rear locker??

[mothertrucker424]

i found a eaton rear in junk yard when i spin the left side forward the right side goes in reverse is this a posi?or just a open rearend?
and how do i tell if its a locker

[drbyrdman]

open

[desertrat]

Yes it is an open diff.

I'm not sure if our trucks w/ Eatons every came factory w/ posi.
Also in my opinion posi-traction is not a locker. Someone might correct me but a true locker will not slip and a posi-traction still slips.
As far as I know there has never been a factory vehicle with a locker rear end, since a locker is not always safe to drive on the streets (but it sure is fun).

[72chevyk10]

if i still have the factory rear i have posi and itl spin the wheels diffrent when theyre off the ground

[justcuz]

Some Eaton 3/4 ton and GM 14 bolts came with a locker from the factory. In fact I may be wrong but the detroit locker (called a No-Spin) was the only traction aiding device available for an Eaton rear end.
The Eaton automatic locking differential also locks. It is a combination of a locker and a limited slip. It has friction discs that tighten up and lock the rear wheels together when the difference in axle speed is over 100 RPM, however it unlocks at speeds over about 20 MPH. This rear end is commonly called the Gov-lock because of the flyweight mechanism that engages the friction discs.
This is a simplified explination, there is a better one on youtube.

[desertrat]

Originally Posted by justcuz

Some Eaton 3/4 ton and GM 14 bolts came with a locker from the factory. In fact I may be wrong but the detroit locker (called a No-Spin) was the only traction aiding device available for an Eaton rear end.
The Eaton automatic locking differential also locks. It is a combination of a locker and a limited slip. It has friction discs that tighten up and lock the rear wheels together when the difference in axle speed is over 100 RPM, however it unlocks at speeds over about 20 MPH. This rear end is commonly called the Gov-lock because of the flyweight mechanism that engages the friction discs.
This is a simplified explination, there is a better one on youtube.

I didn't realize lockers where that high tech back then. Looks like I need to do some learning

[mothertrucker424]

so should i pull this rear for parts ? i not sure price but i have one i'll be swaping into my 1/2 to step up to 3/4 is another one good to keep for parts? also i have been told 14b disc brakes will mount up what is required

i am new to these axles and ya'll have told me alot already thank you

Merry Christmas

[LONGHAIR]

Originally Posted by justcuz

Some Eaton 3/4 ton and GM 14 bolts came with a locker from the factory. In fact I may be wrong but the detroit locker (called a No-Spin) was the only traction aiding device available for an Eaton rear end.
The Eaton automatic locking differential also locks. It is a combination of a locker and a limited slip. It has friction discs that tighten up and lock the rear wheels together when the difference in axle speed is over 100 RPM, however it unlocks at speeds over about 20 MPH. This rear end is commonly called the Gov-lock because of the flyweight mechanism that engages the friction discs.
This is a simplified explanation, there is a better one on youtube.

I'm afraid that you have combined a few things here....

The Eaton axles (HO 52 and HO72) did indeed have "No-Spin" differentials (Detroit Locker) and that was the only traction-aid available in them. AFAIK though this does not apply to the 14-bolt corporate axle though.

Early 12-bolts had a clutch-type Posi-traction that was similar to the car units.

The Gov-lock replaced the older clutch-type posi-traction in newer 10-12-14 bolt GM corporate rearends.
The "Gov-lock" is just an overly complicated clutch-type posi-traction unit. It does NOT lock....it just supplies a bit more pressure to the clutches as it engages. It operates more like and open differential that can "turn into" a posi-traction ans needed. They are way to complicated, with too many tiny moving parts....inside a very stressed part of the driveline. It's called "Gov-lock" because that is the name the manufacturer gave it....GM called it by an option code (G80) They are inherantly weak. With a totally stock and gently driven truck they can live a long time....but with increased performance, bigger tires, and/or abusive driving...it won't last. When they fail, it is generally catastrophic.

[1969 GMC]

I agree with what he said ^ but if you are dealing with a half ton axle, I don't know when they went from the clutch style posi to the gov-bomb.

14 bolts did not come with factory detroits unless it is a military cucv truck, which all had them stock. generally speaking, the 14 bolt gov-bomb is the strongest of all the gov-bombs, but I refer to them as gov-bombs for a reason. When they go, they go. At my old job a C3500 dump chassis w/ a gov-bomb decided to give up the ghost and it ruined just about the entire axle. The brakes, wheel bearings, seals, all the bearings in the diff, gear set, and the gov-bomb itself were all trashed because it went. The best thing you can do for a 14 bolt with one is to take it out and swap in an open carrier from another axle, and a detroit.

edit: If you go junkyarding looking for an older chevy with an eaton and the no-spin, they have the G86 rpo, usually just called no-spin. Trucks equipped also get a sticker or a metal tag riveted somewhere inside the cab to let the operator know.

[Jtrux]

Originally Posted by 72chevyk10

if i still have the factory rear i have posi and itl spin the wheels diffrent when theyre off the ground

Factory posi's will act like open diffs till RPM increases so in your case it's acting normally.

[LONGHAIR]

Originally Posted by Jtrux

Factory posi's will act like open diffs till RPM increases so in your case it's acting normally.

That depends upon your definition of "factory posi". Presonally I do not consider a "Gov-lock" to be a "Posi"....it's a "Gov-lock"

Gov-locks can do all kinds of things in the "jack the wheels off of the ground" situation, depending upon the condition of it's guts. This is what makes then "shakey" at best. As 69GMC said, the only ones with any strength are the 14 bolt units. The whole "watch spring" mechanism is just as bad, but the carrier is much more massive.

A "true" posi would have to be totally wasted (clutchwise) to spin backward like an open differential.

A Detriot (No-Spin) can be "unlocked" by hand, which would get one wheel to spin freely, but it can't possibly spin the other wheel backward.

[special-K]

The Gov-Loc is actually a ball-ramp design that activates off of wheel speed.It`s the sudden engagement that can hurt them.If they would engage at less wheel spin it wouln`t be a bad idea.I don`t know of anyone playing with that.I guess with other designs out there it makes it not worth trying.
I have a Semi-floater 14-bolt with Gov-Loc in my`91 Suburban with big tires.So far so good.I had a problem with a front hub for awhile and I relied on the limited slip to get that thing full of tools out quite a few times.When I ordered my`92 I didn`t spec a G80 because I didn`t want a limited slip or a posi.I didn`t know anything about the G80 at the time and thought it was a clutch-type.I didn`t want the maintinence.I installed my own Locker.

[desertrat]

Sounds complex!

Here is something my simple mind cand wrap around.




Oh yeh, I can understand the complexity of a lincoln locker.
(made a few also)

[special-K]

Let`see,how can I explain it...

Both wheels spin.

[LONGHAIR]

Both of those ^^^ are bad ideas for street use.

[desertrat]

Originally Posted by LONGHAIR

Both of those ^^^ are bad ideas for street use.

You are correct, but it sure can be fun at times.

[mothertrucker424]

i opened mine today and when i spin wheel forward then reverse it sorta locks and it snaps/pops?? why?

[LONGHAIR]

Pictures?

[mothertrucker424]

Originally Posted by LONGHAIR

Pictures?

i took a couple looking for camera cable should have some tonight i hope

[mothertrucker424]

should i pull another eaton from junk yard for a spare parts axle? due to fact of them being rareish

[LONGHAIR]

Who said that they were rare?
They were the standard axle in these trucks, the 12-bolt was an optional piece.
AFAIK the standard for Chevy: HO-52 and coils spring suspension, with options available. The standard for GMC was the opposite: 12-bolt and leaf spring suspension, options on them too. Either truck could be had either way, but w/o specified options, you get the standard equipment.

[mothertrucker424]

Originally Posted by LONGHAIR

Who said that they were rare?
.

i use rare "loosely" i meant due to parts avalibility

[1969 GMC]

Originally Posted by LONGHAIR

Who said that they were rare?
They were the standard axle in these trucks, the 12-bolt was an optional piece.
AFAIK the standard for Chevy: HO-52 and coils spring suspension, with options available. The standard for GMC was the opposite: 12-bolt and leaf spring suspension, options on them too. Either truck could be had either way, but w/o specified options, you get the standard equipment.

when you say 12 bolt you mean dana 60, right?

[justcuz]

To recap I oversimplified my explination of the gov-loc. Gov-loc is not what Eaton calls them. They call it what I called it "Eaton automatic locking differential" . Gov-loc is a consumer nickname that kinda stuck. Like I said a little google and you-tube searching will clarify this. The ramp up on the governor mechanism does tighten on the frictions and discs enough to spin both wheels. The cam locks in place to keep the frictions and discs tight enough to lock the wheels together until it goes over 20 mph. Some guys actually grind weight off the flyweight to make it lighter and stay locked up at higher speeds.
The no-spin Detroit locker was available in the corporate 14 bolt full floater.
I've got one in a 1973 3/4 ton 2wd Suburban. It is factory original, I know, since I am the second owner of this truck. The first owner was a co-worker who bought it new to tow a horse trailer. When he was going to buy a new one, the trade in was insulting, so I bought it from him for my wife to haul our kids and stuff around.
That was my first Suburban, I've owned 3 others since then and still have 3 of the 4 I have owned. The one I don't have, died an ugly death when some jackass in a flatbed pulled out in front of my wife. No habla, no insurance, no more flatbed. I had the cops impound it, they would not release it without registration and proof of insurance, so it got leined by the tow yard and scrapped. Julio had just bought the truck from somebody and had not registered or insured it But he was driving it

[LONGHAIR]

Actually, Eaton calls it "Mechanical Locking Differential" the "Gov-lock" word may have been GMs thing. It was option code G80.

Either way, it does NOT lock. It just applies more pressure to the clutches, they still slip.