Rear end low rumbling/grinding noise only when slow turning

[tmar66]

Only happens in parking lot scenario; low speed, tight turns. Maybe differential, bearings? 2015 v6 auto 69k mi. new tires. It rumbles enough to rattle the dashboard up front and I can really feel it and hear it.
Any ideas?

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[Anthony 05 GT]

Try adding a bottle of friction modifier in the diff case. Cheap, easy first step unless you want to take it in for a tech to get a look.

 

[Bluelightning]

Only happens in parking lot scenario; low speed, tight turns. Maybe differential, bearings? 2015 v6 auto 69k mi. new tires. It rumbles enough to rattle the dashboard up front and I can really feel it and hear it.
Any ideas?

Check your rear hub bearings.

 

[tmar66]

Now in the shop, hopefully a good answer Saturday. Thanks for the suggestions.

 

[tmar66]

The shop thinks it is the differential and a new one he said is around $6000. He wants to verify it with his head technician on Monday to be sure. I'll have to look for alternatives to having them replace it. Maybe a local shop can get one from a pick-n-pull yard. Maybe I can sell it to carmax. I don't drive it that hard, I'm surprised no one else has seemed to have this same issue, at least from what I've seen.

 

[Anthony 05 GT]

$6000 is ridiculous. You can buy a good used one for under 1k. Or better yet, have a qualified tech repair yours.

 

[Guard5.0]

$900 on ebay

 

[RaceHorseV8]

Any update? $6000 is ridiculous! Have the tech check/adjust the gear lash and pinion depth. Then replace the fluid and try it. If it isn't better then rebuild/replace any bad parts. To just junk the whole thing and replace with a new one is a complete copout on the mechanic's part.

 

[Bluemustang]

Any update? $6000 is ridiculous! Have the tech check/adjust the gear lash and pinion depth. Then replace the fluid and try it. If it isn't better then rebuild/replace any bad parts. To just junk the whole thing and replace with a new one is a complete copout on the mechanic's part.

I agree. Maybe take it somewhere else lol. There is no way a differential costs $6000 first of all. That's the cost of a new engine.

 

[tmar66]

Yeah, unfortunately I traded it in and got something different. Just don't need that kind of headache now. I do miss it.

 

[aleccesarenriquez]

Having this exact same issue now after a diff swap.

Used about 2.5 quarts (little more) of Motorcraft 75w140. No additive.

Any recommendations? I will add some additive this weekend, but want to see if anyone else has encountered this issue.

 

[dgtal36]

Same problem here. Replaced the diff fluid and still having the same problem.

 

[p6cl]

A friend had an Ecoboost Mustang and all it was to fix was a bottle of friction modifier. When I took it for a test drive I thought it was the power steering system at first. Added friction modifier and that fixed the problem.

 

[David Burricelli]

A friend had an Ecoboost Mustang and all it was to fix was a bottle of friction modifier. When I took it for a test drive I thought it was the power steering system at first. Added friction modifier and that fixed the problem.

I have the same issue. It makes a rumbling noise in the rear when I turn and go in reverse and turn. Ill try the friction modifier. Keep you posted.

 

[TeeLew]

The shop thinks it is the differential and a new one he said is around $6000. He wants to verify it with his head technician on Monday to be sure. I'll have to look for alternatives to having them replace it. Maybe a local shop can get one from a pick-n-pull yard. Maybe I can sell it to carmax. I don't drive it that hard, I'm surprised no one else has seemed to have this same issue, at least from what I've seen.

Honestly, that's such a massive load of bullshit that there's no reason to ever speak to this shop again.

You've got a V6, which means a Trac-Lok differential. They're $200 new https://www.summitracing.com/parts/fms-m-4204m/make/ford. The install is ~4 hours. A fully load rear housing with a 3.55 gear and Torsen diff is $1k and the install would be faster. https://www.summitracing.com/parts/fms-m400188355b/make/ford

I would look to bearings first. When a Trac-Loc fails, it goes open. They only make noise if you've done work to tighten it up.

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