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
Also - any input beyond rear diff is welcome.
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.
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
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
Ken (Chevy newby)
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.
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.
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.
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.
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.
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.
Hours of sitting here trying to research this here is some of the comments I
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 ?
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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