hey guys just got done installing new Yukon 3.23 gears, and Yukon limited slip. Everything seems great driving without any noticeable noise but when turning I can hear what I think is the clutch packs activating and making noise doesn't sound like a chatter more like a heavier noise. I put in reg diff oil 80/90 and 4oz additive. Someone mentioned it’s normal on new units? Should I be doing slow figure 8s or something to get oil in the clutch packs as some others have done? Thanks
Yes you want to do figure 8 to disengage and reengage clutches. The friction modifier needs to work it's way in. Usually I try to add the additive first and make sure it gets into the clutch pack on the posi unit. Then I add my gear oil. One bottle should be sufficient for approximately 3 quarts of oil. A little extra won't hurt anything. Also if rear is newly rebuilt don't let it get too hot. Short trips at first under 50 mph
The clutches that come in the Yukon’s are polycarbonate,and would not make a squealing sound. They aren’t aggressive enough to do so. A second bottle of additive won’t change it,and you only need ONE bottle. Do you notice if it squeals no matter which way you turn,or only one direction?
Could the squealing noise be coming from the tires, brakes? Definitely the rear? Could it be power steering squeal? Who installed the unit and gears? I just had this exact posi unit installed in my car. Once again definitely do some figure 8's. As long as your not hearing grinding or aggressive whining I would just continue to break it in. How many miles have been put on it?
So far only 15 miles per the book. I was easy on it and didn’t take it over 50. I hear going both right and left on tighter turns. I installed the gears. I am pretty sure it’s coming from the diff. But anything is possible. It’s more of a rubbing type noise not like a belt squeal. But not tire rub sound. Pretty sure it’s the diff. I’ll take her out this morning and do some figure 8s. After I hear the noise I parked it also because I already drove it 15 miles for the first break in procedure.
Took her out for another 5 or so miles and did figure 8s in the church parking lot. The noise at both right and left right turns. I did them idling around through the turns. It’s coming from the rear end area. It’s not a squeal- not sure why I described it like that. It’s like a rubbing but not a grinding per say. But very noticeable on tight turns either way.
I used Lucas 80/90 gear oil and a 4 oz friction modifier (additive for LSD) from O'reillys (closest thing to me). I don't know guys. could it really be that its not GM additive? are these things THAT sensitive? This is disappointing after spending so much money and two weeks of countless hours on the thing. I should probably give Yukon a call as well today.
I would only use the GM stuff, but take the advice of Brian and Jim. They do this for a living. I will say that I once tried another brand of additive and had to go back later with the GM stuff.
Also is the GM limited slip the AC delco stuff? # https://www.amazon.com/s/?ie=UTF8&k...d=kwd-314187313401&ref=pd_sl_8ig6gk0vqv_e_p37
Is that Lucas oil synthetic or conventional? You can NOT run any synthetics with any clutch style or cone-style unit. I would still check to see if your drums are rubbing on the backing plates. Did you replace your axle bearings/seals? If so what did you use?
It’s the conventional. I didn’t replace axle bearing or seals . They looked great and didn’t have issues before with them. What part of the drum could be rubbing on backing plate when turning? I secured the 4 nuts to hold the axle in place nothing seems out of clearance. I picked up some new Lucas 80-90 conventional oil and gm additive from the local dealership. Was going to try new oil and this additive to see if it helps. A bit at a loss
I had A bad experience years ago ,had A buddy install A new posi,I used Lucas gear oil and off brand additive ,it would have grinding sound when going around turns,drove me crazy. The paper work said to use GM gear oil and additive.I put GM oil,additive in ,but would sill do it .I got frustrated and put A nother rear end in my car.I think if I had done that when it was first installed it may have been ok. I'm no professional rear end guy like some on here, but have build A few.I installed A Eaton posi in my skylark last summer ,and my Eaton owner's manual said ,if using non LS gear oil ,add four ounces of GM limited slip additive per one and half quarts of gear lube.Addition friction modifier additive may be used to reduce LSDplate chatter but do not exceed eight ounces per one and a half quarts of lube. That's why I use more than one bottle, and I A ways use GM oil,additive .
Ok went out there and popped diff cover off. Everything looks fantastic honestly. No shavings, all gears in good shape including spider gears in the posi duragrip unit. Hmm ill get the oil and additive in and take her out again. let me know your thoughts on the backing plate thing. UPDATE: Put new gear oil and and gm additive. Took it did circles and figure eights and cruised about 10 miles. Didn’t really get better. Again only on turns, sounds like a rubbing/ binding type noise. Looked at drums and they aren’t hitting the backing plates. The brakes themselves are in that pic but no issues going straight only sharp turning when posi activates. I put 4oz of additive in it. Should I add a little more, The instructions only say 1 4oz bottle so I didn't add more
If the noise is not getting better, can only suspect now that axle bearings may be causing the noise. Perhaps not sitting in exact same location on axle as before. Possibly damaged a bearing on removal/install. Just purely taking an educational guess at this point. I would still not eliminate the possibility of your rear brakes causing the noise. We're the brakes readjusted after reinstall?
I made sure the brakes looked good before sliding the drum on and then hit the pedal in reverse a few times to adjust them more with the self adjusters. I called Yukon and thy said to do more figure 8s and give it about 75 miles. So we will see. It’s very odd that the noise is identical to the video link I posted of another user of their posi having the same problem
