Technical Ducato 2015 - clonk/bank under heavy braking

[xj25vm]

Hi everyone. My Ducato 2015 l3H2 has developed in the last few days a bang when braking heavily. If I slam quite heavily on the brakes, towards the end of the braking, after the van has mostly slowed down, I hear a loud clonk/bang towards the front. I can even feel it through the floor of the cab like some metal is hitting something. Almost like some part is under torque and suddenly gets released. If I am travelling at higher speeds, I might even get to hear 3 bangs in quick succession instead of 1, but never more than 3. I've had a quick look underneath and I didn't spot anything immediately obvious - not that something isn't wrong. If I brake gently, there is no strange noise. Any thoughts on what the likely culprit might be or what I should check next?

 

[bugsymike]

Assuming it is not just the ABS which you may feel under your foot on the brake pedal when on a loose surface, I would check under vehicle on a ramp preferrably for any signs of rust marks around bolts etc. where a bolt isn't pinching a bush securely, such as wishbone inner mounts, brake caliper or carrier bolts or antiroll bar bushes etc. as a starting point.
Can you pinpoint it to one side?

 

[porta]

Mine started doing that, and then the exhaust fell off…looked like it had been stress fracturing for a while. The garage, who I trust with commercials/campers etc traced the excessive movement to gearbox mounting

 

[xj25vm]

Assuming it is not just the ABS which you may feel under your foot on the brake pedal when on a loose surface, I would check under vehicle on a ramp preferrably for any signs of rust marks around bolts etc. where a bolt isn't pinching a bush securely, such as wishbone inner mounts, brake caliper or carrier bolts or antiroll bar bushes etc. as a starting point.
Can you pinpoint it to one side?

I don't think it is the ABS - as I'm familiar with the grinding feel of the ABS, and it does it even with ASR off - which I believe turns the ABS off. Thank you for the suggested bolts to check - I will get underneath and have a good look. The clonk seems to be towards the driver's/right side - as I almost feel like it's hitting something under me when I'm breaking.

Mine started doing that, and then the exhaust fell off…looked like it had been stress fracturing for a while. The garage, who I trust with commercials/campers etc traced the excessive movement to gearbox mounting

That is interesting. An engine or exhaust mount would make some sense. Another thing to check. Thank you!

 

[porta]

If you’re in the Leeds/Bradford area then try Walsh Motors in Yeadon, not cheap but fair, knowledgeable and can take any class of vehicles

 

[camionpilot]

Engine or gearbox mount .

 

[xj25vm]

I've had a good look underneath and I can see a big split in the driver side lower suspension arm rear bushing. Could this be causing the clonks under breaking - or could it be just a coincidence?