The engine gets all the attention on air-cooled Porsches, but the suspension is what makes the car actually enjoyable to drive. And on 964s and 993s that are now 28 to 35 years old, the suspension is almost certainly not performing anywhere near its original specification — even if nothing feels obviously broken.
Rubber bushings, shock absorbers, and mounts all degrade gradually. The change is slow enough that owners adapt without realizing how much performance they have lost. Then they do a proper suspension refresh and wonder how they drove the car in its previous state for so long.
Why 30-Year-Old Bushings Need Replacement
Every suspension bushing in the 964 and 993 is made of rubber or rubber-bonded-to-metal. Rubber has a finite lifespan, and that lifespan is accelerated by:
- Heat cycling: Engine heat, exhaust heat, and brake heat all affect nearby bushings
- UV exposure: Even under the car, reflected UV breaks down rubber compounds
- Ozone: Ambient ozone causes rubber to crack and harden
- Mechanical loading: Tens of thousands of compression and shear cycles
After 25-30 years, even low-mileage bushings are compromised. The rubber hardens, cracks, and loses its ability to flex. Bonded bushings separate from their metal shells. The result is increased free play, imprecise handling, clunks over bumps, and a general vagueness to the steering and chassis response that owners mistake for the car being old.
It is not old. The bushings are old. The chassis underneath is still excellent.
What to Replace in a Complete Refresh
Control Arm Bushings
The front and rear control arms use rubber bushings at every pivot point. On the 964 and 993:
Front: Lower control arm bushings (inner and outer), upper strut mount bearings, and control arm ball joints.
Rear: Trailing arm bushings, lower control arm bushings, and toe link bushings. The rear is more complex because the semi-trailing arm design uses multiple bushings per side.
When these bushings are worn, the suspension geometry shifts under load. The car may wander on the highway, feel unstable during hard braking, or exhibit a vague, disconnected feeling in corners.
Spring Plate Bushings
The 964 and 993 rear suspension uses spring plates that sit between the torsion bars and the trailing arms. The rubber bushings in these spring plates are under constant load and are among the first components to wear out.
Symptoms of worn spring plate bushings: Clunking from the rear over bumps, uneven ride height, and a rear end that feels loose or imprecise during cornering.
Engine and Transmission Mounts
The engine and transmission are mounted to the chassis through rubber mounts that isolate vibration. When these mounts deteriorate:
- Engine vibration transfers directly to the cabin
- The engine and transmission shift position under acceleration and braking
- In extreme cases, the engine or transmission can contact chassis components
Engine mount replacement is often overlooked during suspension refreshes, but these are rubber components with the same age-related degradation as everything else.
Sway Bar End Links and Bushings
The front and rear sway bars connect to the suspension through end links and rubber bushings. Worn end links produce a distinctive clunking sound over bumps, and worn sway bar bushings reduce the bar's effectiveness at controlling body roll.
Shock Absorbers
Original Boge or Bilstein shocks on a 30-year-old 964 or 993 are well past their service life. Shock absorbers lose damping force gradually as the internal valving wears and the hydraulic fluid degrades. Like bushings, the change is gradual enough that owners do not notice until they drive a car with fresh shocks.
How to tell if your shocks are worn: The car bounces excessively over bumps, the nose dives noticeably under braking, body roll feels excessive, and the car feels floaty or disconnected at highway speeds.
OEM Rubber vs Polyurethane
This is one of the most debated topics in the Porsche community, and I have a clear position on it.
OEM Rubber
Pros: Quieter, smoother ride quality, closest to factory ride behavior, good compliance over rough surfaces.
Cons: Will wear out again in 15-20 years (though that is a long time), softer feel.
Polyurethane
Pros: Longer lifespan (potentially 25+ years), firmer response, more precise handling feel, better for track-oriented setups.
Cons: Transmits more road noise and harshness, can squeak if not properly lubricated during installation, less compliant over rough surfaces, higher NVH.
What I Recommend
For a street-driven 964 or 993, I recommend OEM rubber bushings. The ride quality and NVH characteristics are superior, and the handling is excellent when all the bushings are fresh. The car was engineered with rubber bushings, and the compliance they provide is part of what makes these cars so satisfying to drive on real roads.
For a car that sees significant track use, polyurethane in specific locations (control arm bushings, spring plates) makes sense. But I rarely recommend full polyurethane on a street car — the ride quality sacrifice is real and most owners regret it on daily drives.
Shock Absorber Options
Bilstein B6 (Sport)
The most popular upgrade for 964 and 993 owners. These are a firm street/sport shock that offers noticeably better damping than worn originals while maintaining reasonable ride quality. This is what I install most often.
Bilstein B8 (Sprint)
A step up in firmness from the B6. Better suited for cars that see regular track use or owners who want a noticeably sportier ride.
Koni
Koni offers adjustable shocks for the 964 and 993 that allow the owner to tune rebound damping. Good for owners who want flexibility, but the adjustment requires removal of the shock in most cases.
OEM (Sachs/Boge)
Factory replacement shocks are available and provide the original ride quality. A good choice for concours-oriented cars or owners who want to preserve the factory driving experience exactly.
What a Full Suspension Refresh Costs
A comprehensive suspension refresh on a 964 or 993 typically includes:
| Component | Parts Cost | Labor |
|---|---|---|
| All control arm bushings (front and rear) | $800-1,200 | Included below |
| Spring plate bushings | $200-400 | Included below |
| Engine and transmission mounts | $300-600 | Included below |
| Sway bar end links and bushings | $200-400 | Included below |
| Four shock absorbers (Bilstein B6) | $800-1,200 | Included below |
| Ball joints (as needed) | $200-400 | Included below |
| Hardware, miscellaneous | $200-400 | Included below |
| Total parts | $2,500-4,600 | |
| Labor (20-30 hours) | $3,000-5,000 | |
| Complete refresh total | $5,500-9,600 |
The range depends on the specific model, component condition, and whether OEM or aftermarket parts are used. Polyurethane bushings can reduce parts cost slightly but may increase labor if additional preparation is needed.
Alignment and Corner Balance
A suspension refresh is incomplete without a proper alignment. With all new bushings and shocks, the suspension geometry needs to be set precisely.
Alignment: Standard four-wheel alignment with toe, camber, and caster set to specification. For street driving, I use factory specifications. For cars that see track time, we can adjust camber and toe for improved turn-in and stability at speed.
Corner balancing: This is an additional step where we adjust the ride height at each corner so the car's weight is evenly distributed. This makes a meaningful difference in handling balance, especially on track. Corner balancing adds $300-500 to the total.
How the Car Transforms
The difference between a 964 or 993 with 30-year-old suspension components and one with a fresh refresh is dramatic. Owners consistently describe the same experience:
- The steering feels connected and precise instead of vague
- The car tracks straight on the highway without constant corrections
- Bumps are absorbed cleanly instead of causing clunks and shudders
- Cornering feels flat and controlled instead of wallowy
- Braking feels stable and predictable
- The overall sensation is one of tightness and precision
It feels like a new car. Because in terms of suspension performance, it is.
What Repasi's Standard Refresh Includes
Our standard 964/993 suspension refresh covers:
- All control arm bushings (front and rear)
- Spring plate bushings
- Engine and transmission mounts
- Sway bar end links and bushings
- Four shock absorbers (Bilstein B6 standard, other options available)
- Ball joints (replaced as needed based on inspection)
- All associated hardware
- Four-wheel alignment to factory specification
We also inspect items that may need attention but are not automatically included: wheel bearings, CV joints, steering rack bushings, and tie rod ends. If these items need replacement, we provide an updated estimate before proceeding.
If your 964 or 993 has never had a suspension refresh — or if it has been more than 15 years — contact us to discuss what your car needs. The transformation in driving quality is one of the best investments you can make in these cars.
For a broader overview of 964 and 993 ownership considerations, see our 964 vs 993 buyer's guide.
