Popping/Snapping noise under rear seat

Discussion in '2011+ Mustang GT 5.0L Tech' started by Riptide, Nov 18, 2018.

  1. Riptide

    Riptide Will work for Mustang.

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    Linking a video. The noise is produced during throttle inputs or braking. Forward and backward movement of the car. It is bad, and does it constantly. It will do it infrequently over sharp bumps. The issue has been there for a while and gotten worse over time.

    Car has a BMR adjustable UCA + mount. Stock shocks and LCA. Torque is to spec on the mount. Jam nuts on the UCA haven't moved based on visual inspection against a photo taken at time of install. I went over most of what I could get at easily with the seat cushion out. Car also has a DSS aluminum drive shaft.

    This is maddening. I hope it isn't an issue with the sheet metal. Anyone here have a noise like this before?

     
  2. Gabe

    Gabe Whippled Coyote

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    I'd start by checking the tightness of every bolt/nut related to the upper control arm and its mount
     
  3. Riptide

    Riptide Will work for Mustang.

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    The mount should be good. The arm is a pita to check since I can't fit a socket on the end attaching the arm to the mount. Most likely, I will probably end up putting the stock parts back in.

    I am concerned that it is the cv joint in the DSS shaft causing this noise. Swapping that out isn't rocket science but is a pita without all my tools some of which are back in MT right now. I may end up paying ford 125$ to swap it out with the stock part if putting the oem arm and mount back in don't help.

    Not real happy about this situation but is what it is. When you mod cars, sometimes you're gonna have a bad day.
     
  4. 07gts197

    07gts197 forum member

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    To me it sounds more like something hitting the floor pan than the drive shaft. I agree with gabe its probably something loose like uca or its mount.
     
  5. Riptide

    Riptide Will work for Mustang.

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    I dug out the stock mount and arm today. The oem arm and mount are stuck together good. They have a couple green lines on there too which are nearly lined up and makes me think I never did take the two apart after removing from the car.

    I'm planning to get the rear axle on jack stands tomorrow. If I don't find anything obviously causing the issue then out comes the bmr stuff and back in goes the oem.

    DSS told me pinion angle being off could cause the cv joint to bind up. This seemed funny to me since I thought that was part of the reason people bought those things? To avoid having to screw with the pinion angle? Regardless, I doubt anything is going to be obviously loose when I examine it closer. Guess we'll see.
     
  6. Pentalab

    Pentalab forum member

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    Check the big oem rubber bushing at axle end of the UCA. It could easily be trashed, the result being the entire UCA flopping about.

    I have the BMR adjustable poly UCA and mating BMR UCA mount.... + a DSS- DS. Everything is quiet.
    This is on a 2010 auto. BMR fixed length LCA's, poly at both ends, boxed type, 1.25" wide x 2" tall square tubing. + BMR LCA relocate brackets with middle holes used. BMR adjustable PHB was replaced with a whiteline watts link. Eaton tru trac installed. It's all quiet.

    Your's sound like the UCA mount is fubar / loose... or the wrong bolt used at front end of UCA. The problem with the 05-10 cars is... the gas tank has to be dropped to get at the UCA..pita.
     
  7. Gabe

    Gabe Whippled Coyote

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    I didn't have to drop the tank to replace the UCA in my wife's '08 Shelby ... I lowered the mount and it allowed me to remove/re-install that forward bolt.

    This noise kinda sounds like you said that it might be from the wrong size bolt being used in that forward location of the UCA.
    If it's too thin it would allow some back-and-forth movement which would cause a noise.
     
  8. Riptide

    Riptide Will work for Mustang.

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    The bolt is correct. It is the one that came with the arm from BMR. I followed the instructions and did not re-use the bolt holding the arm to the mount. As far as the differential end, I will examine it tomorrow. It would be unusual for that to have an issue since the car has barely 15K on it and relatively light drag strip use on a stock stall.

    If I start the job to swap the oem parts in, and something is broken, then it may become apparent once it is removed from the car. However it might take a load on the part to produce this noise and me pulling as hard as I can on things probably isn't going to point to anything. Though it will be attempted lol
     
  9. Riptide

    Riptide Will work for Mustang.

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    I installed the stock arm and mount. The issue has been solved now.

    I didn't check the torque spec on the fasteners before I removed the bmr mount and arm. It took effort to back the fasteners off so they were not, by feel, loose. The jam nuts did not move and are not obviously loose.

    I'm going to email bmr and see if I can ship the arm and the mount over for inspection as one unit. I did not disconnect them from each other. Maybe they can find something up with it because I sure couldn't.