for winter/snow/ice traction. A locked front axle isn't going to steer very well under the best circumstances, both spinning front tires will make directional control...interesting.

In front, a conventional "limited slip" including the helical-gear jobs like Truetrac probably makes more sense. Less-abrupt engagement leads to a more-controllable vehicle, I'd think.

I've never had the front differential case apart. Can you put a "lunchbox locker" into one of them without messing with the gear mesh adjustments?
 

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'05 Chevy TB EXT
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Discussion Starter · #7 ·
You want the locker in the front axle? I missed that the first time.

I know folks do that, but I think it's more for off-road including competition than for winter/snow/ice traction. A locked front axle isn't going to steer very well under the best circumstances, both spinning front tires will make directional control...interesting.

I've never had the front differential case apart. Can you put a "lunchbox locker" into one of them without messing with the gear mesh adjustments?
Yup in the front ---- like my K5. I only use chains on the front too since with the steering wheels pulling, you can go where you point the steering wheel.
... and another thing --- there's ZERO room in the back wheel wells for tire chains --- as it is, the inner plastic liners get gentle rub marks on them from the rear tires as is.​

The K5 has full-time Posi, the rear has the Gov-Lock. I have never regretted having the hardest pull in the front because if you're just pushing from the rear, you start plowing the front tires and you won't be able to control your direction very well - especially on black ice and hard crowned roads.
An interesting sidebar about having both differentials pulling is that if you for some reason, only had one working brake --- the braking effect would still be on at all 4 wheels.​

The only actual concern I have is the abruptness of the lock-in application ... but with the axle disconnect, it doesn't matter what the lunch box does --- right?

I'm not saying there isn't gonna be a somewhat changed driving style, but I rarely use 4WD on the TB anyway --- so it's only gonna be necessary in and under bad situations ---- not cruising at 80 MPH on Hwy90.

I'm also very capable of setting lash and tooth patterns on differentials --- I've done hundreds -- and although the lunch box is SUPPOSED to go in without messing with the R&P --- I can do whatever is necessary.
 

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2003 chevy trailblazer_ltz
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Let us know how it works out.
 

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'05 Chevy TB EXT
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Discussion Starter · #9 ·
I think right after the thaw-out, I'll drop the diff and reseal and service it and then decide if I wanna put the Lunch Box in it or not.

In the meantime, I'll get in touch with whomever makes and markets that unit, to find if they either have or don't have something that's gonna fit.
 

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2004 gmc envoy_slt
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I think right after the thaw-out, I'll drop the diff and reseal and service it and then decide if I wanna put the Lunch Box in it or not. In the meantime, I'll get in touch with whomever makes and markets that unit, to find if they either have or don't have something that's gonna fit.
Be sure to cover the audible noise aspect of operation. The ones I've been around 2 decades ago, have been aggravatingly noisy - but only when turning of course (on an otherwise normal / quieter exhaust system vehicle). As others have pointed out, this is usually for more serious off roading, rather than a multip purpose / season 4WDriver. t
 

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Be sure to cover the audible noise aspect of operation. The ones I've been around 2 decades ago, have been aggravatingly noisy - but only when turning of course (on an otherwise normal / quieter exhaust system vehicle). As others have pointed out, this is usually for more serious off roading, rather than a multip purpose / season 4WDriver. t
Although it is significantly easier and quicker to install than a conventional limited slip, if I understand the operation of the one in the illustration - it attains more equal distribution through a stick slip ratcheting mechanism - that's a rather crude operation - that is noticeably more apparent in a front axle than a rear.
 

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You want the locker in the front axle?
I wouldn't. Not for something that sees regular street driving. Eaton TruTrac is all I would do and that's because of how it works. Or an e-locker.

The lunchbox locker is the same mechanism as a Detroit locker and when engaged it drives both wheels. When you turn, the outside wheel makes a bigger arc and travels farther, thus faster. What happens is the faster outside wheel ratchets ahead of the diff and the power goes to the inside wheel. It's an odd feeling but you can get used to it and it's fine on the street. Not sure I'd trust someone driving in bad weather if it was their first time with one though.

In the front it can make it push horribly because even though you turn the wheel, the inside wheel is driving. Pure offroad truck - fine, you learn to live with it, but I wouldn't if you want it for regular driving.

The K5 has full-time Posi, the rear has the Gov-Lock. I have never regretted having the hardest pull in the front because if you're just pushing from the rear, you start plowing the front tires and you won't be able to control your direction very well - especially on black ice and hard crowned roads.
My experience is the oposite. Black ice is black ice, so not really a good test and on hard crowned roads even in dry weather they'll make vehicles dance around. In normal snow, light off road I found I had to drive it hard and had to crank the wheel and gas it. It would understeer but it also would grab and pull in that direction so it all worked in the end, but normal driving with a Detroit in the front of an old 70 K10 my cousin had and it would push bad if you weren't careful. I had a Bronco and we both had 33x12.50-15 BFG AT's and I had no problems where his would push. Tires were the same but he was a lot longer, not sure what effect that had. Romping around the two did fine and off road his double lockers crushed my open / limited slip but on snow the Bronco just felt more controlled.

I suspect this is a very subjective area where some people just get used to it and like it. I can't stand FWD in the snow and will take a RWD with snow tires any day of the week over a FWD. But lots of people swear by them and hate RWD so...
 
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