Outer Limits 4x4 Board

I have read through a bunch of other articles about similar 'sounds' coming from the rear and it looks like there are a couple of possible causes. Since I don't exactly know much of the terminology was hoping that someone could narrow it down a bit further and advise on some checks. It is a 97 coily sierra, tin top with 30's & 1 1/2 suspension lift...

So it happends 99% of the time taking of from standing. You hear a clunk sound and a little thud go though the car. it happends 50% of the time through cornering (doesn't matter if you are accelerating or not through. And probably about 75% of the time changing from first to second, as well as jabbing the throttle.

Looking under the car the uni's all seem snug, there is about 2cm roll play in the (tailshaft?) that goes from the transfer into the rear diff.

When I have the car with the handbreak on - shake it back and forth I notice a little bit of roll in the diff (where it attaches to the trailing arms). So basicly im not too sure what I should be looking at, whether I should pull the diff out and check inside? (Pinion?) Or if its something else.

The car does have a locrite which was fitted but recently removed, I am thinking this could of had something todo with it? If putting it back in might solve it I am all for it.

Thanks for ya times guys...

first thing to check is your u-bolts and shackles are all done up... as they can come loose (especially the u-bolts) and create a clunk as the spring moves around on the perch.

after that you're almost guaranteed that its the diff... you can check this by jacking up the rear (both wheels) and start it up and idle in 1st gear - then grab one of the wheels - it should stop turning and the other continue turning (thats why we buy lockers) - usually on doing this you can replicate the clunk if its the diff - although it usually transfers the sound through the axle and sounds like its at the hub.

if it is the diff you really have 3 options, in order of price:
- weld the diff
- replace the centre
- airlocker

Now you just have to hope its a loose u-bolt =P

ITs a coily

well theres your problem!!! no ubolts OR shackles!!! best to go buy some and weld them on.

Haha gottit - weld em on - tighten them up problem solved!

Ill try your other idea probably first though and see if I can replicate - I suspect I will be able to...bummer

So if it was the diff, I can pull the center out and look for obvious signs, if its a no show would re-installing the locrite possibly solve this?

You probably should have mentioned the lockright in the first post..

This would be normal behaviour with it installed, but seing as its come out it could be that when you pulled out the locker the backlash wasnt setup right or maybe you didnt re-install the shims on the outside of the side gears..

Grab a feeler guage, pull it apart, and reset it up per the book..

Have you checked engine/transmission/tc mounts?

hey mate had this exact same thing in my jimny i found out that it was 1 of the pinion shafts that the sun gears in the diff run on had snaped at a 45 degree angle. to fix the problem arb air locker fixed it 4 me $1200 but yeah hope that helps. cheers

The most common cause of the noise is the rear trailing arm rubbing
against the diff mount through the suspension cycle. Mine did it A LOT!
Just make sure the bolts are all tight and grease them occasionally. The
noise will never go away (unless you change the arm) but you can make
it quieter.