Rear clunk - video

[Sleipner]

Hi,

My manual 2017 S550 PP is lowered on Ford Eibach pro-kit and the last few hundred miles it has started producing a "clunking" sound while engine breaking or when lifting the clutch pedal after down-shifting (i think its primarily from the right side rear).

I've just had the differential backlash clocked and adjusted by the Ford dealer (it was within tolerance but on the high side) and after that it was good for a few days until it began again.

People have complained about clunk from various parts in the rear suspension but it doesn't appear while driving over irregularities, but rather it is VERY connected to when releasing the clutch, even very carefully at a stand still.
Also, when engine braking and the rev matches the vehicle speed, mainly on 3rd/4th gear, I get the clunk.

I've lifted the car while loaded on the wheels and can't find anything loose, but thats hard to find too...

The noise is rather metallic and now it is usually 3 rapid knocks in a row when driving off, either fwd or reverse.

Here is a video with me shifting between fwd and R, just getting it rolling a yard or so before changing direction. Loud click is the shifter collar - the "knock" is in the background.

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[Andrewg]

Mine does something similar. Had it since I dropped the cradle and swapped in BMR's poly diff bushing kit. Had it so long now i'm used to it but it still annoys me from time to time. Everything seems to check out and it has had no effect on the actual driving of the car apart from the noise. Just assumed it was always there and the stiffer bushings just transferred the NVH so only heard it after the bushings went in. I noticed when I had the car up on jack stands, I could grab the drive shaft and turn it by hand a few degrees then noticed it clunked as it 'engaged' inside the diff housing. First person i've read about that had something similar to mine but it definitely sounds like it's drivetrain related making the clunk when pressing/releasing the clutch.

 

[Sleipner]

Bump!
Check out the video on top. What is that noise?

This is the same noise but when changing speed slightly on 3rd gear. Smooth road, no sudden jerks or nothing.

 

[Andrewg]

Difficult to tell from the vid but it does sound similar to mine. Can't get a decent video though as we're in lock down over here.

 

[Sleipner]

Difficult to tell from the vid but it does sound similar to mine. Can't get a decent video though as we're in lock down over here.

Here's a new video from today which might be more helpful...

 

[Cdnspeed]

Check Axle nut torque, had the same click, once i torqued it went away

 

[Sleipner]

Check Axle nut torque, had the same click, once i torqued it went away

Yeah... Suspected that. The "ping" when jerking the tire might be a sign, however once the nut is loose and the bearing started clunking, I assume the bearing is gone so might just get Ford to do it on the warranty, however they claim to have checked "eeeeverything" when tearing down the differential.

I feel its better to actually find the fault myself before giving it to the dealer as Ford more or less have had my car more than I have since I bought it new three years ago....

 

[Cdnspeed]

Yeah... Suspected that. The "ping" when jerking the tire might be a sign, however once the nut is loose and the bearing started clunking, I assume the bearing is gone so might just get Ford to do it on the warranty, however they claim to have checked "eeeeverything" when tearing down the differential.

I feel its better to actually find the fault myself before giving it to the dealer as Ford more or less have had my car more than I have since I bought it new three years ago....

Honestly, I'd just take a torque wrench to it some have found them to be really loose.

its not necessarily a bad bearing just a tiny bit of play between the shaft and hub

 

[Sleipner]

Honestly, I'd just take a torque wrench to it some have found them to be really loose.

its not necessarily a bad bearing just a tiny bit of play between the shaft and hub

Checked everything yesterday - all found torqued correctly or almost, however the sound persists.
An update though with a second pair ears involved - noise comes from rear/left, not right as it sounds from inside the car.

If i turn left rear wheel back and forth, the outgoing shaft / bearing from the diff is clunking rather a lot. If I'm turning both wheels the same way as if on the road, its smooth as silk, so I think i'm back to the diff or CV joint on the left half-shaft, but not sure....

 

[cop on my back]

I had something similar and installed GT350 rear half shafts, problem gone.

 

[Sleipner]

I had something similar and installed GT350 rear half shafts, problem gone.

Ok good tip for the future but I don't want to pay for nothing under the warranty. I just want to pin point the problem as the Ford-dealer seems rather bad at doing so and I'd rather have it there for a day or two than several more weeks again before getting it back worse than before.

 

[Sleipner]

Update:
Took it out for a spin on some nice winding forest roads and noticed, after it's warmed up, that I heard a "ticking" noise similar to gravel in the wheel bay from the rear right... So... Wheel bearing?

A thing that struck me today is that when servicing the car last time (nov) the rear right wheel had 7mm and the rest 6mm. My alignment was done rather spot on a few months earlier so that might be a pointer towards bearing?

The main cracking noise when maneuvering fwd/rev though is from left side (confirmed) however the ticking/gravel noise from right might be a hallucination and really originating from the left...?

A new thing that happened today was that the single "knock" now also occurred a couple of times when accelerating steadily on 3rd gear out of a turn (right hand turn i think) and was not just from starting from stand still.

When I came back to the garage I shot the video below, now with steering wheel hard to left, then hard to right and then straight ahead just for reference. It seems at first as it's worse while turning left, but then... Well... Listen.

And as a bonus, there are now up to 5 knocks whens starting from standstill and not just 1 or 3!

 

[moffetts]

Push for new hubs and new halfshafts, ideally on both sides. I chased that clinking noise around for a long time until I replaced the half shafts, then it was gone for good. I will say though that the noises my car made were only audible with the windows down.

 

[Sleipner]

Push for new hubs and new halfshafts, ideally on both sides. I chased that clinking noise around for a long time until I replaced the half shafts, then it was gone for good. I will say though that the noises my car made were only audible with the windows down.

Yeah I guess I'll just have to take it to the shop AGAIN and just hope they find it... New diff, half-shafts and hubs and we're good to go. ;)

 

[V8_MOTOR]

I have the exact same issue on an auto. Left rear 100% I have a carbon fibre driveshaft and 800hp half shafts ready to go on. Hoping that will solve the noise but I think it might be a bushings or a loose nuts etc. Often the noise isn't there when I initially drive off and the car has been parked for a bit. As I drive it suddenly comes on when foot is off the gas and I'm braking and the car is about to come to a stand still. Once it starts, it keeps doing it.

The noise then always comes when going from R to D and D to R. Never if I go R to N to R or D to N to D

I'm going to check things out and report. Video of mine if that helps.

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