Mustang 2 A Arms
Mustang 2 A-arms—engineered as upper and lower control arms for the legendary Ford Mustang II Independent Front Suspension (IFS)—form the foundational steering and suspension architecture of the modern street rod, classic truck, and custom hot rod building industries. Originally introduced on the modest 1974-1978 Ford Mustang II, this compact double-wishbone suspension design revolutionized the automotive aftermarket because its self-contained crossmember eliminated bulky shock towers, freeing up massive engine bay space for big-block V8 and modern LS/Coyote engine swaps. Upgrading from flimsy factory stamped-sheetmetal A-arms to modern mandrel-bent tubular A-arms delivers vastly superior torsional rigidity, incorporates built-in anti-dive geometry, improves caster and camber adjustability, and accommodates high-performance adjustable coilovers or air-ride suspension bags.
Factory Stamped Steel vs Tubular Chromoly A-Arms
When vintage hot rodders first adapted original 1970s Mustang II front clips into 1932 Fords or 1950s Chevy pickups, they utilized factory OEM stamped-steel control arms. The original factory lower A-arms were notorious for flex: they utilized a two-piece design consisting of a stamped lower arm paired with a separate diagonal forward strut rod bolted to the front frame horn to locate the wheel fore-and-aft. Over time, rubber strut rod bushings deteriorated, causing erratic caster deflection, brake pull, and loose steering wander at highway speeds.
Modern aftermarket Mustang 2 A-arms (manufactured by leaders like Heidts, TCI Engineering, CPP, and Speedway Motors) eliminate the troublesome strut rod entirely. Fabricated from thick-wall 1.125-inch to 1.250-inch DOM (Drawn Over Mandrel) tubular mild steel or 4130 chromoly tubing, modern tubular lower control arms feature a rigid fully triangulated, one-piece 'A' design with welded gusset plates. This eliminates brake-induced wheel deflection, ensuring laser-precise alignment stability under violent cornering and heavy braking.
The engineering comparison table below contrasts original factory Mustang II A-arms against modern aftermarket tubular control arms.
| Design & Engineering Feature | Original 1974-78 Factory Mustang II | Standard Aftermarket Tubular A-Arms | Pro-Touring Chromoly Tubular Arms |
|---|---|---|---|
| Lower Arm Architecture | Two-piece stamped steel with strut rod | One-piece triangulated tubular steel | Heavy-wall 4130 chromoly with gussets |
| Upper Arm Construction | Stamped sheetmetal with T-bolt cross-shaft | Tubular DOM steel with billet cross-shaft | CAD-designed tubular with stainless rod ends |
| Bushing Material | Soft vulcanized OEM rubber bushings | Polyurethane or Delrin low-friction | Self-lubricating Delrin / Spherical bearings |
| Caster Adjustment Capability | Limited (+1 to +2 degrees maximum) | Enhanced (+3 to +5 degrees built-in) | Wide range (+5 to +7 degrees pro-touring) |
| Spring / Damper Compatibility | Stock coil springs & shocks only | Coil spring, coilover, or air bag options | Integrated threaded coilover lower mount |
| Torsional Rigidity | High flex under hard cornering/braking | Rigid; zero flex under street load | Ultimate stiffness for track & autocross |
Tubular A-arms featuring built-in positive caster (3 to 5 degrees) provide modern high-speed straight-line stability, preventing vintage hot rods from wandering on interstate highways.
Spring Configurations: Conventional Coils vs Coilovers and Air Bags
When ordering Mustang 2 A-arms for a custom build, selecting the correct lower control arm pocket style is crucial. Lower tubular arms are engineered in three distinct configurations: Conventional Coil Spring, Coilover, and Air Spring (Pneumatic Air Ride). Conventional coil spring arms incorporate a deep stamped-steel spring pocket designed to seat standard 5.5-inch diameter coil springs with an internal shock absorber mounting to a bottom cross-bracket.
Coilover-specific tubular lower A-arms feature a reinforced, flat steel plate cross-member with dual-shear through-bolt mounting tabs. This allows high-performance adjustable coilovers (from QA1, Aldan American, or Ridetech) to bolt directly into the arm, enabling builders to dial in ride height and valving stiffness with a spanner wrench. Upper control arms must also be checked for narrow versus standard width: standard arms fit 56-inch track width street rods, while narrowed upper arms (5/8-inch shorter) provide fender lip clearance on slammed vehicles running wide front wheels.
The suspension spring compatibility guide below outlines lower A-arm pocket requirements across build configurations.
| Suspension Spring Style | Required Lower A-Arm Pocket | Shock Mounting Mechanism | Ride Height Adjustability | Best Vehicle Application |
|---|---|---|---|---|
| Conventional Coil Springs | Deep recessed round coil cup | Standard stud-top / T-bar shock | Fixed ride height (Cut springs to lower) | Budget-friendly classic cruiser builds |
| Adjustable Coilovers | Reinforced flat plate with dual-shear tabs | Eyelet shock bolt with grade-8 hardware | 100% Adjustable via threaded collar | Pro-touring, performance street, modern stance |
| Pneumatic Air Bags | Flat round air spring mounting plate | Relocated external shock bracket | Instant air compressor height control | Slammed show trucks, lead sleds, lowriders |
| Narrowed Tubular Arms | Shortened upper arm (5/8" narrower) | Standard coilover mount | Improves wheel-to-fender lip clearance | Vehicles with deep-dish custom front wheels |
Always grease polyurethane A-arm bushings with synthetic waterproof marine grease during assembly to prevent annoying suspension squeaks over bumps.
How to Install and Align Mustang 2 Tubular A-Arms in 4 Steps
Follow this chassis fabrication guide to install tubular control arms onto an aftermarket crossmember.
Bolt Upper Control Arm Cross-Shaft to Frame Tabs
Mount the upper cross-shaft to the frame crossmember towers using 1/2-inch Grade-8 bolts and alignment shims.
Install Lower Tubular A-Arm into Crossmember Pockets
Insert the lower arm pivot bushings into the frame crossmember tabs; torque the pivot through-bolts to 75-80 ft-lbs.
Connect Upper and Lower Screw-In Ball Joints to Spindle
Install standard K772 screw-in upper ball joints and K719 lower ball joints; seat into the 2-inch drop spindle and torque castle nuts.
Set Baseline Alignment Specs (Camber, Caster, and Toe)
Adjust shims on upper cross-shaft: set caster to +3 to +4 degrees positive, camber to -0.5 degrees negative, and toe to 1/16" in.
Frequently Asked Questions (7 Questions Answered)
Q1: Why are Mustang 2 front ends so popular on hot rods?
The Mustang II IFS is compact, eliminates bulky shock towers, provides rack-and-pinion steering, and creates massive engine bay clearance for V8 swaps.
Q2: What is the difference between stock and tubular Mustang 2 A-arms?
Stock arms use flexible stamped steel with a troublesome strut rod; tubular arms use rigid welded DOM steel in a one-piece design with built-in positive caster.
Q3: What ball joints do Mustang 2 tubular A-arms use?
Most aftermarket arms use Chrysler-style screw-in ball joints: Moog K772 for the upper arm and large press-in or screw-in Moog K719 for the lower arm.
Q4: Can I use coilovers with standard Mustang 2 A-arms?
Only if the lower arm has a reinforced flat coilover mounting plate; mounting a coilover in a deep, unreinforced stock coil cup can tear the metal under stress.
Q5: What are narrowed Mustang 2 A-arms used for?
Narrowed upper arms are 5/8-inch shorter than stock, tucking the top of the tire inward to prevent wide front wheels from rubbing outer fender lips.
Q6: How much positive caster should a Mustang 2 front end have?
Modern street rods drive best with +3 to +5 degrees of positive caster, which provides high-speed straight-line highway tracking without wandering.
Q7: Do tubular Mustang 2 control arms squeak?
Polyurethane bushings can squeak if assembled dry; using specialized synthetic PTFE silicone or marine grease during installation keeps them completely quiet.
Final Thoughts & Key Takeaways
In conclusion, understanding mustang 2 a arms provides essential clarity, practical strategies, and actionable advice. By incorporating these foundational insights, adhering to verified safety guidelines, and following structured best practices, you ensure reliable, long-term outcomes while preventing common mistakes. Stay informed, consult certified professionals when needed, and maintain consistent quality care.