Sunday, December 5, 2021

Volvo C30 AWD Conversion… Yeah, It’s a Thing!

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The C30 was Volvo’s most recent two door hatchback model, produced from 2007-2013. Despite a strong niche following, sales were less than satisfactory for the Swedish manufacturer. The internet will debate on why it failed, but the most common theory is that it was marketed as a hot hatch for the wrong demographic. It was too numb to be sporty, too sporty to be luxurious, and too luxurious to be competitively priced with the rest of the hatchback market.

But what if the T5 (turbo 5 cylinder) was all wheel drive? What if it was a rival to the Golf R, the Impreza WRX, or the later Focus RS?

Polestar, a company known for building Volvo race cars and developing a Volvo-approved performance software “tunes,” took a little blue C30 and turned it into an all wheel drive beast. Utilizing the drivetrain from its chassis sister, the Volvo V50, it was a one-off build that was showcased on TopGear UK and Jay Leno’s Garage in 2012. Technical information on this conversion was mostly kept secret, leaving enthusiasts questioning if an all wheel drive swap was possible for a production C30.

In 2018, a C30 enthusiast and a couple of Volvo master technicians finally made this dream a reality. Despite the doubts and theories, they successfully completed the conversion with nothing more than Volvo parts; no software required! Ruling out custom software complications or swapping computers meant the car still acknowledged its original VIN via OBDII, making the conversion a legal modification in most parts of the world.

While I cannot take credit for the discovery of the all wheel drive conversion, or being the first to complete the swap at home, I am the proud owner of the 7th (known) street legal all wheel drive C30. With a little technical know-how, basic tools, and mechanical competency, anyone can complete this swap on a T5 C30 from the floor of their home garage.

The AWD Swap – What Does It Take?

Initiating this endeavor with a complete all wheel drive donor car would be ideal. Currently in 2021, it is reasonable to pay between $800-$1500 for a 2004.5-2012 AWD S40 or V50 with either cosmetic or engine damage. A running car would obviously be preferred, as it will give you an opportunity to drive the car and test that everything is functioning as it should. It is also nice having access to a full parts car and seeing exactly how Volvo assembled things.

Whether you have a parts car sitting in your driveway, or you are piecing things together from junkyards and classifieds, here are the main components that you will need. You can also still find these as almost complete bundles on the forums, here’s an example we found on swedespeed.

AWD transmission – An auto trans for auto cars, a manual trans for manual cars.
AWD passenger side axle – The front constant velocity axles are dependent upon automatic or manual transmissions. The longer passenger side axle on left-hand-drive cars is also dependent upon an AWD or FWD drivetrain.
Front transfer case
AWD rear motor mount torque arm – It’s slightly different from the FWD torque arm.
AWD downpipe – Whether you keep the exhaust stock or go aftermarket, you will need an AWD downpipe to clear the steering rack and transfer case. The FWD downpipe can be cut and modified to work.
AWD catback exhaust – The FWD exhaust will not fit around the AWD gas tank and rear subframe. Only the muffler can be reused.
Center driveshaft, brackets, and heat shields – Be sure to save the brackets, bearings, and heat shields that accompany the center driveshaft.
AWD gas tank and fuel neck – AWD cars use a saddle tank that goes over the center driveshaft. Be careful removing the tank, as many of the plastic connectors can become brittle with age.
AWD rear subframe with all associated components – This is where a complete donor car is preferred. You need the subframe, the trailing arms, the hubs, the EVAP canister, the ABS wires, the rear axles, the rear transfer case, the haldex unit, and all of the wiring harnesses and connectors running to the AWD components. If it’s connected to the rear subframe, then you will need it.
Rear suspension – You will need the shorter AWD rear shocks with angled mounts and you will likely want to run adjustable coilovers to level the car. Depending on the rear sway bar endlink configuration, you may need to use different end links. I would also suggest adjustable camber arms since the factory arms add an excessive amount of negative camber.
Gen3 Haldex controller – This is the only part that you cannot save from your AWD donor. You will need the updated controller and pressure switch used in the V8 XC90 and some XC70s. Part number 5WP33504-01 or 36001160 worked for my conversion.
Engine mount spacers – You will need to purchase spacers to raise the upper engine mount and upper transmission mount by roughly 3/8th of an inch. I used hardened stainless steel washers from the local hardware store which fit around the engine mount bolts.
Extra wire – When removing the wiring for the AWD components, try to save as much excess wire as possible for routing into the cabin. You will want to have plenty of additional wire on hand, in varying gauges, as well as the necessary solder or connectors for splicing wires.

Let’s Get This Swap Done

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How you go about the conversion process is entirely up to you, but the following is my suggested three step process for anyone performing this swap on jack stands in their garage or driveway. You can also watch my discussion on the conversion here:

Please note: For detailed instructions on removal and installation of the components listed, I would suggest referencing the stickies section on the SwedeSpeed S40/V50 subforum here: https://www.swedespeed.com/threads/s40-v50-technical-information-how-to-diy-faq-and-more.77794/

  1. I opted to start with swapping the AWD transmission, transfer case, and passenger side axle. At this same time, I raised the engine and transmission with the washer spacers and built a custom downpipe to fit. With these parts installed and the clutch bleed, I could continue driving it as a FWD vehicle with the AWD transmission. This first phase is the perfect time to install an upgraded clutch, replace the slave cylinder, and install a limited slip differential.

  1. The second phase of my swap was definitely the most involved. The entire FWD rear subframe can be removed with just a few bolts, then pull the exhaust and gas tank. This is a great opportunity to cut a fuel pump access hole in your floor.

Now begins the puzzle of installing the all wheel drive parts. With the new tank installed, the AWD fuel pump is plug and play with the FWD wiring. Because Volvo used the same chassis for their FWD and AWD P1 Volvos, the AWD rear subframe will bolt right up too. The front wheel drive ABS wiring can be reused, but I would advise getting the longer all wheel drive ABS wires. You will also need to run the haldex wiring into the cabin through the passenger side pass-through; follow the factory ABS wires and you will find the hole.

Once you hook up the center driveshaft and associated components, you can bolt in your AWD exhaust or take the time to fabricate your own. At this point, you may continue driving the car as a FWD vehicle while you break in the new parts, test the old parts, and get your suspension dialed in properly. A four wheel alignment is definitely required after swapping subframes.

  1. The final step is wiring. While only a few wires need to be run, which wires you tap and where you tap them matters. The following diagram is what I used for routing my wires to get a functioning AWD system the way Volvo intended. I would suggest reviewing other AWD swaps on the forums to see what has been done. For unknown reasons, a few people have been unsuccessful with this wiring setup and opted to build manual haldex controllers.

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With the wiring complete, you will need to swap in the updated haldex module. Without this, you will get a traction control error and no power to the rear wheels. This upgraded controller and pressure sensor will also provide quicker rear wheel engagement.

Was The AWD Conversion Worth The Work?

In conclusion, do not expect an AWD Volvo to feel like an Audi or Subaru. This is a dated Haldex system and is built for enhanced traction, not performance. That being said, the added power to the rear will allow the car to launch better, corner faster, and you will set quicker lap times despite the additional weight. The extra rear weight is barely noticeable and actually improves the balance of these front-heavy cars.

The only drawback to owning a conversion car is the worsened fuel economy from the AWD gear ratios and an inaccurate fuel gauge reading. As fuel depletes in the AWD saddle tank, it constantly fills the right side of the tank where the main pump and level sensor reside. This results in a “full” reading until nearly 2/3rds of the tank have been depleted. As the car consumes the remaining 1/3rd of gasoline, the fuel needle will quickly sweep from Full to Empty at a linear rate. I suggest resetting your trip computer with each fill up, knowing that once the needle starts to move, you will need gas soon.

Despite this minor inconvenience, my AWD swap has been satisfactory and problem free for nearly two years. Following the completed conversion, I parted out my AWD donor vehicle and sold the FWD remains to actually make a small profit. While my Volvo may still fall short on performance compared to other AWD cars on the market, it is a pleasure owning one of the few AWD C30s in the world.

Whenever someone says “I saw a car like this on Top Gear, is it AWD?” I can just smile and say “Yes.”

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Michael Hallockhttps://www.michaelchallock.com/
Michael is an automotive enthusiast and YouTube content creator, living amongst the twisty roads of the north Georgia mountains. You may recognize his screen name, MyNameIdeasWereTaken, within the Porsche, Volvo, and Subaru communities.

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