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Front Suspension Noise

Ok Brain Trust... got an issue.

Setup: 2013 Boss LS with Koni struts, Steeda HD CC Plates, Steeda Boss Springs

Issue: When driving over potholes or speed bumps (unless I go very slow) I hear a "clank" and can feel it through the gas pedal.

Diagnostics: I have check all bolts that are touched by a spring change and have torqued them to at least Ford spec. This includes Strut to spindle, Top Strut Nut (the PITA nut), End Link (top and bottom), 4 Strut Mount nuts.

The noise will get progressively worse while driving after I torque everything. If I disconnect one end link (i.e. the link to strut bolt on the passenger side) the noise goes away.

Adjusting caster and camber don't seem to have an affect on the noise.

When I mount the Steeda HD CC Plate on the strut with the Boss spring there is a gap between the top and lower halves of the CC plate. Once the strut is in the car and the weight of the car is on it the gap disappears.

I just received new strut to spindle bolts/nuts and will replace this this weekend.


Grant 302

basic and well known psychic
Sounds like an issue in the plate or top mount. Too much clearance there.

Having the sway disconnected keeps the system from unloading the strut very quickly. So the symptom goes away.
I had the noise happen a little while after I changed springs and reused the strut mounts. Going to the Steeda mounts didn't make a difference.

Should I try new mounts to see if that fixes it? If so, what would you recommend for 2011+ struts with the recessed nut.


Because racecar.
Arizona, USA
Check out your sway bar mounting brackets where the front of the bar mounts to the radiator support. If you're on OEM mounts it's likely that one of these have failed.

When mine failed, it sounded like a "thud/popping" that could be felt in the floorpan of the car/pedal box when going over bumps or transitioning on steep inclines.

Grant 302

basic and well known psychic
Jabooh1 said:
I had the noise happen a little while after I changed springs and reused the strut mounts. Going to the Steeda mounts didn't make a difference.

Should I try new mounts to see if that fixes it? If so, what would you recommend for 2011+ struts with the recessed nut.

If the noise was present with either mount, then I'd look to the swaybar connections like Drew suggests.

The Steeda HD doesn't re-use any of the OEM mount parts, correct?

Grant 302

basic and well known psychic
^ Then there shouldn't be an issue in the top assembly. Look at the sway bar connections.

Jabooh1 said:
Silly question but how do I visually know it failed?

Broken strap or crumbling rubber. The frame mount makes sense for the described floor/gas pedal noise.

302 Hi Pro

Boss 302 - Racing Legend to Modern Muscle Car

If none of the above works, there is a TSB that describes your symptoms very closely. I had this completed on my Boss as I had this noise over speed bumps at parking lot speeds. They replaced the front LCA's that included the Hydro-Bushing at the rear of the front LCA.

Just a thought, but check out the Mustang TSB library on They have a nice library of these publications.

Good luck,
302 Hi Pro
Do you notice if the noise occurs more or less while the car is cool and hot? Like mentioned above, it could be the Hydro bushing TSB issue. My 2013 made a similar noise at about 5K miles and the FLCA's were replaced under the TSB. The issue was related to the fluid in the Hydro bushing heating up too much due to its close proximity to the headers at which point the clunking would commence in a similar fashion yours is.

The only problem with getting a replacement via TSB may be your mentioning of already having a modified suspension. Mine was still stock at the time so I had no issues getting the replacements.

Take a peek under the car and see if you notice if your Hydro bushing has a heat shield wrapped around the top of it or not. If not, its worth a shot to ask the dealer about the TSB work anyway. This is of course assuming the other recommendations earlier in the thread check out OK but the noise still exists.

FWIW...Here is a shot of the "new" revised FLCA installed during the TSB work. Notice the shield.

I have thunking more like a dull rattle when I go over small sharp bumps with my cortex maxium front coils. The noise didn't exist with my old Eibach struts.. however it could be the control arms I know they did a lot of work fixing that - I thought it was more of a grunting squawk noise though.

check the sway links, check the d-brackets, rubber is probably fine.

try jacking up the car and putting a stand under the frame. then pull off the wheel and place the jack under the caliper.. jack it up a little while putting your hand on different places you think might be clunking (top mount area, sway bar mounts, sway links, lower control arm areas including font and back bushings, wheel bearings, etc.. should pin point it.

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