lockers?

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I've been "lurking" for a while now. Recently acquired a new (to me) Chevy: 1998 Silverado Z71 EC.
I'll throw a question in, all responses are welcome. From the build sheet, I
gather the truck came with a 3.42 gear ratio. My question is: Does this vehicle have a locker or an LSD, or is it an open rear diff?
I have nothing to add to the current debate - seeing how this is my first Chevy. Kind of "willed" to me by a living stepfather with Macular degeneration. All options & 56,000 miles. 5.7L Vortec. Only current mods (by me) are K&N FIPK 2 kit and Rhino liner. Still on the learning curve, as it were.
Also - any input beyond rear diff is welcome.
Regards,
Ken
snipped-for-privacy@comcast.net


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Panther1 wrote:

You have to look for the G80 code to know for sure. The G80 is a locker, snoman has been describing it wrong, an LSD when it connects the rear wheels together doesn't connect them 100%, it will allow some slip between that is why it is limited slip. The g80 locker uses clutches yes but locks the wheels 100% together with no slip.
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Alas, no G80 codes. Assuming these cryptic three character codes are the same ones used on the build sheet obtained from the dealer using my VIN number, what does "GU6 - REAR AXLE 3.42 RATIO" mean other than 3.42 gears?
What about "Z82 - HEAVY DUTY TRAILERING EQUIPMENT"?
and what exactly does "Z71 - OFF ROAD CHASSIS EQUIP PACKAGE" include anyway?? Is this just Bilstein shocks (which are damn nice by the way)?
Also - are there any other locker / LSD codes that could be in this alphabet soup?
It would be nice to know that Chevy thought enough of the Z-71 off road package to at least include an LSD! Nissan did (last vehicle was 92 SE King Cab 4x4).
Regards,
Ken (Chevy newby)

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Panther1 wrote:

There are several GU codes for different gears but none of them are lockers

This is usually the trailer connector and a transmission cooler

Depends on the year, sometimes its just the shocks and stickers, other times it adds on other optons such as fog lights

G80 is the only locker they used in the trucks, but I thought z71 triggered it on by default, someone may have ordered it without

You would want a locker, LSD is for streets. Usually the z71 option triggers others like the g80 but someone could have taken the g80 off afterward.
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To clear up the confusion about the G80; 2004 Colorado, 5 cyl, Z71
The G80 is a locking differential. When one wheel spins 100 RPM faster than the other one, the governor locks the diff solid, no limited slip !!! The clutches only serve to make the process smooth. It all happens in a split second and, in loose gravel, I never know that it is locked unless I look at the tracks I leave; gravel spun out on both sides. The only way the diff can be destroyed is, when you step on it hard on a slippery surface and then hit a dry patch with one wheel.
I am very happy with that axle and the operation of the differential. Never had any problems with handling in any road condition.
John
wrote:

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On Sat, 13 Jan 2007 00:52:30 GMT, John

Again no it is not!!! It used clutches and it is limited by clutch capacity as there is NO mechanical "solid" lock like there is in a true locker. (it is not your fault that you believe it is a locker because the name for it is VERY misleading but believeing does not change the facts) It can slip with torque capacity is exceeded which is not hard to do with a 10 bolt and big tires and it is not a sturdy unit either in 10 bolt axles. Also as stated before tha same govenor prevents its operation completely above about 20 MPH. True LSD's and lockers have no spoed limit. ----------------- TheSnoMan.com
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Snowman, get your facts straight. I have the factory service manual and have taken a close look at the differential and, it is a locking differential PERIOD
John

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On Sat, 13 Jan 2007 11:39:06 GMT, John

You are pretty thick on this. IT IS NOT A LOCKER!!!! Lockers DO NOT USE FRICTION CLUTCHES. LSD's do. (this is one of the reasons that call them LSD's because the clutches have limited torque capacity) The GovLoc may have a higher point before clutches yeild than most LSD's but it is still a modified LSD anyway you cut it. You need to look at how lockers are designed and built because they have no friction clutches in them to "lock" them. You can beleive what you want but it does not change the fact that it a LSD carrier that is mislabeled as a locker for sales hype and people like you buy it hook line and sinker. The 8.5/8.6, 9.5 and 11.5 all use the same basic design carrier with 2 spiders gears. The 8.5 and 9.5 have 3 friction plates (with 9.5 being bigger in diamete) the 11.5 has 4 friction clutches (also bigger in diameter). The 10.5 is unique in that it has a 3 spider gear design in a splitable carrier and it too has 4 friction clutch plates and all of them act on one differentail side gear. It should all be noted that one reason the 10.5 is sought after with a OPEN diff for serious off road is because it has a 4 spider gear carrier that has a a drop in detriot locker replacement for it. You simple split carrier remove spiders and install the locker in its place. It is the only rear axle carrier in production today in SUV's that is deemed strong enough for a locker. Others require a carrier replacement. If you have a GovLoc you will have to trash the whole carrier and get a open carrier to convert it to a locker. Serious off roader does not use GovLoc for long because they are not very reliable in some operations and the smaller ones have lomited torque capacity and can be toasted in very short order when that capacity is exceeded. ----------------- TheSnoMan.com
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Snowman, you must be about 5 feet tall; it takes a big man to admit when he is wrong.
The clutches provide limited slip action until one wheel spins 100 RPM faster than the other at which time the governor causes the cam-plate out of it's detent position. The cam-plate has humps that ride up on humps on the cam side-gear and force the differentil side-gears against the differential carrier, locking the axle shafts to the carrier. The clutches have no further part in the operation.
You do have some good information at times Snowman but, you also seem to be living in the past, not current with the latest technology.
John

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Could this be what is in our 1994 3500 dually 6.5TD ? It locked in so good that we pulled a trailer that was loaded and weighed 12,000 lbs. along with the truck loaded and weighing about 10,000 the right wheels were in pure mud no road under it and left were on the road. It pulled the entire load with left wheels only. I've had new limited slips that could have never done that, but then again they were in 12 bolt rears so definitely not as much clutch surface as a big truck 14 bolt rear. What would the numbers be for the rear ? our glovebox has about 50 number combos in it. all just in order.
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wrote:

Bigger axle, more clutches that are also bigger in diameter and holding power which means more power transfer before clutches are over powered. The GovLoc is a lot sturdier in bigger axles but still a clucky beast at times. ----------------- TheSnoMan.com
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Hours of sitting here trying to research this here is some of the comments I found...
GM offers the Gov-Loc, which is a GM OEM full carrier locker available in their Corporate axles. This unit normally operates as an LSD, but a counter-weighted locking mechanism locks the side gears together when the wheels have a speed differential of something like 100 - 200 RPM. It makes a very interesting "BANG" when it engages, and if you ever saw one you would be afraid to have it engage. They seem to work well, though, and GM has offered it for decades.
Gov-Loc is a locker, and an LSD. There is a counter-balance in there that locks the driver-side side gear to the spider gears, effectively spooling the diff when a certain speed differential thres hold has been reached. That's a locker. I'll open one up and show you how it works. Scary stuff. I've disassembled a few of them. My Suburban has one, and it freaks me out every time it engages. I also found one that said the Gov-Loc only came in the GM corporate rears, which as far as I remember is the big 10 bolt. I thought the 14 bolt was a Dana or AAM ? What years did they use what ? Our 1993 3500HD 15,000 GVW is supposed to be a Dana 80 What would be the 14 bolt in our 1994 3500 10,000 GVW dually ?

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This site if for Eaton Automotive and at the end of the page, it says it is the G80 option for GM.
http://www.traction.eaton.com/prod6.htm
Does this help answer any questions?
Karl
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is
There is a link to a short movie on how the Gov-Loc works here: http://www.traction.eaton.com/prod2.htm
Al
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What was the one called that was available for 10 bolt 7.5" rears ? Was that still a gov-loc ? That is exactly what we put in our El Camino... I didn't know what that contraption in there was. I always had just plain old LSD'd usually in my 9" rears (in Chevy's).
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