Porsche 911 Carrera 4
A clean, well-kept 964 Carrera 4 brought in for our Full Preservation programme: dry ice cleaned, properly inspected with the wheels and liners off, then sealed with Bilt Hamber Dynax UC clear protection and cavity wax – preserved while it was already in excellent condition underneath.
Published
In short: what was done to this Carrera 4
This Porsche 911 Carrera 4 came in for a full preservation programme. Unlike projects where dry ice blasting uncovers heavy corrosion or hidden repairs, this car was already a very good example: untidy underneath with road contamination and ageing wax, but fundamentally solid. The wheels and arch liners were removed, the underside dry ice blasted (no water, no abrasive media, no residue), a few minor areas rust-converted, then the whole underbody sealed with Bilt Hamber Dynax UC clear protection and cavity wax. The engine bay was dry ice cleaned to finish, and every stage was documented for the car's history file.
Preserving a well-kept Porsche at the right time
This Carrera 4 was not a rescue project – it was a preservation project. The car had clearly been looked after, and the original amber wax had done a fantastic job of preserving the underside over the years. Rather than waiting for corrosion to become a problem, the owner chose to have it cleaned, inspected and protected while it was still in excellent condition underneath.
That is often the best time to carry out preservation work. The aim was not to bury everything under a heavy black finish, but to remove the recent contamination, expose the well-kept factory surfaces, treat the few areas that needed it, then re-protect the car with a clear coating so it can keep being enjoyed and maintained for years to come.
- Vehicle
- Porsche 911 Carrera 4 (964)
- Service
- Full preservation programme
- Protection
- Bilt Hamber Dynax UC clear coat and cavity wax
- Areas
- Underbody · Wheel arches · Suspension · Engine bay
The full preservation programme
Every vehicle follows the same programme, with the work paused for your decision whenever the condition changes the scope. On a preservation project like this, the emphasis is on careful inspection and a clean, honest finish rather than heavy coatings.
Plan & Preparation
- Bodywork wrapped and protected before any blasting began
- Wheels and wheel arch liners removed for proper access
- Underbody, arches, subframes and floorpan documented
Pre-Inspection
- Alloy suspension, subframes, gearbox casing and floorpan assessed
- Original amber wax noted as having preserved the underside well
- Split underseal, a missing rear tray and a broken fixing flagged
Dry Ice Blast
- Underbody, arches, suspension, subframes and floorpan cleaned
- No water, no abrasive media, no residue
- Gentle on alloy components and original finishes
Rust Conversion Where Needed
- Recent contamination and ageing wax lifted by the ice
- Minor staining and corrosion rust-converted and stabilised
- Only the small areas that needed it were treated
Clear Protection & Cavity Wax
- Bilt Hamber Dynax UC clear coat sealed the underside
- Original alloy and painted finishes kept visible and inspectable
- Cavity wax driven into the necessary internal areas
Engine Bay & Documentation
- Engine bay dry ice cleaned for finish and inspection
- Full before, during and after photographic record
- Condition retained for the car's history file
Untidy in places, but fundamentally solid
With the bodywork wrapped and the wheels and arch liners off, the underside was inspected properly. The alloy suspension components, rear suspension arms, subframes, gearbox casing and front sections all looked set to clean up well – the usual aged, slightly furry appearance over the alloy, with the silver finish expected to return once blasted. The floorpan looked solid, and an amber wax coating across the underside had clearly helped preserve the car rather than cause a problem.
There were a few areas to concentrate on: some underseal had started to split or lift, there was a missing rear tray linked to broken threaded floor fixings, and one fixing broke as the front arch liner was removed – not unusual on an older performance car. None were major issues, but each was documented as part of the process.
Dry ice blast the underside back, lift the ageing wax and road contamination, rust-convert the small areas that needed it, then seal the whole underbody with Bilt Hamber Dynax UC clear protection and cavity wax. The customer saw this stage too – same photos, same conversation.
Revealing how good the car already was
The Porsche was dry ice blasted across the underside, arches, suspension areas, subframes, gearbox casing, front diff area and floorpan. Dry ice was the right method because it removed road contamination, surface grime and the aged amber wax without adding water or leaving abrasive media behind – cleaning the car while preserving its original finishes and delicate alloy components.
As the contamination came away, the quality underneath became clear. This was not about turning a poor car into a presentable one; it was about revealing just how well-preserved the Carrera 4 already was.
The same components, area by area
The before-and-after pairs tell the story best – the same components, cleaned back and clear-protected. The alloy suspension arms returned to a sharp silver finish, the wheel arch and brake area cleaned up cleanly, and the underbody came back without losing any of its original character.
Full underbody
Rear wheel arch
Front lower arm
Rear lower arm
Sealed, but still visible and honest
Once the underside had been blasted, inspected and treated where required, Bilt Hamber Dynax UC clear coat was applied. It was the right finish for this Porsche because it protected the underside while keeping the clean, original appearance of the alloy components, arches, floorpan, subframes and mechanical areas. The finished underside looked sharp, clean and honest – nothing hidden under a heavy black coating, with the condition still fully inspectable.
Cavity wax was then applied in the necessary areas. This protects the hidden seams and internal sections that external coating alone cannot reach – the places where moisture can collect and corrosion can develop quietly over time, even on a very clean car.
The final outcome
After blasting, rust conversion, clear protection, cavity wax and an engine bay clean, the Carrera 4 came up beautifully. The arches were clean, the suspension arms and alloy components had returned to a sharp silver finish, the subframes and front diff area looked clean, and the floorpan had come back extremely well. A few stained areas were treated and protected, but the overall condition was excellent.
The result was a Porsche that looked dramatically different underneath without losing its original character – clean, documented and protected, and ready for long-term ownership.
Preservation is not only for rusty cars
This case study shows that underbody preservation is not only for vehicles with visible rust. For a well-kept Porsche, preservation is about staying ahead of deterioration: removing contamination before it becomes a problem, protecting the exposed surfaces and keeping a clear record of the car's condition. The best preservation work is sometimes the least dramatic – no holes, no major corrosion, no surprises, just a beautiful, well-kept Porsche cleaned, treated and protected properly.
Bilt Hamber Dynax UC protection over the underside
Water, abrasive media or residue from dry ice blasting
Amber wax removed and a well-kept underside revealed
Driven into the necessary internal areas
Dry ice cleaned for finish and inspection
Before, during and after, for the history file
Common questions about Porsche underbody preservation
What work did this Porsche Carrera 4 have done?
It went through our Full Preservation programme: the wheels and arch liners were removed, the underside was inspected and dry ice blasted, the ageing amber wax and road contamination were lifted, a few minor areas were rust-converted, then the underbody was sealed with Bilt Hamber Dynax UC clear protection and cavity wax. The engine bay was dry ice cleaned to finish, and the whole job was documented before, during and after.
Is underbody preservation worth it on a Porsche that isn't rusty?
Yes, especially when the car is already in good condition. Preservation removes road contamination, exposes the real condition of the underside and protects the areas most vulnerable to moisture, salt and grime. Staying ahead of corrosion is far easier than reversing it once it has taken hold.
Why use clear protection on a Porsche underside?
On a well-kept Porsche, clear protection keeps the original appearance visible while still sealing the metal. The alloy components, floor sections, arches and factory finishes stay inspectable rather than being hidden under a heavy black coating, which suits a car where originality matters.
Is Bilt Hamber Dynax UC suitable for Porsche underbody protection?
Bilt Hamber Dynax UC is a clear protective coating used where owners want corrosion protection without covering the original appearance. It suits visible underbody areas, alloy components and clean painted surfaces, provided the surface has been cleaned and prepared properly first.
Does dry ice blasting damage Porsche alloy suspension components?
Carried out correctly, dry ice blasting cleans alloy suspension components with no abrasive media and no water. Pressure, nozzle choice and technique are all adjusted by area, especially around delicate finishes, fixings, rubber, plastics and electrical sections.
Why remove the wheel arch liners before preserving a Porsche?
Arch liners and undertrays can hide dirt, salt, moisture, fixings and early signs of corrosion. Removing them lets the arches, suspension and body sections be cleaned, inspected and protected properly rather than guessed at from the outside.
Should a clean Porsche still have cavity wax?
Yes, where appropriate. Cavity wax protects hidden seams and internal sections that external coating alone cannot reach. Even on a very clean car, those are the places where corrosion can develop quietly, so cavity protection is worthwhile when the goal is long-term preservation.
Was the engine bay cleaned as well?
Yes. The engine bay was dry ice cleaned as part of the same programme. On this Porsche it was mainly aesthetic and inspection-led – lifting contamination and sharpening the finish so future leaks, staining or ageing components are easier to monitor.
Want to preserve your Porsche?
Tell us about your vehicle and what you want to achieve, and we'll recommend the right preservation programme with a quote to match.
Get Instant Quote