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Discussion Starter #1
TLDR: “Grinding”-like vibration coming from differential area. Ideas?

I’ve just gotten back from having my 3rd diff installed in my 2010 V. The first 2 replacements whined horribly on both acceleration and deceleration. This was NOT the characteristic groaning of the LSD. Sounded more like the pinion preload was incorrectly set. This 3rd diff is 95% quieter. I can sometimes hear a slight whine on deceleration, but it’s barely noticeable. Regardless, that’s not the big issue.

Both the first replacement and the third replacement have also had a vibration issue. The second one was perfectly smooth, but the other 2 vibrate with a strange, “grinding” feel. My best analogy is to imagine packing a bearing with a mixture of sand and grease, then spin it. That is what this feels like. It’s only apparent above 65 mph, but it gets progressively worse as the car accelerated.

Any ideas? I’ve had the driveshaft indexed 90° with no apparent effect. I’m going to try indexing 2 more times to see if this changes anything. What else could cause this aside from bad bearings in the differential? Both me and the dealer and going to be pissed if we have to go with a fourth replacement.

Btw, good luck to anyone getting a diff replacement from the dealer. Hope your luck is better than mine. This is potentially 3 in a row that are junk from the factory. Luckily I have a good service manager, seems like others have been told just to “deal with it” when the new diff still has problems.
 

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TLDR: “Grinding”-like vibration coming from differential area. Ideas?

I’ve just gotten back from having my 3rd diff installed in my 2010 V. The first 2 replacements whined horribly on both acceleration and deceleration. This was NOT the characteristic groaning of the LSD. Sounded more like the pinion preload was incorrectly set. This 3rd diff is 95% quieter. I can sometimes hear a slight whine on deceleration, but it’s barely noticeable. Regardless, that’s not the big issue.

Both the first replacement and the third replacement have also had a vibration issue. The second one was perfectly smooth, but the other 2 vibrate with a strange, “grinding” feel. My best analogy is to imagine packing a bearing with a mixture of sand and grease, then spin it. That is what this feels like. It’s only apparent above 65 mph, but it gets progressively worse as the car accelerated.

Any ideas? I’ve had the driveshaft indexed 90° with no apparent effect. I’m going to try indexing 2 more times to see if this changes anything. What else could cause this aside from bad bearings in the differential? Both me and the dealer and going to be pissed if we have to go with a fourth replacement.

Btw, good luck to anyone getting a diff replacement from the dealer. Hope your luck is better than mine. This is potentially 3 in a row that are junk from the factory. Luckily I have a good service manager, seems like others have been told just to “deal with it” when the new diff still has problems.
So my experience with a new diff in my V was better, but I immediately changed the fluid after 500 miles. I continued to change it after 1000 miles for the next 3 tunes or so until there were no more metal particles visible in the oil. Using Blackstone I've learned that a 10K interval is about the max you want on a street car. The new diffs seem to generate a ton of material as they seat in and unless flushed could contribute to excessively high wear and noise at surprisingly low miles. My original diff was changed at about 36K due to noise. No vibration though. Am now at 78K. So even though this one is quiet now. Drain and check it. Shorten your service interval. What mileage did the first one start making noise at? Good luck.

Sent from my SM-G955U1 using Tapatalk
 

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So my experience with a new diff in my V was better, but I immediately changed the fluid after 500 miles. I continued to change it after 1000 miles for the next 3 tunes or so until there were no more metal particles visible in the oil. Using Blackstone I've learned that a 10K interval is about the max you want on a street car. The new diffs seem to generate a ton of material as they seat in and unless flushed could contribute to excessively high wear and noise at surprisingly low miles. My original diff was changed at about 36K due to noise. No vibration though. Am now at 78K. So even though this one is quiet now. Drain and check it. Shorten your service interval. What mileage did the first one start making noise at? Good luck.

Sent from my SM-G955U1 using Tapatalk
Thanks for your input. I plan on putting a couple hundred more miles on this replacement (currently at ~200 on it) and then change the fluid. I was debating on using the GM fluid or trying the RP 75w-140 with some additional friction modifier. Still deciding on that.

My original diff lasted 125k miles. It started making a "womp-womp-womp" sound on deceleration, otherwise it had been perfectly good.
 
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