Originally Posted by evan7024
The front differential suddenly quit locking in, I have vaccum going to the transfer case switch but not going through it to the differential when I engage the transfer case. I tried two new vaccum switches and still no vaccum to the differential! I can jump vaccum across the rubber plug at the transfer case and the differential will lock! what is going on here?
It seems like your front axle disconnect is going bad. This is a common problem with the D30 in the YJ's. Luckly, there are a number of products out there to fix the issue.
Crown Automotive makes 2 different options to lock the collar. First, you can permanently lock it with their Posi-lock Permanent Lock Kit
. This will make your front axle live all the time, so all you have to shift is the t-case.
They also make a Selectable Posi-Lock Kit
. The kit eliminates the vacuum disconnect and changes it to a cable actuated system. Both kits are easy to install and should only take you around an hour or so.
Let me know if you have any questions about either kit. I'll be happy to help!