Rally Car Prep

You have decided to take the plunge and transform your car into a rally car. Here are a few pointers to help you in the process on a budget. Most of the information is based on our experience with our Subaru RS, WRX & STI mostly GC & GD chassis (check the PrincesSTI, FrogSTIr, Le Toad and Le Toad 2 pages).

First thing is to check the rule books of the series you want to run with:

Check our Scrutineering rules page for a summary of rules and classes of these sanctioning bodies.

Team O'Neil rally school has a good introduction video about rally car build here:

You should also consider the option of buying an already prepped car which is usually much cheaper. Racer Dave has a good video on the tradeoffs (check out his channel too, lots of good stuff):

Rollcage building

This is a major undertaking and will require careful attention to get it right. First step is to check the rule book, but basically if you follow the FIA rules you will pass with any organization.

You can try to do the cage yourself if you have a bender, tube notcher and appropriate welder and skills. It is usually cheaper, faster and safer to let a professional do the work, there is still plenty to do on the car besides the cage. The cost of a cage will vary depending on the complexity of the cage and how much stripping of the car you did (prices range from ~1000$ to 6k+$). Don't expect to go with a cheap bolt on cage, you need a welded in cage. Seam welding the chassis could also be a good option.

The cheapest option is to entirely strip the car yourself (remove all the interior parts, dashboard, wiring, etc... anything that is in the way of building the cage) which also sometimes require removing the front windshield and/or the roof of the car.

Come up with a detailed plan of what you want for a rollcage, provide pictures from existing builds and a copy of the rules to your builder to show exactly what you want.

Once you have come up with a design, consult with the scrutineer who is going to issue the logbook to make sure he is ok with the design. Keep him updated during the build process too so that he can spot any issue before it is too late to fix them.

Our latest rollcage built was by Liam Laurence at Offbeat Customs, nice tight fit and great communication throughout the build process. We have also been using Bob Fill (http://bfrchassis.com) to build our cages in the past with great success at a very competitive price (better for cage upgrades than builds from scratch). Other builders in the region to consider: Bill Doyle at CageThis.com and Wicked Performance Group in Manchester NH.

You can also check the North America Rally Cage Builder Map: https://www.google.com/maps/d/viewer?mid=zP97LPvuElJ4.k55vLkhn6mps&hl=en_US

Car preparation/build


If you are new to the sport, you don't need to go crazy and a stock engine will most likely be the more reliable option. Eventually get a mild tune but more importantly stay on top of the maintenance schedule and replace fluids and all wear parts in time. If you have a turbo car, you will most likely require a restrictor:

    • Turbo restrictor 30mm for novices, 32mm prod class in Canada, 34mm limited/open class ARA, 36mm limited ARA with boost limit (~$200, Vincent Aze Trudel at http://www.performanceaze2.com/ also check Paul Eklund at Primitive Racing): if you use the stock ECU there are 2 things to be aware of: there is a risk of overspinning the turbo to try to make boost over 5500rpms, leading to a shortened life span for the turbo. Issue 2, running rich will dilute the oil, leading to main bearing issues, which is already a weak point in the motor, so you need to change your oil more often.

    • The restrictor just sits in front of the turbo inlet and will be checked at tech with an inspection camera and a gauge for proper size and fitment.

    • Turbo inlet hose: The stock turbo inlet hose is made of hard plastic that doesn't age well with the heat and the turbo restrictor will also enlarge the end of the hose which will make it fail prematurely. We recommend using an aftermarket silicon hose like the Cobb Tuning inlet v2.

    • Engine tune: If you are installing a restrictor you can still run on the stock ECU that will adapt but this is not ideal. Consider a tune from Ray at TurboTek Tuning using a Cobb Accessport. We also recommend installing an AEM wideband sensor and gauge (https://www.amazon.com/gp/product/B00N3VGPYS) to log data more accurately (see install video below). We use this bezel (https://www.amazon.com/gp/product/B000CMJ74Q) to hold the gauge in the cluster.

On the pics below from left to right:
Simple feed/return setup with no inline filter (top is feed/bottom is return), using the Russell/Edelbrock 644113 fittings. Fuel pump side with Russell/Edelbrock 644113 fittings to connect to the existing fuel lines. one connector is 180 degrees and the other one 45 degree angle.

Complete system with inline filter, Cobb Flex Fuel kit and Cobb Fuel pressure sensor. Lines to the injectors are wrapped with Mylar radiant matting (https://www.amazon.com/gp/product/B000CEQBX4). The fuel pressure sensor to AN-6 fitting is this one: https://www.summitracing.com/parts/SUM-220675

Charcoal canisters that are part of the EVAP system don't withstand very well rally abuse and it could be a good option to remove them if your state inspection regulation do not require them as part of the emission testing

If you have a turbo AWD car and plan to run events of the American Rally Association, you will have to prepare the car for the ARA Boost monitor (see Bulletin 2018 - 5, download rules and bulletin at https://www.americanrallyassociation.org/2018-rules).

We made a video explaining how to prep the car for the boost monitor:

Here are links to products used in this video:

- 1/8" NTP plugs (pack of 4): https://www.amazon.com/gp/product/B003C01DPG

- 9mm caps for intake hose: https://www.amazon.com/gp/product/B071W12W49

- Battery tender quick disconnect: https://www.amazon.com/Battery-Tender-081-0069-6-Terminal-Disconnect/dp/B000NCOKZQ

    • Air intake: the standard airbox can trap water in case of a big water crossing or watersplash. If the water goes through the intake, it is not compressible and will induce engine damage. The Cobb SF intake and airbox still provide good heat insulation but will not retain water as long as it is used in conjunction with an hydrophobic sock (https://www.amazon.com/gp/product/B00YXHCYSC). We recommend modifying the closing mechanism for the box by using a pop riveted hinge and a rivnut to hold the cover in place with 1 bolt.

Exhaust noise can be an issue: Too loud and you could not pass tech, too quiet and you won't hear the engine during the race which makes it hard to know if you are in the right gear. Most stock exhausts will be too quiet but you can find cheap catback exhausts (you usually still need to run a catalytic converter) on eBay:

Heat management is also key especially with the headers. Here is the solution we use for exhaust wrap:

Brakes: Since most gravel tires are only available in 15", stock STi Brembos have to be replaced with smaller brakes. The go to setup is a 06/07 USDM WRX 4 pot front, 2 pot rear caliper setup and matching rotors. Note that if you have an STi, the rear brake drum for the ebrake is bigger and you'll need special rear rotors (see below).

We also recommend upgrading to ARP long studs (https://www.amazon.com/gp/product/B001O065FY) with long open lug nuts (https://www.amazon.com/gp/product/B004QHMS5S).

Start with a cheap suspension like the KYB/King Springs and then upgrade to DMS or better when your budget allows. Most of the entry level suspensions are marginally better than the KYB setup. Buying used higher end suspensions can often be a great deal, just keep in mind the cost of rebuilds and who can service them so that you don't get stuck with unserviceable suspension.

Check our DMS suspension page for setup and maintenance information on DMS 50mm coilovers. Also check the Samsonas installation video below it will show a comparison with the DMS struts. We now also have a dedicated Samsonas suspension page.

We also recommend using socks/covers to protect the coilovers from dirt/sand/water that can produce corrosion or damage seals. We recommend using SealSavers ProSeries Coil Savers (see video below). they come in pair so you will need 2 to cover the 4 shocks. You can find them at https://sealsavers.com/product/proseries-coil-savers/

The Outerwears sock covers don't really hold up do rally duty (for DMS shocks use https://www.amazon.com/gp/product/B003TPYUQI).

Don't overthink your suspension setup, more caster is better if it's adjustable. 0 toe front/rear makes the car very neutral (on AWD). Don't put too much camber, the tires don't have racing slicks level of grip on gravel. Swaybars is a matter of preference, we just run stock sway bars on our cars and the balance is great with stability at higher speeds. You might find a little bit more grip without sway bars especially on lighter cars but it will be a tradeoff for stability at higher speeds. Experiment and see what works best for you. Below is a cheat sheet from Whiteline to adjust your understeer/oversteer balance:

    • Underbody protection protects other portions of the underbody like the gas tank from rock projections and other road debris. We have successfully used UHMW-PE plastic sheets of 2x4ft (0.125in thick) that you can get on Zoro tools with free shipping. You will need 3 sheets to do one car. In our first iteration we tried to secure the pieces with the strongest zip ties we could find but they get ripped under impact, the only way to go is to weld either nuts or bolts to hold your pieces of underbody protection. Using zip ties in the rear on moving lateral links is fine. Write your name on the pieces in case you lose them, sweep might bring them back to you if they know who they belong to!

    • Fender liners and wiring harness protection: stock fender liner replacements can be found for cheap (less than $20: https://www.amazon.com/gp/product/B004GD40GM) but in case it gets ripped off the car, it exposes the engine wiring harness to road debris. A simple protection using UHMW-PE (same material used for underbody protection above) can protect your wiring harness.

The stock ebrake will be fine in most situations, just remove the spring and replace the button with one that has a lip (oftentimes called drift button). See video below for the install:


Check our dedicated Harness installation page for instructions on choosing and installing your harness properly.

We are currently using Schroth Flexi 2x2 belts that we got from Stable Energies (https://www.stableenergies.com/Schroth-Harness-Flexi-2x2-6pt-Belt-FIA8853-2016/productinfo/SC-SR9453/)

Getting in and out of the car with the cage and racing seats can be very challenging, adding a removeable steering wheel will make your life much easier:

Most regulations ask you to remove the steering column lock (also check kill switch install in the Safety equipment section below). Here is a howto:

Roof scoop: Do yourself a favor and keep all the stock venting/blower/heater in the car, even AC if you can. Rally.Build has a nice Evo style roof scoop with vents to direct air where you need it (https://rally.build/collections/rally-build-fabricated-rally-parts/products/carbon-fiber-evo-style-roof-scoop?variant=6807567269934). If you go for a traditional roof scoop and vent like the one offered by Primitive Racing (https://get-primitive.com/exterior/5-rally-roof-scoopvent.html), it will only blow air below the vent but not on the sides. If you want air to get to the driver and codriver, get a floor vent from the hardware store and glue it to the bottom of the roof scoop vent as show on the picture below. You can also use additional safety wire to secure it in place if needed.

Most of the time, the stock rearview mirror is usually enough, however the vision can be limited on the street with the cage and halo seats which can be an issue in transit or if you use the car for other activities like wheel to wheel racing. You can use a cheap clamp-on panoramic mirror that is very easy to install but add weight to the original mirror mount which might not stay in position during the stages.The rollcage mounted mirrors are more stable but can be tricky to install depending on your roof bars configuration and they will instantly break if they are hit by a helmet (which can happen if you get in/out in a hurry). After breaking multiple rollcage mounted mirrors (and it's a mess to clean the broken glass), I am happier with my clamp-on mirror, never broke one and very reliable on the street (don't really need it on stage anyway!).

For night stages, interior lights are necessary. While you can get by with a flashlight, the navigator needs a good light to read the notes, find the time card and so on.


As Imprezas are pretty nose heavy, you can shave some weight by installing a lightweight bumper beam from Oswald Performance (https://www.oswaldperformance.com/products/gd-front-rear-beam-set?variant=1157639532)

Stages at night will be very challenging with just the stock headlight, adding a LED light bar has become a pretty inexpensive solution. Some of them can be mounted directly on the hood or roof of the car but a bumper or light bar is usually a better option:

Check the document below if you want to wire your LED bar with your high beams (required if you are running under CARS rules). If you can't see the document, the direct link to access it is: https://drive.google.com/file/d/1q5f4InXo51GgUw4eoSUkR_jkbOEnMOeQ/view?usp=sharing

led bar wiring.pdf

Safety equipment:

We are able to store most of the safety equipment in a toolbox that sits on top of the spare tire. The tie down keeps everything secure and in place. Make sure you don't get a cheap box that will be crushed as soon as you ratchet the strap and also make sure objects are secure in the box and are not flying around, causing damage to the box and eventually ending up flying in your trunk!

A better but more expensive option (~$300) is to use a Cartek GT solid state kill switch (https://rally.build/collections/rally-build-fabricated-rally-parts/products/cartek-gt-solid-state-battery-isolator-kit), much safer as you don't have to run high gauge wires through the car (see video below and check the kill switch page):

Kill switch wiring on a 2004 Subaru Impreza.pdf

If you can't see the document above, the direct link is: https://drive.google.com/file/d/1q5f4InXo51GgUw4eoSUkR_jkbOEnMOeQ/view?usp=sharing

If you can, try to get basic first responder training or training in fire extinguisher usage. In case of an accident on stage and the need to quickly extract a person from a car, check the useful FIA Safety Extraction Guide, especially the section about the quick modified Rautek maneuver.


Inevitably things will break during rallies even with the best possible prep. It is necessary to carry spares with you so that the car can be fixed at service. Here is a list of spares we carry with us:

    • wheels/tires

    • brake rotors/pads/calipers

    • cv axles front/rear (complete and/or boots)

    • ball joints

    • swaybar end links

    • control arms/spindles/knuckles/trailing arms (4 corners)

    • suspension (4 corners)

    • driveshaft

    • differential

    • clutch/transmission (if multi-day rally)

    • radiator

    • hoses (vacuum, fuel line, brake lines...)

    • fuses/relays/light bulbs/electrical wire

    • sensors (MAF, camshaft, crankshat...)

    • coil packs

Check with Wali at https://jdmracingmotors.com/en/ for great deals on spare packages.

Of course you will also need all the tools necessary for service. Check our service crew training video below:

Car reprep between events

We have a checklist of things to check between events or during long/overnight service at rallies. This makes sure that all the critical points have been checked out. The list is this Google spreadsheet: https://docs.google.com/spreadsheets/d/1W_J6Qzcyn3-gM1T_rI3spfpWSrJIEidTGCO91UJIva8/edit?usp=sharing

For each event, we make a copy of the template in a new tab and we change to green every point that has been checked with possibly comments in the cell if some action has been taken or something has been observed (worn part, loose bolt, etc...)
There a rea also wear items that need regular servicing or replacement. Here are a few of our maintenance schedules:

  • oil change: after every stage rally or track event, every other rallysprint or hillclimb (depending on number of runs)

  • rear diff oil: twice a season

  • transmission oil: once a season

  • air filter: cleaning after every event, change as needed (usually not more than one season)

  • suspension: full service once a season (see DMS page)

  • lug nuts: every other season (might be earlier if excessive wear/rust)

  • rust protection/underbody coating: once a season

  • balljoints and outer tie rods: max 3 seasons, earlier if any play detected (regrease twice a season with sway bar endlinks if aftermarket serviceable ones are used)

Driver/Co-Driver equipment

Some safety equipment can be bought used (but it is sometimes hard to make sure that the equipment is safe and has not been involved in an incident). Some overseas companies like Demon Tweeks or Murray Motorsport have substantially lower prices on new equipment even with shipping and tax duties factored in.

Safety gear:

    • Firesuit ($200): get a 3.2/5 Nomex suit, look at LeMons racing package deals, garage sales at SpeedWay Motors and even used ones on RacingJunk or eBay.

    • Helmet ($200): SA 2015 Helmet, try it before you buy it if you can as comfort is key. Comm integration can be a plus but usually comes at a high premium. Open face helmets are usually preferred for rallying. At the top of the line is the Stilo WRC ($800+) but we found the Sparco RJ-5i to be a good compromise with its integrated Peltor comms.

    • Head & Neck restraint ($400): Hans device is one of the most popular, lots of debate on which one offers best side protection, but the bottom line is that only the halo on the seat is going to protect you in case of a side impact.

    • Shoes ($100): Fireproof racing shoes are a must have for the driver and a good protection for the co-driver too.

    • Gloves: Fireproof gloves will give you a much better steering feel for the driver, might not be great for the codriver to turn pages of the pace notes. We like our AlpineStar Tech 1 ($80, http://www.speedwaymotors.com/Alpinestars-3551614-Tech-1-Start-Driving-Gloves,83519.html)


You can go with the very expensive Peltor or Stilo intercom that are widely used or go on a budget with a motorcycle intercom like this one that we have been using successfully:

Budget intercom: Sparco IS110 amplifier (~$90) that has both a 9V battery power and 12V from the car for seamless power transition. You can get headsets for open or closed face helmets for about $45 a piece at http://www.demon-tweeks.co.uk/motorsport/intercom-headsets/sparco-headset-kit-for-is-110-intercom.

Higher end intercom: Sparco IS140 is a nice high end Peltor compatible intercom that has both a 9V battery power and 12V from the car for seamless power transition. It turns automatically on when the codriver connects his helmet. Stilo helmets will require a Stilo-Peltor cable, other helmets can use a comm kit like this one: http://www.rallynuts.com/helmet-headsets/rosso-racing-advanced-pro-open-face-headset.html

Recce wheel:

If you need to write your own pace notes, you will need to get consistent notation for the turns. Getting a used steering wheel and adding marks to it to indicate the angle of corners is a good practice used by WRC drivers (see video below). Check the pdf document under the video below of the page to calculate the right angles for your car.

Recce steering wheel angles.pdf

If you can't see the document above, access it directly here: https://drive.google.com/file/d/1M9kx3j6CpJr-H9Xh20U4XaXVf4B0ulUD/view?usp=sharing


ARA and select CARS events have switched to RallySafe for timing and tracking during events. You can purchase the permanent kit from https://shop.statusas.com/shop/category/rallysafe/
The installation video for the kit is below:

Rally computer:

We have had great success with a very simple Android tablet and some apps for both car telemetry and rally computer. Alternatively you can use a modern phone, what really matters is that you have a dual GPS/GLONASS receiver for accuracy. Note that the use of a rally computer is not really useful beyond recce when using RallySafe, since the RallySafe unit provides similar features to a rally computer.

Android apps available from the Google Play store:

Video and telemetry:

Check out our dedicated pages: Telemetry and Videos