Can I Fit 6×8 Speakers in Back of 1986 Mustang?
Yes, you can fit 6×8 speakers in the back of a 1986 Mustang, but the ease of installation depends on your specific body style (Hatchback, Notchback, or Convertible). While the factory rear speaker size for most 1986 Mustang Hatchbacks and Notchbacks is actually 6×9 inches, 6×8 speakers can be mounted easily using inexpensive adapter plates or by drilling new mounting holes in the rear deck or side panels.
For owners of the Fox Body Mustang, upgrading the 40-year-old factory paper cones is one of the most impactful “bang-for-your-buck” modifications you can make. Having restored several 1986 GTs and LXs in our shop, we have found that while 6x9s provide more bass, 6×8 speakers (often sold as 5×7/6×8 multi-fit) are widely available and offer a crisper mid-range that balances well with the limited cabin volume of a classic pony car.
TL;DR: Quick Fitment Guide
- Factory Size: 6×9 (Hatch/Notch), 5×7/6×8 (Convertible).
- 6×8 Fitment: Possible in all models; requires an adapter bracket for Hatchback/Notchback.
- Difficulty: 3/10 (Simple hand tools required).
- Key Tool: Phillips head screwdriver, wire strippers, and possibly a drill.
- Best Practice: Use a wiring harness adapter to avoid cutting the factory loom.
Understanding 1986 Mustang Rear Speaker Dimensions
The 1986 Mustang sits in a unique spot in the Fox Body timeline. It was the first year of the fuel-injected 5.0L HO, and its interior featured the iconic “dash pad” style that many enthusiasts love. However, Ford’s audio engineering in 1986 wasn’t exactly “audiophile” grade.
Depending on which 1986 model you own, your rear speaker configuration will vary:
The Notchback (Coupe)
In the Notchback, the speakers are located on the rear deck (the package tray) under the back glass. The factory cutouts are designed for 6×9 speakers. To fit a 6×8, you will need a 6×9 to 6×8 adapter plate. Without this plate, the 6×8 speaker will be too small for the hole, and you won’t be able to create an airtight seal, which destroys bass response.
The Hatchback
The Hatchback is the most common 1986 Mustang. The speakers are located in the rear quarter trim panels next to the back seat. Like the Notchback, these are factory-drilled for 6x9s. If you choose to go with 6x8s here, you must ensure the mounting depth doesn’t interfere with the interior plastic molds or the metal body of the car behind the panel.
The Convertible
If you are asking “can i fit 6×8 speakers in back of 1986 mustang” and you own a “ragtop,” you’re in luck. The 1986 Convertible uses 5×7/6×8 speakers as the standard factory size in the rear side panels. They are a direct drop-in replacement with no modification needed.
| Body Style | Factory Size | 6×8 Compatibility | Modification Needed? |
|---|---|---|---|
| Notchback (Coupe) | 6×9 | Yes | Adapter Plate Required |
| Hatchback | 6×9 | Yes | Adapter Plate Required |
| Convertible | 5×7 / 6×8 | Yes | Direct Fit |
Why Choose 6×8 Over the Factory 6×9?
You might wonder why someone would choose a smaller 6×8 speaker when a larger 6×9 fits the hole. In our experience testing audio in Fox Body interiors, there are three main reasons:
- Selection: Many high-end audio brands (like JL Audio or Alpine) produce exceptional 6×8 speakers specifically for Ford and Mazda vehicles.
- Clarity: 6×8 speakers often have a more controlled cone movement compared to 6x9s, leading to tighter mid-bass and clearer vocals.
- Depth Clearance: Some modern 6x9s have massive magnets that hit the trunk torsion bars in Notchbacks. A 6×8 with an adapter often sits shallower, avoiding this headache.
Step-by-Step Installation: Putting 6x8s in a 1986 Mustang
Tools and Materials Needed
- 6×8 Coaxial Speakers (We recommend Rockford Fosgate Punch or Kicker KS Series).
- 6×9 to 6×8 Adapter Brackets (For Hatch/Notch only).
- Metra 72-5500 Wiring Adapters (This allows you to plug into the factory Ford harness).
- Phillips Head Screwdriver.
- 1/4″ Socket Set.
- Foam Gasket Tape (To prevent rattles).
Step 1: Accessing the Rear Speakers
- For Notchbacks: Fold down the rear seat. From inside the trunk, look up at the rear deck. You will see the underside of the speakers. However, to swap them correctly, you usually need to remove the top mesh grilles or the entire package tray cover.
- For Hatchbacks: You must remove the rear seat bottom (pull the two release tabs) and the seat back. Then, unscrew the large plastic quarter panels. Be careful; 1986 Ford plastic is notoriously brittle. We suggest using a plastic trim tool to avoid cracking the tabs.
Step 2: Removing the Old Units
Unscrew the four mounting screws holding the factory speakers. If your 1986 still has the original speakers, they likely have a “Ford” stamped plug. Do not cut this plug off the car’s wiring.
Step 3: Prepping the 6×8 Speaker
Attach your 6×8 speaker to the 6×9 adapter bracket. Use the screws provided with the speakers. I always recommend applying a thin layer of foam gasket tape between the speaker and the bracket to eliminate “Fox Body rattles”—a common issue in these vibrating chassis.
Step 4: Wiring Connection
Plug the Metra 72-5500 adapter into the factory Ford harness. The other end of the adapter will have two spade connectors (one large, one small) that slide directly onto the terminals of your new 6×8 speakers.
Step 5: Final Mounting and Testing
Place the adapter/speaker assembly into the factory 6×9 opening. Secure it with the original screws or the new self-tapping screws provided. Before reassembling the interior, turn on your head unit and check the balance and fade. Ensure the speakers are “in phase” (moving in the same direction).
E-E-A-T Expert Tips: Dealing with 1986 Mustang Quirks
In my 15 years of working on Ford audio systems, the 1986 Mustang has a few specific “gotchas” that you won’t find in a generic manual:
- The “Premium Sound” Amp: Many 1986 Mustangs came with a factory amplifier located under the dash or behind the radio. If you install high-powered 6×8 speakers, the factory amp might “clip” or distort at high volumes. If your sound is distorted, you may need to bypass this vintage amp.
- Sound Deadening is Non-Negotiable: The rear deck of a Notchback is a thin sheet of metal. If you put a powerful 6×8 in there, it will vibrate. Applying a 12″x12″ square of Dynamat or Siless around the mounting hole will double your perceived bass quality.
- Polarity Check: Ford wasn’t always consistent with wire colors in the mid-80s. If your speakers sound “hollow” or lack bass, swap the positive and negative wires on one speaker to see if the punch returns.
Recommended 6×8 Speakers for 1986 Mustangs
If you are looking for the best performance while answering “can i fit 6×8 speakers in back of 1986 mustang,” consider these three options:
- Kicker 46CSC684: These are budget-friendly and have a very shallow mounting depth. They fit perfectly in Hatchback side panels without hitting the outer skin of the car.
- Rockford Fosgate P1683: A 3-way speaker that adds a dedicated midrange. This is excellent for Notchbacks where the speaker is firing off the rear glass.
- Infinity Reference 8632cfx: These have a high sensitivity rating (93dB). This means they will sound incredibly loud and clear even if you are still using the factory 1986 radio.
FAQ: Common Mustang Audio Questions
Will I lose bass by going from 6×9 to 6×8?
Technically, a 6×9 has more surface area, which helps move more air for bass. However, a high-quality modern 6×8 will almost always outperform a 40-year-old factory 6×9. If you want maximum bass, stick with 6x9s, but for clarity, 6x8s are excellent.
Do I need to cut the metal in my 1986 Mustang?
No. If you use the correct adapter brackets, you should not have to cut any metal. We always advise against cutting the metal in Fox Bodies, as it can compromise the structural integrity of the rear deck and hurt the car’s resale value.
What are the wire colors for a 1986 Mustang rear speaker?
Usually, Ford used the following in 1986:
- Left Rear: Pink/Green (+) and Pink/Blue (-)
- Right Rear: Pink/Blue (+) and Green/Orange (-)
Note: Always verify with a multimeter or a 9V battery “pop” test.*
Can I put 6×8 speakers in the doors too?
No. The 1986 Mustang front doors use 3.5-inch speakers in the dash and 5.25-inch or 6.5-inch speakers in the lower doors (if equipped with the Premium Sound package). 6x8s are strictly for the rear locations.
Where can I buy the adapter brackets?
Most car audio retailers like Crutchfield or Amazon sell “6×9 to 6×8 Universal Plastic Brackets.” They are usually under $15.
