My long-term E24 project.

I came to own this car in a fairly peculiar way, at least for me. I’d posted a CL ad to buy older BMWs, specifying E30 parts in particular. I got an intriguing email from a potential seller, asked if I’d consider buying a complete E24 project. This sounded promising…as the seller described the project, it kept sounding better and better. First off, it was red. Other great news: it was a “Florida car” (thus little-to-no rust) and the original motor had been upgraded…with an S38B35! The current owner had bought this car many years ago with the complete M5 swap already performed, making it essentially into an M6. He parked it after the S38B35 spun a bearing, and had decided to cut his losses. The motor had been removed, the crank was repaired, but it was all still in boxes.

So I went up to see it. As described by the owner, there was no motor in the engine bay. That is certainly a handicap, but I’m pretty handy with motor swaps. However, the rest of it was pretty spectacular. Under the dust, the car didn’t appear to have any rust at all! ZERO! That’s unusual in the E24 world. The car also had very low mileage…odometer stated 73815. The car was also fitted with most available factory options for that year (happily with the exception of an automatic transmission). All my personal favorites were present and accounted for: power leather sport seats, front & rear spoilers, driving lights, “HiFi” Stereo system, even the rear sunshade! The chassis also had some tasty factory and aftermarket upgrades (full Bilstein Sport setup, IE performance springs, M5 brakes, upgraded roll bars). The Getrag 280 and 3.91 large case LSD were still in the car. Nice parts, very rare and expensive, good investments, well worth buying. In addition, the car had some aftermarket improvements: a Momo leather/alcantara steering wheel and an r134 A/C upgrade. In so many things, it’s just as important to see what really IS there instead of what ISN’T. Best of all, the story made sense. A quick AutoCheck actually verified that number, and reported a relatively clean title history. It completely matched the seller’s description. I always steer clear of funny business, especially since older cars can easily become a rat’s nest of paperwork if you’re not careful.

I was strongly tempted to make an offer on the entire lot of parts. Have you ever heard an S38 wide open at full throttle? It’s intoxicating! However, budgetary constraints kept my ambitions very modest. While an S38 is a lovely motor, they are quite expensive to rebuild & maintain. They’re also not a whole lot more powerful in American specification than the European M90 SOHC they are loosely based on. Being very short on cash, I made an offer I could barely afford on the entire lot. The seller looked crestfallen, but asked for a few days to think it over. As promised, he called me back. Unexpectedly, he countered with a much more involved deal: he wanted it all gone, but my offer was too low. Perhaps we could split it up somehow? The chassis could be mine for my offered price, but any M5 parts (transmission, differential, brakes, etc.) would be pulled, marketed & sold – by me – on his behalf. There were also some minor paperwork issues to deal with on the title. Despite a generous commission, this is a lot of work and carried a bit of risk. I’d never done anything like this before, but with a bit of work and a bit of luck it was a win-win situation. Both of us could come out well ahead of the game. This project would cost me far less in the long run due to sweat equity, and the seller would benefit from my modest skills with marketing classic BMW parts.


So that’s exactly how the deal went down. I wrote up a bill of sale detailing our contractual obligations, handled the paperwork (with his late father’s estate’s executor, no less), then had the car transported to my place. I removed the transmission, driveshaft and diff; sold them to a nice fellow out east. The motor ended up being parted out, getting sent worldwide. I personally delivered the bulk of it to North Carolina! Several venues were helpful (enthusiast forums, CL, Panjo, eBay). We split those proceeds over the next year. In the meantime I proceeded to look for a decent replacement powertrain.

Eventually I found a donor. It was once a very desirable car: an ’82 635CSi in full European trim, imported via the “grey market.” However, circumstances had not been kind. It was a totaled-out multiple flood victim, no title, sitting in a field, infested with vermin. Why would I buy a piece of junk like this? As a car, it was a massive liability. The poor thing practically screamed “tetanus”. But as a collection of parts…it had a huge amount of potential. It had only run 117K miles. The Euro “dirty” M30B34 (high-compression/no catalyst) was mated to a rugged Getrag 265/6 transmission with a single-mass flywheel and heavy-duty clutch. A large-case diff would complete the transplant into the American-spec Zinnoberrot.

Well, I had hoped to make one car from two…but that’s certainly not how it ended up. Here’s the breakdown:

  • My original 635CSi project was a chassis with a suspension, even missing the front brakes. Happily, the chassis is already fully upgraded with Bilstein Sports, thicker sway bars and lowering springs (Ireland Engineering?).
  • The motor, transmission and brakes were harvested from the ’82 European-spec 635CSi. I used the powertrain for a few months, but the valve seals were really bad. I’ll rebuild the high-compression B34 eventually. For now, I’ve tossed in a ‘temporary’ B32 with some upgrades. If the Euro B34 needs too much work, I recently came into a pretty fresh US B34 (as originally fitted to the car). I perpetually seem to have an M30 or two in the garage, it’s nice to have spares. Both engines came to me along with transmissions I wanted (yep, both were 265/6 overdrives). The transmissions & other associated parts sold off pretty quickly, but the motors stayed behind. Both are too nice to part out, so they’ll get used in something or other.
  • I found a limited-slip differential in a ’99 Z3 2.2. Sadly, the Roadster had been t-boned; it was getting parted it out. It’s one of the rare Torsen geared types, made by Zexel in Belgium. Since it’s not the more common clutch-type, it shouldn’t wear out. This one is a 3.46 ratio, a little too “tall” for most enthusiasts. No drag races for me, but it should be great for highway driving. A big hedonistic GT like the E24 isn’t meant for chasing pink slips, now is it?
  • Some decent wheels: 7.5×16″ cross-spokes originally fitted to an E32, but came to me with an ’85 635CSiA parts car. These updated 16″ “Style 5” “basketweave” wheels are a very popular choice. They’re a timeless design, relatively common, and offer far more choices for performance rubber than the original 14″ wheels. They’re also far more economical to replace than the 390mm Michelin TRX tires I bought with the car! I’m also considering 17″ E36 M3 “DS2” wheels, might have been from a ’98? Not really a performance upgrade, they’re unexpectedly big and heavy for being M-Tech parts. I just think they look nice. The larger wheels are also a subtle update, filling the fender wells and modernizing the silhouette. Since the E32 wheels have cracked tires, I swapped on a set of newer Borbets with snow tires. They don’t match the car’s style very well, but they’ll get me past our annual safety inspection.
  • It needed an exhaust system too. I sold the M5 system, but eventually a well-used system from an E28 535i turned up at my buddy’s garage. It needs quite a bit of welding but is otherwise sufficient. I’ll be updating that as well, once I find a good stainless header. I’ve actually just located one: the ’85 635CSiA parts car has a set of nicely made downpipes, unfortunately with a generic catalytic converter. However, it’s attached to a BillyBoat “TriFlow” stainless rear section. Hopefully it’ll pass inspection.
  • The brakes are from an E32 740i…all except the front rotors…they’re the lighter OEM parts from an E24 M6. If I get back to the PnP I’ll grab the E32 rear arms too, since they have bearings & reinforcing struts.

I’ve also updated the 80s electronics with donations from other machines:

  • The injectors came from several scrapyard I5 non-turbo Volvos.
  • A ’91 535i donated its Motronic 1.3 DME, sensors and mounting hardware. I’m currently updating it with an ’89 635CSi harness to make it all fit properly. The E34 harness isn’t quite long enough, since the E34 has a very convenient electronics bay on the passenger side of the engine compartment.
  • My scruffy E23 735i turbo donated a sweet AEM wideband O2 sensor supporting emulated output (that replaced an older TechEdge wideband O2 from a Euro E23 745i I rescued a while back).
  • The Hella H4 E-Code headlights were part of an E30 purchase I made in Wisconsin.
  • As mentioned, a Hawaiian ’89 635CSi gave me an engine wiring harness of the proper version and length.
  • The OEM Alpine CM5907 stereo head unit is from a scrapyard E28.
  • I’ve found some compatible Hella driving lights, they’ll replace the cracked lights currently installed in the front spoiler.

Finally, I needed quite a few new parts. The radiator had a hole, virtually all hoses needed replacement, the lift pump was dead, some suspension parts were badly worn and the motor needed many gaskets. I’m sure there was more but you get the general idea.






If you’re keeping count, that’s twelve donors (!). There could have been more, but I missed out on a few really good deals. These are the best parts I could find & fund; hopefully the sum of these parts ends up being better than the original! Early driving tests have been very promising.

I’m still working on this project…As we roll into fall 2018, the delays have piled up. Time for another winter slumber. Before I roll her back into the garage, I was inspired to try newer wheel designs. What do you think of these Motorsport wheels? They’ll require fairly thick spacers to fit the E24 hubs, but the design is growing on me. If I don’t sell them first…maybe they’ll be part of the package next year. These were standard equipment on the late-model E36 M3, usually in a staggered fitment. BMW labelled them “style 39”, M3 owners call them “Double-Spoke 2”, colloquially they’ve been dubbed “sunflowers”. I think they’re pretty.

Well, here it is December 2019…as you can probably tell, I can delay a project with the best of them. This car hasn’t moved in months, and what am I doing? Putting off any hard work to shop for wheels [car jewelry]. It’s fun! What can I say?

As much as I liked those M3 wheels, they’ve been sold. I did find some other Motorsport goodies locally, a set of Z3 ///M wheels. Bolt patterns and hub spigot both match between the E24 & E36, but the MZ3 used unique rear wheels, likely due to their modified E30 rear suspension. This set is known at BMW as the “style 40”, colloquially as “Roadstars”. Curiously, they were only offered as a staggered set; 7.5×17 et41 up front and 9×17 et8 out back. The front needs approximately 20mm of hubcentric spacers with some extended lugs, I figured that low-offset wheel would be OK as-is on the rear.

Here’s the first test fitting:

  • The current style 5 is a 16×8, 23mm offset running 215/60 R16 tires.
  • The MZ3 fronts are 17×7.5, 41mm offset running 225/45 ZR17 tires.
  • The MZ3 rear set are 17×9, 8mm offset running 245/40 ZR17 tires.

That’s slightly less forward grip and a lot more aft. I worry that the slight front weight bias of the E24 would make the rear end feel a little hefty. Maybe I’ll run truly against fashion and run the fatter wheels up front? I’ll have to ponder this one.

Wheel fitment is a pretty important part of any automotive project. I’d strongly recommend that you consult a wheel size calculator before making any purchases. I’ve been using one from Motoristo recently. Check it out here.

So, according to Motoristo, the front wheels have 12mm less inner clearance and 24mm less protrusion. I’ll need some chunky spacers to make that work, at least 15mm. The rear wheels have 2mm less inner clearance and 30mm more protrusion.

2020 02 update: So I sold the MZ3 wheels and found another set of staggered DS2. They do need some touch-up, but otherwise are straight & round. Here’s a teaser:

These wheels are slightly too big for the car, but handling should (might?) improve. In all honesty, these are a cosmetic upgrade…more or less some blingy wheel fun. As compared to the current 8×16″ set, the fronts are slightly narrower (7.5×17″), rears are slightly wider (8.5×17″). My current thoughts are to mount up some tires that mimic the E36 M3 that donated these wheels. To maintain the original rolling circumference of the TRX 390mm (~25″) I’ve found recommendations for 225/45R17 in front and 255/40R17 in the rear. Additionally, I’ll need 15-20mm front spacers to set these 41mm offset wheels near the ‘proper’ 20mm stock offset for 7″ wide wheels. Measurements to follow, along with some pics, of course…

I found some cracks on the old tires, so I tossed on a spare set of snow tires. They’re mounted on big chunky Borbets, but the style is too modern. It conflicts a little. At least they’re safe!

Another month goes by, I bought yet another set of wheels, this is an M-Tech set from an E39 540i. Pictures will follow…

Now that the spring weather has finally arrived, the car is ready for the road. It’s been a lot of work, and I feel it’s certainly worth it. To celebrate, here’s some ‘driving’ style pictures, with my tasty Momo wheel:

The wheel isn’t perfect, to be totally honest. It looks like the upper cover is leather, but it’s just foam. It’s also secured with an adapter (as they are in almost all cars), but the steering wheel internal lock ring is ever-so-slightly too small. That makes the unlock action a little stubborn at times. But those are small quibbles with an otherwise first-rate piece of equipment. This wheel is very nice to use, and a surprisingly important part of the whole experience. It’s a LOT better than the BMW 4-spoke, I feel that it’s also superior to the M-Tech three-spoke as well.

Next time, I’ll get into the leather-wrapped mushroom shifter. It’s the most perfect implement ever built…for the purpose of gearboxing.

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