MTEC Shift Spring Install (RSX / Civic Si Shifter Mechanism)
Introduction
The MTEC shift spring kit replaces the factory detent springs inside the manual-transmission shifter mechanism to firm up gear selection. Once fitted, the shifter feels tighter and more precise, with noticeably less slop between gears; the trade-off is heavier effort, which is most obvious when selecting reverse. The kit ships in a sport version tuned for everyday driving and a stiffer race version aimed at auto-cross and drag use. This procedure covers removing the shifter assembly from the transaxle, opening it, swapping in the new springs, and sealing everything back up. It applies to the Acura RSX (DC5) and its Honda Civic Si (EP3) sibling, and pairs well with other shifter upgrades such as base and cable bushings. Only 6-speed cars have the reverse lock-out connector called out below. All required internal hardware and the washer stay with the car; you are only exchanging the springs. Adapted from a community writeup by Jamdc5 on Club RSX (https://www.clubrsx.com/threads/diy-mtec-shift-spring-install.811426/), including corrections from the follow-up discussion.
Reference
Tools Required
- 8 mm Allen (hex) wrench or socket
- 10 mm socket
- 12 mm socket
- Ratchet
- Torque wrench
- Pry bar
- Knife or gasket scraper
- Floor jack and jack stands
- Clean rag or towel
Parts Required
-
MTEC shift springs (sport or race version)
-
Honda liquid gasket (HondaBond)
-
Multipurpose grease (optional, for the select-lever pivot)
Safety Warnings
- ⚠ Always support the vehicle on jack stands before working underneath. Never rely on a floor jack alone.
- ⚠ Reverse can become notably stiffer to select with the firmer springs, especially the race version. Ease into the gate rather than forcing it.
Step-by-Step Instructions
1 Raise the car and expose the transaxle-side bolt
Remove the intake tubing as needed to reach the top of the transmission (this varies by intake, so it is not detailed here). Raise the front of the vehicle with a floor jack and support it securely on jack stands before going underneath. With the car supported, locate the single fastener at the front face of the transmission and back it out using the 8 mm Allen wrench; you may find it easier to reach from below the car.
2 Release the shifter cables
At the transmission end of the two shifter cables, pull the retaining pins and slide each cable off its stud. Set the pins somewhere safe so they can go back in the same spots during reassembly.
3 Disconnect the reverse lock-out (6-speed only)
On 6-speed cars, unplug the electrical connector for the reverse lock-out solenoid at the shifter mechanism. Skip this step entirely on any transmission that does not have that connector.
4 Unbolt and lift out the shifter mechanism
Remove the four bolts securing the shifter mechanism to the transaxle. Slip a pry bar underneath and lift gently to break it free of the sealant. Once it releases, work it out, rotating the body slightly if it snags on surrounding components.
5 Clean the assembly and mating surface
Set the mechanism on a towel and wipe it down. Use the scraper or knife to remove all of the old liquid gasket from around the cover so the new sealant will have a clean surface to bond to.
6 Open the mechanism to reach the springs
Remove the 12 mm bolt that clamps the spring pack and interlock together. Draw the interlock assembly downward, keeping it as one unit rather than letting the parts fall apart; leaving it intact here makes reassembly far quicker.
7 Swap in the MTEC springs
With the assembly separated, take out the factory springs and the select stop plate. Fit the new MTEC springs in their place. The small spring seats under its washer, which is already on the car, so confirm the washer sits on top of the smaller spring as you reinstall. Optionally, slide the shaft fully up to release the select lever at its pivot, clean off any debris, apply a light coat of multipurpose grease, and refit it.
8 Reassemble and torque the clamp bolt
Squeeze the spring pack and interlock back together and refit the 12 mm bolt. Tighten it to 23 ft-lb.
9 Seal and remount to the transmission
Lay a moderate bead of Honda liquid gasket around the shift-arm cover mating surface, enough for a seal without excess squeeze-out. Set the mechanism back onto the transaxle and start all four bolts. Two of the bolts are longer than the other two, so return each to its original hole; viewed from the front of the car toward the rear, positions 1 and 2 take the short bolts and positions 3 and 4 take the long bolts. Tighten them to 9 ft-lb in a criss-cross pattern for an even, leak-free seal.
10 Refit the front transaxle bolt
Apply a small dab of liquid gasket to the 8 mm Allen bolt at the front of the transmission, thread it back in, and torque it to 29 ft-lb.
11 Reconnect cables and wiring
Slide the shifter cables back onto their studs and secure them with the retaining pins. Reconnect the reverse lock-out connector on 6-speed cars.
12 Verify shift action before driving
Recheck every fastener and connection. Row through all gears, including reverse, to confirm each engages cleanly. Only take the car out once shifting is smooth and every gear selects properly.
Pro Tips
- 💡 The race springs are stiffer than the sport springs and give the biggest change from stock feel; the sport springs suit a lighter everyday touch. Both are usable as daily drivers.
- 💡 Expect a short adjustment period. Throws become crisp and more predictable, but the added effort takes some getting used to.
- 💡 A torque wrench is strongly recommended, though the original author noted the job can be done carefully without one if you have a feel for the fasteners.
- 💡 Keeping the interlock assembly together during disassembly saves noticeable time on reinstall.
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