AP9engineering

This part started as a problem on my own car.

Original rear hatch trims for the Saab 900 Classic are almost always warped or shrunken — so I developed a proper reproduction to OEM standards.

After testing and installing it myself, I decided to produce a small run.

Saab 900 Classic Hatchback – 3 & 5 door

Available now.
DM for info.

Recreating Saab 900 Carlsson Wheel Arches – A Different Approach

One of the biggest challenges of keeping an older car on the road is finding quality replacement parts, especially when originals are no longer available. That was the case with the wheel arches for my Saab. While there are some great aftermarket options out there that provide affordable solutions, I wanted to take a different approach—one focused on achieving the highest possible accuracy and durability that I can.

The aftermarket wheel arches I previously used were made of polyester resin and fiberglass, which is a common material choice for small-scale production. While it works for many applications, it does have limitations, such as shrinkage, brittleness, and reduced weather resistance. On my car, cracks and blisters developed not long after painting and installation. Instead of trying another set, I eagerly wanted to engineer my own solution.

Finally, just recently, I was able to source brand-new original wheel arches, which allowed me to create precise molds. Using high-heat epoxy and carbon fiber I did just that. From there, I used prepreg carbon fiber and the correct processing methods to recreate these parts with OEM-level accuracy. In addition to the overall shape and curvature even the original part numbers are embedded, and the surface finish is just like the factory parts even though I realise the parts will eventually be sanded and painted over. Still, thanks to the choice of materials and process, these arches maintain their exact shape and exceed OEM durability—handling even extreme temperatures up to 120°C without issue.

For me, these small projects are never just about making replacement parts but also about pushing quality and precision as far as I can.

You know it’s time for an upgrade when your suspension parts look like they belong in an archaeological dig. Since the original control arm bearing anchorages are extinct (or just hopelessly corroded), I've stepped in and started to design brand-new CNC-milled reinforced replacements.

Why? Because with the beefed-up braking system, I need a chassis that won’t fold like a lawn chair under pressure.
Braking hard shouldn’t feel like rolling the dice on whether your suspension holds up. So, I'm making sure everything stays exactly where it should—no surprises, no sudden disassembly. 💪⚙️

Recently created this short video of the process of making the caliper cooling ducts. If anyone is interested in seeing what has gone into making such a part then feel free to take a look.

Making carbon fiber brake cooling ducts Sharing some insight what goes into making rally inspired carbon brake cooling ducts for a restomod project.

Half way update for the front rotor cooling. The new caliper adapter arrived from manufacturing recently and as I 3d printed the duct models in advance I was able to work on making the moulds as well as one of the parts in carbon. Now it was just bolting them on and obviously they fit perfectly just like they do in cad.
This small carbon part here is just half of the rotor cooling duct. The second half will come to life very shortly as well and then I have completed all the hardware for the front brakes. Apart from brake lines and the ducting hoses themselves. I guess I'm not finished with this at all... But I'm getting closer.
All the carbon parts for these brakes are made with prepreg carbon in an autoclave.

I've been designing this brake setup for quite some time now. And things change along the way. A good example here is the brake caliper bracket which I was happy with until I realised that there is not much room in this area to accommodate the disc cooling duct and the best place for it is next to the caliper cooling duct. So eventually a new bracket needed to be designed that in a way integrates the disc cooling ducts which guide air directly to the center of the rotor.
While I wait for this new bracket to be machined I can work on the ducts and create stiff and lightweight carbon versions of those. On the table are MJF printed PA12 Nylon versions which is my go to plastic printing solution due to it's good surface finish and more accurate features.

After this the front brakes should largely be finished. Next I'll dive into creating new brake lines throughout the car while also creating some brackets and routings for the air hoses themselves.

Lowering springs are cool! But it’s also more work to the bump stops as you increase the likeliness of bottoming out. Which is also cool at Eau Rouge Spa, but maybe not as much anywhere else. Luckily I like solving problems and not having these parts available did not stop me completing the new suspension setup with all new parts by making these spring seats and bump stops myself.

The same but different. When I started the renovation of my Saab I knew I wanted to do something different with the wheels and update the brakes. Things kept escalating and I ended up here. Custom 17inch wheel from who were very kind and helpful making the changes I requested. Brake calipers and disc from Alcon with some of my own designed cnc hardware and of course some carbon fiber parts which is my personal passion.

I'm planning to restock the Saab C900 spring bushings. For best price and availability I'm opening up a preorder so that everyone can get a complete set of 8 or any other number of specific bushings.

Let me know of your interest by sending me an email to [email protected]

Caliper cooling duct for the Saab front brake setup finally a physical object. Turned out exactly as expected thanks to the use of CAD and 3d printing during the development process. The purpose of this part is to direct fresh air to the pistons and pads and help keeping the brake fluid temp in check. The observant probably notices that the next step is figuring out the disc cooling.

Front brakes are starting to take shape. Disc and caliper cooling are the next milestones in this “Saab 900 brakes” subproject that keeps on escalating…