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ZBUM's Nissan Z31 300ZX Transmission Information Page
The Z31 came with three different manual 5 speed transmissions. All manual non-turbos used a 5 speed Nissan transmission (FS5W71C) which is quite reliable. The 84-86 manual turbos used a Borg-Warner T-5 5 speed (FS5R90A). The 87-89 manual turbos are internally, the same as the nissan transmission found in z32 turbos, trucks, pathfinders, etc (FS5R30A). All manual transmissions have synchros on all forward gears. If you change the gear oil in your transmission on a semi-regular basis it should give you absolutely no trouble at all. That is, provided you don't beat the poop out of it.
| It has been generally regarded that the FS5R90A transmission found in the 84-86 turbo 5 speeds is not very strong. People seem to blow these up with as little as 300 horsepower. The good side is they are cheap and easy to rebuild. Rebuild kits are as cheap as $125 on ebay. Any short throw shifter or rebuild kit made for the 5-speed Mustang will work fine in this transmission. |  |
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| The second strongest Z31 manual transmission is the FS5W71C found in any 5 speed non turbo Z31. This transmission is internally the same as the transmission used in the 240SX, 180SX, Silvia, etc. A few people who have blown up their FS5R90As have swapped to the Z31's FS5W71C transmission and not had problems. A lot of 240SX owners have the 240SX version of this transmission mated to their SR20DETs and KA24DETs running 400+ hp with no problems. Any short throw shifter made for the 240SX (S12, S13, S14, S15) will fit perfectly in this transmission. |  |
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| The king daddy of the Z31 manual transmissions is the FS5R30A. This transmission is the same design internally as the transmission used in the Z32 300ZX models. The gear ratios and bell housing are the main differences. There are Z32s running their version of this transmission with well over 600 horsepower and are not blowing them up. There are a few short throw shifters that will work with this transmission. They are usually the cheaper/generic short throws made for the FS5W71C. Because of the design differences, no Z32 short throw shifter will work in the Z31's FS5R30A transmission. A lot of people take the stick apart and cut a small section out of it to give the shifter a shorter height. This does shorten the distance travelled, but it does not actually shorten the throw. |  |
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Automatics suck, but there are some people who still insist on buying them. All automatic Z31s used the 4N71B transmission. Change the fluid every so often, and check the level every time you change your engine oil. Also, if you overheat your car for whatever reason and it has an automatic, CHANGE THE TRANSMISSION FLUID IMMEDIATELY!!! If you don't, your transmission will blow up as a result of the fluid getting overheated in the cooler and burning inside the transmission, and this is bad. Of course, you could avoid this by putting in a manual transmission, and have more power and economy to boot! The overdrive switch in the automatics has a temperature sensor that does not allow the transmission to shift into overdrive until it is sufficiently warmed up to avoid possible damage. Level 10 makes an upgrade that will allow your transmission to hold 500+ hp. Click here for more details.
All Z31 transmissions are completely interchangable. They have no problems bolting up to the motor. One problem is they don't always mount to the body correctly. You may have to drill and tap new holes for the transmission mount. Another problem comes in when you try to mount the driveshaft. Each transmission has it's own output shaft size and overall length. Finding the appropriate driveshaft for a two seater is no problem. Just find another two seater that had the same transmission and take that driveshaft. If you have a four seater, you're going to have a more difficult time. Only in Canada did the North American market get a turbo four seater. And almost all of them were automatics. So you'll need to find the appropriate driveshaft for the transmission you just bought and have the driveshaft lengthened. If you get a FS5W71C, there are plenty of 2+2 5 speed models around.
The only thing left is to determine if your differential companion flange is correct for the driveshaft. The 84 to 86 had a different style than the 87 to 89 models. If you swap to the NA transmission, find the appropriate driveshaft for your year to save money. If you go from the FS5R90A (T5) to the FS5R30A (Nissan Turbo), you will also need to buy the appropriate companion flange.
There are several different manufacturers of lighter flywheels for the Z31. The non-turbo and the 84-86 turbo came with a 240mm flywheel. The 87-89 turbo came with a 250mm flywheel. This isn't the overall diameter of the flywheel, it is the diameter of the clutch surface area. The overall diameter of the flywheel is the same. Different manufacturers have made these different ways. Some will include the different mounting holes for the different sized/spaced clutches. You can use any Z31 flywheel in any of the manual transmissions. Just be sure you use the appropriate clutch. Be aware that using some of the FS5R30A clutches on the other transmissions may require you to grind down some of the inside of the transmission bell housing to fit properly.
| FS5W71C 1984-1989 | FS5R90A 1985-85 | FS5R90A 1986 | FS5R30A 1987 | FS5R30A 1988-89 | 4N71B | |
|---|---|---|---|---|---|---|
| 1st | 3.321 | 3.350 | 3.350 | 3.324 | 3.324 | 2.458 |
| 2nd | 1.902 | 2.056 | 2.056 | 2.077 | 2.077 | 1.458 |
| 3rd | 1.308 | 1.376 | 1.376 | 1.360 | 1.360 | 1.000 |
| 4th | 1.000 | 1.000 | 1.000 | 1.000 | 1.000 | 0.686 |
| 5th | 0.759 | 0.779 | 0.752 | 0.760 | 0.711 | ----- |
| Rev | 3.636 | 3.153 | 3.153 | 3.382 | 3.382 | 2.400 |
Transmission Fluid Levels:
| trans | models | capacity | type |
|---|---|---|---|
| E4N71B | automatic | 7-3/8 qt | Auto Trans DEXRON |
| FS5W71A | 84-89NA | 4-1/4 pt | API GL-4 |
| FS5R90A | 84-86T | 4 pt | API GL-4 (SAE 80W-90) or type DEXRON |
| FS5R30A | 87-89T | 5-1/8 pt | API GL-4 |
Fluid Temperature Ratings:
| temps * | weights |
|---|---|
| below 50oF | 75W |
| below 86oF | 80W |
| below 104oF | 75W-90 80W-90 |
| between 14oF and 86oF | 85W |
| between 32oF and 104oF | 90W |
| above 50oF | 140W |