1987-'91 BMW 325i: A more attainable alternative to an E30 M3?

[Editor's Note: This article originally appeared in the May 2018 issue of Classic Motorsports, back when Bavarian Autosport was still in business.]

You can call the E30-chassis 3 Series the last of the classic, upright BMWs. The M3 homologation special may be the halo model, but the more common 325i and 325is are still favorites among the enthusiast community.

Expert

Gordon Arnold
Bavarian Autosport

The 1987–’91 325i and 325is are very nimble and comfortable classic BMW chassis; both models were equipped with rear-wheel drive and offered as two-door coupes, four-door sedans and two-door convertibles. The iconic two- and four-door 325iX models came with four-wheel drive.

The ergonomics and interior feel are just current enough to keep these classics from seeming too dated. You don’t feel like you’re driving a 1969 Beetle. With this noted, the E30 does remind us of a 1969 Camaro–not especially a bad thing. To top it off, a stock but not worn-out E30-chassis 325i or 325is can run circles around most five-passenger sports sedans from the ’80s thanks to its light weight and agile chassis.

So, what’s not to like? The M20B25 “small-block” six-cylinder is a bit low on power for a performance chassis, especially considering the 2.5-liter E30’s 1:16 power-to-weight ratio. Fortunately the chassis makes up for it, and the 3.73:1 differential certainly helps it feel, well, peppy.

Even though the engine isn’t a powerhouse, we always suggest that modifications start in the suspension and brake departments. Basic spring, shock and sway bar upgrades pay huge dividends that move the E30 chassis into real sports car territory. For those who prefer not to lower the chassis or would like more compliance, upgrading shocks and sway bars makes an E30 that can cruise all day, chew up country blue roads, and soak up poor road surfaces without beating up its driver or passengers.

For the sportier driver, the time will come when the stock brakes no longer suffice. The stock brakes are fine for a mild track day on street tires as well as most blacktop carving. They’re small but still have plenty of power to stop the car. A major shortcoming becomes apparent when they’re asked to stop the car over and over again at threshold levels: They simply cannot dissipate the heat quickly enough. Sourcing high-temperature, high-friction pads (such as the Cool Carbon S/T and S/T Plus) and running a high-temperature brake fluid (ATE or Motul 600 or 660) will help the stock rotors and calipers function quite well for more strenuous track days and any street driving.

Taking care of a classic BMW E30 is actually quite easy and not especially expensive. Doing your own work and purchasing parts from a mail-order BMW specialist (like Bavarian Autosport) can keep ownership costs well within reach of almost any automotive enthusiast or hobbyist. Additionally, a huge online E30 community exists on social media as well as marque- and model-specific forums.

When shopping for a 325i or 325is, bumpers can a deciding factor. Buyers may prefer the early E30 with the U.S. DOT 5 mph bumpers (used through May 1988 on rear-drive coupes and sedans) or the later international bumpers that sit closer to the body and are painted body color.

The 325is option package is desirable for a sporting enthusiast as it includes sport seats, a three-spoke sport steering wheel, a small trunk lid spoiler, slightly lower and firmer springs, firmer shocks, and a limited-slip differential. All of these were options on the standard 325i models. The early 325is models received a quite nice-looking front spoiler/apron that was installed after the vehicles landed in the U.S. None of the apron parts are available today, however, so beware of one that needs repair.

With the newest E30 model being some 27 years old, be aware of common rust. “They all do that” problem areas include all four rocker panel jacking points; under the taillights; the trunk panel cutouts for the license plate lights; the sunroof panel; the left and right trunk “cubbies” that hold the battery (right) and jack (left); and the rear valance. Otherwise, all common old-car areas must be inspected: bottoms of doors, floors, spare tire well, frame rails, etc. Finally, the fuel tanks rust at the seams and tops due to crud and moisture accumulation. Look for evidence of fuel stains on the outside of the tank. Fill the tank 100 percent and check for leaks, too. Tanks are readily available but a PITA to replace.

The M20 engine is very robust but does use a camshaft timing belt; replace the belt every 50,000 to 60,000 miles or five years. If you’re buying a car with no service history, replace the belt and tensioner before running it much. Like the engine, if the rest of the drivetrain fares well on a test drive, it will likely serve well for a good long time with a standard fluid and hard-part maintenance program.

While the M20 engine can be fully built and hotrodded, that’s often fairly expensive compared to swapping in more horsepower. The E30 platform is likely the most heavily engine-swapped BMW ever. The most common swaps are the next-generation M50/52 engine (E36-chassis 325i and 328i) and S50/52 engine (E36-chassis M3). These do bolt in to some degree, and the internet contains a wealth of shared info on how to do it. We can say from experience that an S50/52-swapped E30 is a very fun machine.

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