Groaning noise while turning slow

[SlowyoteJay]

Hello all, I’ve been dealing with this issue for a little while, and I’ve been trying to pin point the issue before I take my car into Ford and pay $200 for a simple diagnostic. I have a 6MT 2019 Mustang GT with the Steeda Stop the Hop Handling Ultimate Kit (part #555-2129H). I have everything installed minus the differential bushing insert (part #555-4443). Roughly a month after the parts were installed, I noticed a groaning noise (like something is rubbing) more than likely coming from the rear when I turn left/right slowly in first gear or turn while reversing slowly. I went back to retorque all installed parts to spec but that didn’t fix the issue. Tires only have roughly 5k miles on them and have been recently rotated. I don’t notice a big difference in drivability but I just want to know your thoughts. If it’s apart of the NVH that comes with the kit, then I’m fine with that. I just want to know if there is an issue and what it could be.

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[Park]

I had that happen to me a few years ago and it was the diff clutch plates. It made that sound in R and only when cold.

 

[SlowyoteJay]

I had that happen to me a few years ago and it was the diff clutch plates. It made that sound in R and only when cold.

Yeah I hear it more when the car is first being used. The car only has 28k mi on it and the diff has never been touched. The diff clutch plate should still be under warranty right?

 

[Mike Pfeifer]

Change your diff fluid. Don’t forget the friction modifier.

 

[SlowyoteJay]

Change your diff fluid. Don’t forget the friction modifier.

I guess it is about that time. I just have to check the owner’s manual to see how much fluid and additive to put

 

[Mike Pfeifer]

I guess it is about that time. I just have to check the owner’s manual to see how much fluid and additive to put

I had to do mine at 9500 miles for that exact reason. I think spec is 9mm below fill hole. That’s for the modifier and fluid. I have a giant syringe that I mixed it up in first before filling, way easier than trying to pump it into the diff directly from the bottle.

 

[SlowyoteJay]

I had to do mine at 9500 miles for that exact reason. I think spec is 9mm below fill hole. That’s for the modifier and fluid. I have a giant syringe that I mixed it up in first before filling, way easier than trying to pump it into the diff directly from the bottle.

Thanks for the idea. Recommendation on fluid? I’m seeing mixed reviews on motorcraft and Royal purple

 

[Park]

My problem started at 5K , covered by warranty. No problem with 49K on it now, 2020 EB, AT.
Not the one in the picture, that’s my GT

 

[Mike Pfeifer]

I used motorcraft fluid and the motorcraft modifier.

Check this out for getting the fluid in there: https://a.co/d/12fRJdT

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