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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #1
howdy. after 65k miles I've got what I think is some play in the rear suspension, the "thunk" usually occurs when transitioning between acceleration / deceleration or during downshifting (6M).
The recent engine upgrade and healthy cam has made the thunk more pronounced, specially when trying to roll at slow speeds.
I checked the rubber coupler at the transmission and driveshaft, i think it's possibly worn bushings in the cradle that houses the rear diff.
Has anyone ever upgraded from stock to aftermarket bushing and did it resolve the issue?
Any help is appreciated.
 

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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #2
incase anyone else has this issue, i think I found what my issue is and it looks easy to fix:
 

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Steve did a write up in the performance section on the poly cradle bushings. For me I just go solid be done with it. Theres a guy on one of the FB charger/challenger pages made his own out of Aluminum. He did it CNC so hes got the program.

As far as the shucking...as I call it at slow speeds mine does it too. I had the dealership check everything out years ago and I torqued the cradle bolts ...maybe 165 ft/lbs cant remember the spec. Its just part of the design and compounded with the the electronic throttle control and parking lot speeds. I got a 70's long wheel base 3/4 truck thats about the same...........:surprise:
 

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I need this. Any recommended replacement brand or just OEM?
 
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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #6
I'm going with OEM. I considered using poly or solid but don't want the noise / vibration transferred to the chassis.
I figure if it's good for 60k miles, the next one should last atleast 30k with the added power.
 

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replace the pinion bushing and see if that clears it up

As you're aware, on the Getrag '09 - '14 equipped models, you let off the clutch abruptly or have the power train "rock" at low speeds you'll get clunking. The 3 point diff mounting has that symptom.

With the miles you have and the mods, it probably has wear and moves around more as you're putting more power to the ground.

The later '15+ 4 point mounting that the ZF diff uses doesn't seem to exhibit that characteristic. Has a "tighter" feel and doesn't have the clunk when loading / unloading drive line
 
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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #8
replace the pinion bushing and see if that clears it up

As you're aware, on the Getrag '09 - '14 equipped models, you let off the clutch abruptly or have the power train "rock" at low speeds you'll get clunking. The 3 point diff mounting has that symptom.

With the miles you have and the mods, it probably has wear and moves around more as you're putting more power to the ground.

The later '15+ 4 point mounting that the ZF diff uses doesn't seem to exhibit that characteristic. Has a "tighter" feel and doesn't have the clunk when loading / unloading drive line
Are you referring to the item in post#2 or something internal?
I am going address this once I'm back home.
It always had a slight amount of play or slack, even when new, due to the differential mounting design you mentioned.
The amount of slack has gradually increased, and the cam now exasperates the issue when trying to creep around at slow speeds.
 

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Post #2 that bushing would probably have a lot of impact on the up /down rotation of the center section.

Bushings would be a wear item and with the amount of torque going through the driveline its going to show up eventually.
 

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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #10
the part numbers incase anyone needs them
4578085AA - bushing half
4578191AA - bushing half
6509315AA - bolt

I was able to source them locally for really reasonable, $15 for one and $18 for the other (re-using original bolt).
Waiting on some sub 100* degree temps for install
 
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replace the pinion bushing and see if that clears it up

As you're aware, on the Getrag '09 - '14 equipped models, you let off the clutch abruptly or have the power train "rock" at low speeds you'll get clunking. The 3 point diff mounting has that symptom.

With the miles you have and the mods, it probably has wear and moves around more as you're putting more power to the ground.

The later '15+ 4 point mounting that the ZF diff uses doesn't seem to exhibit that characteristic. Has a "tighter" feel and doesn't have the clunk when loading / unloading drive line



My '16 deff does this.
 

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2010 Challenger 6M- Brilliant Black, 426 stroker, Hellcat rear cradle, ZF 3.90 diff, DSS 1 piece
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Discussion Starter #12
finally got a chance to replace the bushing, was able to use a friends lift...it was kind of a pain in the ass to be honest.
I had a hell of a time stuffing my hands and arms up around the half shaft and roll bar to reach the top of the bushing. Took a buddy and I about 15 minutes to get it out and install the new one.
It did fix my "thunk" problem, with 65k miles on the odometer the old bushing was shot.
Next up is the large bushing on the rear off the diff. It looks like there are only 2 large bushings holding the diff to the cradle...
 

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finally got a chance to replace the bushing, was able to use a friends lift...it was kind of a pain in the ass to be honest.
I had a hell of a time stuffing my hands and arms up around the half shaft and roll bar to reach the top of the bushing. Took a buddy and I about 15 minutes to get it out and install the new one.
It did fix my "thunk" problem, with 65k miles on the odometer the old bushing was shot.
Next up is the large bushing on the rear off the diff. It looks like there are only 2 large bushings holding the diff to the cradle...
You're correct 3 mounting points on the Getrag diff.

The newer ZF diffs have 4 mounting points and a revised IRS cradle to accommodate that
 
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