Creak/ Crunch/ Shudden when stopping-- why?

[mateospeed]

I'm getting a strange noise/ feeling when coming to a complete stop in my '98 Yukon (350, 4wd). It seems like it's coming from the rear of the truck, and is just slightly creepy. It somewhat resembles the sound/ feeling any car makes if you stop, then release the brakes JUST ENOUGH so that it sort-of creeps forward, shuddering as it does so. The difference b/w that situation and this one is that it's one big crunch/ creak, instead of a series of little ones, although the noise is rather similar.

A quick glance under the rear suspension shows nothing missing or out-of-place. I did get a little worried that perhaps something is slipping in the leaf springs, etc.

I recently pulled and re-installed the transmission (4L60E) while doing a rear main seal replacement, but did not dig into the tranny at all. To do so, I have to remove and re-install the torsion bars as well.

While I doubt those things are related, I thought it was pertinent information.

Any thoughts as to what this sound is? Has anyone experienced it before?

Thanks!
-Mateo

[Z71_guy]

drum or disc brakes in the rear, i would start with the brakes inspect and replace as necessary

[mateospeed]

drums. Inspect reveals nothing out of the ordinary.

[wpnsgy]

If the rear brakes have no loose or missing hardware are the properly adjusted??? this sound you describe is usaully associated with a spring or piece of hardware floating around in the drum and the shoes not being held properly in place. If you find no problem there check your suspension for broken leaf spring ect in the rear.

[cartier]

did u check your emergency brake to make sure its not on or maybe it could be partially seized up , to check it just get underneath it and pull on the cable coming from your drum it should move when you pull on it . if it's not any brake parts look in your rear diff case could be a problem there yukon and tahoe's are famous for rearend problems, and also i would check your rear wheel bearings they would make a cruching noise as well. you should find out the prob before you keep driving it. i just put a new rear end in my 97 yukon and it cost me 2500, all because of my rear wheel bearings . bearing went then i kept driving down the highway then it longated the axle housing and ruined my rearend on the truck.

[mateospeed]

i will check the parking brakes, but would assume that if they were stuck on, it'd be really difficult to get the rear drums off, which it was not. My rear wheel bearings don't sound or feel bad, but holy crap, with a horror story like that, I think I'll go check them again! I haven't been getting any noise or vibration from them, so I assume they're ok, but I'll shake the wheel anyways.
Thanks for the input, y'all!
-Matt

[2COR517]

You might need to lubricate the driveshaft slip yoke where it goes into the tcase. If they get dry they can cause all sorts of problems.

[2COR517]

yukon and tahoe's are famous for rearend problems

Really? Tahoe, Yukon, Suburbans are a dime a dozen around here. I have never heard of anyone having rearend problems.

[daddytech]

i will check the parking brakes, but would assume that if they were stuck on, it'd be really difficult to get the rear drums off, which it was not. My rear wheel bearings don't sound or feel bad, but holy crap, with a horror story like that, I think I'll go check them again! I haven't been getting any noise or vibration from them, so I assume they're ok, but I'll shake the wheel anyways.
Thanks for the input, y'all!
-Matt

with it being 4 wd I would change out the transfercase fluid, and rear end gear oil and make sure your U joints have plenty of lube in them also. We had an issue here with our 2000 AWD where it would make noises similar to what you described and shift hard at times too and it was the transfer case chain and gear that came apart and sent the chain in the case through the top of the transfer case. ours started out with just a little grinding or grabbing and if we'd have addressed it with changing the fluid as soon as everything started then we may have gotten quite a bit more usage out of it before we had to change out the whole transfer case.

I have heard U Joints make a similar noise and if you don't do the annual change of the oil in the differential it's probably time for that too because there could be a lot of gear grindings in there causing noise or vibration.

[vncj96]

If the u joints are shot they will make that very noise, mine did, and it is because the needle bearings in side are actually coming out of the casing. Over years of punishment from the torque the ujoints get pressure put in them from the twisting action from off the line, and this can cause the thin bearings inside to slip out. I replaced mine, a pretty easy job but never took any pics of what this looks like.

[mateospeed]

Now, this sounds like a reasonable idea: U-joints. That makes a lot more sense, seeing as it's make the thunk noise when just leaving the line as well, as soon as throttle is applied. I'll take the joints apart and take a look at the bearings. Thanks!
-Matt

[daddytech]

so what is the final verdict on this one??? U Joints or something more sinister ??

[mateospeed]

so what is the final verdict on this one??? U Joints or something more sinister ??


Well, unfortunately, I haven't had the chance to tear it down yet. A quick check under the truck with the transmission in park reveals some slop in the joints, which could certainly cause the problems. Interestingly, we just got a whole bunch of rain (10+inches in one day!!), causing some flooding. The truck didn't get flooded (only about 2 inches of water), but 2 things happened:
1) An ant hill took refuge inside my truck to avoid the rising water. Balls.
2) The crunching got better. Not back to normal, but better. Strange. It had now dried out, and I will be towing my boat this afternoon. It'll be interesting to see what has changed. I'll report back.

I'm still planning on replacing the joints, so we'll see what that does.
-Matt

[daddytech]

yeah if there is slop in the shaft with it in park i'd say you are on the right track , interested to see if that resolved the issue or not.