Swapping your 5-speed automatic (5AT) Nissan G35 to a 6-speed manual (6MT) transmission is a popular and rewarding modification for car enthusiasts. This guide, built upon existing community knowledge, aims to provide a more detailed and SEO-optimized resource for those looking to undertake this project. While this guide focuses on the mechanical aspects of the swap, remember that proper electrical connections are crucial, although for this specific swap, extensive ECU wiring and gauge selection as typically associated with aftermarket ECU installations are not the primary concern. However, understanding basic automotive wiring practices is beneficial.
Essential Parts for Your 6MT Swap
Before diving in, ensure you have all the necessary components. Careful planning and parts collection are key to a smooth conversion.
Hydraulic System:
- Clutch Pedal: OEM is recommended for direct fitment.
- Clutch Master Cylinder: OEM or OE replacement ensures compatibility.
- Clutch Piping: OEM or aftermarket replacements designed for the G35.
- Clutch Line: OEM or aftermarket replacements.
- Clutch Slave Cylinder: OEM or OE replacement.
Drivetrain Components:
- 6MT Clutch Kit: Choose between OEM or aftermarket performance kits. Include:
- Pressure Plate
- Pressure Plate Bolts
- Clutch Disk
- Throwout Bearing
- Pilot Bushing
- Alignment Tool
- 6MT Flywheel: OEM or aftermarket performance options.
- 6MT Flywheel Bolts: OEM recommended.
- 6MT Transmission: OEM unit.
- 6MT Shifter: OEM or aftermarket performance shifters.
- 6MT Rubber Grommet with Bracket: OEM, typically from any MT Nissan.
- 6MT Driveline: OEM or aftermarket performance driveshafts.
- 6MT Differential: OEM or the existing 5AT differential can be used.
Interior Parts:
- 6MT Brake Pedal: OEM or modify your existing 5AT pedal.
- 6MT Center Console: OEM for a clean factory look.
- 6MT Shifter Trim: OEM to match the center console.
- 6MT E-Brake Setup: OEM or hydraulic handbrake with line lock.
- 6MT Shift **:** OEM or aftermarket performance options.
Electronics:
- 6MT ECU: OEM 6MT ECU or consider reflashing your 5AT ECU with tuning software. The 5AT ECU can function adequately.
- 6MT EFI Harness: While listed, this is not essential. The 5AT harness can be adapted with simple wiring modifications.
- 6MT Hazard Light Switch (03-04 G35): OEM.
Important Pre-Swap Checklist: Double-check that you have sourced all necessary parts before commencing the swap to avoid delays and frustration.
Frequently Asked Questions (FAQ)
Q: What parts are not absolutely necessary for the swap to function?
- 6MT EFI Harness: The 5AT harness is adaptable, simplifying the electrical work.
- 6MT ECU: Your 5AT ECU will work, or you can reflash it for optimal performance.
- 6MT E-brake: Not essential for basic functionality.
- 6MT Differential: The 5AT differential works, offering longer gearing which can improve fuel economy but slightly reduce acceleration.
- 6MT Gauge Cluster: The 5AT cluster will function, although some warning lights may be illuminated.
Q: How difficult is this 6MT swap for a DIYer?
If you are comfortable performing a clutch replacement, you possess the core mechanical skills needed for this 6MT swap. The complexity is comparable to a clutch job with added steps for component replacement and minor wiring.
Q: What modifications are required beyond direct bolt-on parts?
The primary custom work involves:
- Clutch Pedal Installation: Integrating the 6MT clutch pedal into the 5AT chassis.
- Shifter Hole Modification: Cutting an opening in the transmission tunnel to accommodate the 6MT shifter.
Q: What’s the DIY cost estimate for this 6MT conversion?
The total cost is highly variable depending on parts sourcing (new vs. used, OEM vs. aftermarket). Budget-conscious swaps using primarily used parts have been completed for around $700 USD (assuming some parts were acquired at no cost). Expect to pay significantly more for new parts.
Wiring Guide for 6MT Swap
While this swap minimizes complex ECU wiring, some electrical work is necessary, primarily for the starting system. Reverse lights and the neutral position switch wiring are simplified if using the 6MT harness (which is not required).
Starting System Wiring
The 5AT chassis harness lacks a clutch interlock switch. To enable starting, you must bypass this or wire in the 6MT clutch pedal switch.
Option 1: Clutch Interlock Bypass (Easier, Non-OEM Feel)
Bridge a switched 12V+ source directly to Terminal 53 (Grey/Red Stripe Wire) on the IPDM (Intelligent Power Distribution Module). This will allow the car to start without pressing the clutch pedal. Locating a reliable switched 12V+ source is crucial. Use a multimeter to confirm a wire is only powered when the ignition is on.
Option 2: Wiring the Clutch Interlock Switch (OEM Feel)
If you acquired a 6MT clutch pedal assembly, it should include the clutch interlock switch.
- Connect a switched 12V+ source to one terminal of the clutch interlock switch.
- Connect the other terminal of the switch to Terminal 53 (Grey/Yellow Stripe Wire) on the IPDM.
This option restores the factory clutch-start safety feature, requiring the clutch pedal to be depressed to start the engine. Using appropriate gauge automotive wire and secure, weatherproof connectors for these connections is recommended for reliability.
Neutral Position Switch Wiring
The neutral position switch signal is primarily used for cruise control functionality. If you are forgoing cruise control or using an aftermarket steering wheel setup (which often disables cruise control), this wiring step is unnecessary.
To retain cruise control:
- Locate Pin 102 on the ECU (Green/Orange Stripe wire).
- Connect Pin 102 to one of the spade terminals on the Neutral Position Sensor (located on the 6MT transmission).
- Ground the other spade terminal of the Neutral Position Sensor to any clean chassis ground point.
This completes the essential wiring for basic 6MT swap functionality.
6MT Swap: Step-by-Step Guide
Transmission Removal (5AT)
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Vehicle Lift: Safely raise the G35 using jack stands or a vehicle lift. Maximize height for comfortable working space.
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Exhaust Removal: Disconnect and remove the catalytic converters, Y-pipe, and oxygen (O2) sensors.
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Transmission Fluid Drain: Drain the automatic transmission fluid.
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Driveshaft Removal: Disconnect the driveshaft at the differential. Remove the carrier bearing. Withdraw the driveshaft.
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Transmission Mount Disconnect: Unbolt the transmission mount. The transmission will now rest on the crossmember.
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Sensor and Line Disconnection: Detach all sensors, the gear selector cable, transmission cooler hard lines, and the transmission fluid fill/drain plugs.
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Bellhousing Bolt Removal: Remove all bolts securing the bellhousing to the engine. Disconnect the starter and set it aside. Unbolt the transmission crossmember (4 bolts) to detach the transmission from the chassis.
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Transmission Extraction: Carefully pull the 5AT transmission out. Be prepared to catch remaining transmission fluid from the torque converter. Use a large drain pan.
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Lower Brace Removal: Remove the large brace that sandwiches part of the lower compression arm.
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Torque Converter and Flywheel Removal: Remove the torque converter. Access the bolts from behind the lip on the engine block. Once removed, unbolt and remove the automatic transmission flywheel/flexplate. The engine should now appear as shown:
Interior Disassembly: Center Console
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Shifter Removal: Place the automatic shifter in neutral. Remove the AT shift ****.
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Shifter Bezel Removal: The shifter bezel is held by clips. Carefully pry it up to remove. Disconnect connectors for seat warmers, ashtray lights, and hazard switch.
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Center Console Removal: Remove the four screws securing the center console (two near the radio, two on the sides).
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Park Cable Disconnect: Disconnect the park cable that releases the ignition key.
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AT Shifter Assembly Removal: Unbolt and remove the automatic shifter assembly (4 x 10mm bolts). Disconnect the wiring harness.
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Shifter Bracket Removal: Remove the underlying shifter bracket. It is typically held by clips and can be pried off with a flathead screwdriver.
Interior Disassembly: Seat and Clutch Pedal Prep
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Seat Removal: Remove bolt covers and bolts securing the driver’s seat. Disconnect the electrical connectors underneath the seat.
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Kick Panel and Lower Dash Cover Removal: Remove the driver’s side kick panel (bolt at the rear, pull towards passenger side). Detach weather stripping and the retaining clip. Remove the lower dash cover. Disconnect electrical connectors for the interior temperature sensor, trunk switch, dimmer switch, VDC switch, and hood release.
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E-Brake Assembly Removal: Remove the e-brake assembly. It is secured by four bolts. The upper bolts may require a wrench (ratcheting wrench is helpful). Disconnect the e-brake cable under the dash.
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VDC/ABS/TCS Module Relocation: Unbolt and carefully lower the VDC/ABS/TCS module. Unplug the electrical connector (reconnect later).
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Brake Pedal Removal/Modification: Remove the automatic brake pedal. If not replacing, cut it down to a smaller size to provide clearance for the clutch pedal.
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E-Brake Bracket Removal: Peel back the carpet and cut the insulation to expose the e-brake bracket spot welds. Use a spot weld drill bit to remove the bracket.
Next Steps: Installation of the 6MT components (clutch, flywheel, transmission, pedals, etc.) will follow in reverse order, along with shifter hole modification and wiring as outlined earlier. Detailed instructions for these steps will be provided in a follow-up guide.
Conclusion
This guide provides a foundational overview of the 5AT to 6MT swap for the G35. While electrical wiring is simplified in this conversion compared to standalone ECU installations and extensive custom gauge wiring, understanding basic automotive electrical principles is still recommended. Remember to always prioritize safety, double-check connections, and consult professional resources when needed. This swap significantly enhances the driving experience of your G35, offering greater control and driver engagement.
