Building a BMW 318ti Rally Car

eEuroparts 318ti 830x553

Story by eEuroparts.com This covers what goes into turning a stock BMW 318ti into a full-blown stage rally car, evading the “but why” question entirely. For those …

Story by eEuroparts.com

This covers what goes into turning a stock BMW 318ti into a full-blown stage rally car, evading the “but why” question entirely. For those of you looking to get into rally or simply to switch to a BMW, just like any car there’s a few common challenges with BMWs that’ll need sorting out and you should be aware of. We love the 318ti platform and its BMW partsfor a number of reasons, but this is about the build so let’s get started!

Racing Equipment – The Roll Cage

You may be surprised at how much work goes into creating a vehicle like this, only to dangle it in the face of ultimate destruction.  From the ground up, we completely stripped our car down to the bare metal. All little non-essential metal bits and pieces were removed with an angle grinder; we removed the paint, sound deadening, and any other BMW parts that would only be dead weight. Our metal fabricator has built all three of our cages (as well as a few cages and roll bars for other racers).

BMW 318ti Rally Car 1

When building the parts of a cage, one thing to consider is just how small the interior of the car gets afterward. On this cage, the main hoop was moved back to the rear seat riser, the roof bars were bent just a little more to get in tighter to the roofline, we added a dash bar, front strut bars, a sill bar, and bent everything to be a little tighter to the shell.

Ultimately that allows for more room in the car and makes it safer by keeping the cage further away from us. After looking at how some of the higher-level cars did their aft supports, we decided to connect to the tops of the rear shock towers, which reduces some of the loading stress from the suspension system on the shell and transfers it through the cage. To protect our BMW suspension parts, the front shock towers were also double layered to keep the towers from stretching out and allowing the struts to punch through.

BMW 318ti Rally Car 2

Interior Parts & Safety Gear

Once the cage and chassis are set, you need proper interior parts for racing. Seats and belts are some of the more expensive interior aftermarket parts. The price level in which you buy into depends on how many rallies you plan on running. Our first setup was OMP TRS-E seats, which were about $300-$350 each, and we had G-Force camlock 3” harnesses for around $150 each. That gear was fine to start out with.

While that gear worked well, the harnesses could be a bit tough to tighten up and the seats could start getting uncomfortable after ten hours. Granted, any seat could get uncomfortable after that. We now have OMP HTE-R seats, which are about $900, but are far more comfortable and the head bolsters give better protection in a side impact.

Intercoms are another important item in a rally car. Communication between the driver and co-driver is vital, as hearing a note incorrectly could cause a serious crash. We started with a Peltor FMT-120 Analog intercom. It’s a solid entry-level intercom and works well. Last year we switched to a Stylo DG-10 intercom after I accidentally broke the intercom connector on my side.

The DG-10 is a digital intercom which has a 12v input feed instead of an internal battery supply, active noise canceling, and stage and transit modes. The stage mode can adjust the preset volume levels, turn off the Bluetooth feature (don’t want to get phone calls during the stage), and can turn on auxiliary audio output for in-car cameras. The overall sound quality of the Stylo is much better.

Other safety gear needed in your rally car are fire extinguishers, three hazard triangles, a first aid kit, a fuel/fluid spill kit, and a belt cutter/window breaker. The rally rulebooks have general guidelines, but it’s important to think about where those items should go in your car. Put the safety-related items like the belt cutters, first aid kit, and at least one fire extinguisher within easy reach. Everything else (triangles, tools, spill kit) should be visible and easy to access when needed.  This is one of the reasons hatchbacks are so popular in rally, try yanking all this gear out of a trunk in the heat of the moment.

Yes, it will be mounted on a wheel prior to an actual rally.

Underbody Protection is a Must!

Protecting the car’s parts and systems is something we learned through trial and error. During our first events, we ran without underbody protection, leaving exposed critical car parts such as the engine oil pan, drive shaft and driveshaft flex joint, control arms and, of course, the brake lines. With this car we wanted to make protection a priority. We run a ¼” aluminum skid plate underneath to protect our BMW’s transmission and engine parts, and we used roll cage tubing for the attachment mounts. For the floor pans and rear trailing arms, we are using ¼” HDPE sheets which should help protect against punctures and wear on the floorboards and rear control arms.

Originally, we had mounted aluminum plates to protect our stock fuel tank. With this car we installed a fuel system inside the main compartment. This keeps the bottom of the fuel cell much higher, and we enclosed the entire fuel system with its own firebox to hopefully help contain any potential fires.

Engine Parts for Rallying

We are still running an M42 motor with mostly OEM and Aftermarket BMW engine parts. For rally, you do not need a crazy amount of power. Our car has just over 100hp to the wheels and we have podiumed at several events. The mods to our BMW engine and drivetrain parts that we found most useful were a lightweight flywheel (a JBR aluminum flywheel shaved 20 lb off the stock part), a higher ratio rear end (around 4:1 or slightly higher ratio are ideal for this setup), and the biggest performance improvement was from the standalone Link Fury ECU, which we also had professionally tuned.

Upgrading to a standalone ECU should be one of the first major performance parts upgrades to any car destined to race. It makes life easier having a good foundation to work with and (with a proper tune) can ultimately make even the stock engine parts last longer under hard racing environments. We have more usable power throughout the powerband now. We upgraded our radiator setup by installing a BMW aftermarket Mishimoto 6-cylinder radiator and Mishimoto expansion tank. eEuroparts.com actually put aBMW engine cooling system kittogether to perform the same upgrade on your E36. From initial testing, the setup seems to be working perfectly.

BMW Electrical Parts

One nightmare most people have with BMWs is the electrical. I swear, there is more wiring in a stock E36 than a Saturn V rocket. Not only is it full of wires, but everything is all balled up and looks like a big, colorful spaghetti-mess. When we decided to go with a new standalone ECU, we also decided it’d be a great time to completely strip out all the wiring in our new BMW 318ti rally car.

For a guy that used to sweat simple electrical work like making a three-wire harness for an old carburetor VW Golf, this was like getting thrown into the deep end of a pool. But if you take your time and break everything down, it’s only moderately painful.

We worked on the electrical in the engine harness, wiring in the fuel injectors, coil packs, various sensors, etc., as well as in the vehicle chassis harness. We’ve now made two full sets of wiring harnesses since starting rally. There is a lot that we learned while doing it, but taking your time is the most important thing.

Ergonomics is something that we started to appreciate more with each race. When you are cramped inside a rally car with a full roll cage and racing seats, it can get uncomfortable quickly if things are not placed in the car thoughtfully. We wanted to reduce the clutter for the switches and keep the tools and essential items placed in easy-to-reach areas. I learned how to work with fiberglass over the winter and formed new 318ti interior parts such as a new dashboard, door cards, and other interior panels. I wanted to form them to be better suited for our needs.

We spent time to ensure the seats, pedals and steering wheel were positioned properly. We replaced the BMW stock pedal setup with a pedal box and replaced the old steering wheel and switch panel setup with a detachable steering wheel and a wireless switch panel on the wheel. These interior parts upgrades can help reduce fatigue and make long days in the car more comfortable.

Rally Suspension System

Finally, arguably the most important part of rally — the suspension parts. While we knew how important a good suspension system was for handling, we did not know how much wear and tear cheaper suspension parts would put on the rest of the car’s parts during a rally event. Driving competitively, our suspension parts would barely last half of an event before the shocks completely blew out. At that point, the car handled like a waterbed on wheels.

Not only did our car become a handful to drive, it also allowed the car to bottom out more, damaging various parts in the underbody, as well as the rest of the suspension parts. For our second season, we tried the Bilstein HD shocks, which worked well for the events we ran, but we only got about two events out of them, so we continued looking. For the next upgrade on our BMW 318ti suspension, we got a set of fully integrated coil overs.

Though this performance upgrade was about $2,000, the difference was clear: the car handled much better. During the same events that really beat up the car with the old suspension system, we had far less damage with the new performance suspension. The car did not bottom out as much, and we also seemed to be wearing out our other BMW parts, such as the control arms and tie rods, at a much slower rate. This performance suspension lasted for about two full seasons. We finally blew out the dampers at the last race in our old car.

This season, we decided to go big and get a set of Reigers, which are quite a bit more expensive than our last suspension system; and also, the single most expensive part on the car. Along with the new dampers, we built custom trailing arms and a new rear sub frame out of roll cage tubing. These new suspension parts should be stronger than BMW’s stock set and reduce the failure points. Hopefully with this new suspension we will have better performance while reducing damage to other parts and systems of the car.

We’ve taken the lessons we learned from our last car and past seasons and have tried to apply them in our own way to build a better rally car. We hope our experience will help save you from finding something out the hard way!

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