Being an FWD vehicle, the Subaru 1000 has drive shafts at the front and both ends of these are connected by constant velocity joints. 

The constant velocity joint comprises a CVJ (Constant Velocity Joint) on the wheel side and a telescopic DOJ (Double Offset Joint) on the differential side. This use of two constant velocity joints basically resolves the issue of unpleasant vibrations that occur during turning and acceleration when using a cross-shaped joint. 

Features of the two constant velocity joints are as follows: 

• ・The constant velocity joint does not have the bend moment act on the shaft as in the case of a cross-shaped joint; it is compact; moreover, because it has no imbalance, it has little vibration and can run quietly. 
• ・Because the ball conducts smooth rolling movement, it entails hardly any loss. 
• ・Because the joint is sealed, there is no need for greasing. 

(Note) The Subaru 1000 was the world’s first mass produced car to adopt drive shafts based on combination of this DOJ and CVJ.

(Source: Extracted from the Subaru 1000 Sales Sheet 1966-1) 

Center pivot steering system

 The Subaru 1000 adopts the center pivot steering system whereby the brake drums are separated from wheels and the kingpin axis line is aligned with the tire centerline.
 When the brakes are located inside the wheels as in commonly adopted steering systems, it is difficult to insert the kingpin into the wheel and it is impossible to align the tire centerline with the kingpin axis line.

[Features of the center pivot steering system]
- Tire friction with the ground surface is minimized and steering effort during low speed driving is lightened. 
- Weight under the spring is mitigated, ground contact of the tire is improved and better performance is realized in terms of ride quality and running stability because road impacts are not so quickly transmitted to the handle.
- Since a larger steering angle can be secured even in the same size tire house, it is possible to reduce the turning radius.

(Note) Because an aluminum alloy front brake drum equipped with numerous fins is adopted, this provides excellent cooling effect

(Source: Extracted from the Subaru 1000 Sales Sheet 1966-1)

Brakes

The Subaru 1000 uses highly effective duo servo brakes on the front and stable leading-trailing brakes on the rear. Since the braking balance of the front and rear brakes is appropriately set, braking is certain and safe. Moreover, both the front and rear brakes are the automatic adjusting type.

Parking brake is a hand operated brake acting on front wheels.

[Inboard brakes]

Revolutionary inboard type brakes are adopted as the front brakes in the Subaru 1000. The so-called center pivot steering system is adopted whereby the brake drums are separated from wheels and the kingpin axis line is aligned with the tire centerline. 

Inboard brakes have the following features:

１． Through adopting the center pivot steering system, tire resistance on the ground surface is minimized and steering reaction is mitigated.
２． At the same time, a large steering angle of the handle can be secured.
３． Weight under the spring is mitigated, ground contact of the tire is improved and better performance is realized in terms of acceleration, ride quality and driving stability.
４． Because the brakes are separated from the wheels, it is difficult for mud and water to infiltrate.

Also, because an aluminum alloy front brake drum equipped with numerous fins is adopted, this provides excellent cooling effect.

(Source: “Subaru” magazine – Subaru 1000 extra edition (issued May 20, 1966))

Dual Radiator

The Subaru 1000 became the first domestic car to adopt a unique dual radiator cooling device in its engine.
Unlike generally adopted cooling systems, the dual radiator has no cooling fan in the main radiator, but its mechanism is composed of the main radiator, sub-radiator, reserve tank and small motor fan for the sub-radiator. 

The dual radiator has the following characteristics. 

1. The cooling fan causes little power loss in the engine and enables good high-speed performance and fuel economy.
2. The engine is especially durable when climbing hills and crawling and there is no danger of overheating.
3. Users are liberated from fan noise.
4. There is no need to replenish or replace radiator coolant for a long time (every two years). Antifreeze solution that contains anti-rust solution is used as the radiator coolant.
5. In winter, the sub-radiator is used to provide the heating performance of the 2,000 cc class engine.

(Source: “Subaru” magazine – Subaru 1000 extra edition (issued May 20, 1966))

Engine

The Subaru 1000 is equipped with a horizontally opposed four-cylinder water-cooled four-cycle engine possessing total displacement of 977 cc. In terms of performance, the engine has a compression ratio of 9.0 and maximum output of 55 ps/6000 rpm. The maximum torque is 7.8 kg/3200 rpm.

The Subaru 1000 engine has the following characteristics: 

1. It is a horizontally opposed engine and, because it is made from aluminum alloy, it is light and compact and has good cooling performance. 
2. Through designing a combustion chamber with high compression ratio and mechanical octane value, the engine has high output and high performance.
3. The engine is designed to provide excellent durability.
4. Fuel economy is good thanks to the high compression ratio and so on.
5. Since the engine is horizontally opposed, it has good balance. Because it has no cooling fans and so on, it generates little vibration and noise and is quiet. 
6. Since the engine is made of aluminum and has a new type combustion chamber with high mechanical octane value, it can use regular gasoline. 

(Source: “Subaru” magazine – Subaru 1000 extra edition (issued May 20, 1966))

Based on the required conditions for passenger vehicles that were presented by Shinroku Momose, the engine design department proposed three engine types, namely the transversely mounted in-line four-cylinder engine, the longitudinally mounted V-type four-cylinder engine, and the transversely mounted horizontally opposed four-cylinder engine.

“It was because the drive shafts could be equal length and also made longer. In FWD development at that time, the greatest problem was the drive shaft joints. Excellent joints were subsequently completed just before launch of the Subaru 1000, however, in order to avoid placing load on the joints, it was necessary to extend the drive shafts and make them equal length. However, this was difficult to achieve with the transversely mounted in-line four-cylinder engine.”

Development of the horizontally opposed engine was thus commenced, and the first engine to be designed was an 800 cc 36 HP engine, and based on this a 796 cc, 41 HP prototype was manufactured. This was subsequently upsized to a 923 cc, 46 HP model then a 977 cc, 47 HP model, and finally the EA-52 Engine 977 cc, 55 HP model was developed for mass production.

Aluminum was adopted as the material for the crank case and cylinder head in order to reduce weight. At that time, aluminum was 14 times more expensive than iron; moreover, because this wasn’t a typical in-line four-cylinder engine, all machine tools had to be specially ordered. Every time something cropped up, there was a discussion over whether the horizontally opposed four-cylinder engine was really the best choice. Even so, the engine development team built an aluminum horizontally opposed engine based on the steadfast belief that “a good product will always sell.”

As a result, the EA52 engine turned out to be 15 percent lighter than conventional in-line four-cylinder engines. At that time, in development of common mass production vehicles, engine and car body performance was pursued, but this was the first time that an effort to improve driving was made through reducing the engine weight. This was very unusual, but this most important weight reduction was thoroughly conducted in the Subaru 1000.

(The above contents were edited using extracts from Cartopia Vol. 314 and Vol. 382).

1.The evolution of the horizontally opposed engine.

Over the 22 year lifespan of the Leone there were two full model changes to the new, and the all new Leone. While sharing a common engine block, the displacement of the 4-cylinder EA series horizontally opposed engine displacement was gradually increased from 1100 cc, to 1200 cc, 1300 cc, 1400 cc, 1600 cc, through to 1800 cc.

In order to comply with the 1970’s American Clean Air Act
and Japanese exhaust emission regulations, the Subaru Exhaust Emission Control - Thermal and Thermodynamic Control (SEEC-T) system which uses a secondary air intake and thermal reactor was introduced. Thus, Subaru launched the most regulation-compliant model before any other Japanese automotive manufacturer. In 1982, the world’s first 4WD AT model with the high-performance EGI turbo-charged engine was developed. From then on, Subaru has been continually striving to refine their turbo charger technology as an essential component of their vehicle lineup. During the second full model change in 1984, the 1800 cc engine was modified to have an OHC design.

2.The establishment of Subaru AWD technology.

An important element in the symmetrical AWD cars of Subaru is the horizontally opposed engine, i.e. power unit. Subaru mounted the horizontally opposed engine for the first time in the Subaru 1000 and over the next 40 years has refined this extremely unusual automobile power unit. Subaru selected the horizontally opposed engine because it contains a number of elements that make it ideal as the power unit for four-wheel-drive vehicles. How much did the engineers who developed the Subaru 1000 know about the potential of the horizontally opposed engine? Here, we have collected the testimony of engineers who worked on development at the time to find out why they chose the horizontally opposed engine.

Shinroku Momose, who was the automobile design leader for Subaru at the time, told designers that the engine for the FWD sedan to be newly developed could be any type so long as it satisfied the following five conditions.

1. Since the vehicle is FWD, locate the deferential gear in the center of the car body in order to make the drive shaft operating angle as small as possible.
2. Since the locations of pedals are decided to make driving easy for the driver, these cannot be changed.
3. The engine height has to be low in order to keep the center of gravity down and increase the degree of flexibility in body design.
4. Since the vehicle is FWD, the front overhang needs to be shortened.
5. Vibration should be reduced in order to enhance the ride quality.

Mr. Motomitsu Honda, who was an engineer in the engine design department at the time, looks back as follows.
“Mr. Momose was not fussy about the type of engine. Since top priority is given to the people riding the vehicle, he presented the required dimensions and performance and said that any type of engine would suffice providing that the engine and mission met those conditions. We generated all the ideas we could think of and eventually narrowed these down to three possible plans.”