RG's 1985 S52 SWAP E30

Updated: Aug 14, 2018


If you have been following me for a while, you know I am no stranger to E30s. I have had my fair share of late model ones, convertible ones, and swapped engine ones. I currently have a M50 swapped track car, and a M20 swapped E30 Touring (previously M40). Surprisingly, about a year and a half ago, I have never owned or swapped a S52 into an E30. Well since all the cool kids were doing it, I decided I would see what all the hype was and jump into it.

When I’m looking for cars or parts, I usually let nature takes its course and not make deals happen. I feel like when you try to force something, it is not meant to be, and usually comes out as a bad deal. The first piece of the puzzle I found was a 1997 automatic e36 m3, in which the front bumper was falling off, and the entire car was spray painted in flat black plasti dip.


If you think buying a missing title car is sketchy, you’re right, but I didn’t need the car, I only needed the engine. I grabbed my trailer, drove 2 hours south and picked up this beauty. The car did run, but only one gear worked. Luckily I only needed one gear to drive it on the trailer, and for $1800 I was off.



I immediately started pulling the engine, and selling off the rest of the parts to recoup some of money. Coincidentally, I was able to make enough money back, to break even, hence giving me a free S52B32. I placed the engine on a stand and shoved it in the corner waiting to find the body this heart deserved.


As I stated above I have owned quite a few E30s, but there was always one style I particularly had a crush on. I figured if I was going to build a E30 from the ground up, I should make it my dream E30 spec. If you haven’t seen this car by now, the spec I am referring to is the early model mtech1 E30 with the slimmer chromer (I know not a word) euro bumpers. Something about this style just screams classic 80s to me. The low hanging valances, the drooping side skirts, and being this kit only fits on an early model e30, it receives the slimmer, arguably, better looking taillights, compared to the bigger ones fitted on the late models.



After months of negotiation, I ended up finding a clean 3 owner 1985 325e 5 speed in Polaris silver, or what was left of it. The overall condition of the car was pretty great, with black leather interior, a crack free dash, and minimal body damage. The car came with a couple mods to get me started, but needed to be gone through like any other 30 year old car. Luckily it already had euro bumpers, which saved me a lot of time and money.


Getting the car in the garage, I started to dismantle the car into a million pieces removing all the suspension, exhaust, axles, and rear subframe. I was privileged to team with Revshift for all of my bushings. I ended up going with their black 80a poly bushings, to give the car more of an OEM feel, as this was a street car. I would also highly recommend these to anyone looking for an aftermarket replacement but is not interested in the solid type alternatives. I was very impressed with the quality of the product and ride after installation.


Once the bushings were dialed in, I focused my attention on the suspension. The car came equipped with some aftermarket coilovers, but after disassembly, found the shocks were completely blown. I reached out to my friends at FCPeuro and Summit Racing, and purchased all new Koni Yellow adjustable shocks and 2.5” 450lb linear springs. I decided to harvest some of the components of the coilovers that came on the car, particularly the adjustable spring perches, and create my own coilovers. I wanted to have the car lowered, but not sacrifice ride quality. To accomplish this, I cut off the OEM spring perch, cut 2 inches out of the stock strut assembly and welded it back together. I purchased new spring perches to fit my 2.5” diameter springs and welded these on as well. Since the strut tube is shorter, I had to order shorter overall shocks. I reached out to my friends at Ground Control, and they pointed me in the direction of using VW Corrado shocks for the front. The reason for all this, is because when you lower a car, but keep the stock shock, you are fundamentally shortening the stroke of the piston. This will cause premature wear and possibly cause you to ride on the internal bump stops at all times. By choosing a shorter shock body, with a longer travel piston, I can achieve proper ride quality a while being a few inches lower. In the rear I used the adjustable spring perches with a 2.5” diameter spring and Koni adjustable shocks.



With almost everything completed mechanically under the car, I focused on pulling the engine out. As stated above, this was 325e, which came with a M20B27. Although the engine was very healthy, it left much to be desired as far as performance. A couple hours later, I had a rolling shell.



During this entire process, I was also focusing on the S52. With around 180k miles, there was no doubt it needed to be gone through and there is no better time than when it is on a stand. Every accessory, hose, harness, sensor came off the engine and the head was pulled. Just to be safe, I took the head to the machine shop to be decked and cleaned. Putting it back together, all the usual wear items were replaced including seals, gaskets, chain tensioners, and chain guides etc. For safe measure, I also welded the oil pump nut to the sprocket, since this has known to back off and cause oil starvation.



Although I could have used the G260 that came off the M20, I decided to source a ZF transmission from a e36 M3. I felt like this would be the strongest and most robust option, and I was not wanting to replace a transmission down the line. Finding a differential was quite easy, since I had the perfect one sitting around in my parts pile, a 3.25 LSD. I thought this would pair perfectly with the S52.


At this point in the build, it is around January 2017. There were a couple big events coming up in which I was determined to finish. The main focus was to take the car to The Vintage BMW car show in Asheville NC in May, and then have it completely done as a getaway car for my wedding in June. You may think, well Justin, you do have 5 months. Yes, but swapping the engine was only half the battle. This was my dream spec build remember? I still had to source a mtech 1 kit, get a glass out paint job, and reassemble. To complicate things even more, I was closing on a new house in April, while also planning for a wedding.



Now that the S52 refresh has been complete, I mated it to the ZF transmissions and horse shoed it into the car. Hooking up the clutch line, fuel lines, and driveshaft was a fairly straight forward process. To save time, I ordered an adapter harness for the early model E30 to the S52 engine harness. This saved me about a week of wiring. That being said, I spent countless hours in the wiring diagrams verifying every wire, and running continuity tests to alleviate any electrical issues. I sent off the DME to Markert Motorworks in Lawrenceville GA to have the swap tune put on. This tune deleted the EWS, secondary air pump, post cat 02 sensors, and raised the redline to 7000RPM. I ended up keeping the S52 manifold despite the popularity of switching to an OBD1 early model M50 manifold. The reason behind this was not only simplicity, but the late model intake manifold is said to give lower end torque. Since this was going to be a street car and not a track car, I figured I could benefit from lower end torque over higher. Finally, I stayed OBD2 with this car, simply because I had all the sensors, and the ability to scan the car for issues.



The day has finally come. The car was all wired up, I removed any extra wires that were not needed for the swap, the headers were open and I was ready to make some noise. Hopping in the driver seat I nervously turned the key for the first time. VROOMMMMM! The car cranked right up. The grin on my face traveled from ear to ear and I was overjoyed. I immediately dropped it down off the jack stands and went to annoy the neighbors. Its such a great feeling to build a car like this and take it on its maiden voyage. All the money, sweat, and blood was worth the journey.


Parking it back in the garage, I realized this was only a stepping stone; there was a lot more to come. Because of time and budget, I sourced a complete fiberglass mtech 1 kit from Classic Euro Parts. Although shipping took a good 6 weeks, the kit came in undamaged. Unfortunately, it was not plug and play and required light sanding, drilling and fitting to make it look right. The only complaint about the entire kit were the side skirts. They came in wavy, and had no good way of installing them. Because of this I ordered OEM 325is side skirts from BMW.



With the entire kit fitted, it was time to remove all the glass, trim, bumpers and lights to get it ready for paint. I took the car to a local shop and had them spray it the original Polaris silver. The car came out beautiful and I finally saw the light at the end of the tunnel. After trailering it home, I began putting the car back together. One bolt at a time, masking off the paint, praying I do not scratch it. Luckily the interior was well sorted and didn’t require much attention other than cleaning. The final task was the exhaust. I used OBD1 e36 downpipes which cleared the E30 subframe perfectly. I drove the car to an exhaust shop, where they welded up a 2.5” pipe to a vibrant ultra-quiet resonator and a dual tip Magnaflow muffler.

At last, the car was complete just in time for The Vintage car show in Asheveille NC. After many months of searching for the correct car, rebuilding the engine, replacing all the worn components, I had a completely new car. Without driving the car more than 100 miles, I hopped in the car with my soon to be wife and headed up to North Carolina. Slaloming through the mountain back roads and hearing the noises from the S52 was pure magic. The car handled brilliantly and looked the part as well.





Less than 3 weeks after The Vintage, I was set to get married. Thankfully my patient wife was more than willing to hop in this small 80s car with no AC on a hot South Carolina June day. After cramming her beautiful poofy dress in the car, we left the church holding hands in a car I completely rebuilt. The feelings and emotions were above any day I have ever experienced. Life is good, God is good, and I was excited to see what was coming next. Thanks to Katie for being supportive with the entire venture, and being such a trooper in our getaway car. I love you.


BUILD IT. RACE IT.






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