Front Diff help?? Need some direction

[sinstr]

So, truck was making some very loud sounds last time offroading. Loud grinding and popping when I was locked or when on the street while turning.

I drained all the front fluid... not a single metal shaving, fluid is super clean. I have not removed the front cover but do not see a reason to.

Inspected the half shafts, if I twist them, they may rotate about 1mm before making contact. I think they have always done this, normal??

Tie rods are all solid, no movement.

Front diff crossmember..... Ive already broke one of these, and it didnt sound like this. However, James did break one wheeling, and now that I think about it, my truck was making the same noises. While, the nut has not dropped from the bottom like last time mine failed, there is about a 2-3mm gab between the bushing and washer (located between the diff and crossmember). Some one tell me if this is normal!!! I took a 3/8" ratchet, and was able to turn the bolt very easily and tighten up the bolt and eliminate the gap. Still have not test drove it (all the ucp is hanging loose). But thinking about it more, if my diff cross member bushing was loose, and it was moving, it was also transmitting the sounds thru the UCP, making me think I had a huge fail of sort.

Input..... anyone. Somebody take a look at there front diff bushing and tell me it they have a gap please. I really want to go wheeling this weekend.

 

[H3slate]

With the crossmember loose, you would be hearing a metallic banging going over bumps. When this happened to mine it felt like the front right tire was going to bounce off and I could feel it through the gas pedal and steering wheel.

I would still be concerned about the grinding when turning. Other than the noise, how did the truck feel driving on the road home? Did it wander, was there a vibration in the steering wheel?

If you have the front diff fluid drained, you might as well take a peek under the cover. There are a couple of bolts that are difficult to get off, but it would definitely be worth a look to inspect the gears.

Another thing to look at is the front driveshaft. Specifically inspect the cv boot where it connects to the transfer case. This has been a known problem and with the diff having too much movement could cause this part to fail.

Good luck!

 

[sinstr]

Filled up the dif and went for a test ride. All seems fine. Even did some urban wheeling in a retention ditch and flexed the truck on a loading dock ramp. Last time my crossmember failed, it was a slight bump when stopping or letting off the throttle, but no noise. This time is sounded like James failure. When his went, we all thought he killed his front diff. I will check the drive shafts tomorrow. Truck is driving like normal right now. Still would like somebody to look at the crossmember bushing and tell me if there is a gap.

 

[Bigunit]

sinstr, there's a lot of info in these crossmember threads that may help answer your questions:

http://www.hummer4x4offroad.com/for...lllpppppp-Is-this-right&highlight=crossmember

http://www.hummer4x4offroad.com/for...crossmember-bushing-fix&highlight=bushing+fix

http://www.hummer4x4offroad.com/for...-Front-Diff-Crossmember&highlight=bushing+fix

http://www.hummer4x4offroad.com/for...-Front-Diff-Crossmember&highlight=bushing+fix

If you have any questions about the front diff cross member, you've come to the right place! :wink:

 

[4speedfunk]

The noise could be a number of things. Grab some wrenches and tighten everything up...skidplates, center diff bushing, outboard diff bushings, steering rack. All of these can make the popping you describe.

The steering rack bushing on the passenger side is a constant source of problems. This bushing tends to go soft and tightening the clamp alone usually doesn't last. The bolt will bottom-out before the bushing gets tight...so to remedy this, put a 1-1/2"ODx1/8" thick washer between the frame and the backside of the bushing. This will take up the slack and allow you to get a couple more turns on the bolt, thus clamping the rack tighter against the crossmember. 08H3 came up with this idea, and it seems to hold quite well for a long time. In fact...I think it works better than putting a new bushing on. Your old bushing is "pre-compressed" so when you add the washer, it stays tight. A new bushing will tighten just fine the first time but, within 10K miles...it will be loose just like the old one, and once again the bolt will bottom-out before it gets tight. So...save your money. Buy a washer instead of a new bushing. You will notice an immediate improvement in your steering, and its one less rice crispy under your truck.

Front driveshafts make a very distinct "tubular clanking" when the CV goes bad. This noise usually occurs in 4LO and tends to go away (or be less noticable) above 30mph. Grab a flashlight and take a close look at the rear end of the front driveshaft. If you see wetness or goo on the underside of the floor where it bolts to the T-case...it most likely means the CV boot has been torn. I've seen these so bad that you can actually see the steel balls inside the CV joint, and 50% of the rubber boot is missing! DOH! Unfortunately...a 49-cent washer won't fix this. Its time for a new shaft.

 

[sinstr]

Thanks Bigunit for the link to the new crossmember, may look into sending my trail spare and having it exchanged. I have a trail spare, but have loaned it to another CHO member who broke his diff bushing. Im on my second crossmember, and this current bushing has not fialed, just the bolt is very loose (could turn it by hand). Anybody know what the torque setting is for the bolt?

 

[Bigunit]

Torque setting for that bolt is 110 N-m (81 lb. ft.).

BTW, make sure to use some locktight on the nut. Mine has come loose several times & have already sheared-off 1 of those bolts. I now have 3 replacement bolts (GM part #11518692) & nuts (GM part #11516078) for just in case!

 

[MaxPF]

Inspected the half shafts, if I twist them, they may rotate about 1mm before making contact. I think they have always done this, normal?

I've done a few half shafts in my day, and rotary play is not normal.