Not just another how-to. This one is quick, simple and does not require any special parts.
My vacuum lines rubbed against the exhaust on the way to off-road on the beach. Yes the lines melted! I managed to get a partial vacuum for the day. Then had the task of figuring out what to do about fixing it. I could have gone with a cable job, but, since I have an Aussie front locker, I wanted something more permanent. What I basically did was force the vacuum to always be closed and not allow movement by removing the vacuum altogether!
1. Remove the disconnect plate and hoses: 4 bolts
2. Remove the 4wd switch
3. Remove the three (3) E-clips holding the vacuum piston in place.
4. Examine the fork for damage.
5. Using an old castle nut reassemble the parts.
6. Slide the piston back in, fitting the castle nut (groves towards the fork), then the fork. The fork should be in the exact same position as factory slid all the way engaged (towards the switch)
7. Insert a bolt through the switch opening and push the piston as far in as possible. You want to be able to put the E-clip in holding the nut against the fork.
8. Insert the E-clip holding the piston housing in place.
9. test to make sure nothing moves. It should be a tight fit with little movement.
10. (inside the axle) Slide the locking into the locked position. This may require jacking the passenger side of the axle to spin the tire.
11. Place the fork and cover back into place, making sure the glides fit into the locking ring groves.
12. Bolt cover
13. Refill gear oil
14. Cap vacuum lines
15. disconnect switch and store wires somewhere safe in the engine compartment (I zip-tied mine under the battery tray.
The castle nut was chosen as it was the perfect thickness and covers enough surface area to not damage the parts. This fix works perfectly and will last as long as the fork doesn’t break or the locking ring holds. Then it’s time for a solid axle swap!
*This fix is NOT recommended for differentials without a limited-slip. Fully locked differentials should always be operated in off-road conditions only as they can cause damage in normal highway driving.