Project Grey Mustang 5.0: Part 7 – Testing BMR Suspension’s Rear Control Arms


Installation of the spherical bearing side of the rod required gently tapping it in with a small hammer.  BMR builds these parts to very exact tolerances, because that helps cut down on NVH.  After installing the panhard rod and brace, we re-centered the rear axle by measuring both sides using a plumb bob and a ruler to make them even.  I applied blue thread locker to the jam nuts to help keep them from backing out.


Here’s the axle side installed.  BMR places all of their adjusting hardware on one side to make track-side adjustments that much easier.
By “plumb bob” I mean “O2 sensor bung and string.”

We next moved onto the lower control arms and brackets.  BMR’s lower control arms are similar to their panhard rod in that they also have a combination of polyurethane bushings on the chassis side and Heim joints on the axle side.  BMR also sent their relocation brackets, which feature 3 holes instead of 1 to fine-tune both anti-squat geometry and roll steer characteristics.  (For a discussion of roll steer as it applies to solid-axle cars like Project Mustang 5.0, click here.


BMR’s control arm relocation brackets are beautifully constructed and 100% bolt-in.

After uninstalling the original control arms, which are held in by two large bolts on each side, BMR’s adjustable brackets bolt to the axle where the stock control arms were.  Those “fingers” on the rears of the brackets reach up and hold the bracket in place, keeping it from slipping and ensuring the thrust angle of the rear axle stays at 0°.


Here’s that lower control arm again.  Whereas the stock control arm is puny stamped steel, the BMR piece is tubular 4130 Chromoly steel.  It features the same polyurethane bushing and Heim joint as the panhard rod.

After installing and torquing the brackets, the next step is to adjust the lower control arms.  These are adjustable for the ability to change the thrust angle (useful if the car’s torque boxes or axle are slightly out of spec), the wheelbase, or the pinion angle.  Because we don’t want to do any of those, we set them to the stock length using the stock arms and two bolts as a “jig.”


This is the easiest way to get both control arms the same length.  It also allows you to put your foot on the lower arm to get the jam nuts good and tight (after applying thread locker, of course).

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