The best metric chassis tubular upper control arms optimize strength, weight, and serviceability for GM G-Body and other metric frame cars. This guide highlights five strong options, explaining who each product suits, what makes it stand out, and any limitations to consider. Each arm is designed to bolt to factory metric frame mounts and accommodate common ball joints. Whether you race IMCA cars or run a mid-size stock chassis, these arms balance durability with straightforward installation.
| Product | Best For | |
|---|---|---|
| Speedway Motors IMCA Spec Left Upper Control Arm | IMCA Stock Car racers needing a left-arm, metric fit | Lightweight tubular steel with reinforced attachment |
| Speedway Motors IMCA Stock Car Metric Upper Control Arm Kit | Track-day garages valuing complete hardware | Factory-style installation with included mounting hardware |
| Speedway Motors IMCA Spec Stock Car Upper Control Arm Kit | IMCA class racers needing a chromoly alternative | Chromoly construction with aluminum cross shaft |
| Speedway Motors Metric Chassis Left Upper Control Arm | Mid-size GM metric chassis enthusiasts | 8.5 inch length with tubular chromoly design |
| Speedway Motors Right Hand 8 Inch Upper Control Arm | Right-side replacement for metric GM chassis | Greaseable bushings and durable steel cross shaft |
Speedway Motors IMCA Spec Left Upper Control Arm
Best for: IMCA Stock Car teams needing a left-side metric upper control arm. This tubular steel arm uses 1″ OD tubing with a .092″ wall and includes a 1/4″ thick steel mounting plate for ball joints. It fits 1978-87 GM metric frame mounts with 6-7/8″ center-to-center spacing and relocates stock brackets for easier installation. The design emphasizes durability without adding excessive weight, making it a solid choice for moderate-to-high track demands.
Why selected: The combination of tubular steel construction and a steel cross shaft yields robust strength for repeated cornering and threshold loading. Its metric fit ensures compatibility with common G-Body track cars. The included mounting plate helps secure a reliable ball joint interface.
Limitation: Installation depends on precise frame geometry; verify your 6-7/8″ mounting spacing and existing bracket compatibility before purchase. Some teams may require additional hardware if converting non-standard mounts.
Speedway Motors IMCA Stock Car Metric Upper Control Arm Kit
Best for: Track-day cars needing a complete metric upper control arm kit with cross shaft and installation hardware. The kit uses 1″ OD, .092″ wall tubing and a robust steel cross shaft, offering improved strength over OEM stamped arms. It bolts to stock 1978–1987 GM G-Body frame mounts (6-7/8″ spacing) for a factory-style install.
Why selected: It provides a full hardware package, reducing sourcing friction for teams. The direct metric fit helps ensure proper alignment and handling consistency for IMCA or street-to-track transitions.
Caution: While complete, confirm the cross shaft length and mounting hardware compatibility with your precise frame and ball joint type to avoid fitment issues during assembly.
Speedway Motors Metric Chassis Left Upper Control Arm
Best for: GM mid-size metric chassis enthusiasts seeking a tubular chromoly upper control arm with a steel cross shaft. The 8.5 inch length is suitable for staggered control arm setups common on 1978-87 GM midsize stock cars. The chromoly construction enhances resistance to bending and fatigue in competition settings.
Why selected: Chromoly offers a favorable strength-to-weight ratio, improving suspension response, especially under high-load cornering. The 8.5″ length aligns with typical metric arm geometries for better bump steer control.
Limitation: Chromoly parts can be more demanding to weld or modify if you plan custom spacing; ensure compatibility with your frame contours and mounting brackets before attempting modification.
Speedway Motors Right Hand 8 Inch Upper Control Arm
Best for: Right-hand side replacement on GM metric chassis with a need for a durable, greaseable upper control arm. This arm uses a tubular steel design with a steel cross shaft and greaseable bushings to enable smoother suspension movement over time.
Why selected: The right-hand orientation and 8-inch length fit common metric G-Body track cars, facilitating balanced cross-axial geometry when paired with a corresponding left-arm option. It is a straightforward replacement that supports reliable steering response.
Caution: Verify that your frame mounts align with 6-7/8″ center-to-center spacing, and check whether your ball joint type is compatible with the K5208 or equivalent options for a secure mount.
Buying Guide: Metric Upper Control Arms For GM Metric Chassis
- Fitment and Geometry: Ensure the control arm matches your GM metric frame mounts (commonly 6-7/8″ center-to-center). Confirm that the arm length (8.5″ vs 8″) aligns with your existing suspension geometry to avoid bump steer and toe misalignment.
- Material and Construction: Tubular steel arms offer durability with reasonable weight; chromoly variants provide higher strength-to-weight ratios for aggressive racing. Aluminum cross shafts reduce unsprung weight but may limit mounting options if not paired with compatible bushings.
- Ball Joint Compatibility: Check whether the arm supports K5208 ball joints or equivalent. Some kits use reinforced mounting plates for ball joints; verify cross-shaft design and mounting plate thickness.
- Hardware and Installation: Kits that include castle nuts, cotter pins, grease zerks, and mounting hardware simplify installation and reduce sourcing steps. Assess whether the factory-style mounting brackets are relocatable for track-specific setups.
- Durability Under Racing Conditions: For IMCA and stock-class rules, choose arms with reinforced mounting plates and cross shafts designed to withstand repeated loading during cornering and hard braking.
- Maintenance and Service: Greaseable bushings allow easier periodic maintenance. Consider sleeves and bushings replacement availability if you maintain a budget or prefer quick maintenance cycles.
Frequently Asked Questions
- What is the advantage of tubular upper control arms over stamped arms? Tubular arms offer higher strength-to-weight ratios and improved resistance to bending, especially under track conditions that place high loads on suspension components.
- Do these arms fit 1978-87 GM metric frames? Yes, most listed options are designed for GM metric frame mounts with standard 6-7/8″ center-to-center spacing, but verify your exact frame configuration before ordering.
- Are aluminum cross shafts better than steel? Aluminum cross shafts reduce unsprung weight and can improve suspension response; however, steel cross shafts are typically stronger and more durable in heavy-duty racing environments.
- Should I buy a full kit or individual arms? A full kit with installation hardware simplifies setup and ensures compatible components, but individual arms are suitable if you already possess matching hardware or require a specific left/right pairing.
- What should I check before installation? Confirm mounting spacing, ball joint type, and compatibility with your frame brackets. Ensure the arms’ length and geometry won’t introduce excessive bump steer.
- Is it necessary to grease the bushings? Greaseable bushings facilitate maintenance and smoother operation over time, especially in competitive environments with frequent suspensions cycles.