I have a 2000 GMC van with Gov-lock rear (G80). Jack it up and tires spin opposite like open rear. They apparently act as a locker only when needed to save fuel. On my 96 Roadmaster (also code G80) when I jack it up it acts like a POSI...both turn same direction. When did Gov-lock start to be used? I have read 1974. Did they have POSI and Gov-lock available at the same time?
Never learned much about them, though my parents had Gov-lock on our '79 Chevy Van. Found an interesting vid that describes operation and potential modification: Devon
Your 96 Roadmaster should have an Auburn cone style posi unit in it. Some as the Caprice police cars of that era.
It needs to see about 100-150 rpm difference to get the weights to spin out and lock in........it also won't engage over about 20mph.......but if locked in b4 it will stay locked in. Some of the parts get gummy with dirty fluid........the system work pretty nice when all the parts are good and moving......when engaged its more of locker id say than a posi unit.......the hard its pushed the harder it pushes back on the rampped engagement. When it 1st came out it had some issues as 1 tire would already be up and turning then very abruptly lock uo and it caused it to break itself often
Glad my Roadmaster doesn't have one.......odd that cars got posi and trucks gov-lock. Couple days ago at US13 Dragway, Delmar, DE.
Watch some ofvthe incline test hills with rollers and the traditional posi units can only send so much power across.......high spring loads help but cause other issues. You can find pictures and videos of all types of units broken, they are not a race application, they are not a major off road rock crawling unit. But for whst they were intended for eaton units do very very well. They were ment for transfer of power from a wheel on ice, or snow, or sand or mud to the wheel on the higher traction surface........if you go banging the throttle hard given the nature how the work, they hold 1 piece forcing the other tighter.......and the higher the traction difference and wheel difference the harder they ramp in.........if the wheel speed difference is to high on engagement slamming to the side up to speed of down to the traction side speed.....those forces all go through the case.........and a rocking action aggressively is where most break from what I know. Over the last 30ish years we have had 10 or so vehicles with these units all worked great for us........
I blew up a 3.73 gov lock with a stock 5.3 and mild off road use. Went to a whole different rear end with a clutch type possi and 4.10 gears. Much better
Just keep the Auto lockers (gov locker) on the street, towing snow plowing etc in regular driving applications and it will work fine . They are stock units do stockish stuff with them. YOU want to do none stock stuff burn outs offroading racing get aftermarket Units. That should keep you in check. Jim JD Race
It’s one of the ways a 10-bolt will get a bad name. They throw one of those gov-lock units in their car and blow it up,then think the 10-bolt is a bad rear. Either that or they think their car makes real power. Both always false.
Yah the cases especially. I have seen so many pinion supports climb out of the case and ruin driveshaft and transmissions soo MUCH what a waste of money... They think they are saving but they are not when it takes out half the drive line. Jim BUY ALL aftermarket third member for a 9" Period. Street you will be fine. Track and full spools etc. Aftermarket ONLY. or flip the coin.
The gov locks work well to save the tires vs a locker. They do drive perfectly fine in normal driving and they are quite controllable in snow and ice conditions. As an added bonus they don't have clutches to wear out vs the typical limited slip. They only suck for burnouts, racing, and hard core off roading. For daily drivers they work quite well.
