I have a 2000 gmc jimmy SLT 4X4. I have a front of car vibration at about 45mph and up while turning. I have replaced a ton of things on the front suspension but need help. here's what i've replaced in the past couple of years. both front wheel hubs, all ball joints, upper control arm bushings, power searing box, searing idle arm, inner tie rod ends.

The only thing I can think of is the cv joints in the front axels. or the front diff.

questions: how do I check the front diff and see if its bad?
how do I check the front axels?
what else could it be?
also what are normal behaviors of a diff. how much play sould there be? and in 2 high should the wheels turn in opposite directions or turn independenty?

 

You can drain the front diff fluid & look for debris. That should be a pretty good indicator as to the health of your front diff.

The CV shafts usually click while turning and should be noticeable more so at slow speed parking lot maneuvers.

When in 2HI, the front wheels should spin independently. There is a disconnect in the passenger side extension tube that allows the passenger axle shaft to freewheel while the driver side axle only turns the spider gears in the diff.

 

Thanks for the info. I'll look at the diff tonight or tomorrow. Is there anything else I should look for while I'm in the diff. If I do see metal shavings or other debris what needs to be replaced. also would it be better to replace the entire unit from a junk yard or rebuild the one I have.

Thanks!!

 

It is MUCH easier to swap the diff out for a good used one than it is to rebuild one of them. There are some special tools that are 'almost' required to rebuild one of these IFS front diffs properly. I say 'almost' because you can do it without them, but you have to be very creative and that can often waste time & money.

 

OK. I've now changed out the Diff oil and there was very little sediment in the fluid but it was very low. After filling it back up took it for a test drive no change. Still get a throbbing/vibration while turning but there is a new issue. I hear a grinding like a blown bearing but its too subtle to be a wheel hub. So to the questions.

Where are the bearings in the diff and how hard are they to change out?
Also any other ideas on what would make a rubbing/grinding sound that isn't something I've already replaced?

I have done a little more research on the inerds of the front diff/axle. There are several bearings on the long side of the diff. What would be the most likely bearings to fail in the diff/axle that could cause this problem. and are these bearings lubed by the diff oil? If they are i bet these are the problem b/c the fluid was so low.

 

It probably isn't a bearing. Have you checked out the actuator cable yet? Your front axle might be partially engaged.

And do yourself a favor, get a manual. Even a Chilton or Haynes manual is better than nothing, but you can often find factory service manuals on eBay for a bit more $$. It is the best investment you can make if you plan on working on your truck yourself.