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Clunking in rear with diff bushings. driveshaft/differential?

Tugger50H

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Ok wasn't sure where to put this thought I read somewhere on the forums that somebody had a similar problem without diff bushings.

I have 2015 GT with an auto. I can hear a clunking sound coming from the driveshaft/differential. To me it sounds like the differential has too much backlash or its a ujoint angle issue.

I didn't have the car very long before I installed steeda's differential bushings, subframe spacers, and IRS supports. Although the noise became immediately noticeable after the install. I have double and triple check every bolt I have touched and torqued to proper specs.

Its not that big of a deal but also can be annoying when driving in stop and go traffic. I notice it when I first accelerate and when I first let off the gas. You can hear the clunk and feel something moving slightly. So it seem like the obvious cause would be the diff bushings but I really don't really see how they can move. The clunk is more active and noticeable if I put the car in neutral before coming to a slow and steady stop. Also I can create the clunk while parked shifting from drive to reverse which make me think it more in the driveline than the diff bushings. My hunch is its the rear ujoint hopping around or the backlash in the rear end.

Anybody else have diff bushings installed? Do you have this issue? I have the steeda black bushings installed. I'm thinking about uninstalling the diff bushings and seeing if it persist but thought I would check with you guys before I go through the hassle.
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Rogues Gambit

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Ok wasn't sure where to put this thought I read somewhere on the forums that somebody had a similar problem without diff bushings.

I have 2015 GT with an auto. I can hear a clunking sound coming from the driveshaft/differential. To me it sounds like the differential has too much backlash or its a ujoint angle issue.

I didn't have the car very long before I installed steeda's differential bushings, subframe spacers, and IRS supports. Although the noise became immediately noticeable after the install. I have double and triple check every bolt I have touched and torqued to proper specs.

Its not that big of a deal but also can be annoying when driving in stop and go traffic. I notice it when I first accelerate and when I first let off the gas. You can hear the clunk and feel something moving slightly. So it seem like the obvious cause would be the diff bushings but I really don't really see how they can move. The clunk is more active and noticeable if I put the car in neutral before coming to a slow and steady stop. Also I can create the clunk while parked shifting from drive to reverse which make me think it more in the driveline than the diff bushings. My hunch is its the rear ujoint hopping around or the backlash in the rear end.

Anybody else have diff bushings installed? Do you have this issue? I have the steeda black bushings installed. I'm thinking about uninstalling the diff bushings and seeing if it persist but thought I would check with you guys before I go through the hassle.
Same issue with my Eco, so I'n subscribing.

I just assumed it was do to driving around in S all the time
 

dwaleke

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The Diff bushings may not be the cause but they amplify any noises going on in the rear end.

Pull out the diff bushings and see if the problem gets better.
 

JohnD

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Most people refer to it as the thud. With a manual on every shift you get "thud-thud" with clutch in-clutch out, and when you lift off the throttle and get back on it. I'm told it's lash in the driveshaft/rear end. Not noticeable when brand new, but after a few thousand miles it starts and now it's really noticeable. Any stiffer than stock bushing material is going to make that noise worse for sure.
 

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jasonstang

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Nothing you can do. It's simple physics. The gears have to have back lash to work properly.
 

wildcatgoal

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Sounds like Ford's wonderful driveline slop, the NVH from which is only going to be amplified if you add differential bushings.
 

xXANCHORMONXx

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When I had my EB I had every single joint replaced with delrin or converted to a spherical bearing.

The clunking was horrid.

When I bought my Shelby I did the exact same thing with one exception. I didn't touch the differential.

No nvh for me on my car.
 

Jeff_oddo

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Mine makes a very slight thud when I let off the gas and then press it again. Other than that, no other issues with my rearend. Just installed heavier FRPP Axles and BMR differential poly inserts this week. Car actually feels much smoother when cruising at highway speeds compared to before. Not sure if it's the diff inserts, new heavier axles or both combined, but I like it.
 

Jeff_oddo

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Noticed it some more last night while driving back from the track.
 

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VinnAY

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Backlash has to be there for it to work, you can mitigate it by going easier with the clutch pedal and shifter, don't mash it to the floor, puuuuush it to the floor. Pause a second moving the shifter...remember even when it's in neutral things are spinning and if you give it a second to stop before you put it in gear and going easy on the pedal a lot of the noise with be mitigated. But then you intentionally made it worse with the mods :)
 

jdoug

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Same issue for me and I have posted about it before-- noticeable clunking only after installing the red differential bushings. I can only imagine how much worse it would be if I had used the black ones.
 

BLSTOIS

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Same issue for me and I have posted about it before-- noticeable clunking only after installing the red differential bushings. I can only imagine how much worse it would be if I had used the black ones.
I've got it pretty good in the first 3 gears with the black ones. I thought I didn't get the front bolts tight enough, but after seeing other people with the same issue, I'm glad that its just "noise" and not my rear end about to explode.

Does everyone else just get it at low rpms and gears plodding around? Clutch dumps, and redline shifts, mine behaves well
 

jdoug

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Yes it's really only noticeable in mild driving-- my wife notices it when she drives the car because she babies it more than I do.
 

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It's the diff bushes for sure. Been there done that. If you watch the videos from BMR and FTB, you'll see how much the diff moves and cushions the shifts. No movement = no cushion AND more sound transfer. Unfortunately, they are such a good thing for curing wheel hop...
I'm curious about fitting half the kit. Eg rear portion only, to see if a balance can be struck.
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