Wishbone Suspension Guide
Suspension is what separates a smooth-riding vehicle from a bone-jarring mess. The double wishbone suspension is one of the most capable designs in Scrap Mechanic — offering excellent wheel travel, consistent camber, and superior handling. This guide covers suspension types, wishbone construction, tuning, and terrain-specific setups.
Suspension Type Comparison
| Type | Travel | Handling | Complexity | Best For |
|---|---|---|---|---|
| Basic Spring | Short | Poor | Low | Simple cars, early game |
| Trailing Arm | Medium | Medium | Medium | Rear suspension, trucks |
| Double Wishbone | Long | Excellent | High | Off-road, racing, performance vehicles |
| MacPherson Strut | Medium | Good | Medium | Front-wheel drive cars, compact vehicles |
| Solid Axle | Medium | Medium | Low | Heavy trucks, towing, simple design |
| Tank Suspension | Very Long | Poor on road | High | Tanks, tracked vehicles, extreme off-road |
Double Wishbone Build Steps
The double wishbone uses two parallel A-arms (upper and lower) to control wheel movement, with a spring/damper providing support. This design keeps the wheel perpendicular to the ground throughout the suspension travel.
Components Needed (per wheel)
- 2x A-arm (wishbone) structures — upper and lower (build from blocks/beams)
- 2x hinges — one at each end of each A-arm (4 total per wheel)
- 1x wheel hub / upright — connects A-arms to wheel
- 1x spring + damper (or suspension block) — provides support and damping
- 1x wheel + tire
- Steering hinge (for front wheels only)
Construction Steps
- Build the chassis mount — Create a rigid mounting point on the vehicle frame for the suspension
- Build lower A-arm — Construct a V-shaped arm, mount to chassis with two hinges at the wide end
- Build upper A-arm — Construct a shorter V-shaped arm, mount above the lower arm with two hinges
- Connect wheel hub — Attach the outer ends of both A-arms to the wheel hub/upright
- Add spring/damper — Mount between the lower A-arm and chassis (or upper arm and chassis)
- Attach wheel — Mount wheel and tire to the hub
- Add steering (front) — Connect a steering hinge between the hub and a steering actuator
- Test and adjust — Compress the suspension, check for binding, ensure full travel
Key Geometry Principles
- Parallel arms — Upper and lower A-arms should be roughly parallel for consistent camber
- Longer arms = more travel — Longer A-arms allow greater wheel movement
- Roll center — The intersection of the A-arm lines determines the roll center; affects body roll
- Camber gain — Properly designed wishbones maintain negative camber during compression for better grip
- Ackermann steering — Front wheels should toe out during turns for proper steering geometry
Parameter Tuning
Suspension tuning is the art of balancing comfort, handling, and performance. Adjust these parameters to suit your vehicle and driving style.
Spring Rate
- Soft springs — More comfort, more body roll, more travel. Good for off-road.
- Stiff springs — Better handling, less body roll, harsher ride. Good for racing.
- Weight matching — Heavier vehicles need stiffer springs to support the weight
- Front vs rear — Front springs often stiffer (engine weight); rear softer for traction
Damping
- Compression damping — Controls how fast the suspension compresses. Too soft = bottoming out; too stiff = harsh ride
- Rebound damping — Controls how fast the suspension extends. Too soft = bouncing; too stiff = wheels don't follow terrain
- Balanced setup — Slightly more rebound than compression is typical for good handling
Ride Height
- Low ride height — Better aerodynamics, lower center of gravity, less roll. Risk of bottoming out.
- High ride height — More ground clearance, better off-road. Higher center of gravity, more roll.
- Adjust via spring preload — Compress the spring slightly to raise ride height
Camber
- Negative camber — Top of wheel tilts inward. Better cornering grip. Typical for performance vehicles.
- Positive camber — Top of wheel tilts outward. Better straight-line stability. Rarely used.
- Zero camber — Wheel perpendicular. Even tire wear. Good for general purpose.
- Dynamic camber — Wishbone suspension naturally adds negative camber during compression
Toe
- Toe-in — Front of wheels point inward. Better straight-line stability. Typical for rear wheels.
- Toe-out — Front of wheels point outward. Better turn-in response. Typical for front wheels.
- Zero toe — Wheels parallel. Minimal tire wear.
Different Terrain Settings
| Terrain | Spring | Damping | Ride Height | Camber | Travel |
|---|---|---|---|---|---|
| Paved Road / Racing | Stiff | Firm | Low | Negative (-2 to -3°) | Short |
| Dirt / Gravel | Medium | Medium | Medium | Slight Negative (-1°) | Medium |
| Off-Road / Rocks | Soft | Progressive | High | Negative (-1 to -2°) | Long |
| Sand / Desert | Soft | Soft | High | Slight Negative | Long |
| Snow / Ice | Medium | Soft | Medium | Zero to Slight Negative | Medium |
| Mixed / General | Medium | Medium | Medium | Slight Negative (-1°) | Medium |
Tank Suspension
Tracked vehicles (tanks, bulldozers) use a different suspension approach — multiple road wheels on each side, often with individual springs or a torsion bar system.
- Road wheels — Multiple small wheels along each track, each with its own suspension
- Torsion bars — Long metal bars that twist to provide spring action
- Christie suspension — Large road wheels with springs, high speed capability
- Bogie suspension — Pairs of wheels on a shared bogie with a single spring
- Track tension — Adjust track tension to prevent derailing; too loose = track comes off, too tight = excessive wear
Common Problems
| Problem | Cause | Solution |
|---|---|---|
| Suspension bottoms out | Springs too soft or travel too long | Stiffen springs, add bump stops, reduce travel |
| Vehicle bounces excessively | Damping too low (rebound) | Increase rebound damping |
| Harsh, jarring ride | Damping too high (compression) or springs too stiff | Soften compression damping, use softer springs |
| Excessive body roll | Springs too soft or roll center too high | Stiffen springs, add anti-roll bar, lower roll center |
| Wheels don't follow terrain | Rebound damping too high or springs too stiff | Soften rebound, use softer springs |
| Suspension binds / sticks | A-arm geometry misaligned or hinges binding | Check A-arm parallelism, lubricate hinges, ensure free movement |
| Uneven tire wear | Incorrect camber or toe settings | Adjust camber to near-zero, set proper toe |
| Vehicle pulls to one side | Uneven suspension settings left/right | Match spring rates and damping on both sides |
Racing Car Example Setup
For a high-performance on-road racing vehicle:
- Suspension: Double wishbone, all four corners
- Springs: Stiff (front slightly stiffer than rear)
- Damping: Firm compression, firm rebound (slightly more rebound)
- Ride height: Low (as low as possible without bottoming out)
- Camber: -2.5° front, -1.5° rear
- Toe: Slight toe-out front, slight toe-in rear
- Anti-roll bar: Stiff front, medium rear (reduces understeer)
- Tires: Low-profile, wide, sticky compound
Suspension Building Tips
- Test in Creative first — Experiment with suspension geometry in Creative before committing resources in Survival
- Build one corner first — Perfect one wheel's suspension, then replicate it for the other three
- Use rigid mounting points — Flexible chassis mounts ruin suspension performance; reinforce the frame
- Ensure free movement — No blocks should interfere with suspension travel throughout the full range
- Match left and right — Identical settings on both sides for balanced handling
- Start soft, stiffen up — Begin with softer settings and gradually stiffen until you find the right balance
- Test on different terrain — A setup that works on flat ground may fail on rough terrain; test everywhere
- Document your settings — Write down spring rates, damping, and geometry so you can replicate successful setups
Related Guides
- Vehicle & Truck Building — Integrate suspension into your vehicle design
- Piston Mechanics Guide — Use pistons for adjustable suspension and ride height
- Controller & Logic Circuits — Active suspension and electronic damping control