Factory option locking rear diff for 94 jimmy/blazer?
 

Hey guys, the owners manual for my 94 S15 jimmy mentioned something about a factory locking rear diff. My truck didn't come equipped with that but I was wondering if I would be able to pull a locker from a salvaged blazer/jimmy. So here are my questions...
Are the locking diff trucks hard to find?
Is it possible to create your own switch for the locker?
Is it worth it/are they dependable?
And how can I identify a truck with the locker?

Thanks!

Your options are to put a G80 unit in it from a later S10/Blazer or you can purchase one of these to put in it.

http://www.summitracing.com/parts/PWT-1931-LR/

There are plenty of threads on this subject.

Or just weld it shut, but this way tends to break on the road.

Inside the glove compartment you will a sticker there, look for the three letter code of G80. This is the factory locking differential unit. They are not that hard to install. Just remember the bolts on the ring gear are left-handed. If not you will have lots of trouble taking them off! LOL

These are not LOCKERs. It is a "Locking Differential". Meaning it drives like an open diff, but if excess spin is detected at one wheel, it will clutch up like a posi. At low tire rpms, it says locked for better low end power and easier take off, etc.

G80 Gov-Lock. Look into it, it is an interesting design. If your's come with it (there are a TON of GM vehicles that did) then if you do not feel it (i.e. spinning one wheel at take off) then it could be broken as it is operated by weights and clutches and anything designed to "lock up" when spinning, will take considerable wear an tear over the years depending on driving habits

Oh gotcha, well a limited slip is better than an open diff IMO. I checked the RPOs for my truck like 96blazernut suggested and I don't have the G80 option. Is the RPO code same for every car that would come with it? (like 1st and 2nd gen s-series trucks, tahoes, suburbans, etc.) And would a G80 diff from another GM car fit in my S15? My local junkyard has a ton of 1st and 2nd gen s-series trucks so I'm sure one of them is bound to have what I want. And are the RPO codes in the same spots for the 1st and 2nd gen cars (in the glovebox)?


Oh and one more thing... are they durable? Would I have to worry about a junk yard diff being bad? Thanks guys!

Would this diff work in my truck?
http://cgi.ebay.com/ebaymotors/10-Bo...item4cec186f25

I got mine from a 98 Blazer. I would stick with the second gen trucks. I'm sure that there is a interchange list for them somewhere.

Mine has been very durable. I haven't beat it much yet but thats to come next summer.

Oh ok, but both of your trucks are the 2nd gen models (in 94, they introduced the new pickups but the SUVs like my jimmy remained the same until 95). So my question is if it would fit into my 1st gen, but I'm assuming it will. And I found this neat vid on youtube about g80s... http://www.youtube.com/watch?v=p8nAbg5suFw

It should just drop right in.

These axles have earned the nick name gov-bomb, sine they are know to blow up inside.
THAT BEING SAID: most people breaking them are guys building streetable racers that want the benifits of a locker without the drive/ride problems of a full time locker...

If you are going to yank one, :icon_google: images will be your best friend. look for rebuild, regearing, and salvage how to's. these things have anumber of moving parts. the more that moves, the more that can break. look at the images for every identified problem, that way when you are at the JY, you can crack it open and take a peak before it's in the garge and you get screwed.

I would say it's better than an open diff (no sh*t right) and better for a daily driver than just fusing (welding) the gears of another axle since you will run into problems with the other compenents being too weak.

the Gov-Lock rears have been around since like '75 or so, maybe a bit earlier. you should have NO trouble finding one. just make sure the teeth and spline counts are right. you will not have fun with a 30 spline if you have a 28 etc.

Also if you want a JY locker you would have to be extremely lucky. either crack the right diff and score, or find one of the like 4 vehicles offered with an OEM locker (like Dodge Powerwagon) gl with that though :icon_teeth:

Thanks for the tips! Where can I find out my truck's spline count? And I also heard about the G80s blowing up... but that's from people doing too many burnouts on asphalt and high power race car applications too. I might look online for a G80 with a guarantee/return policy...
Oh and did anybody put a G80 in the front as well?

Here is a nice down and dirty write up from another forum found via :icon_google:

The marketing term "Gov-Lock” was originally introduced by GM in 1973 when the first "locking rear differentials” were introduced as a replacement for the dangerous positraction units, the Gov-Lock rear-ends were essentially a cross between a limited-slip and true locking rear differential utilizing clutches and plates that transferred torque to the rear wheels, the Gov-Locks were built by various manufacturers (none by Eaton) these differentials were notorious for failing (exploding), the Gov-lock rear ends were discontinued In the mid 80's due to their high failure rates.


GM then got with Eaton to develop a high quality mechanical auto-locking differential that is heavy-duty, GM dropped the use of the marketing name "Gov-Lock” and the RPO code "G80” was adopted as the new marketing name.


The Eaton locker does use clutches but only as part of the cam unit that engages the locking feature, the clutches do not transmit engine torque and for this reason the Eaton rear-ends do not fail and "explode” in the way the old GM Gov-Locks would.

The G80 is available in all GM light duty truck axles including the 8.6”, 9.5” and even the 10.5” axle which is used behind the 650ft/lb of torque Duramax engine.
Due to the nature in which trucks are used (and sometimes abused) the Eaton G80 units are not infallible but the failure rate is now very minimal in comparison.

The Eaton G80 is intended to benefit the average truck buyer by transmitting torque to both rear tires when wheel slippage occurs, this feature works well in instances where one tire is off the ground or on ice or other slippery surfaces but it is not always optimum for off road (4X4ing) use, many off-roaders prefer to have full manual control of their differential locking mechanism and to engage it prior to entering an area of poor traction and for these folks the G80 is not suitable.


sorry for the double post but this would have made the last un-readable due to length :p

As usual AB has hit the nail on the head. They are good units. I have had no trouble with mine. My Sonoma is a 94 but it has the 93 running gear in it. I dropped the G80 in mine with no trouble.

if your scared of them you can get locking diffs from summit racing.

Thanks! I think I might stick with the G80 since it's much cheaper than those other powertrax locking diffs. I don't wanna dump too much money in my truck for now (I have a 91 trans am convertible I'm working on). I could see why serious off-roaders might prefer something other than the G80 but for the off-roading that I do, a G80 should be a BIG help, especially after getting stuck in this and helplessly watching only the 2 wheels without traction spinning:
http://i751.photobucket.com/albums/x...1101091625.jpg
:icon_doh::icon_teeth:

And would it be a bad idea to use the G80 as a front diff too?

I remember that pic!

I have asked that question in another thread. I'm gonna put one in my Sonoma and see how long it lasts.

Hahaha yep! I posted up a thread about a month ago about this situation (i think i called it "last time i'm EVER doing this alone again" or something like that) :icon_goofygrin:

i'm surprised that no one has mentioned this yet.........

"It will fit any GM vehicle with 8.5 rear / 30 spline axles 1989 thru 1998. Fits half ton trucks, Suburban, Van, and most rear wheel drive cars. This will also fit GM full size 4 X 4 solid 10 bolt 8.5 front axles 1989 thru 1991"

this will NOT fir our trucks-the S seris have 7 5/8 diff's, not the 8 1/2.

i've put Auburn posi units in before, never had any issues with them-and i'm overly hard on my trucks.

This one here on Ebay is not a bad deal and will fit the S-series trucks.

http://cgi.ebay.com/ebaymotors/GM-7-...item2ea9a64afe

They definatly make the G80 for 88 and earlier 7.5 26 spline and 88 and later 7.625 28 spline differentials and in the midsize blazers and s-10's the front differential is a 7.25 IFS witch means they dont make a G80 for the front you can buy a powertrax lock right for the front but if you want to be able to steer when in 4x4 in the throttle and avoid striping the teeth off the front axle engagement connector and sleeve its not for you.