88 4X4 "pops" when taking off...

[SinistrV6]

88 4X4 \"pops\" when taking off...

My truck seems to be "in a bind" whenever you get ready to take off after coming to a stop. Sometimes it pops "free" immediately, other times it takes a few feet. So far I've been through the rear differential, u-joints, replaced the transmission mount and had the tranny serviced (no problems found). The spring u-bolts are tight and all the spring bushings appear to be in good shape. Any suggestions would be appreciated. I suspect the transfer case chain. Is that possible. This truck is 100% stock and has spent 99.97% of its 125k miles on the asphalt.
Thanks,

 

[MOABDADC22]

Re: 88 4X4 \"pops\" when taking off...

Fill out your profile so we know what 100% stock is.........thanks.

 

[Blazer1970]

Re: 88 4X4 \"pops\" when taking off...

It is the slip yoke on the rear t-case output. Pretty much all of the '88 and up trucks do the same thing. What happens is the when you apply some torque to take off, the splines on the slip yoke are jammed together so they don't want to slip. At the same time, your pinion is trying to lift from the torque as the truck starts to move, which requires the yoke to slip into the t-case a little bit. Once the pinion gets high enough so the force overcomes the friction on the slip yoke splines, they let go with a thump. On my '88 truck, it would sound like someone behind you was blowing their horn at you. You can fix it temporarily by pulling the rear driveshaft and greasing the splines on the slip yoke, but it will come back eventually. I drove my '88 truck with it doing that for 90,000 miles, and it never caused any kind of problem.