Thunk, Grinding from Driveshaft/Differential.

[GangstaCowboy]

Hi Members,
Recently picked up a 98 Yukon 4x4 for a fun car. Has been running great for about 7 months. However over the last two weeks I noticed a squealing grinding noise from under the vehicle. After playing around with it this morning, the sound seems to be coming from where the drive shaft connects with the differential in the back. When shifting into drive or reverse it seems to flex and twist more than I would think is normal. Once driving it makes popping metal noises or a constant grinding sound. Sometimes its fine, so it is intermittent but it is definitely rotational. I haven't had a chance take the back tires off yet to check, but the drum brakes are crusty as heck so possibly the a problem there? Any advice? Truck is still drivable but sounds terrible. Is there an input shaft or bearing I can check on the diff or drive shaft? Also on a side note I noticed the front drive shaft rotates while driving when 4x4 is not engaged. Is this normal for a 98 yukon? My f250 did not rotate when in 2wd mode. Thanks in advance for any help. I will post any new information I have once i check out the drums in the back.
T

---------- Post added at 01:47 PM ---------- Previous post was at 01:42 PM ----------

Sorry, just noticed I posted in the 2007+ forum, should be in the 99-down.

 

[Donnie Yukonie]

check the u joints probally about gone also yes i do believe (not 100 percent) the front drive shaft is engaged all the time at the transfer case and locks into the front dif when 4x4 is engaged i learned that when my front u joints went bad , or it may be the otherway around. someone will be able to verify this or correct me if i am wrong, id check the u joints first however thats what it sounds like to me , also a "honk or a clunk" from the rearend when tourqe is either applied or taken off of these trucks is common mine has been doing it for years and two of my buddies gm tahoe and silverado do this as well

 

[GangstaCowboy]

Would a bad U joint make the grinding metallic noise during driving? The noise varies in intensity from not being present to a very loud BANG when taking off along with the grinding noise, almost like when your brakes wear down to nothing. There was a rusty metal tab that I removed from inside the u joint that had broken on one side. However that made no difference to the sound.

 

[SunlitComet]

yes check your u-joints for play and grease the yoke on font of the shaft.

 

[GangstaCowboy]

Thanks for the tips. I checked the u joint and did not find any play or signs of damage. I will take the joint out in the morning to inspect it.

 

[Donnie Yukonie]

are you sure the noise is coming from this location ? cuz if not could be a number of things and what comet set if you dont have the sealed u joints pop some grease into them they might be running dry

 

[retorq]

I had a rear drum spring break on me and fall in ... damaged the drum, made sounds like what you described.

 

[GangstaCowboy]

Thanks for all the tips. I took the drive shaft out and sure enough the rear u joint was toast. One side was bone dry and all the needle bearings were broken or just rust. I replaced the rear bearing for now to get back not the road butt will probably have to all of them soon. The bearing was in so tight i had to take the shaft to a mechanic shop to press it out, i banged away at it for 2 hours. Major noise is gone and no more clunking, shifts smooth. There is stil a slight scraping noise which could be the other bearings we ring out or the rear drum brakes being rusty as he'll. Thanks for the help

 

[Donnie Yukonie]

no problem and if they were the OE u joints they are telfloned in i had the same problem took it to a shop and watched them torch the teflon out of them , and your right about replacing them ujoints is somthing i do all at once because normally when one is bad the others soon follow

---------- Post added at 05:00 PM ---------- Previous post was at 04:57 PM ----------

Would a bad U joint make the grinding metallic noise during driving? The noise varies in intensity from not being present to a very loud BANG when taking off along with the grinding noise, almost like when your brakes wear down to nothing. There was a rusty metal tab that I removed from inside the u joint that had broken on one side. However that made no difference to the sound.

just read this and relized somthing dont remove those "tabs' i believe your talking about the c-clips which help hold the joint in place just an fyi

 

[SunlitComet]

grease the yoke splines as well.