1999 Silverado 4X4 unit problem

  • 1 POST

When I engage the 4x4 unit, as long as I drive the truck straight, there is no problem, however, when I make a turn, 45 degrees or more, the truck makes a clunking (metal to metal) sound from the front unit.
Can someone please inform me as to what may be the problem? I was told that it may be the CV joints needing replacement, but how would I know this?

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Saturday, December 30th, 2006 AT 12:31 PM

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  • 12 POSTS

To check my CV joints I've always first grabbed the shaft and tried to shake it. I shouldn't feel any play. Then I've raised the front end and again grabbed the shaft and shook it. Still should not feel any play. After checking that way I'll grab and hold the shaft with the front end still up off the ground and then tried to move the tire clockwise and counter clock wise just a small amount. When I move the weel the shaft should also try to turn at the same time. A delay means play (ware). I'd also do this with the wheels turned when the joint is being used the most. If in a straight line your not hearing it though even while applying and taking away torque I wouldn't think the problem would be there but since its easy to check would definatly do so just cause I'm there. With it only doing it in a turn sounds like a planetary problem to me. The planetary gear in the diff allows one wheel to spin faster than the other in a turn. In say a right turn the right wheel needs to travel less distance than the left wheel. The left wheel will have to turn faster than the right to catch up. The planetary gears allow this. You can check them for noise by putting the truck in 4 wheel drive and lifting only one side. Put your transfer case in nuetral. Leave the key on so the solenoid stays locked but don't run engine. Now spin the tire that is in the air by hand. It should spin without binding. Some drag will be there because of the brake caliper but you should not feel like a catch and release type binding feeling while spinning the tire. You should also be seeing the drive shaft from the transfer case to the front diff turning. If not then that wheel is not connecting inside the diff. Witch could mean bad shaft, bad shaft splines, or stripping gears. When doing any of these checks with the front end lifted try to block the front end up off the ground at the lower control arms. This helps to keep all the drive line there closer to its loaded state like it would be going down the road. Hope this helps.

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Sunday, December 31st, 2006 AT 1:12 PM

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