Rear differential problem
Thread Starter
7th Gear
Joined: Feb 2012
Posts: 7
Likes: 4
From: Valdosta GA
Rear differential problem
I’m not sure if I’m posting this in the right place, but I believe I am. I bought a 15 z51 back in January from buyavette in Atlanta. And pretty much have had no problems at all. But last week I decided to have the rear differential and transmission changed. As I get there to pick it up my mechanic pulls me aside and tells me that the trans fluid change went great. But there was a small problem with the rear diff change. He then showed me a small bolt that was stuck on the magnetic drain plug. It wasn’t very big and looked like it had a alan head. It had a a thread or so on the bottom of the bolt. So it looks like it sheared off something. The crazy thing is there is no noise at all coming from the rear diff at all. The old fluid didn’t have a lot of metal shavings in it. So I am at a loss as to what that small bolt goes to. This Wednesday I am taking it back in to have the rear diff possibly pulled to figure out what went wrong. Just thought I would ask and see if any one has any insight into what might have happened.
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Humm.....no prior odd noises or vibrations with the rear diff....do you have trust in your local dealer?
Burning Brakes
Joined: Aug 2018
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If there were no problems with the performance of the diff, why spend money to look for one? If there is no leak, no noise and no issue, not sure there is a “problem”? Drain plug either did it’s job or bolt was picked up during an earlier fill. Either way, diff is good.
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If there were no problems with the performance of the diff, why spend money to look for one? If there is no leak, no noise and no issue, not sure there is a “problem”? Drain plug either did it’s job or bolt was picked up during an earlier fill. Either way, diff is good.
Melting Slicks
Joined: Sep 2021
Posts: 2,555
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I'd try and find an exploded view of the differential and identify possible bolts it could be. The head is countersunk, you can measure the diameter.
There can't be that many bolts it could be.
After you know where it might have come from you can decide if the failure is catastrophic.
Maybe start sourcing a replacement and keep driving it? I'd be paranoid over every bump and tire chirp if it were mine.
There can't be that many bolts it could be.
After you know where it might have come from you can decide if the failure is catastrophic.
Maybe start sourcing a replacement and keep driving it? I'd be paranoid over every bump and tire chirp if it were mine.
Burning Brakes
Joined: Jun 2019
Posts: 1,212
Likes: 939
From: Georgetown, Tx
I don't buy the countersink screw coming from the inside of the differential. These type fasteners are not designed to take the load the differential is expected to handle.
There are very few bolts inside the differential, and the ones that are in there should all have heads. Imagine the hell you'd go through if the head of the countersink bolt gets stripped so bad that a tool could not remove it.
I'm no expert with Corvette differentials, but I've never seen a flathead/countersink fastener in any differential I've serviced.
Ask the guy at the parts counter to print out an Exploded View of the Differential Carrier and Case Assembly, and the Parts List. I'm sure you'll find that countersink fastener is not there.
There are very few bolts inside the differential, and the ones that are in there should all have heads. Imagine the hell you'd go through if the head of the countersink bolt gets stripped so bad that a tool could not remove it.
I'm no expert with Corvette differentials, but I've never seen a flathead/countersink fastener in any differential I've serviced.
Ask the guy at the parts counter to print out an Exploded View of the Differential Carrier and Case Assembly, and the Parts List. I'm sure you'll find that countersink fastener is not there.
Drifting
Joined: Jun 2013
Posts: 1,428
Likes: 478
From: Maryland, USA
if in your situation, if you have no issues i would leave it as well. if for some reason it was inside there and got on the magnet without causing any noticeable damage id say keep on riding.
Thread Starter
7th Gear
Joined: Feb 2012
Posts: 7
Likes: 4
From: Valdosta GA
I don't buy the countersink screw coming from the inside of the differential. These type fasteners are not designed to take the load the differential is expected to handle.
There are very few bolts inside the differential, and the ones that are in there should all have heads. Imagine the hell you'd go through if the head of the countersink bolt gets stripped so bad that a tool could not remove it.
I'm no expert with Corvette differentials, but I've never seen a flathead/countersink fastener in any differential I've serviced.
Ask the guy at the parts counter to print out an Exploded View of the Differential Carrier and Case Assembly, and the Parts List. I'm sure you'll find that countersink fastener is not there.
There are very few bolts inside the differential, and the ones that are in there should all have heads. Imagine the hell you'd go through if the head of the countersink bolt gets stripped so bad that a tool could not remove it.
I'm no expert with Corvette differentials, but I've never seen a flathead/countersink fastener in any differential I've serviced.
Ask the guy at the parts counter to print out an Exploded View of the Differential Carrier and Case Assembly, and the Parts List. I'm sure you'll find that countersink fastener is not there.
Intermediate
Joined: May 2022
Posts: 42
Likes: 22
From: Florida
I wouldnt be so sure that the bolt came from inside the dif, how do you know that the drain plug wasnt placed in a pan or on a surface that then attracted the bolt that came from an external source? did the mechanic specifically say he found the bolt stuck to the drain plug immediately after it was removed? or later.. if later, I could see any number of ways it could of got there. just a thought.
Melting Slicks
Joined: Feb 2018
Posts: 2,177
Likes: 1,044
From: North Texas
Check the bolt for closely for scrape, gorge, or any other marks that would indicate that it was caught in the running gears or moving parts. If there is any indication of such start looking deeper into the unit. Borescope. If no marks then I would not worry about it.
If the exploded view of the Diif shows this type of bolt at all, well all bets are off. Could not be a issue but engineers don't add extra bolts just for fun.
I'd be looking for an answer, then go from there.
If the exploded view of the Diif shows this type of bolt at all, well all bets are off. Could not be a issue but engineers don't add extra bolts just for fun.
I'd be looking for an answer, then go from there.
Racer
Joined: Apr 2019
Posts: 262
Likes: 130
From: Effingham county GA
What is the probability that the bolt sheared from the differential while you are driving and the bolt lands safely onto the magnet while the car is running down the road? Statistically, you may have a better probability of winning a lotto. 
