Manual Transmission

Gear Ratios
KA24(D)E & SR20DET (S13/S14):
1st- 3.321
2nd- 1.902
3rd- 1.308
4th- 1.000
5th- 0.759

CA18DET (S13)
1st- 3.321
2nd- 1.902
3rd- 1.308
4th- 1.000
5th- 0.838

SR20DET (S15)
1st- 3.626
2nd- 2.20
3rd- 1.541
4th- 1.213
5th- 1.000
6th- 0.767

Modifications:

Short Shifter

A short shifter changes the fulcrum point of the shift linkage, this allows for a shorter throw to engage the gears.

Clutch

A clutch exists in Standard Transmission (manual) cars in order to separate the motor from the driveshaft for shifting and stopping. A clutch consists of a Flywheel, which is bolted to the Crankshaft of the motor, and a Friction Disc, which is splined and slides on the Manual Transmission input shaft, and a pressure plate which is bolted to the flywheel Depressing of the clutch pedal (which can be hydraulic, fluid, actuated or manual) separates the friction disc from the flywheel face by depressing the pressure plate, thus allowing the engine to spin free of the driveshaft/tires. Engaging the clutch by releasing the clutch pedal forces, via springs, the friction disc to contact the flywheel, which causes the transmission to spin the driveshaft and tires.

Old Definition:

In a car, you need a clutch because the engine spins all the time, but the car wheels don't. In order for a car to stop without killing the engine, the wheels need to be disconnected from the engine somehow. The clutch allows us to smoothly engage a spinning engine to a non-spinning transmission by controlling the slippage between them.

(Thanks to http://auto.howstuffworks.com/clutch.htm)

Clutch Reviews

Flywheel

A flywheel is another component of the drivetrain in a Standard (manual) transmission vehicle. The Flywheel is bolted to the crankshaft of the motor. The job of the flywheel is to cause the transmission to spin via friction from the friction disc (which bolts to the manual transmission).

While lighter flywheels are theoretically better, the reduction of inertia between firing cycles of the motor can in effect reduce efficiency of the motor, countering its own intended purpose.

Old Definition:

An aluminum flywheel is a great modification to free up drivetrain loss, Create less shock damage on hard shifting from reduced inertia, Help the engine rev and respond quicker, and reduce time for the RPM to drop between shifts so during racing a rev match may be achieved sooner.

Flywheel Reviews

300ZX Transmission Upgrade

A '90-'98 300zx VG30DE or VG30DETT manual transmission can be installed using an adapter kit made by Mazworx Racing, which includes the adapter plate, shifter re-location bracket, transmission crossmember, steel driveshaft (optional aluminum or carbon) and associated machining of the bell housing to fit the SR20DET or KA24DE.

Xcessive Manufacturing also makes an adapter kit, which allows the use of an un-modified 300ZX (z32) transmission/bellhousing.

The 300zx tranny upgrade is the best thing for high powered sr(s) that are blowing through transmissions.

Automatic Transmission

Automatic to Manual Transmission Swap

WHAT YOU NEED

shifter & transmission.

(EDIT - TYLOR DURDAN - Also need the manual spacer plate between the motor and the transmission) - Not necessary

clutch & brake pedal. - Auto brake pedal can be cut

master & slave cylinder.

5 speed bellhousing to engine bolts(flange is thicker on manual needing longer bolts)

steel hydraulic lines, which will deliver pressure from the clutch master cylinder to the clutch slave cylinder, which pushes on the throwout bearing. - braided line can be used instead of steel ones

manual tranny crossmember.

manual flywheel w/ bolts.

manual transmission driveshaft or custom one piece driveshaft for a manual transmission.

Computer for a manual transmission car. (Not always necessary. A ground loop can be installed to the starter circuit connector under the hood [Black w/ White stripe and Black w/ Yellow stripe wires are the two wires on this circuit, and jumpering eliminates the need for the new ECU]) (EDIT-WRONG! regardless of which ECU you use, this is a needed jumper. This part of the harness is a mechanical break in the starter circuitry interupted by the transmission itself. - Tylor Durdan)

Pilot bushing to install in crankshaft of engine. - called spigot bush

Shop manual (these are available on ebay. You will need it for the wiring modifications needed to install the neutral safety switch and clutch safety switch so the cruise control will work.)

MODIFICATIONS THAT NEED TO BE MADE

The hole for the clutch master cylinder and the 2 mounting bolts must be drilled out of the firewall. This is very easy, as they are clearly marked out on the firewall.

I found that a 1 3/8" hole saw works perfect for the hole for the master cylinder to mate to the firewall. Use a center punch to line it up before drilling or you'll be disappointed with the fitment. (WJ)

The hydraulic hard lines for the clutch must be installed.

The brake pedal must be replaced with the assembly for the manual transmission (don't forget the brake light switch).

You can cut your auto brake pedal down to size with a grinder, dremel, etc. instead of performing the long task of swapping the brake pedal. (WJ)

Clutch pedal from your model year is the best bet. I used an S13 pedal on my S14 but had to fab two spacers (1 1/8" or so) to make it work for the mounting bolts as the S14 pedal has spacers built into the pedal assembly whereas the S13 uses spacers attached to the interior firewall. If you are using spacers ensure that the clutch pedal assembly lines up successfully with the existing or swapped brake pedal. (WJ)

The shift lock feature of the automatic transmission must be defeated. This can be done two ways. 1: Run a new wire from the ignition cylinder to the starter solenoid. 2. Bypass (short)the switch.

If retaining the auto radiator, block off the transmission cooler lines located on the bottom of the radiator.

Remove the automatic bushing adaptor from the crankshaft and install the manual pilot bushing. The automatic adaptor is a real PITA to get out. The most effective way that "I" know of is to use a carbide side cutter and carefully cut a slot in it, then compress it with a good set of vice grips and then pull it out. I have broken 3 pilot bushing pullers trying to get it using the "right tool".

I successfully used the bushing puller after cutting the automatic bushing with a dremel and cutting wheel at 12/3/6/9 o'clock and then at 1:30/4:30/7:30/10:30. Warning! Be careful to NOT cut into the crankshaft with any tool. (WJ)The boy's over at Team Clockwork Performance use a large pipe wrench (monkey wrench) inserted into a large pipe for leverage and use a twisting motion to get the bushing out. One person holds the crank from spinning with a socket and breaker bar while the other spins the bushing enough times for it to slide off. Use this method with caution.

Nissan 240SX Performance Modification/Transmission

Contents