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I have an 87 Wrangler with the terrible vacuum actuated front differential. Sometimes it works sometimes it doesn't. Every once in awhile it won't come out of four wheel drive and other times it won't go in. Right now it will go in and out of four wheel drive but the light won't go off. I replaced my shift motor and it will hold vacuum. I'm in need of a solution. I was thinking of installing the bds rock lock. Suggestions would be appreciated.

 

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The light is vacuum controlled - it's on the firewall next to the battery - maybe the light-actuator thingy is sticking?. (easy to check.)

If it is stubborn to go in and out, maybe the sliding spline is sticking, and needs to be lubricated. Someone suggested putting some grease on the sliding spline thing on the axle.

Other than that, you could have a cracked or broken line not getting you full vac power to the motor. Check the lines back to the transfer case actuator and see how they look. The line runs down to the front axle on the passenger side fender well under the hood. Check there also for kinks, binds, cracks, whatever.

Hope it helps
Pete

88YJ, 4"susp, 33"BFGMT, 9k#winch, rear homemade swingout, reb.258, 999, 4.10, weber32/36, GMHEI.
 

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Hey Pete and mcw, that somebody was me!!/wwwthreads_images/icons/smile.gif

I've found out through personal experience of this problem with the shift motor assembly in the Dana 30 front axles in XJs and YJs. I had trouble with my collar sticking on the half shaft splines due to a lack of lubrication. I grease them now as part of the routine maintenance performed on the Jeep. Since doing this, I've had no further problems with the vacuum shifter system.

If you want to, you could definetly install the cable actuator in place of the vacuum motor. It will work fine and provide you with the capability of a 2wd low range. However, it would still be a good idea to grease the collar and splines because if they stick, it really doesn't matter what kind of actuator you have. Good Luck!/wwwthreads_images/icons/smile.gif
 
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