Contents

• Introduction
• Engine
• Drivetrain
• Brakes
• Suspension
• Body
• References/Bibliography

The Datsun/Nissan 720 pickup was Nissan's first foray into the 4 wheel drive mini-pickup market. It was introduced as a 1980 model and continued until 1986 when the current Hardbody style (model D-21) was introduced as a 1986.5 model. Prior models of Datsun/Nissan mini-pickups were the 521 and 620 which did not offer a 4 wheel drive option. The 720 features an independent front suspension with torsion bar springs, a leaf spring live axle rear suspension and a 4 cylinder engine displacing 2.0 litres at introduction later enlarged to 2.4 litres. Longbed and extra-cab models were also available.

Nissans have a reputation for having aftermarket parts that are expensive and hard to find. However, there are still quite a few significant aftermarket modifications you can make to your truck. Also, with a cutting torch and welder, anything is possible. Some wilder modifications I've seen were a 720 body over a shortened Chevy frame and drivetrain and another one with a solid front axle conversion.

Much of this document is centered towards the 4wd variant of the Nissan 720 pickup. However, some of it may be applicable to the 2wd variants as well.

Additions, corrections and suggestions are welcome. Please send them to the e-mail address above. I should also add that while I have made every effort to ensure the information in this document is as accurate and safe as possible, it is provided for your assistance only on an as-is basis. I am not responsible for anything that happens as a result of you modifying your truck.

1. Description

The 1980 model featured the L20B engine which essentially was a carryover from the 620 model trucks that preceded the 720. It was a single overhead cam engine displacing 2 litres. The 1981-1986 models had the Z series carbureted engine which featured a single overhead cam operating adjustable rockers, crossflow head and dual spark plugs for each cylinder. 1981-1983 models had 2.2 litres of displacement designated Z22 while 1984-1986 had 2.4 litre engines designated Z24. 1984-1986 models had computer controlled carburetors with an oxygen sensor in the exhaust manifold.

Engine |  HP @ RPM  | Ft-lbs @ RPM
-------+------------+-------------
L20B   |  97 @ 5600 | 102@3200
       |            |
Z22    |  98 @ 4000 | 117@1800
       |            |
Z24    | 103 @ 4800 | 134@2800

2. Things to watch for

The Z24 engines are reputed to be prone to head gasket failure and not last more than 100k miles. As with all aluminum head engines, overheating the engine will likely warp the head. Be sure to maintain the cooling system in proper working order by changing the fluid every year or two, checking the radiator level regularly and making sure the thermostat is operating properly.

If you replace the head gasket yourself, the operation is mostly straightforward with the exception of the timing chain tensioner. The recommended service procedure is to shove a piece of wood between the chain guides so that the tensioner doesn't slide out of its bore and the chain doesn't fall down into the front cover and lose its alignment against the crankshaft pulley gear. However, I've had the head off of two different Z series engines and in both cases, the tensioner fell out of its bore. The first time was in a friend's truck and he was able to remove the distributor and oil pump and maneuver the tensioner back into its bore. The second time was in my truck and I gave up and removed the timing cover. Significant portions of both the head gasket and the oil pan gasket contact the timing cover so removal and installation of the timing cover without removing the oil pan and head can be tricky. Access to the oil pan is extremely difficult without dropping the front differential.

While you have the timing cover off, replace the front crankshaft seal; it's cheap insurance against oil leaks. Also, Nissan Motorsports (through your Nissan dealer), sells a timing chain tensioner with a retainer so that it doesn't slip out of its bore. It may be useful if you anticipate removing the head and/or cam in the future and it costs around $80. See the Nissan Motorsports Parts Catalog for details.(*)

Another thing to watch for is the exhaust head pipe where it joins to the exhaust manifold. It contains a 2 into 1 Y connection which is prone to cracking. Look for cracks in the webbing at the center of the Y. From the factory, there is a heat shield over this section of the head pipe. It may be beneficial to leave the heat shield off to prevent stress on this section.

3. Modifications

Modifications that are 50 state legal include replacing the exhaust system aft of the catalytic converter and a K+N air filter. Apparently, the head pipe between the manifold and the cat is 2" diameter while the system aft of the cat is 1 3/4". Going to a 2" cat-back system will help reduce backpressure. My local muffler shop recommended against going larger since you may lose low end torque. The K+N part number for their replacement air filter is E-2760 and can typically be had for under $30.

Mostly smog legal modifications include a high energy ignition and an exhaust header. Jacobs makes a high energy ignition system. I have heard that it improves throttle response but does not add much power. Doug Thorley makes an exhaust header with smog fittings that bolts to the stock head pipe for around $250. They are chromed and come with a lifetime warrantee. Pacesetter supposedly makes a header without the smog fittings and requires modification of the head pipe.

Not quite smog legal modifications include a cam regrind from Automotive Customizers or Nissan Motorsports. Without increased intake flow from a new carburetor (see below) it's effectiveness is somewhat limited. Nissan Motorsports also sells high performance pistons. See the Nissan Motorsports Parts Catalog for more information.(*)

While definitely not smog legal, adding a Weber carburetor can significantly increase your horsepower. Hardbody and Pathfinder owners are known to snatch 720 intake manifolds because later fuel injected engines won't take Webers. Nissan Motorsports also sells 44mm dual 2bb Mikuni side drafts for the Z series engines. See the Nissan Motorsports Parts Catalog for more information.(*)

Advance adapters makes mounts, headers and adapters for swapping in a GM 4.3 litre V6. They also have adapters for TH350 and 700R transmissions to connect to the transfer case.

1. Description

The transmission on the 720 drives a divorced transfer case (that is, transfer case is separate from transmission). Later model Hardbodies and Pathfinders have a transfer case that is "married" (attached) to the transmission. The transmission shaft enters the transfer case at the top while front and rear driveshafts exit from the bottom. The transfer case is protected by a good sized rock shield and the selector lever is located between the driver and passenger seats.

June 1983 and earlier trucks use a H190 rear end (190mm) which is the same as used on the previous 620 trucks. July 1983 and later trucks (including 4cylinder Hardbodies to 1992) use a C200 rear end (200mm). This is incompatible with Pathfinder and V6 Hardbodies which use the H233B (233mm) rear end and the Patrol which uses another completely different rear end. All 720s use a R180 front differential (180mm).

Both automatic and manual locking hubs were offered from the factory on the 720. The auto locking hubs are of the variety that you must stop the truck to engage the hubs and back up 3 meters to disengage. With the hubs engaged, 4H can be engaged at speeds up to 50mph.

2. Things to watch for

The divorced transfer case is known for making noise when the system is worn or abused. If inspecting a truck for purchase, pay particular attention to this. Synthetic gear lube may help.

The front axle employs half shafts with constant velocity joints (CV joints). Be sure to periodically inspect the rubber boots for cracking or leaking.

3. Modifications

As of yet, the only lockers that are available for the C200 rear differential are ARB Air Lockers for the rear differential. According to Nissan Motorsports, Detroit Locker makes a locker that will fit the H190 rear differential. However, the 3/8" holes will have to be drilled out to accept the 10mm bolts used in the H190. See the Nissan Motorsports Parts Catalog for details.(*)

Limited slip assemblies are available from Nissan for the C200 rear differential and the R180 front differential. See the Nissan Motorsports Parts Catalog for details.(*)

If the paucity of available lockers has you down, you can swap in an '86 and up Toyota 8" rear axle. The spring pads and hydraulic brakes lines just bolt on. However, the emergency brake cables will have require rigging a mixture of Nissan and Toyota parts. You'll need a Spicer-to-Toyota yoke available at most good driveshaft shops. The Spicer end is the same as that for a 1/2 ton full-size Chevy. Note that Toyota used both a rectangular and a square bolt pattern. Either one will work but be sure to use the correct yoke.

Centerforce clutches are also available for these trucks. The 1980 L20B engine uses the same 225mm clutch as the 1981-1983 Z22 engines. The later Z24 engines use a a 240mm clutch.

The 720 came stock with 215/75R15 size tires which are 28" in diameter. 30x9.5-15 size tires will fit at stock height with no rubbing while 31x10.5-15's will fit with some rubbing. I wouldn't recommend tires larger than 31" without swapping in lower gear ratios anyways. See the Nissan Motorsports Parts Catalog for available gear swaps. (*)

1. Description

The brake system in this truck is very conventional with front disc and rear drums being used. 1980-1983 models use 2 opposing pistons in front with the outward facing piston pushing against a yoke. Later model trucks use a single piston caliper. A load sensing valve is mounted to the frame ahead of the rear axle to modulate the brake pressure to the rear brakes. This valve is not serviceable. When bleeding the brake system, be sure to bleed the load sensing valve first.

2. Things to watch for

The brake pads and shoes do *not* employ a wear sensor. Therefore, they will scratch the rotor and/or drums without warning when they wear out. Check the condition of these items frequently.

While you are checking the condition of the front pads, also keep an eye on the flexible rubber hoses that run from the frame to the calipers. Make sure they are not cracked or leaking. These rubber brake hoses are relatively expensive (around $70).

3. Modifications

Stainless steel brake hoses can actually in some cases be cheaper than the factory rubber hoses. Earl's Performance Products' stainless steel brake hoses cost roughly half as much. However, Earl's hoses are *not* completely DOT certified for street use. They meet all of their criteria except one. You have been warned; it's not my fault if you install them and they fail on you.

1. Description

All Nissan 720s use a conventional live axle suspended by leaf springs the rear and an independent front suspension with torsion bars attached to the lower A-arms. 1980-1983 trucks use tension rods (trailing links from a forward crossmember to the A-arms) to control caster while later trucks use compression rods (leading links from the A-arms to a rearward frame member). The rear of the 4wd models have the spring over the axle while 2wd models have the spring under it. Some people complain that the rear springs are too stiff. I personally don't notice it. However the rear doesn't sag when I tow and I don't see any 720's riding nose high like I do IFS Toyotas.

2. Things to watch for

Rubber bushings are subject to deterioration, especially the tension/compression rod bushings.

The front suspension often has problems with camber. Mine is is maxed out on adjusting shims and it still has half a degree of negative camber. Polyurethane bushings in the A-arms wear out quickly and create substantial play in the front end to the point where front end alignment is difficult. Stock rubber bushings work better here.

Stock torsion bars can sag with time and lose their springr rate. They can also twist and break the mounts to which they are attached. The A-arm nuts which hold the pivot shaft have also been known to come off or loosen. A 1/8" hole drilled through the nut and A-arm pivot shaft with a cotter pin inserted will solve the problem.

3. Modifications

Polyurethane bushings from Energy Suspension, Dick Cepeck, and ProThane are available for the rear leaf springs and shackles, front compression/tension rod, front A-arms and shock absorber eyes. I won't get much into the debate between rubber and polyurethane, but suffice it to say that the hardness of polyurethane bushings give better handling and they are much more resistant to rotting and contamination. However, the softness of rubber bushings give a softer ride and may allow for more suspension travel.

For lifting the front of the truck, Superlift makes upper control arms designed for 1.5"-3" of lift over stock. Front lift is accomplished by turning the torsion bar adjusting bolts at the rear crossmember. Rancho makes a heavy duty torsion bar while dual stage torsion bars are available from Nissan Motorsports and Automotive Customizers. The heavy duty bar can make highway driving stiff while a dual stage bar will retain the softer ride on the highway while providing a secondary rate for heavy duty and off-road conditions.

To lift the rear of the truck, Superlift makes longer shackles for a 1" lift. Several other companies (Rancho, Hellwig, Rugged Trail) offer add-a-leafs. The 1980-1982 trucks use a different spring rate than the 1983-1986 trucks so an add-a-leaf on an early truck will raise the rear 1"-1.5" but will raise the rear of a later truck 2"-3".

Double shock kits are also available from Nissan. See the Nissan Motorsports Parts Catalog for more information.(*)

Body

1. Description

Sometime during the model run of the 720, the manufacturer's name changed from Datsun to Nissan. The name change began 1983 while 1984 was the first complete year that they were called Nissan. Long bed and King Cab bodies were available for both 2wd and 4wd models.

4 different hoods and 3 different beds were used throughout the life of the 720. The distinct hood styles are 1980, 1981-1982, 1983-1984 and 1985-1986.

1980-1982 models can be identified by a bed with an outside facing lip, rear tail lamp assemblies mounted horizontally down near the bumper line and an exposed weld (see "Things to Watch For" below). 1983-1984 models also have outside facing lip and exposed weld but the rear tail lamp assemblies are mounted high up on the corners with a vertical orientation. 1985-1986 models have smooth sided beds with inside facing lips and tail lamp assemblies mounted vertically high up on the corners.

The 1980-1982 models have a dash pod with square instruments while 1983-1986 models have a dash pod with round instruments. Tachometers and clocks in the pod were optional and are actually quite rare. Certain 4wd models also have a voltmeter and oil pressure gauge located below the climate controls and above the stick shift.

Cornering lamps, bumpers, front aprons, headlight cases and grilles are consistent between the 1983-1986 models. The same parts are also consistent between 1980-1982 models. Most other body parts are interchangeable between any model year.

2. Things to watch for

As mentioned above, the 1980-1984 trucks have a bed with an exposed weld that is very susceptible to rust. Even in California, I've seen rust along the weld lines of these beds. The seam is located about 1/4th the way up from the lower edge and runs the entire length of the bed. 1985 and 1986 models have smooth sides which aren't nearly so susceptible.

3. Modifications

The bench seats are notorious for being uncomfortable. The 720 came with both bench seats and bucket seats and therefore have mounting points for both. Measuring the mounting points and finding a substitute seat in the junk yard will help make the truck more bearable on long drives. I hear that Mazda 626 bucket seats will fit.

Both 2" and 3" body lift kits from Automotive Customizers, Performance Accessories and Rugged Trail are available. See the above "Drivetrain" section for recommendations on lift height vs. tire clearance.

The stock speakers are located in the side kick panels in front of the door and are hard to get to. Aftermarket 5" speakers can be installed in the doors but involve some cutting of metal.

If you don't have the factory voltmeter and oil pressure gauge, the space in the console above the stick shift and below the climate controls makes a great space to mount a fog/driving light switch or aftermarket gauges. I had a friend fabricate a polished aluminum panel for that spot and I fastened it with black 4-40 socket head hex screws from a hobby shop.

References/Bibliography