Persistent Rear Clank During Flex – Need Ideas

[bronco504a]

Hi everyone,

I’ve been chasing a clank noise in the rear of my Bronco for quite some time, and after multiple workshops and many replaced parts, the sound is still there. I’m hoping someone here may have experienced something similar or can point me toward something I may have missed.

Vehicle

2023 Ford Bronco 4-Door Wildtrak Sasquatch
ICON suspension setup (Stage 4 kit with additional ICON arms – effectively Stage 7 geometry)

Description of the Noise

The sound is a single clank / knock that occurs during suspension flex.

Examples when it happens:
• When the vehicle articulates during flex
• When one side of the rear suspension is compressed more than the other


Important detail:

Sometimes if I flex the same side twice, the noise does not repeat the second time. If I flex the opposite side, it may happen again.

I can feel the impact through the floor under my feet, which makes it seem like the sound comes from the center of the vehicle, although mechanics believe it originates somewhere in the rear.

What It Feels Like

It feels like something shifts under load and then settles suddenly, creating a clank.

During hard acceleration in sand, it has occasionally felt like the rear drivetrain loads and releases suddenly.

Parts and Components Already Checked / Replaced

Rear suspension:
• Rear shocks replaced
• Rear springs replaced
• Track bar replaced
• Control arm bolts inspected multiple times
• Bushings inspected

Braking:
• Rear brake calipers replaced

Drivetrain:
• Rear differential opened and inspected internally
• No obvious internal damage found

Inspection:
• Multiple workshops inspected the vehicle
• Suspension components checked for looseness
• Mounting bolts checked and retorqued
• Alignment performed

None of these solved the problem.

Additional Finding

During one alignment check, the shop noticed the driver-side rear differential housing had a small bend, which was corrected.

However, the clank remained after the repair.

Other Observations
• Noise is not constant
• Happens only during articulation or heavy suspension load
• Sometimes does not repeat immediately

What Has Been Ruled Out (so far)

Based on parts swapping and inspections:
• Rear shocks
• Rear springs
• Track bar
• Brake calipers
• Obvious differential damage
• Loose suspension bolts

Current Suspicions

At this point the remaining suspects may be:
• Rear driveshaft slip joint binding
• Control arm sleeve shifting under load
• Axle housing / bracket movement during articulation
• Something internal to the drivetrain that only appears under flex

Question

Has anyone experienced a similar clank that only appears during articulation or heavy suspension load?

If so:
• What ended up being the cause?
• Are there known Bronco issues that produce this behavior?

Any ideas or tests I should try would be greatly appreciated.

Thanks in advance.

Sponsored

 

[SierraBronco]

Dang. That’s annoying. Might be time to try mounting some gopros under there and doing some forklift tests, assuming it’s a suspension shifting issue.

We’ve had the driveline rub against the tank, but it never clanked on us. Also the axle shifting sideways and the swaybar arms making contact with the links then bending/breaking, but that shouldn’t be an issue with the panhard bar still in place.

 

[bronco504a]

Dang. That’s annoying. Might be time to try mounting some gopros under there and doing some forklift tests, assuming it’s a suspension shifting issue.

We’ve had the driveline rub against the tank, but it never clanked on us. Also the axle shifting sideways and the swaybar arms making contact with the links then bending/breaking, but that shouldn’t be an issue with the panhard bar still in place.

I tried lifting the car using a lift and putting it down each time with one tire up using bricks. But i did not get the sound, it needs some engine load. Thought about the go-pros but i feet if i get anything using this method it would be purely luck

 

[GI_Jo_Nathan]

During one alignment check, the shop noticed the driver-side rear differential housing had a small bend, which was corrected.

Having a hard time understanding what you mean by this?

 

[bronco504a]

Having a hard time understanding what you mean by this?

I had a miner bend in the differential, and i fixed it

 

[GI_Jo_Nathan]

I had a miner bend in the differential, and i fixed it

Sorry still can't comprehend. That's just not something that's normally possible. Any pics?

 

[bronco504a]

Sorry still can't comprehend. That's just not something that's normally possible. Any pics?

Its not visible, but we found out during the alignment. Very minor and we have shops that could fix it.

 

[JP2]

I'm really interested to see what you come up with because I have the same exact thing when my passenger side rear wheel drops down while the rest are under compression

 

[PWillette]

Hi everyone,

I’ve been chasing a clank noise in the rear of my Bronco for quite some time, and after multiple workshops and many replaced parts, the sound is still there. I’m hoping someone here may have experienced something similar or can point me toward something I may have missed.

Vehicle

2023 Ford Bronco 4-Door Wildtrak Sasquatch
ICON suspension setup (Stage 4 kit with additional ICON arms – effectively Stage 7 geometry)

Description of the Noise

The sound is a single clank / knock that occurs during suspension flex.

Examples when it happens:
• When the vehicle articulates during flex
• When one side of the rear suspension is compressed more than the other


Important detail:

Sometimes if I flex the same side twice, the noise does not repeat the second time. If I flex the opposite side, it may happen again.

I can feel the impact through the floor under my feet, which makes it seem like the sound comes from the center of the vehicle, although mechanics believe it originates somewhere in the rear.

What It Feels Like

It feels like something shifts under load and then settles suddenly, creating a clank.

During hard acceleration in sand, it has occasionally felt like the rear drivetrain loads and releases suddenly.

Parts and Components Already Checked / Replaced

Rear suspension:
• Rear shocks replaced
• Rear springs replaced
• Track bar replaced
• Control arm bolts inspected multiple times
• Bushings inspected

Braking:
• Rear brake calipers replaced

Drivetrain:
• Rear differential opened and inspected internally
• No obvious internal damage found

Inspection:
• Multiple workshops inspected the vehicle
• Suspension components checked for looseness
• Mounting bolts checked and retorqued
• Alignment performed

None of these solved the problem.

Additional Finding

During one alignment check, the shop noticed the driver-side rear differential housing had a small bend, which was corrected.

However, the clank remained after the repair.

Other Observations
• Noise is not constant
• Happens only during articulation or heavy suspension load
• Sometimes does not repeat immediately

What Has Been Ruled Out (so far)

Based on parts swapping and inspections:
• Rear shocks
• Rear springs
• Track bar
• Brake calipers
• Obvious differential damage
• Loose suspension bolts

Current Suspicions

At this point the remaining suspects may be:
• Rear driveshaft slip joint binding
• Control arm sleeve shifting under load
• Axle housing / bracket movement during articulation
• Something internal to the drivetrain that only appears under flex

Question

Has anyone experienced a similar clank that only appears during articulation or heavy suspension load?

If so:
• What ended up being the cause?
• Are there known Bronco issues that produce this behavior?

Any ideas or tests I should try would be greatly appreciated.

Thanks in advance.

I'm not familiar with the Icon Stage 4 kit...how much lift is there? I'm just spit balling...if the lift is substantial, say 3" or more, and you don't have a trac bar relocation bracket it could possibly shift the axle enough during flex to maybe make the coils groan/pop/clank

 

[JP2]

Maybe a cracked top hat on the shock?

 

[bronco504a]

I'm not familiar with the Icon Stage 4 kit...how much lift is there? I'm just spit balling...if the lift is substantial, say 3" or more, and you don't have a trac bar relocation bracket it could possibly shift the axle enough during flex to maybe make the coils groan/pop/clank

The lift is adjustable, i did not lift it a lot maybe 1.5-2” maximum above the normal OEM SAS lift. I did not install a relocation bracket

Maybe a cracked top hat on the shock?

i have changed the shock and installed another one that was on my friend car, sadly same case..

 

[Brian_B]

Sorry still can't comprehend. That's just not something that's normally possible. Any pics?

I can't really figure it out either. I guess you could have a cocked axle tube, slight enough that the axle spines don't get destroyed.

I have no idea what it is definitively. My guess would be normal frame flex but that's causing something to pop out, which could be anywhere.

 

[GI_Jo_Nathan]

I can't really figure it out either. I guess you could have a cocked axle tube, slight enough that the axle spines don't get destroyed.

I have no idea what it is definitively. My guess would be normal frame flex but that's causing something to pop out, which could be anywhere.

That's pretty much my best guess as well. But honestly fixing an axle housing with a cast iron Center section seems like a bit of a liability to me. Total replacement I feels like it makes the most sense.

 

[SierraBronco]

That's pretty much my best guess as well. But honestly fixing an axle housing with a cast iron Center section seems like a bit of a liability to me. Total replacement I feels like it makes the most sense.

This is that opportunity for a D60 that the OP needs

 

[Brian_B]

This is that opportunity for a D60 that the OP needs

Definitely would fix that noise.

Sponsored