Rear end issues

[169mph]

Good afternoon,

I had my car on my lift to check for leaks or anything else abnormal. My rear deferential has had a very small gasket leak. Rarely see a drop. Today I found this….What’s causing the scoring? Did I bottom our? Any help would be appreciated.

2019 Backdraft cobra with a roush 427ir; 3300 miles

[169mph]

[169mph]

I can see that the CV joint has made contact with the differential carrier. I don’t think it’s a continuous thing. What should I be looking for? Rear bushings? Bad shocks? Forgive my ignorance. Thanks for the help

[spdbrake]

For your diff to twist twist and make contact on the R/H CV extension the aft R/H mounting bolt would have come completely out.
Diff cover looks like this. https://www.ebay.com/p/1726580184
If the Forward diff bolt (typically shears) broke the you'd have loud clunking as you gassed it.

[hauss]

Looks like your bolts inside have come loose or broken inside of your cv joint. This happened to me. I would remove the axle check threads replace with new bolts and red lock tight. The threads I am referring to are located on the flange next to the pumpkin.

[eschaider]

Take the wheel and spring off and disconnect the shock so you can move the suspension through it's full range of motion. If it touches your differential carrier, as you believe it does, and nothing else is loose, you need to limit the travel of rear suspension (recommended) so it can not contact the differential cover or clearance the differential carrier (not recommended).


Ed

[169mph]

I appreciate the feedback but unfortunately I haven’t had time to investigate further. I drove the car once since I noticed the rubbing. I drove it a few miles and I didn’t hear anything unusual. It felt fine but I didn’t drive it hard. I put it on the lift immediately afterwards and the only thing that seemed unusual was the driver’s side cv joint was felt considerably warmer than the passenger side. I’m referring to bronze section that’s scuffed up. Thanks for the help

[hauss]

still waiting what did you find? last report was last year

[169mph]

Before I start removing stuff I checked for missing or loose bolts. The only bolt that wasn’t torque to spec was the forward / front hex bolt that attaches the differential to the carrier. The bolt wasn’t backed out so can’t imagine it causing the problem. I found a torque spec of 52 ft/lbs. not sure if that’s correct. When I raised the rear end and spun the wheels I do hear slight rubbing sound at each wheel. I checked the front wheels to compare and got the same sound. I believe it’s normal. Can’t imagine all four wheel bearings failing at the same time. I did notice the rear end bushings look worn to me. I’ll post a picture of hex head bolt and the bushings. Again I appreciate any feedback.

[169mph]

Pics for reference

[spdbrake]

The second bushing pic you posted is the rear suspension carrier that bolts to the car's frame which should not cause your problem.

So if all three diff mounting bolts are tight. (Not the 4 suspension carrier bolts)
The aft two bolts I'm more concerned with actually.
Circled in this junkyard pic.



The CV joint extender blocks are tight and not wobbly etc..

Your bushings look fine and you reported 3k miles on the last summer, but what build # is your car.

I'd paint the affected (scraped CV joint extender block) and drive the car a bit.
See if the rub issue returns. You may have pick up some crap flipped up of the road.

[eschaider]

Your original concern, in post #1, was the scuffing / scoring of the CV carrier closest to the diff housing on what looks to be the passenger side of the car. While torquing loose bolts is always a good thing to do, unless the various suspension components are loose enough to move around contacting the CV carrier, they are most likely not the source of the scuffing of your CV carrier.

If you want to know what is causing the CV carrier scuffing then you need to move the car's rear suspension mechanism, on that side, through the full range of it's motion until you find the item that is contacting the CV carrier. The bad boy should be eminently apparent.

Once you have found that item, then you will have answered the question you posed in your initial post — everything else while possibly interesting ultimately is, at best, just window dressing in the resolution of how your CV carrier became scuffed.



Ed

[169mph]

Thanks for the picture. Those bolts are there. Look fine I posted another picture to show what the cv joint flange is rubbing

[spdbrake]

Rgr, You only found the front diff bolt was loose and aft ones were tight. I was hoping the diff had slid aft. But that really not the issue as the rub area you circled is above the CV adapter not just aft.
The CV adapter is bolted directly to the output flange of the diff so there is no movement of that part during operation. Ed's advice to remove the spring from the perch and run the suspension thru its travel limits would be useful IF the issue was outboard of the CV.

I assume you've pushed and pulled on the CV adapter to see the possible the internal bolts were loose?
Its not at all unusual for the BDR axle bolts to loosen. I've come very close to launching an axle (two bolts remaining). Why I drill my bolts and safety them, Locktite 272 and Locktite primer were not enough to prevent the issue.


Back to my earlier post on the possibility you flipped some the trash in there. The purpose of the paint is to see if you have a new rub of not.

[hauss]

listen to spdbrake his description is way more detailed then mine a few post back I had the same problem twice until I fixed it myself first time brought it to a local mechanic. This is something that I regularly check and keep a eye on. After the fix however it has been two years now and no more issues.

[169mph]

Originally Posted by hauss

listen to spdbrake his description is way more detailed then mine a few post back I had the same problem twice until I fixed it myself first time brought it to a local mechanic. This is something that I regularly check and keep a eye on. After the fix however it has been two years now and no more issues.

What was the fix? Limiting the suspension travel? Missing CV joint flange bolts? Thank you for your response.

Mike

[cycleguy55]

Originally Posted by 169mph

Thanks for the picture. Those bolts are there. Look fine I posted another picture to show what the cv joint flange is rubbing

Is there a fracture in the metal, just above the top right of your red circle?

See this: https://drive.google.com/file/d/1vIc...ew?usp=sharing

[169mph]

Originally Posted by cycleguy55

Is there a fracture in the metal, just above the top right of your red circle?

See this: https://drive.google.com/file/d/1vIc...ew?usp=sharing

I thought you found the problem. I was pissed and happy at the same time. It’s not a crack. the weld and shadows make it look like a crack. I took another pic from different angle. The bushings look horrible to me.

[cycleguy55]

Originally Posted by 169mph

I thought you found the problem. I was pissed and happy at the same time. It’s not a crack. the weld and shadows make it look like a crack. I took another pic from different angle. The bushings look horrible to me.

Agreed, those bushings look awful. Try a set of quality urethane bushings.

[hauss]

Originally Posted by 169mph

What was the fix? Limiting the suspension travel? Missing CV joint flange bolts? Thank you for your response.

Mike

My fix was retaping the threads on the flange installing new bolts with red locktight. Spdbrake has sent you pictures and goes even further than I that"s why I said to listen to him.