I’ve only done this a few times, because its really not worth it in most scenarios. It’s really quite simple mechanically, but the real complications come from the wiring. Any model newer than 2000 you’re probably better off just finding the same car in manual (assuming it exists). Older cars have much simpler wiring and you can convert it with only a few wiring changes, and then just leaving all the existing Automatic wiring in the car.



Scenario 1: as part of a larger conversion (like a turbo swap), since you have the opportunity to focus on the wiring harness, you’d want to just swap out the whole harness for a manual one. It will save time and hassle in the long run.

Scenario 2: do the minimal possible to convert to manual. You will have to target and spot-fix the various wiring quirks for clutch, neutral, reverse lights, etc., which could vary by car.

Scenario 3: you have an SVX in which case bust out the welder because you’ll be making custom parts. I’ll post about this later.



PARTS:

You will need:

1. manual transmission. pick your flavor

2. rear differential to match ratio of manual transmission (unless its the same ratio)



3. driveshaft from a manual transmission version of your chassis



4. flywheel and clutch appropriate for your transmission

5. entire clutch/brake pedal assembly with relevant sensors, cables/lines, master/slave cylinder, fork, etc (see my previous post about cable/hydro clutches)

6. manual shifter linkage

7. manual transmission crossmembe/mount



8. ECU pinout and wiring harness info, and time to focus on it

EDIT: #9: Forgot you need a manual starter too



STEPS:

1. Strip all the auto parts from the car: transmission, torque converter, driveshaft, rear diff if needed, shifter assembly, pedal box. I believe you can leave the TCU plugged in so it can forward signals about neutral/brake/reverse along to the rest of the car. Its been a while so this could be optional, I don’t remember.



2. Install flywheel and clutch to engine. This is a good time to reseal the oil separator plate and replace the rear main seal on the engine. DO THAT.



3. Install pedals w/sensors (see notes below) and clutch actuation (master/slave) etc. Make sure you properly bleed the clutch if doing a hydraulic setup.



4. Install transmission carefully, using the crossmember and mount. This is a good time to replace the output shaft oil seal on the transmission, and upgrade the mount to a Group-N. Also drain/fill the transmission with 75w90 fluid (read elsewhere about this, I use RedLine 75w90NS for transmission and 75w90 standard for rear diff).



5. Install shifter linkage. This is a good time to upgrade bushings (round one and rear mount).



6. Once the trans is in place, the linkage is set, the clutch feels good, install the driveshaft and everything else (exhaust, axles, etc.). Note: you should be able to reuse the front axles unless you have a <05 chassis and installed an 05+ manual trans, you’ll need axle stubs or male stub axles, or if you did FWD>AWD, you’ll need AWD axles.)



NOTES / WIRING:

- Pedal sensors. There’s a clutch sensor to detect when the clutch is all the way in, and there’s a brake sensor to detect when the brake pedal is pressed at all. If you have cruise control the plug has 4 wires, or 2 wires without, though I believe the sensor is the same either way (verify on your car). Also if you have cruise there’s another sensor on the clutch to know when you press it in at all (to cancel the cruise). Should just be a 2-wire, and I don’t know how you’d go about wiring that into the cruise computer.



- Neutral sensing. Without proper neutral sensing, your car could trip a CEL for idle air control, or just run weird since it could be using the wrong map thinking you’re in gear when you’re not and vice versa. You need to take the 2-wire neutral sensor from the manual transmission and pin it into the automatic wiring at the “neutral” pin. The other pin is probably a ground



– Extra note on neutral sensors: 6 speed transmissions use an opposite sensing neutral sensor than a 5 speed; example, “sensor on = neutral” or “sensor off = neutral”. I did a 6speed swap in my 5speed legacy and the ECU thought I was in gear when I wasn’t and vice versa. I only figured it out because I have a Subaru Select Monitor and could read the ECU code for how it was reading that sensor. Just had to swap the sensor and it was fine.



- Reverse lights. You need those to work, no questions. Find the 2 wires from the manual transmission reverse sensor and wire them in to the auto wiring where “reverse” pin goes. The other pin is probably a ground

- Optional: swap in a manual transmission gauge cluster, so there’s no PRNDL tree

