Well here lately while pulling my equipment i have noticed a good bit of a grinding noise coming from the rear chunk is what it feels like when making a turn from a stop or accelerating making a turn at a low speed.

I know this can be related to the limited slip rear end and adding additive can help. But heres the skinny....... I did the service in the rear end about 8k ago. Followed guzzles instruction as i like a review on it since it dosent get done on the regular basis like the engine oil.

So i put in the correct weight of Mobil 1 Full Syn with the additive already included in each bottle. I was told that it was NOT nessacary to use a slip additive with this Mobil 1 full syn. Didn't tow anything for about 5k and now I'm back working and hauling a lot and have noticed it grinding bad when making turns.

Should i just add a some slip additive to it ? If so how much ? I just don't want to tear it up or something to give. Its hard hearing the noise when your pulling 6k out of the shop on to the highway but another when your turning out on to the highway with 18k. Makes my cheeks pucker

ADVICE ??????

 

I had one 10.5 sterling grinding like you describe, the carrier bearings were gone and the 3rd member was moving side to side and grinding on the case. quite obvious what the problem was when I removed the back cover.
also had one that lost the pinion bearings and it ground a lot but also threw gear lube everywhere.

 

I had the same issue with my Excursion, I needed new bearings in the diff. You might be able to save the gears if you get in done in time. The shop that did mine said its a pretty common if the diff was ever run low on oil or had a leak no one took care of. Pull the fill plug, if there is lots of shiny metal flakes on it, the bearings are likely toast.

 

I replaced my carrier bearing about 5 years ago and the u-joints about the same time.

When you say 3rd member what are you referring to ? Im not to familiar with rear ends...... YET !

 

My Diff to my knowledge has NEVER leaked. I changed it at 98k when i bought the truck back in 05 and 3 times since. Never seen a leak and seems as it always has fluid.

I will pull the plug in the next few days and post back my findings.


Curious though when folks say if you hear it add some more additive to it, but if i got the mobile 1 full syn containing the additive i shouldn't have to do a thing correct ?

 

correct, mobil 1 synthetic gear lube is LS rated and doesn't need any modifier. if it is LS clutch chatter that you are hearing adding some friction modifier will make it go away.

 

I had the pretty much the same problem. I never could hear a grinding but could feel a shutter or feel a vibration coming from the rear end when I would pull out from a dead stop and turn right or left. Just for a split second though. Changed my fluid to Royal Purple 75W-140 and problem/concern went completely away. It had the friction modifier already in it as well. I pull a 31" 5th sometimes and still no problems........

 

The third member is the ring gear/spider gear combination that the axles slide into and the the pinion gear drives.

 

haven't had time to check the plug to see how much if any metal is visible on the magnet.

i changed it with the mobile 1 and to my knowledge using that you didn't need any friction modifier.

 

I used the mobil 1 syn, i will look when I'm at the shop tomorrow to see exactly what the bottle says.

How can i tell whats clutch chatter vs possible gears grinding ?

If the mobil 1 supposedly comes with the modifier in it and it is clutch chatter I'm hearing/feeling whats the best modifier to get and how much should i add ???

 

I use K & W because that is what the parts store delivers, squirt about 1/4 to 1/3 of the tube in and see if it goes away if not add more

 

Ok so its been a real long two weeks with work and other things, i finally got a chance today to jack the rear up and stick it in neutral and spin the wheels check the drive line etc.
Chunk sounded good when i was spinning the wheels, drive line u joints and carrier bearing seem good to my inspection no play except for the rubber around the carrier was a bit mushy but not bad. I checked the fluid and in the chunk and it was really clean and the magnetic plug had NO big metal shavings on it. It had very small particles collected which i would consider normal.
I added about 4oz of K&W TransX friction modifier to the chunk. Drove about 4mi home from the shop and it did seem a bit smoother.
I probably won't be able to really tell as i won't be towing till next week so we will see how it goes.

So what happens if you ad to much modifier ??????

I also did notice a very very small amount of up and down play in the passenger side rear wheel. Driver side felt real tight. Passenger side i grabbed the bottom and top of the tire and tried lifting up and down with all my might as i did the driver side and got the passenger side to move just as bit...... Bad wheel bearing ???? Im guessing so and if thats bad it might be causing the noise. Its very small amount of play as i had to use all my might to even feel it.
Im doing all of my suspension bushings here in the next few weeks so when i pull all the wheels off to get the springs off i will inspect it further.

 

So i pulled about 4k or 5k about 1/4 mi. My 25' flat bed with a 250gal fuel tank on it with about 200gal of fuel in it. Had to move it.
Still noticed the grinding feeling a bit. Mainly when turning right. Couldn't really tell as the journey wasn't far but still felt like it was there. Should be pulling 16k or 18k next week 20+ mi to a job in town and it should be enough to tell if it worked.

Can anyone give me some insight on the previous post.

 

Sounds like the right wheel bearing may just be a little loose, not likely your noise.

My was the thrust washers behind the spider gears. Silent for the first hour or so of towing but would grind bad when turning sharp after that. Most noticeable turning from a stop but any tight turn under power would do it.

 

Mine dose it first thing in the morning and there after. Dosent matter if its cold or hot. Very unnoticeable at all with no trailer. Unloaded sharp turn under med to hard acceleration you get a hint of a grinding in the rear.
Hook up a trailer and you can feel it. But only when turning from a stop. From start to stop going straight u feel nothing.