MacPherson strut

The simplest front end: a strut (spring + damper in one) does double duty as the upper locating member, plus a lower control arm and (if steered) a tie rod. There is no upper arm — the strut locates the top of the hub. This is the locked, verified reference setup.

Parts → roles

Shock (FL_Spring) fields: Tophat = FL_Tophat · Tophat Rotates = ON (the top mesh is the shaft) · Lower Mount = FL_Shock_low · Body Bone = FL_StrutBody · Body Anchored At Tophat = ON · Spring Bone = FL_Spring.

Hierarchy

FL  (corner node)
├── FL_Hub                Hub · SteerCamber
│   ├── FL_LowerArm_end   (no component — lower-arm target)
│   ├── FL_Steer_end      (no component — tie-rod target)
│   └── FL_Shock_low      (no component — Shock Lower Mount, ON the kingpin axis)
├── FL_LowerArm           Arm → FL_LowerArm_end
├── FL_TieRod             Arm → FL_Steer_end
├── FL_Tophat             (Shock Tophat — fixed on the body)
├── FL_Spring             Shock
└── FL_StrutBody          (Shock Body Bone — the strut tube)

Why it’s set up this way

• No upper arm — the strut is the upper locating member, so only the spring/strut + lower arm + tie rod exist.
• The strut rotates with the hub (kingpin) and locks its bottom to FL_Shock_low — put that marker where the strut bolts to the knuckle, on the line from the Tophat to the lower ball joint.
• Tophat Rotates is on because the tophat mesh is the shaft/rod — it stays pinned at the top mount but tilts down the strut line.

Type gotchas

• The strut tube is the Shock’s Body Bone, not RidesWithHub — RidesWithHub would swing its top off the fixed tophat.
• Keep FL_Tophat on the body side (not under the hub).
• Tie rod telescopes so its end stays on the steering arm through lock + travel.

Mirror to FR (Scale X = −1, rename FL_→FR_, set Corner = FR on every component). The rear of a MacPherson car is usually a different type — see multilink or trailing-arm.