Previously installed a Yukon 3:73 an LSD. Got all new bearings an axle bearings. The gears ended up burning up so I got a replacement set. Install everything , got about 350 miles on it break in process. Making a u turn the other day and noticed a grinding noise like rubbing griniding. Thought the brakes were rubbing the rotor wrong pads were low so I changed them still same noise. It’s only if you making a sharp turn either way. It’s loud grinding binding noise not chatter or slipping. I’m leaning towards the LSD carrier. On straight line driving it’s quite no noises. Any suggestions or thoughts I would greatly appreciate it. The cars a 95 z28 A4. W/ rear disc. An it’s only got 55,400 miles on it. RLCA are new , panhard bars new ,torque arm bushings are new , u joints new. I’m kinda at a loss.

 

Did you use the recommended LSD additive?

 

Ya I used Lucas 80-90 heavy duty conventional an the 4oz bottle of the gm additive that I bought from the dealer. 4oz bottle acdelco. It’s just the oddest thing. I don’t know if somehow a axle bearing went bad they are new koyo bearings , or if the lsd unit is trying to lock up an it’s to slow or something because it’s just at low speed making hard left or right turns. Like I make a u turn to park on my street or pulling out of my drive way both fully turned one way or the other an I get that noise. An you can feel it from the rear of the car. Actually walked around the rear as someone drove in circles an listened you can hear it coming from the rear outside By the tires an the center cap even like resinates cuz it’s plastic. I’d hate to pull the diff cover 200 miles before the break in periods over an pull everything an it end up being something stupid. I’ve seen some threads about this very similar to what I described but no solutions or what fixed it.

 

i'm facing the same problem after changing my carrier from 2-series to 3 -series.. the left rear caliper is rubbing against the rotor.. after some search, i found many people faced the same problem..
the solutions i found:

1- grind the brake caliper housing from the side where it touches.. (i don't recommand)..
2- add GM shims on the ends of the axle.. which means you have to remove the axle and slide them in..
3- get a M12 washers and insert them between the caliper bracket and mounting hub..

hope this helps..

this is the link for the guy who had the same issue and fixed it..
https://www.camaroz28.com/forums/sus...5-axle-886958/

also search under (axle end play) (caliper touching router) (rear noise when turning left) (gm axle shims)..

 

Thank you man , I went to the dealer with the shim part number but none in stock. Like 1 dealer in the country has 1 apparently. I checked the other thread an the washer seems to be easy enough. I got some M12s from work it’s worth a try. I do notice now that the caliper is very close to the rotor so I’d imagine that could be it just odd that I don’t see like super excessive wear on it or the rotor being as the noise is so bad. Hoping to get time tomorrow to shim It With the washer an Test it. Will keep posted soon as I do thanks again.

 

so I tried the m12 washers unfortunately that actually brings the inside of the bracket closer to the rotor then it already is an just pushed the outside away from the rotor. I honestly would have to grind the mounting bracket but they look well centered once I got the wheel off. I cleaned everything up an put it back together, I took it for a ride I’m thinking something in the rear is not right, it won’t make the noise until it heats up , at first it’s just a almost rubber rubbing noise then it starts that grind. Idk if it’s a wheel bearing or the LSD unit. I’m about to remove the Yukon parts all together an return them for a refund. I have not had any luck what so ever with that company an there products. Put the stock unit an gears back in an see if the noise goes away. I’m going to inspect the rear , swap the c clips with new ones , an just really look at the wheel bearings an all even tho it’s all new an go from there will keep posted thanks

 

i did the M12 washers too.. it did take care of the loud squeeking sound.. but i still had the grinding noise (not much)..
just now i decided to remove the M12 washer and insert it on the bolt next to it (holding the caliper).. and guess what? noise gone.. caliper right in the centre.. and little to no end play..
took it for a test, full circles and tight turns, no noise what so ever.. give it one last shot and hopefully it will work for you too..

P.S. i used one washer only, on the top bolt.. maybe you need to have them on both bolts.. check first..

 

i inserted one washer before the golden nut.. this isn't my picture.. i didn't get a chance to snap one..

 

so you installed the washer where the caliper bolts to the bracket? what i did was install two of them on the bracket but that just brought the bracket closer inside. i even grinded the little rust off the rotor where the pad was catching it. once i take the cover off an the seals out of the axles an inspect the bearings ill try the one washer in the actual caliper. i dont think my caliper pins are bad either . they slide fine an have very min play in them.

 

So UPDATE.

I put a new set of pads on , took the diff cover off , everything looked normal , everything is tight an clean. Put new additive in an fluid , put new studs an lugs on.

Looked at the rotor an bracket spacing looked fine , took it for a ride didn’t hear any noise , Parked it ,

went for a long ride , brought it home no noises. Sits for a bit go to get some dinner soon as I leave the driveway turn all the way to the left reverse boom grinding noise , almost every turn I made it ended up making noise. all the way till I got home on sharp slow turns.

I just do not get what it can be. It feels like it’s rear end an sounds it. I have a brand new Yukon posi unit an new gears bearing the whole shabang Expect axles.

my rear tires are really worn down almost slicks do you think maybe it can be slipping to the side on turns an causing the posi to engage an diss engage wrongly? I’m at a loss.

also I hear a squeaking chirping , rubber rubbing noise coming from near the trans ? Output shaft seal/bushing ? Like I’m stumped it shift perfect , nothing wrong there almost wondering if the grinding is coming from up there now.

 

Sorry to hear you still facing the same problem..

Question:
Have you considered taking it to a chevy dealer and see what they come up with? insted of brain storming and spending money on replacement parts and labor.. at this stage, don't you think spending 70 dollars for a diagnosis is worth it?

Hope you figure it out and wish you all the best.. Don't give up..
Keep us updated..