Suzuki Jimny

Originally belonging to the kei class, Japan's light automobile tax/legal class, the company continues to market a kei-compliant version for the Japanese and global markets as the Jimny, as well as versions that exceed kei-class limitations. Suzuki has marketed 2.85 million Jimnys in 194 countries through September 2018.

History

The history of Suzuki four-wheel drive cars began in the latter half of the 1960s, when Suzuki bought a Steyr-Puch Haflinger to study with the intent of building a kei-class off-road vehicle. A better opportunity presented itself in 1968, when Suzuki was able to buy bankrupt Japanese automaker Hope Motor Company, which had introduced a small off-road vehicle called the HopeStar ON360. The tiny Hope company had been unable to enter series production, and only about 45 were manufactured. The first Suzuki-branded four-wheel drive, the LJ10 (Light Jeep 10), was introduced in 1970. The LJ10 had a 359-cc, air-cooled, two-stroke, in-line two-cylinder engine. The liquid-cooled LJ20 was introduced in 1972 with the cooling changed due to newly enacted emission regulations, and it gained 3 hp. In 1975, Suzuki complemented the LJ20 with the LJ50, which had a larger 539 cc, two-stroke, in-line three-cylinder engine and bigger differentials. This was originally targeted at the Australian market, but more exports soon followed.

The Jimny8/LJ80 was an updated version of the LJ50 with an 800 cc, four-stroke, in-line four-cylinder engine, followed by the Jimny 1000/SJ410 and Jimny 1300/SJ413. An updated version of the SJ413 became known as the Samurai and was the first Suzuki officially marketed in the US. The series from SJ410 to SJ413 was known as the Sierra in Australia, and remained the Jimny in some markets.

The new Jimny was released in 1998, and now bears the same name in all markets. The 1998 release used the G13BB EFI engine, replaced by the M13AA EFI engine in 2001 and the M13AA variable valve timing engine in 2005, in conjunction with a minor interior redesign.

Overall construction

All four Jimny generations have separate frame and body ("ladder frame chassis"). The body has no structural carrying role. It serves only as a cabin to protect the occupants from the elements, provide comfort, and protect them in the case of a crash.

Suspension

All four Jimny generations have dependent suspension (solid-beam axles) both at the front and rear axles. This used to be a common suspension design for all-terrain vehicles up to 1990s, but has become a rarity in vehicle design in the 21st century. Dependent suspension is particularly well suited for all-terrain duty, both from the durability and performance perspectives.

The first two Jimny generations used leaf-sprung suspension at all four wheels, with the third and forth generations using coil-sprung suspension at all four wheels. Some late second-generation models had coil-sprung suspension, as well.

Steering

All four Jimny generations have recirculating=ball steering mechanism, which is particularly well suited for all-terrain duty, but relatively imprecise on-road compared to modern rack-and-pinion steering construction.

Transmission

All four Jimny generations have manually user-selectable part-time four-wheel drive (4WD) transmission, where the default (on-road) transmission mode is two-wheel drive, rear-wheel drive). Rear-wheel drive can never be disengaged. The user, however, can (dis)engage the front-wheel drive (FWD) manually at any time under certain operating conditions. When FWD is also engaged, this provides 4WD.

Jimneys have no centre (interaxle) differential. This has a positive effect that at least two wheels, where each wheel is on a different axle, have to lose traction for the vehicle to lose traction when in 4WD transmission mode. However, the negative effect is that 4WD transmission mode must not be used on any surface not rather slippery, especially if having to steer. In other words, 4WD transmission mode should be used only on rather slippery surfaces, like snow, ice, mud, loose gravel, wet grass, and sand. Wet asphalt, wet concrete, and hard-packed gravel are not considered slippery enough. All this is irrelevant when not using 4WD transmission mode.

All four Jimny generations have manually user-selectable dual-ratio (dual-range) gearing mechanism. The two ratios or ranges are called "high range" (for regular on-road driving and light to moderate all-terrain driving) and "low range" (for moderate to hard all-terrain driving and for all-terrain towing). The overall transmission gearing ratio is exactly halved when the vehicle is in low=range transmission mode. This has the effect of the vehicle moving about half as fast, but with double torque at the wheels in any transmission gear. For example, the fourth gear in low range behaves similar to the second gear in high range, andthird gear in low range behaves similarly as "1.5th gear" in high range. The transmission gearing range is selectable only when the vehicle is in 4WD transmission mode. Therefore, low range cannot be used for on-road towing.

The (dis)engagement of 4WD transmission mode and the switch from one gearing range to another is performed by a dedicated transfer case mechanical unit, which is separate from the regular gear box unit. All four Jimny generations have a transfer case with an attached selection lever protruding in the cabin between the main gear box lever and the handbrake lever. The lever allows the user to select 2WD-H, 4WD-H or 4WD-L transmission modes at will. The only exceptions are later production years of third-generation Jimnys (more info in a dedicated chapter), which do not have a selection lever, but instead have servo-actuated mechanism to perform the same actions when invoked by the push of certain buttons in the cabin.

Factory rear differential locker

LJ80, SJ410, and early SJ413 vehicles sold in Germany (and perhaps in some other countries) were fitted from the factory with a manually operated, mechanical rear differential locker. A cable connected the locker to a small, dedicated lever in the cabin near thehand brake lever. By operating the lever, the driver could manually fully (un)lock the rear differential.

The reason for inclusion of the differential locker was legislative in nature. LJ80s, SJ410s, and early SJ413s had a parking brake that locks the gears in the transfer case instead of braking the individual rear wheels directly and simultaneously (like in most passenger vehicles). That design has several advantages, as well as an important disadvantage - because of the open rear differential, the handbrake has no effect when the transfer case is in two-wheel drive (rear-wheel drive) mode and when one of the rear wheels is raised in the air. Therefore, relying on the parking brake itself would be dangerous in some relatively rare situations. German law required that this risk must not exist. Instead of redesigning the parking brake system for that market, Suzuki appeased the legal requirement by the inclusion of a rear differential locker.

Later SJ413s (and all Samurais) have a parking brake that simultaneously brakes both rear wheels directly (like in most passenger cars), so the parking brake alone could hold the vehicle still in any situation, at least in theory. This parking-break design appeased the German legal requirement, so no differential locker has been factory fitted to such SJ413s nor to any Samurai, nor offered as an optional equipment.

A retrofit of a genuine rear differential locker to LJ80s, SJ410s, and SJ413s, which lack it, is possible by using the parts from a dismantled LJ80 (usable on another LJ80 only), SJ410,or early SJ413 (usable on both SJ410 and SJ413, which had that locker. A retrofit from SJ41x is not easily possible onto a Samurai because of wider track and axle than SJ41x.

HopeStar ON360

The vehicle was originally developed by the Hope Motor Company of Japan in 1967 and available as the HopeStar ON360 from April 1968. It used a Mitsubishi 359 cc (21.9 cu in) air-cooled, two-stroke ME24 engine, which produced 21 PS (15.4 kW; 20.7 bhp) at 5,500 rpm, and 32 N⋅m (23.6 ft⋅lb) of torque at 3,500 rpm. Brakes were Daihatsu units, the rear axle was sourced from the Mitsubishi Colt 1000, and the wheels were sourced from the Mitsubishi Jeep. It was a very basic two-seater vehicle with no doors, but a sturdy 4WD system allowed it to go off-road. Top speed was 70 km/h (43 mph), 30 km/h (18.6 mph) in four-wheel drive mode. The tiny Hope company sold very few ON360s, only 15 in the domestic market and another 30 exported to Southeast Asia, although 100 ME24 engines were purchased. Hope proceeded to sell the design to Suzuki in 1968, after Mitsubishi declined to take over production.