Datsun used three 5-speeds for U.S. Zcars

One version from 1977-80

One version from 1981-83

Most Common Questions About Swapping Later Transmissions in the 240Z model.
1. Will a 5spd. from the 280Z or 280ZX fit in my 240Z?
2. What needs to be changed in addition to the transmission when putting a newer style 4spd. or 5spd. in my 240Z.
3. Will the newer style transmissions bolt right into the older Z Cars?
4. Are the shifters interchangeable?
5. What else needs to be changed along with the newer style transmission when installing it in the older style Z Cars?

Background:
Datsun used a three piece case design for the four speed transmissions installed in the Z Car from 09/69 through 07/71 (FW471A). With the introduction of the 1972 Model Year 240Z's in 07/71 Datsun introduced their redesigned four speed transmission (FW471B). The newer "B" style transmission utilizes a two piece transmission case so it is easy to tell the two apart. (see the picture below)

In addition to the redesigned case, the newer transmission had a redesigned shift lever and associated shifting mechanism. This resulted in the shift lever being moved about 2.25 inches toward the front of the car. In turn, the area cut out of the transmission tunnel for the shifter to enter the passenger compartment was also re-located farther forward in the cars produced from 07/71 forward. This in turn drove the need for a redesigned center console with the area for the shift lever also moved forward (the center console for the "72"+ model year 240-Z's has the ashtray located behind the shifter).

Given the oversized area cut-out in the sheet-metal of the transmission tunnel, for the shift lever in the first place, it is not necessary to remove an additional 2.25 inches of sheet-metal to install the newer style transmission in the older style bodies. Something less than an inch of additional space has to be provided. That, or the shift lever on the newer style transmission has to be bent in an "S" shape, to provide the necessary clearance.

On early 240's, you will have to cut a small amountof metal from the front/right edge where the shifter goes through the trans tunnel when using a 5-speed. Otherwise the throw into 5th gear will hit. This cutting is the price of a 5-speed trans and is not a big deal at all, the console covers it.

Nissan called the '77-80 trans a "wide ratio" while the '81-83 was called a "close ratio" 5-speed. The early one has the lowest 1st/2nd gears for acceleration, but a wide spread between 2nd and 3rd. The later one has a taller 1st/2nd but a tighter spread between 2nd and 3rd. It also has a much taller 5th for cruising. Your choice.

The early 5-speed is a 4-speed with 5th and reverse sharing the same fork. He said it's common for people to "blow" 5th gear as the fork is weaker. He stated the later 5-speed is a genuine 5-speed which is stouter. I call the early one a 280a and the later a 280b to keep them straight.

Looking a little closer - in the picture below you can see that the centerline of the shifter on the type "A" transmission in the foreground (line #3); sits 2.25 inches behind the center line of the shifter on the type "B" transmission (line #1). Line #2 is the rear end of both the transmissions.

The type "B" transmission shown in the pictures above has the Nissan Competition Shifter installed (Part #. As you can see, it is shaped in an "S" curve so that the newer style transmission can be installed in an early style Z car. The stock shift lever is more or less straight on the newer "B" style transmissions. Therefore one needs to either: a) remove additional sheet-metal from the transmission tunnel toward the front of the car, or b) bend the stock shift lever in an "S" curve or, c) order the Nissan Competition Parts "Shift Kit" Part number 99996-E3030 - shown installed in the picture.

Either Transmission: will direct bolt to any of the "L" series six cylinder blocks. The output spline is the same on either transmission - so any drive shaft that fits one, fits the other as far as the output spline is concerned. The shifters are not interchangeable between the type A and Type B transmissions, nor are they interchangeable between the 4spd. and 5spd.

When installing the newer style "B" transmissions in Z Cars built before 07/71 make sure that you have at least 1/2 inch of clearance ahead of the shift lever when it's in 1st. , 3rd and 5th gear. If the sheet-metal on the transmission tunnel interferes with the shift lever the transmission will pop out of gear, because it was not fully engaging the gear to begin with.

LUBRICANT

The trans specs call for 75/90 gear oil or ATF.

75/90 has a lot of additives and cushions the gears and synchros well, but gets thick in cold temperatures.

ATF (10W) is used to give quicker shifting and gear engagement, and makes cold weather shifting easier.

Some people use ATF in normal Z transmissions. But I don't think that's wise: 1970's transmissions are designed for a heavier oil to cushion the brass synchros and gears. The later T5 can use ATF because it was designed to, not because the oil is superior.

There are 2 rear trans-crossmembers on 1st generation Z's.

On 1970 style bodies they came with a one-piece unit with a single hole in the center, with 1 vertical bolt on each side into the frame.

On later 240-280's they were a heavier two-piece mount with 1 horizontal rubber bolt/bushing on either side.

You also need to check the the exact position trans tailshaft and the driveshaft. Transmissions have to indexed inline with the differential flange, no angles in the driveshaft in any direction...you should have 2 degrees or less angle between the two. Use washers between the rear trans member and the bracket to raise and lower the rear of the trans to adjust this.

DIFFERENTIAL FLANGE

The differential flange used on all ZCARs from 1970 through '83 was a round 4-bolt design that took 8mm bolts.

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Yes, a real Borg-Warner 5-speed came in the turbo 280ZX. It arrived at the end of the L28's life, when hydraulic heads, CV axles, and engine management systems were coming on the scene. It's a first generation Borg-Warner T5 like the ones in early 1980's Mustangs while the bell housing was replaced with a special Nissan version to let it fit onto a L6 motor. Datsun was worried a stock 5-speed wouldn't hold up which is why the 1981 turbo only came with an automatic.

While this isn't the "world class" T5 you find in late '90s cars, people have been racing Mustangs with them since the early 1980's with great results. The shorter 1st and 2nd gears of this model are slanted towards helping a turbo engine off the line, I believe this was rated to take 265 ft/lbs of torque which is fine for a 6-cylinder.

Borg-Warner doesn't make T5 transmissions anymore.

TRANSMISSION TIPS

Don't unscrew the large 22mm nut on the top/driver side of the transmission. It's NOT the oil filler nut. It's really the pivot bolt for the shifter arm that controls reverse. If you take it out it disconnects the arm and drops a circlip into the bottom of the trans. You have to completely open the trans case to reset everything.

If you do have to open the case, take off the shifter, and drive a pin out of the main shifter rod and slide off the rear housing after removing 8 large bolts around the housing. This allows you to take the top cover off the trans and remove the shifter to expose the gears.

The Nissan T5 came with a poor-quality shifter, it's simply a straight rod out of the top of the trans.

FORD SHIFTER: Over the years Ford perfected the T5 shifter, the late 90's Ford Mustang shifter being the one to use on a T5. The dogleg angle greatly improves leverage and shifting feel. It also has a hard rubber damper that cuts down on buzziness. The only downside is that when in 1st, 3rd and 5th gears the shifter arm sits about 2 inches forward of the stock one on a first generation Z. This means you will need to modify the front of the console a bit. However, it improves shifting, smoothness, and overall drivability by such a huge amount it's worth the trouble.

THE BETTER SOLUTION: As good as the Mustang shifter is we recommend getting a true "short-throw" version. B&M and Summit Racing are the ones to use. The Summit version has a nice fat arm with cool gated spring action from side to side and the baseplate is solid aluminum. The T5...feels like a Formula 1 car now, very solid and fast, a major improvement over the excellent Mustang shifter....no kidding!

The T5 came with a L6 Nissan 2+2/turbo clutch and respective flywheel. Interestingly, while the turbo and coupe flywheels are identical in weight (23 lbs), the turbo clutch cover is measurably heavier. It's much stouter, with thicker fingers and metal case, and sits higher. Using a turbo clutch adds unwanted weight and inertia to the engine. Use the widely available "Zoom" brand coupe clutch (after changing the throwout bearing collar from 2+2 back to a coupe version).

The trans specs call for 75/90 gear oil or ATF.

75/90 has a lot of additives and cushions the gears and synchros well, but gets thick in cold temperatures.

ATF (10W) is used to give quicker shifting and gear engagement, and makes cold weather shifting easier.

This T5 lore may be why some people use ATF in normal Z transmissions. But I don't think that's wise: 1970's transmissions are designed for a heavier oil to cushion the brass synchros and gears. The T5 can use ATF because it was designed to, not because the oil is superior.

There are several ATF versions though, make sure you don't get "Type F" or "ATF+3". "Dexron-3/Mercon" is what you want. All brands have to meet the same standards to say Dexron3/Mercon, some use synthetic-blend Valvoline ATF.

The Nissan T5 came with a special driveshaft to fit the 280ZX. It is stouter and fatter than other Z driveshafts, has a different spline count on the front end, and a square flange on the rear. In other words, the only driveshaft that will fit the T5 is the one that came with it. A 240/260/280 driveshaft cannot be modified to fit.

LENGTH: The T5 driveshaft is almost the same length as regular Zcar driveshaft, but the T5 transmission is a few inches longer. This means if you use a Nissan T5 trans/driveshaft in a first generation Z the driveshaft will be too long by about 2-3 inches. The solution is to have a custom driveshaft made, or have the stock one shortened. Most driveshaft shops can fabricate one if you tell them what you want, about $300. A cheaper solution for us budget ZCAR people is to have the stock one shortened and rewelded, about $100. This gets tricky because driveshafts should be shortened only at the ends for balance reasons. And for some reason Nissan T5 driveshafts neck down to smaller diameters right at the flanges. This means that after cutting, the yoke and flange ends are too small to weld up to the center tube.

The turbo T5 cars used a special square flange with 10mm bolts. The bolt-holes are also in a slightly larger parallelogram shape (not quite square) like the earlier flange.

The bolt holes might look spaced similarly, but they're not. You can't drill or modify the older flange though or you would damage it and throw off the balance. This flange used to be available from the Nissan dealer for $55. On the parts list of 1983 R200 differentials, it's the flange for the 5-speed turbo L28E. If you can't find the flange at the dealer, try to find a turbo differential in the junkyard. Even if you don't need the differential buy it just to get the front flange home. When you get there you will need to use an /impact wrench to break loose the 24mm nut on the front of the differential, then use a puller to draw out the flange. The new one then slips on by tightening the nut back on. Torque it to 130lbs.

This is the rear crossmember that holds up the back of the transmission. The T5 uses the same rubber trans mount as the other Z transmissions, but the mount sits rearward about 2 inches, making the crossmember bolt-up tricky but not hard. You have to be a little ingenious and fabricate one yourself.

The spread of the ratios feels great. Compared to a 1977-80 5-speed 1st is very low making 0-60 runs much quicker and there is a tighter spread between 2nd and 3rd. 5th gear is also very high, and 70mph with my 4.11 is only at 3500revs.

With the stock shifter, the action is different from a standard Z. It has shorter throws between 1st/2nd, 2nd/3rd, 3rd/4th and at first might feel a bit notchy. However, this notchiness is actually caused by the poor stock Nissan shifter, not the transmission. The solution is to replace the shifter with a short-throw one which transforms it into a completely different transmission.

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NOTE: There are 2 different aluminum cog "sleeves", a '75-80, and '81-83 with different cog "offsets". If you look closely in the picture above notice how the red cog is offset slightly to the right, and the blue to the left. This means you must keep the sleeve with the transmission it came in, and only swap the cog. Otherwise the cog may not mesh the proper way inside the trans. The weird one is the larger red 4.11 cog which requires a later ZX sleeve to fit into the older '77-'80 trans. But will the red cog fit into a later 280b? I don't believe so since the red cog is much larger than the white. So I'm using a white cog on my 4.11 rear which makes my speedometer read 10mph fast.

Flywheels are identical in diameter and weight at 23 lbs (only the contact area is wider). But a turbo pressure plate and disc clutch are heavier than the coupe version by a few pounds. So how much performance is actually lost with a heavier turbo clutch assembly? Truthfully the only time you really need a stronger clutch is if your engine torque overpowers the clutch and causes it to slip. I

Measure the width of your flywheel's shiny clutch contact surface.

If it's 225mm wide then you have a coupe version which uses a 550lb pressure-plate.

If it's 240mm wide then you have a 2+2/turbo version with a 780lb plate and a wider disc.