Difficulty: Intermediate to Advanced | Time: 3–5 hours | Applies to: 1992–1999 BMW E36 3-Series (325i, 328i, 318i, 318is, 325is, 328is, M3 — sedan, coupe, convertible).
The E36 was never designed for a double DIN head unit. If you've got a 1992–1999 BMW E36 3-Series — whether that's a 318i, 325i, 328i, or M3 — BMW gave it a single DIN radio slot above the HVAC controls, and that's it. The stock cassette deck and single DIN setup doesn't cut it anymore, and upgrading to a modern double DIN receiver means cutting the OEM plastic tray out of the dashboard, relocating the climate control unit below it, and making the whole thing look like BMW intended it that way.
It's not hard. It's not reversible. And when it's done right, it completely modernizes the interior.
Video Walkthrough
Prefer watching it first? Here’s the full YouTube version of this install:
Watch on YouTube: https://youtu.be/fqlQOMyMNx0
Before You Start
Here's what the BMW E36 service manual actually tells you about the radio: it's a single DIN unit held in by hex-key screws behind small square covers on either side, and you need the anti-theft code before you disconnect anything or the factory radio locks up. That's about it. The manual has nothing to say about fitting a double DIN unit, because BMW never imagined you'd want to.
The manual does document two types of climate control heads in the E36. Early models (roughly pre-mid-1995) have rotary-knob controls — four knobs, a separate control module in the center console, and a flexible shaft for the heater flaps. Later models (approximately mid-1995 onward) have digital display controls with buttons, where the control module is integrated into the head unit itself. This matters because the digital units are deeper and require more trimming to relocate. We'll cover both.
A few other things to know going in:
- This is a permanent modification. You're cutting the OEM plastic radio/HVAC tray out of the dashboard. Once you start, there's no going back. You could theoretically fabricate a replacement tray, but let's be realistic about that.
- Work on a day where you're not in a rush. Iterative test-fitting is the difference between a clean install and a hack job.
- If your car has an OEM anti-theft radio, get the code before you disconnect anything. The service manual is very clear about this — enter the wrong code and the radio locks permanently.
- We recommend removing the trim piece around the center console and optionally the glove box. The trim is delicate on these cars after 25+ years, and having it out of the way also gives you room to route wiring.
Which install is yours? Not sure whether you have analog or digital climate controls? Look at your HVAC panel:
Four rotary knobs = analog. Buttons and a digital display = digital.
If you have analog controls, your install is Steps 1–9 and 12–13 — skip Steps 10 and 11 entirely. If you have digital controls, you'll follow every step.
What You're Replacing
You might hear this job referred to as: E36 double DIN swap, E36 stereo upgrade, E36 single DIN to double DIN conversion, E36 radio replacement, E36 head unit install, E36 cassette deck upgrade, or just "that thing where you cut your dash and hope for the best." Same job, different forum titles.
What this guide does NOT cover: Wiring. Every head unit has a different harness, and the specifics depend on your unit, your car's options, and whether you're running an amp, keeping the factory speakers, adding a subwoofer, or all of the above. We'll tell you when to connect things, but the wiring itself is between you and your head unit's instruction manual.
What You'll Need
Parts
| Part | Notes |
|---|---|
| Double DIN head unit | Any standard double DIN unit works. We used an Atoto S8 Ultra (slim profile), but this guide applies to any double DIN receiver. Slimmer units are easier to fit. |
| E36 Double DIN Head Unit Bezel | Creates the factory-look surround for the head unit opening. Manufactured in ABS with OEM BMW interior texture. |
| E36 HVAC Square Adapter | Converts the rounded HVAC faceplate to square edges to fit the lower relocation slot. Fits analog and digital climate control units. |
| E36 HVAC CCU Relocation Panel | Higher-spec option — same relocation function as the Square Adapter but includes switch openings for a cleaner finished look. |
| E36 OBC Delete Cubby | Replaces the OBC or sunglass holder with a factory-style storage pocket. Great for a phone or charging cable. |
| Wiring harness adapter | Head-unit-specific. An E36 wiring harness adapter matched to your head unit brand avoids cutting the factory harness. |
| Head unit mounting wings/brackets | Most double DIN units include these. Universal cages may not fit — see fitment notes below. |
Save a few bucks: The E36 Double DIN Conversion Kit bundles the bezel and HVAC adapter together at $35.99.
Tools
| Tool | Purpose |
|---|---|
| Phillips screwdriver | Center console removal |
| Small hex key set | OEM radio removal (hex-key screws behind square covers) |
| Mini ratchet set (e.g., Harbor Freight Icon) | Getting into tight spots in the console |
| Trim removal tool | Prying trim pieces without breaking them |
| Oscillating tool with flat blade | Cutting the OEM plastic tray |
| Die grinder with flap disc | Smoothing and shaping cut edges |
| File or deburring tool | Cleaning up rough cuts |
| Shop vacuum | Plastic dust collection (run continuously while cutting) |
| Sharpie or marker | Marking cut lines |
| Furniture felt slider pads (adhesive-backed) | Creating mounting tension for the head unit |
| Double-sided tape | Bezel mounting |
Fitment Notes
Universal cages don't fit. We tried a universal double DIN cage from Amazon. It will not fit into the E36 center console opening. Don't waste your time. Use the mounting wings/brackets that come with your head unit instead — they bolt directly to the head unit and create the friction fit inside the opening.
Slim head units are easier — and standard-thickness units can be a real problem. The E36 doesn't have a ton of depth behind the dash. A standard-thickness double DIN unit will physically fit the opening, but you'll fight for every millimeter of clearance behind it, and depending on your mounting approach, it may not work at all. We used an Atoto S8 Ultra specifically because it's a slim-profile unit. If you haven't bought a head unit yet, measure the depth of your console opening before you order and compare it against the unit's chassis depth. Slimmer is better here — this isn't a suggestion, it's a lesson people learn the hard way.
Analog vs. digital climate control matters. If your car has the early rotary-knob HVAC controls, the relocation is simpler — the unit is shallower and generally drops into the lower position without needing to trim the housing. If you have the later digital display climate controls, plan on some grinding. The digital unit is deeper and hits the structural metal and rear ductwork behind the console. We'll walk through that in the HVAC section.
Both HVAC relocation adapters fit both control types. Whether you have analog or digital, the HVAC Square Adapter or the HVAC CCU Relocation Panel converts the rounded OEM faceplate to the square edges needed for the lower slot. May require minor sanding on the sides for a perfect fit.
Step 1: Remove the OEM Radio and HVAC Controls
Start by getting everything out of the center stack.
Radio removal (per the service manual):
1. Carefully pry open the small square covers on the left and right sides of the radio. 2. Use the appropriate hex key to turn the radio mounting screws counterclockwise. 3. Pull the radio straight out of the opening. 4. Disconnect the harness connector(s) from the rear.
HVAC control head removal:
For rotary-knob models: pull off the outer rotary knobs, remove the two screws behind the knob bezels, pry off the faceplate gently, then push the control head back through the dash opening and out through the MID opening. Disconnect the harness connectors and the heater duct control flex-shaft.
For digital display models: reach into the dash through the MID opening and push the control head outward. Disconnect the harness connector and remove.
Also remove:
- The center console trim piece around the radio/HVAC area — this is fragile on older cars and you don't want to crack it while you're working
- The glove box (optional but recommended) — gives you access for wiring and reduces the chance of damaging interior panels
- The MID / OBC module from the center dash position
Keep all your hardware organized. You'll want the HVAC connectors and harness accessible for when you relocate it.
Step 2: Mark Your Cut Lines
With the tray exposed, you can see the plastic bridge that separated the radio from the HVAC — that's what has to come out to make room for the double DIN opening.
Use a Sharpie or silver marker to draw your cut lines. You're creating an opening tall enough and wide enough for the double DIN head unit to slide through. Keep your lines straight and give yourself a little margin — you can always remove more material, but you can't put it back.
Take a breath here. This is the point of no return.
Step 3: Cut the OEM Tray
Use an oscillating tool with a flat blade. This is the cleanest option for cutting the plastic — we've seen people use Dremels, jigsaws, and various other things, but the oscillating tool gives you the most control in a tight space.
1. Start your shop vacuum and keep it running the entire time. This cut makes plastic dust and it will get everywhere if you don't stay on top of it. 2. Cut along your marked lines, keeping the blade straight. 3. Work one side at a time. Don't rush it. 4. Once the section is free, remove it.
The dust situation will be better than you expect if the shop vac is right there, but it's still going to make some mess. Mask off anything you're worried about.
Step 4: Deburr and Smooth the Opening
After the cut, you'll have rough edges, burrs, and possibly some melted plastic. Clean it up.
1. Start with a file or deburring tool to knock down the obvious rough spots. 2. Switch to the die grinder with a flap disc for smoothing and shaping. A sanding pad would technically be better for this, but a flap disc works and it's what most people have on hand. 3. Pay attention to the corners — the head unit is square and the OEM opening has rounded transitions. You may need to notch or square off the corners so the unit can slide through cleanly. 4. Vacuum as you go. The flap disc makes fine dust.
Don't try to get it perfect in one pass. This is an iterative process — smooth, test fit, smooth some more.
Step 5: Test Fit the Head Unit (Iteratively)
This is where patience pays off. Don't skip test fits, and don't remove too much material at once.
1. Install the mounting wings/brackets on your head unit. 2. Slide the unit into the opening and check clearance on all sides. 3. Mark any areas where it's binding or sitting too high with a Sharpie. 4. Remove the unit, take off about 1/8 inch of material where needed, and test fit again.
You're looking for the unit to slide in smoothly without the wings collapsing inward (too tight) or the unit flopping around (too loose). There will be a small gap between the head unit and the opening — that's normal and that's what the bezel is for.
When we did this install, the first test fit showed us sitting about 1/8 inch too high. A few rounds of marking, grinding, and re-fitting got us where we needed to be. Don't skip this process.
Step 6: Install the Felt Pads
Once the opening is dialed in, add the furniture felt slider pads to create mounting tension. These go on the inside walls of the opening where the head unit's wings make contact.
This looks like a soft, low-tech solution. It isn't. The felt pads create a surprising amount of compression, and combined with the bezel, they hold the unit firmly in place — including under hard driving. Track guys and canyon guys, this holds.
We doubled up our pads where we needed more thickness. Use what you have and adjust until the head unit slides in with firm resistance but doesn't require a hammer.
Alternative: hard-mount with screws. If you'd rather bolt it in than friction-fit it, there's another approach that works well. Attach L-shaped brackets to the sides of the head unit, then run small screws down through the plastic bracket that sits between the center vent and the radio opening. Use countersunk/flat-head screws so they sit flush and don't interfere with the center vent above. Tape or glue the nuts on the underside to keep them from falling while you tighten. This creates a solid mechanical mount — the head unit won't move at all, even if you push on it. The trade-off is more hardware, more fitment time finding the right screw length, and you're putting holes in the vent bracket. For most people the felt pad method is simpler and holds just fine, but if you want a hard mount, this is the way.
Step 7: Connect Wiring and Install the Head Unit
With the opening prepped and pads in place, it's time to get the head unit wired and seated.
1. Connect your wiring harness adapter to the head unit. 2. Connect the antenna cable. 3. Route any additional cables you're running (USB, charging ports, etc.) — do this now while the console is open and accessible. 4. Slide the head unit into the opening. If there's interference on one side, check that a cable isn't bunched up behind it. 5. Adjust the position so it sits where you want it before the bezel goes on. 6. Test it. Power it on, confirm it works, check that the antenna picks up, and verify any connected features before you button everything up.
Step 8: Install the Double DIN Bezel
The E36 Double DIN Bezel covers the gap between the head unit and the dashboard opening, giving it that factory-look finish.
1. Apply double-sided tape to the top and bottom edges of the bezel. Keep the tape proud of the front face just slightly, and wrap it around the edge — this gives the bezel both adhesion and a little extra thickness where it contacts the dash. 2. Trim any tape that's wider than the bezel so nothing shows once it's installed. 3. Peel the backing off the tape. 4. Position the bezel around the head unit opening, pressing firmly. 5. With the console trim still off, you can reach behind and apply a little pressure from the rear to make sure everything sits flush.
Be as creative as you need to be with the mounting — there's no single right answer here. Double-sided tape is what we use and recommend, but if you have another method that gets a clean result, go for it.
Step 9: Relocate the Climate Control Unit
This is the second half of the job. The HVAC controls move from their original position (which you just gave to the head unit) down to the slot above the switch panel — where the OBC or sunglass holder used to live.
Install your HVAC relocation adapter into the lower slot. You have two options here:
- The HVAC Square Adapter converts the rounded OEM faceplate edges to the square edges the slot requires. It's scanned from the original and maintains the OEM interior texture, right down to the cigarette lighter slot.
- The HVAC CCU Relocation Panel does the same job but includes switch openings for a cleaner, more finished look. Either one works — pick whichever fits your build.
Both pieces have a "U" shape that accommodates the climate control unit and fits analog or digital CCUs.
If you have analog (rotary-knob) climate controls: The unit is relatively shallow. It should drop into the adapter and the lower slot without needing to modify the housing. You may need some minor sanding on the adapter sides for a snug fit, and double-sided tape can help in spots where the dashboard has seen better days. Skip ahead to Step 12.
If you have digital climate controls: Keep reading. You have some trimming to do.
Step 10: Disassemble the Digital Climate Control Unit
Before you put a grinding tool anywhere near the climate control housing, take the electronics out. Grinding ABS generates real heat — enough to damage the PCB if it's still inside. Some people skip this step and grind with the electronics in place, then hope nothing got cooked. Don't be that person. The disassembly takes five minutes and eliminates the risk entirely.
1. Remove the two screws from the climate control module. 2. Pop off the faceplate — it's held by four screws on the back. 3. Push in the two retaining tabs and slide the circuit board out.
If you haven't taken apart an E36 climate control unit before, this video walks through the disassembly so you can see exactly where the screws and tabs are.
Set the PCB and faceplate somewhere safe and clean. You'll reassemble everything after trimming.
Step 11: Trim the Digital Climate Control Housing
The digital CCU is deeper than the analog version, and it hits two things when you try to seat it in the lower position: the structural metal piece behind the console and the HVAC ductwork in the back. Both sides of the housing also rub against the opening.
The goal is to remove as little material as possible while getting it to seat.
1. Use the die grinder with a flap disc to roll down the ridges on both sides of the housing. 2. Sand down the back of the housing. There's an indentation on the rear surface — use that as your depth reference. Sand down to approximately the low point of that indentation. You're looking at roughly 1/4 inch off the back — just enough to clear the heater control box behind it. Don't go deeper than you need to. 3. Notch out any material that's preventing the housing from clearing the structural metal. 4. Sand down the sides where they're rubbing. 5. Test fit after each pass. This is the same iterative process as the head unit opening — mark, grind, fit, repeat.
The housing is solid ABS. It can handle the grinding. Don't be afraid of it, but don't go overboard either.
How much you need to remove depends on what's behind your center console. If you've got amp cables, aftermarket wiring, or other additions back there, you'll need more clearance. Our install was running the head unit and stock wiring only, so we didn't have to remove much.
Step 12: Reassemble and Install the Climate Control
Once the housing fits the lower slot:
1. Reinstall the PCB into the trimmed housing. 2. Reattach the faceplate. 3. Reconnect the harness connector(s). 4. Test all climate control functions before you go any further. After grinding, you want to confirm nothing got damaged — buttons respond, display works, fans blow. Do this before the console goes back together. 5. Seat the climate control unit into the HVAC adapter in the lower slot.
If you dialed in the fit correctly, the CCU should press-fit snugly into the adapter without needing adhesive. A properly trimmed housing in a properly seated adapter holds itself in place through friction alone. If it's loose, you took off too much material — double-sided tape or a thin bead of hot glue on the adapter edges will make up the difference.
If you're replacing the OBC or sunglass holder module that used to occupy the slot above, now's the time to decide what goes there. We replaced ours with the OBC Delete Cubby — works great for a phone, charging cable, or whatever else you want within reach. Some rubber liner in the bottom keeps things from rattling.
Step 13: Reassemble the Console and Final Checks
With the head unit mounted, bezel installed, HVAC relocated, and everything tested:
1. Reinstall the center console trim piece. 2. Reinstall the glove box if you removed it. 3. Tidy up any wiring — secure loose cables away from moving parts. 4. Do a final function check: head unit, climate control, any switches or ports you wired in. 5. Take a step back and look at it.
You just modernized an interior BMW designed in the early '90s. It should look clean, integrated, and like it was always meant to be there.
Troubleshooting
The head unit sits too high or won't slide down far enough. More material needs to come off the bottom of the opening. Mark where it's binding, pull the unit out, and take off another 1/8 inch with the flap disc. Test fit again. This is almost always an iterative process — don't try to nail it in one cut.
The head unit is loose and floppy in the opening. Add more felt pads or double them up. You need enough compression that the unit slides in with resistance. The bezel adds additional friction, but the felt pads are doing the real work. If it's still moving around, the opening may be slightly oversized — more tape or thicker pads will make up the difference.
The universal cage doesn't fit. It won't. The E36 console opening isn't standard. Use the mounting wings/brackets that came with your head unit instead.
The digital climate control unit won't seat in the lower position. It's hitting the structural metal or rear ductwork. You need to trim the housing — see Steps 10-11. Remove the PCB first, sand down the sides, back, and notch out any material contacting the metal. Test fit after each pass.
The analog HVAC unit won't seat in the lower position. Analog units are shallower and usually don't have this problem. Check that the HVAC Square Adapter is seated properly and that nothing is blocking the slot from behind. Minor sanding on the adapter sides may be needed.
The HVAC Square Adapter is a little tight on the sides. That's by design — it's meant to fit snugly. Light sanding on the sides will dial it in. If your dash is slightly warped or damaged from age, double-sided tape can help secure it.
Plastic dust got everywhere despite the shop vac. Yeah. That happens. A thorough interior vacuum and detail after the install is part of the job. Mask off the seats and carpet if you want to minimize cleanup.
The head unit powers on but there's no audio. Wiring issue — not covered in this guide, but check your harness adapter connections, speaker wire assignments, and ground. The E36 service manual documents the factory radio connector terminal designations if you need to trace the OEM side.
A Note on NLA Parts and Why These Exist
The OEM plastic tray you cut out has been NLA for years — not that you'd want it back. The Treedy Labs bezel and HVAC adapters exist because people keep doing this mod and deserved better than generic trim pieces from the internet. They're manufactured in ABS to match the OEM interior texture, so the result looks like a factory option BMW never offered. Cheaper AND stronger than the alternatives, and designed to actually fit this specific car.
Wrap-Up
That's the complete install. You've cut the OEM tray, fitted and mounted a double DIN head unit, relocated the climate control, and buttoned everything back up. The hard part was being patient with the test fitting — everything else is just cutting and sanding.
While you've got the console apart, it's worth inspecting anything else in the area — wiring condition, HVAC ductwork, switch operation. You're not going to want to pull this apart again.
Got questions? Tag us on socials or hit us at info@treedylabs.com. Show us the build when it's done — we actually want to see it.