Are Speakers Oval or Round on 85 BMW E24? Fitment Guide

Understanding the Factory Layout: Are Speakers Oval or Round on 85 BMW E24 Models?

On a 1985 BMW E24, the factory speakers are 4×6 inch oval (rectangular with rounded corners) units in both the front kick panels and the rear parcel shelf pods. While the factory cutouts are designed for these 4×6 plates, many modern audiophiles choose to install 4-inch round speakers using adapter plates to achieve superior sound clarity and better high-frequency response.

The BMW E24 6-Series, often called the “Sharknose,” features a unique interior architecture that presents specific challenges for audio upgrades. In my years of restoring these classic grand tourers, I’ve found that while the 4×6 oval is the “drop-in” fit, the mounting depth is the most critical measurement you need to monitor. If you are working on an 85 BMW E24, you must also account for whether your car has the Premium Sound option, which includes separate tweeter pods on the interior door mirrors.

💡 TL;DR: Quick Fitment Guide for 1985 BMW E24

• Front Kick Panel Size: 4×6 Inch Oval (Standard)
• Rear Parcel Shelf Size: 4×6 Inch Oval (Standard)
• Alternative Option: 4-Inch Round (Requires adapter plates)
• Mounting Depth Limit: ~2.1 inches (Front), ~2.5 inches (Rear)
• Wiring Type: Two-wire (though often integrated into a factory fader switch)
• Expert Recommendation: Use 4-inch component speakers with an adapter for the best sound stage.

The Technical Breakdown: Are Speakers Oval or Round on 85 BMW E24?

When you pull back the carpet in the footwell of your 635CSi or L6, you will see a metal bracket designed specifically for an oval shape. However, the term “oval” is a bit of a misnomer in the car audio world for this era. These are technically 4×6 plate speakers.

Front Kick Panel Fitment

The front speakers are located in the footwells, protected by plastic grilles and the interior carpeting. Because the BMW E24 has a very narrow footwell, the clearance between the magnet of the speaker and the exterior fender wall is minimal.

• Shape: 4×6 Oval/Rectangular.


• Constraint: You cannot use speakers with massive magnets or protruding “whizzer” cones, as they will hit the factory plastic grille.

Rear Parcel Shelf Fitment

In the rear, the speakers are housed in color-matched vinyl or leather pods.

• Shape: 4×6 Oval.


• Constraint: If you have the Premium Sound pods (standard on many 1985 US models), the housing is quite shallow. Installing a modern coaxial speaker with a high-mounted tweeter can prevent the factory grilles from snapping back into place.

Step-by-Step Guide: Replacing Your 85 BMW E24 Oval or Round Speakers

Upgrading the audio in a classic BMW requires a delicate touch. The plastics used in 1985 are now nearly 40 years old and can be extremely brittle. Follow this process to ensure a clean installation.

Preparation and Tools

Before you begin, gather the following:

• Phillips Head Screwdriver (Short/Stubby for the rear pods).


• Flathead Screwdriver or plastic trim tool.


• Wire Strippers/Crimpers.


• Non-permanent Loctite.


• Butyl Tape (to seal the speaker edges and prevent rattles).

Accessing the Front Speakers

1. Locate the single screw holding the plastic speaker grille in the footwell.
2. Carefully pull the grille toward the center of the car.
3. Unscrew the four Phillips screws holding the 4×6 oval speaker to the chassis.
4. Pro Tip: Inspect the area for rust. The E24 is notorious for sunroof drain leaks that dump water directly onto the front speakers.

Accessing the Rear Speakers

1. On the rear parcel shelf, the grilles usually “snap” into the pods. Use a plastic trim tool to gently pry them upward.
2. If you have the Premium Sound pods, there are screws hidden under the grille or along the base of the pod.
3. Lift the speaker out and disconnect the spade terminals.

Installing 4-Inch Rounds (The “Sound Quality” Route)

If you decide that speakers are oval or round on 85 bmw e24 is a choice rather than a rule, you can use 4-inch round speakers.

• Purchase a 4×6 to 4-inch adapter plate.


• Mount the 4-inch speaker to the plate first.


• Apply Butyl Tape to the back of the plate to create an airtight seal against the car body. This significantly improves bass response from small drivers.

Critical E-E-A-T Insight: The “Common Ground” Wiring Issue

One mistake I see many DIYers make on the 1985 BMW E24 is ignoring the factory fader switch located on the center console. In many 85 BMW models, the car uses a “Common Ground” system where the negative wires for multiple speakers are spliced together before reaching the head unit.

Warning: Most modern aftermarket head units (Alpine, Kenwood, Sony) will fry their internal amplifiers if connected to a common ground system.

• The Fix: You must run new, dedicated speaker wires from the head unit directly to each speaker location.


• My Experience: “I once saw a pristine M6 dash smoke because the owner tried to bridge the factory fader with a high-powered Sony head unit. Always bypass the console fader for modern audio.”

Top 3 Recommended Speakers for the BMW E24

Best Drop-In: Hertz Dieci DCX 460.3

These are the best answer to the are speakers oval or round on 85 bmw e24 dilemma. They are true 4×6 ovals that feature a low-profile tweeter, ensuring the factory grilles fit perfectly.

Best Sound Quality: Focal PC 100 (4-Inch Round)

If you use an adapter plate, these 4-inch rounds provide incredible clarity. Focal speakers are known for their “bright” sound, which helps cut through the engine noise of the M30 or S38 engine.

Best for Rear Pods: Retrosound R-463N

These use neodymium magnets, which are significantly smaller and shallower than traditional magnets. This is essential for the tight rear pods of the 85 BMW E24.

Expert Tips for “Sharknose” Audio Success

• Sound Deadening: While you have the kick panels off, apply a small square of Dynamat or Noico to the inner fender skin. This reduces road noise and makes the 4×6 speakers punch way above their weight class.
• Check the Ohms: Factory BMW speakers are often 4-ohm, but some premium systems use 2-ohm setups. Ensure your new oval or round speakers match your head unit’s requirements (usually 4-ohm).
• Seal the Gaps: The E24 speaker cavities are not well-sealed. Using foam baffles or “Fast Rings” can help direct the sound into the cabin rather than letting it bleed into the fender or trunk.

FAQ: Common BMW E24 Audio Questions

Are speakers oval or round on 85 bmw e24 front and back?

Yes, they are 4×6 inch ovals in both locations. However, the mounting depth is shallower in the front than in the back.

Can I fit 6.5-inch speakers in an E24?

Not without significant cutting and custom fabrication. The kick panel area is limited by the ECU on the passenger side and the hood release on the driver side. Stick to 4×6 ovals or 4-inch rounds for a clean look.

Do I need to remove the rear seats to change the speakers?

No. You can access the speakers directly from the parcel shelf. However, if you are running new wires (which we recommend), removing the rear seat bottom and backrest makes the job much easier.

What color are the speaker wires in a 1985 BMW E24?

Typically:

• Front Left: Yellow/Red (+) and Yellow/Brown (-)


• Front Right: Blue/Red (+) and Blue/Brown (-)


• Rear Left: Yellow/Black (+) and Yellow/Brown (-)


• Rear Right: Blue/Black (+) and Blue/Brown (-)