How to build a proper Porsche rally car

Three Tuthill Porsche 911 rally cars are taking part in the Baltic Classic Rally at the end of this month. All three are special 911s but, as I had this one to hand last week for a few pics and it was the cleanest it’s been for several years, I thought it would be cool to share a few details.

It used to be that when a 911 got too tired or scruffy for road use, it was broken for parts or sold to a motorsport firm and converted into some sort of race or rally car. These days, the story is different. Few people turn up to rallies in air-cooled Porsche 911s nowadays, as the cars are just so expensive. When someone does decide to compete in a Porsche 911, the cars have generally been built pretty carefully.

Tuthill Safari cars are a good example of this. Built to a tried-and-tested recipe, the first step with a bare metal shell is to fix any rust and add all of the strengthening carefully detailed in Tuthill’s in-house manual. This used to be a closely guarded secret, and some details are still kept under wraps, but the team is often happy to share information and help with other engineering, as it did with Jeff Gamroth’s Rothsport Racing 964s which recently took part in the Baja 1000 event.

Rally Car Shell Preparation

The bodyshell preparation is perhaps the most important part of the process. Having seen many cars built elsewhere eventually turning up at Tuthills to be sorted, the big problem is usually rust. So many 911 competition cars are not stripped properly or rustproofed to a very high level after restoration, so they have started (or continued) to rust before they are even finished being built. By the time they turn up for fettling, the rot has really taken hold and the major expense of rust repair is inevitable. This renders all other work done on top of the rusty shell as useless. So sorting the rust is the most important thing to start with.

The car seen here has been around Tuthills since I started going there in 2003. As with most Tuthill rally builds, it was originally imported from the west coast of America, so there was little or no rust to worry about. I’ve driven it a few times over the years and it has clocked up thousands of miles of rallying since being built, including wins on the Costa Brava and Isle of Man historic events. It has also taken part in both Morocco Historic and Safari Classic rallies, as well as a few runs on Below Zero Ice Driving.

Porsche legend, Björn Waldegård, drove this car on the first Colin McRae Memorial Rally and I think Colin’s dad (and former British rally champion), Jimmy, used it on the same event the following year. Now the car has passed to new owner and experienced competitor, David Danglard, a fresh book begins in its history. The first chapter of that is the Baltic Classic Rally, which starts on May 28th and runs all around Northern Europe, loosely following the Baltic Sea coastline.

FIA HTP Homologation Requirements

FIA rally homologations set out most of the specs for a competition rally car carrying an Historic Technical Passport (HTP): essential to rally on international events. If it wasn’t on the original homologation back in the day, then you can’t use it now. Some exceptions include fuel tanks and modern damper systems, which are often exempt from regulations or waivered on the grounds of reliability. But it all starts with the original FIA paperwork.

This car was built for FIA and later upgraded to run on Safari, but the process of creation is basically the same. With the shell mods and a full roll cage in place, the chassis was fitted with a mix of homologated parts and other equipment developed for rally use. Dampers are key to performance, and historic compliant EXE-TC dampers without remote reservoirs are used on most Tuthill Porsche 911s. For a proper Safari effort, the team brings damper technicians to the event to strip and rebuild dampers in accordance with service plans, but these high-end dampers can take a number of historic endurance events like the Baltic before needing rebuild.

Brake calipers may be free on some events, but FIA cars use standard Porsche brakes, which are good enough for historic endurance when running proper pads and discs. Tuthill’s dash-controlled twin-master cylinder pedal box is fitted to all 911 rally builds. Some events do not permit adjustable brake bias, so the system is disabled for those. Small details include a spare throttle cable run from engine to pedal, so if a throttle cable breaks on event, you simply clip in the new one front and rear.

Oil lines are usually run in the car for obvious reasons, wrapped in tight-fitting heat wrap. A central oil tank is fitted to the rear firewall, with a level check tube easily viewed and keeping things simple. The oil system on a proper 911 rally car is a joy to behold, as is the fuel setup with twin Messerschmitt fuel pumps up front on proper Safari cars: again double-headed for reliability. Some rally cars use twin tanks in case of poor fuel, but the Tuthill spec is usually one large – 100l or more – foam-filled fuel tank, sited high up between the front towers and a reworked floor in the front compartment, which then allows two spare wheels to be carried (de-rigeur on historic endurance).

Electrics are kept to a minimum, though many competitors ask for additional spurs to power cameras, GPS systems and so on. The entire wiring system is replaced with a modern competition loom, designed to run fire extinguisher systems, bonnet lamps, Halda rally timers and the like. Bull bars front and rear are there to help recovery and allow towing as much as prevent damage from wildlife or other contact and they are very handy things! They do not add a great deal of weight to the chassis and also allow the bumpers to be lightweight GRP.

Substantial body guards are fitted under the car, to help the 911 survive high-speed running on rough terrain and also survive impacts from hard landings. These are aluminium, but still weigh a fair bit. The good thing about the guards is that all the weight is carried low down. Even with Safari-spec ground clearance, the cars handle beautifully on road (with road tyres).

My last solo drive of a Tuthill Safari car was a return loop from HQ in Wardington to Derry in Northern Ireland using Gilberto Sandretto’s Safari 911 (above). The car was supremely comfortable to drive and that 3-litre engine did not miss a beat. I am sure the new owners of this storied 911 rally car will enjoy their debut event with it and hope to share some road trip photos upon their return.

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