Nissan Fairlady Z432 (1970)
Publication: Motor Fan
Format: Road Test
Date: June 1970
Author (Roundtable): Hajime Mizutsu, Osamu Hirao, Kazumi Yotsumoto, Kenji Higuchi, Kuniyuki Tanabe, Yuji Sakakibara, Yasuhei Koguchi, Kunitaka Furitani, Masahide Sano, Taizo Tateishi, Atsushi Watari, Hiroshi Okazaki, Minoru Onda, Mineo Yamamoto, Kenzaburo Ishikawa, Toshihide Hirata, Motor Fan Editorial Staff (uncredited)
With America in Mind
Magazine: First, please tell us about the aim of development for this car.
Mizutsu: This car was planned the year before the current Bluebird was announced, the same year that the R380 won the Japan Grand Prix. Therefore, the technical foundation of the Fairlady Z project was to base it on the suspension of the Bluebird and the engine of the R380.
The proposition given to us was two contradictory requirements: first, it had to have the potential to compete in races and rallies, and second, it had to have the same ride comfort as a passenger car, and be practical enough to be used as a sedan. It also had to be mass-produced, which means it had to be cheap and have an appropriate weight. On top of that, it had to be fully suitable for America, which had traditionally been the main market for the Fairlady.
So, in relation to the fact that it is a high-performance sports car that can also be enjoyed for long-distance drives, we focused on how it can be used for a variety of purposes to meet a variety of tastes, and so we chose to offer two engines: the S20 engine from the R380 as a high-performance engine, and the six-cylinder L20 engine used in the Cedric as a passenger car-like engine.
Specifically for the US market, we increased the displacement to 2.4 liters. This was due to issues with the US exhaust regulations, and since we export a considerable number of Bluebirds to the US, we used the L24 type, which has the same bore and stroke as the 1.6 liter engine, so there are many commonalities.
At the beginning of the planning, there was a great deal of uncertainty about the body, such as whether to make it an open-top or closed body, or whether to make it a two-seater or a four-seater. However, as expressways continue to develop, speeds will naturally increase and distances traveled will become longer. In this kind of era, convertibles are no longer necessarily comfortable to drive. In that sense, we thought about noise, airtightness, improved comfort including the effectiveness of heating and ventilation, and also safety in the event of a rollover, so we went for a closed body. As for the two-seater arrangement, we concluded from market research in the U.S. that two seats would be sufficient.
We used strut-type suspensions for both the front and rear. We chose the strut type for the front because it has strong lateral rigidity and because we could soften the rigidity of the front and rear to a certain extent, taking into account the issue of harshness. We chose struts for the rear wheels because being a two-seater allows the strut towers to be high enough. This reduces camber change, almost completely eliminates axle steer, and can even reverse the jack-up tendency during cornering, so we think it is a suspension that offers a high degree of flexibility in terms of stability.
As for the steering, the rack-and-pinion gears are the same as those of the Laurel, but the total gear ratio is made sharper than the Laurel, with a lock-to-lock ratio of 2.59 to improve response.
As for ride comfort, the spring constants are different between the Z432 and the Z equipped with the Cedric-type 6-cylinder engine, with the Z having the same spring constants as the Bluebird, while the Z432 is stiffer, improving driving and handling. So, I think the biggest issue in planning was that we had two fundamental aims, and we wanted to offer a choice of engines, suspensions, etc. and attract a wide range of users.
We currently have a production capacity of 2,000 units per month, of which we plan to export about 1,500 units and sell about 500 units domestically.
Hirao: Will this be produced in parallel with the previous Fairlady?
Mizutsu: Yes, we are producing them in parallel. According to market research in the US, there is also a demand for open-top cars, so we decided not to switch all at once and to see how things go.
The “Long Nose/Cut Tail” Style is Typical of Modern Sports Cars
Hirao: How would you describe this styling?
Yotsumoto: When we first first thought about the style, we were quite torn between making an aerodynamic-looking car, a hot car, or a specialty car like the Mustang. We tried a Mustang-type car, but in the end we decided to go with a true sports car image.
Since it is a sports car, the aerodynamic look was the main goal, so we made a small model and had an aerodynamics expert look at it. The length of the car does not necessarily match the aerodynamic aspects, but we made it that way to give it an aerodynamic image. We had a lot of trouble with the relationship between the bumper height and the angle of the nose, and the legal regulations for the height of the headlights, so the big theme was how to incorporate the safety dimensions of the car in a way that still looks cool.
For something that looks low and long like a sports car, the legal dimensions are quite an obstacle. In that respect, it may seem old compared to futuristic-looking cars like the Mercedes C111 or the Lotus Europa, but from the legal standpoint and in terms of mass production, I think this style is a typical example of a current mass-produced sports car.
I think it’s a styling trend that has changed from the streamlined style of the past to the cut tail and wedge type of the present. In other words, I think this car is a typical example of an era. The stylists did some hot stuff during development, but when you think about mass production and and exporting the car to the US, I think it naturally settled down to this level.
Higuchi: The one I saw at the car show had something like a spoiler on the rear, which looked pretty cool…
Yotsumoto: From a styling standpoint, I think the spoiler should really be an option for the sports version… Also, since this car is primarily intended for export, the roof height is generous, so if you slope the rear of the fastback, there’s no room in the dimensions to give it a ducktail.
Watari: Could you expand the glass area in the doors a little more? If the window sill was a little lower, you’d be able to lean against it comfortably.
Hirao: It looks like you’re sitting in a well.
Yotsumoto: Maybe the seat is too low. The seat can be adjusted up and down.
Thinking 2+2
Magazine: We wonder about a 2+2…
Mizutsu: I think we’ll wait and see for a while longer about the 2+2. It seems like there are a lot of voices in Japan saying they want a 2+2, so I think we’ll consider it again if the demand seems sufficient in terms of number of units.
Magazine: Is it possible in terms of styling?
Yotsumoto: There’s the issue of head clearance in the rear seats, so I think it will be quite difficult, to be honest.
Mizutsu: And the struts are exactly where the seats would go..
Tanabe: We considered it from a design perspective. However, after doing some research, we found that even Jaguar’s 2+2 E-types are not often seen in the US, and even in Japan, not many people buy them. In the end, the element of wanting to respect individuality, especially considering that the US is the main market, the issue is whether 2+2s will really sell. Also, for us, it’s a problem of whether we can make a 2+2 that complies with Japanese regulations and retains a good shape. In the US, 2+2 means that you can ride in the back if you can fit yourself in, but here, it’s not permitted unless the width for one person is 400mm and the seat height is according to the standards. So, if we make it into a shape that meets those standards, it will become a pretty big car…
Magazine: Now, please tell us a bit about the engine.
Sakakibara: The basic structure of the Z432’s engine is that of the R380 engine, and it has been modified to make it easier to produce, easier to install in the car, and easier to maintain. At the planning stage, the Skyline 2000GT-R and this Z series were being developed almost simultaneously, so the engine for the GT-R and this one are made almost the same. However, there were some parts that had to be changed due to the nature of the cars and the installation. Specifically, only exterior parts such as the shape of the oil pan and the shape of the air cleaner have been changed.
Koguchi: There is a big price difference between the base Z and this Z432, but how much of this is due to the difference in the cost of the engines? I also heard that the wheel discs (made of magnesium and steel) cost about 50,000 yen each…
Mizutsu: The Z432 engine costs about three times as much, because it is not produced in large quantities and is close to being tuned up.
Sakakibara: It is an engine that requires a lot of handwork, so a fair amount of effort goes into building it. For example, we manufacture them with a level of precision that is higher than machine work, so it takes a lot of man-hours. We also manufacture them with the intention that they will be easy for users to tune in the future, so I think that this is the reason for the increased cost.
Magazine: What is the production volume?
Tanabe: We receive orders for several dozen units per month. The price is high, and we don’t think there will be a high demand.
For “Second Youth”
Magazine: Now, please tell us the results of the power performance.
Furutani: First, in the time-to-distance acceleration tests, it took 4.0 seconds to reach 50m, 6.3 seconds to reach 100m, 9.8 seconds to reach 200m, and 15.5 seconds to reach 400m. In terms of time to speed, it took 2.6 seconds to reach 40km/h, 3.8 seconds to reach 60km/h, 6.3 seconds to reach 80km/h, 8.7 seconds to reach 100km/h, 11.7 seconds to reach 120km/h, and 15.3 seconds to reach 140km/h.
For overtaking acceleration, from a speed of 30km/h in third gear, it took 1.9 seconds to reach 40km/h, 4.6 seconds to reach 60km/h, 7.8 seconds to reach 80km/h, 11.0 seconds to reach 100km/h, and 15.2 seconds to reach 120km/h. From 40km/h in top gear, it took 2.9 seconds to reach 50km/h, 4.9 seconds to reach 60km/h, 9.2 seconds to reach 80km/h, 14.5 seconds to reach 100km/h, and 19.6 seconds to reach 120km/h.
The 0 to 50m time of 4.0 seconds is the same as the Skyline GT-R. The limited-slip differential worked very well, and the acceleration was excellent.
Magazine: What about the fuel economy, vibration and noise?
Sano: First, the fuel economy at a constant speed was 14km/l at 40km/h, 15.2km/l at 60km/h, 14.4km/l at 80km/h, 12.8km/l at 100km/h, 11.1km/l at 120km/h, and 9.4km/l at 140km/h. It’s best around 60km/h, but there’s little drop even on the highway.
Practical fuel economy was measured at 7.1km/l at an average speed of 22.1km/h at 40km/h, and 6.5km/l at an average speed of 26.2km/h at 60km/h.
Magazine: Next, let’s review the ride and noise measurements from the Watari Laboratory.
Tateishi: First, in terms of suspension vibration frequency, the vibration frequency is 1.5cps for the sprung mass and 13cps for the unsprung mass.
Noise level inside the car were 65 hones at 40km/h, 67 hones at 60km/h, 72 hones at 80km/h, 75 hones at 100km/h, 79 hones at 120km/h, 84 hones at 140km/h, and 84 hones at 150km/h.
External noise while driving in second gear was 74 hones at a steady speed of 50km/h, 81 hones when accelerating through 50km/h, and 46 hones for background noise.
Watari: It depends on what the aim of this car is, but for enjoying long-distance driving, the sound level is a little high. However, if you’re driving on a circuit, the noise won’t be a problem. Also, there are some peaks in the sound level, but if you eliminate these, I don’t think you’ll notice the noise level as much even if it’s high overall.
Magazine: The ride is quite firm. Are there any optional settings available?
Mizutsu: We simply change the spring constants to match the engine.
Tanabe: We’re also aiming for grand touring. So, when we asked what kind of people drive sports cars in America, we were told that young couples of course drive them, but then they have children and they don’t have time for sports cars. So they move on to big station wagons, but when they outgrow them and their children become independent, what will they drive then? Often, they’ll want to enjoy their “second youth.” At that time, they will probably want to drive a sports car again.
They will prefer to ride in a two-seater car, which will allow them to avoid having to carry any unnecessary passengers and respect their privacy. In that sense, we were asked to think of a car that I could drive to relive my youth (laughs).
Magazine: Although we did not conduct any instrumented handling or stability tests this time, we were told that the car has good stability thanks to the use of a strut-type suspension at the rear.
Koguchi: This car’s struts are located in front of the axle, but how does handling stability differ if they are located above the axle or behind the axle?
Hirao: I don’t think you can say in general.
Tanabe: The main idea was that we didn’t want the struts to stick up too high and intrude on the interior packaging… so it has nothing to do with handling stability.
Mizutsu: We decided on the geometry, such as the height of the differential and the angle of the link on the strut side, to see where we could minimize the camber change… the car has a tendency to sink at the rear when cornering and accelerating.
Exceptional Cornering
Okazaki: We pushed it as far as we could on the Murayama test course, with the speedometer reading speeds up to 200km/h. Even at this speed, when we swung left and right, it was easy to keep the car in check, and I think it was quite comfortable to drive. However, considering the sharp handling characteristics of the SP and SR Fairlady models, which are pure sports cars, I think that the handling characteristics of this Z series are about 60% stability and 40% maneuverability. Considering the nature of the car, I think this is actually a good thing.
Tanabe: When we were making the SR, we wanted to increase the number of people racing, so we thought of it as a car that could be used in amateur races without much effort. After that, it was used that way in the United States and Japan, but market research in the United States showed that about 20% of the cars were used by women. This created a dilemma: if we made it too stiff, it would make it unsuitable for general use, and at the same time, if we made it only somewhat stiffer, it wouldn’t be hard enough for racing. This would be a case of “too short for the sash, too long for the belt," in other words, not suitable for either purpose. Ultimately, we decided that if we made it any harder, it would not be marketable to general users, so we stopped trying to make it stiffer and instead focused on making it softer as a specialty car.
However, although it has not yet been released, we are considering stiffer springs as an option for the “Z432R.”
Okazaki: I thought the steering response at high speeds was good, but there was a sense of elasticity. I found that a little unpleasant…
Tanabe: I think it is partly because of the tires, but when used for racing, the rigidity of the rubber in the steering link is increased, so that may be why the street model has a softer feel.
Watari: I think it could be made a little better by choosing the stiffness of the suspension material more appropriately.
Mizutsu: We could make the upper part a little stiffer, but that would affect the harshness and make the feeling a little worse, so we went for a softer setting.
Tanabe: The springs of the Z432R are 5.5kg/mm in the front compared to the standard 1.8kg/mm, and 5.6kg/mm in the rear compared to 2.1kg/mm. The front dampers are also stiffer, with 130kg on the rebound side compared to the standard 35kg, and 90kg on the compression side compared to the standard 20kg. The rear dampers are also very stiff, with 120kg compared to the standard 80kg on the rebound side, and 85kg on the compression side compared to the standard 20kg. When combined with tires with high lateral rigidity, it becomes a car with good maneuverability, suitable for circuits.
Okazaki: The Z432’s engine is quite heavy, so does that mean the understeer will be too strong in races?
Tanabe: I think it depends a little on the stabilizer settings, but I think it will have mild understeer. Our race driver actually drove this car without any modifications at Fuji Speedway, and he said that compared to a tuned-up SR311 Fairlady, it is a little slower on straights, but cornering is very easy and it could get through corners with ease.
Tall Interior Height
Magazine: Next, please provide the data from the Higuchi Laboratory.
Onda: The dimensions are almost the same as the Toyota 2000GT, with a slightly shorter overall length, slightly higher overall height, and slightly wider overall width. The interior was designed with the American market in mind, and the interior is also quite high at 1045mm. The seats hold the body well, and it feels like you sink into them.
Yamamoto: Are the magnesium wheels die-cast?
Tanabe: No, they’re cast. We don’t make many of them.
Yamamoto: How much do they weigh?
Tanabe: About two-thirds the weight of steel.
Okazaki: Actually, while I’m a bit on the thin side, I think I’m of average height, and the shape of the seat itself is fine, such as the points that support my lower back and the curve of the seatback, but perhaps because the seat is tailored to the American market, it feels loose when I sit in it, or rather, very loose. So, I think that if enough units are sold in Japan, I’d like to have a seat that fits us more perfectly… (laughs).
Watari: It was perfect for me (laughs). However, the headrest gets in the way when backing up, so I think a retractable type would be better.
Repeated Crash Tests
Magazine: Professor Higuchi, please tell us about safety.
Higuchi: The safety scoring criteria are based on sedans, so this kind of sporty car usually gets lower scores in some areas. For example, if the bumper was wider and more durable, the score would be higher. This is safety as seen by the naked eye, so we don’t know if there are, for example, collapsible or breakaway parts, since we don’t actually crash the car, but if there are areas that look dangerous, specifically the front grille, which is pointed, it gets about one point lower. Everything else is above average, and the total score is 89 points out of 100. The result is a little lower than the 92 to 93 points for a 2-liter class sedan.
Tanabe: This car has been crash tested quite a lot. We’ve crashed about 60 cars, including prototypes and production prototypes. And the issue of collapsible and breakaway parts was something we put a lot of thought into, and we did a lot of work on.
Ishikawa: In a real crash, how far would the steering wheel intrude in a 30 mph (48 km/h) impact?
Tanabe: Of course, making the nose longer reduces air resistance, but from a safety standpoint, it also serves the purpose of absorbing energy, so the rigidity is not too strong to absorb an impact. The steering shaft is also staggered midway for this reason.
Higuchi: The steering wheel is also energy absorbing, isn’t it?
Tanabe: Yes, it is a lantern-shaped, collapsible type.
Magazine: Next, let’s look at the weight and capacity data from the Funaken Ship Institute.
Ishikawa: Weight-wise, with a spare tire, tools, and about 80% full gasoline tank (60 liters), the car was 1,075 kg. The distribution is 557kg for the front wheels and 518kg for the rear wheels, which is 52%/48%. With two people on board, it’s about 50%/50%. The right front wheel is about 35kg heavier than the left, but it will be left-hand drive when exported, so I think that’s the reason. As for the alignment, the toe-in and camber are quite strong, but they decrease when two people are on board. The rear also had a strong toe-in, but the camber was almost zero.
The brakes are a mixed system, with discs in the front and leading/trailing drums in the rear, and a servo booster. In addition, the rear brakes have a pressure control valve, so it’s a braking system with everything you would expect. The hydraulic pressure regulator is designed to operate at a pedal force of about 10kg and a deceleration of about 0.3g. The servo’s rest point seems to be at a pedal force of 20-25kg and a deceleration of about 0.5g. Therefore, the pedal force for 0.6g is a little large, coming in at 33 kg. On the road, it is lighter, and the 0.6g pedal force is about 26kg. The distribution of the braking force was 66:34 with a pedal force of 33kg. There seemed to be a slight imbalance between the left and right wheels, even though the front wheels use discs. The rear wheels were well balanced.
The mechanical parking brake acts on the rear wheels, and the left and right braking forces are well balanced. The force required to obtain a braking force of 20% of the total weight is 27 kg. The ratchet is also very effective, and the figures show that it can be parked on a 1/5 gradient with a force of 30kg.
The operating force of each control is light. The gear lever is about 2kg. The clutch is normal, at 12kg to disengage and 8.5kg to engage. The accelerator weight is 0.5kg at a constant 50km/h, and about 3kg for sudden acceleration.
Okazaki: The brakes themselves are very effective. It only takes a moment to slow from 130-140km/h to 100km/h.
Ishikawa: The parking brake is also equipped with an auto-adjust function.
Tanabe: Right, when you pull the handbrake, the rear brakes are automatically adjusted.
Magazine: What do you think of the Porsche-synchro transmission?
Koguchi: I like it, but some people don’t like it, and want a more definite, crisp feeling.
Watari: Isn’t the gear lever a little too long to hold at the top? However, I suppose if it were shorter, it would become heavy.
Tanabe: However, the Porsche synchro becomes softer the more you use it.
Magazine: Did you ever think about putting the SR Fairlady’s four-cylinder engine in the Z series?
Mizutsu: The plan was to make the car not only hot in performance, but also quiet in terms of riding comfort, so while it started out as a four-cylinder, we decided to go with a six-cylinder engine. For now, we’re not considering a four-cylinder.
Magazine: Finally, can you tell us about the field of view?
Hirata: When the seat is in the middle position, the height of the viewpoint is 106.9 cm, the distance to the windshield is 56.5 cm, and the distance to the rearview mirror is 55.5 cm. The visible range through the windshield was 90.5° in total from left to right, and 26.5° up and down. The rear window was 46.0° in total from left to right, 13° up and down, and the wiper wiping range was 74.5°. So, the dead angle in the horizontal plane, including the viewpoint, is 56° overall. Expressed in solid angles, the area in front of the driver’s eye is 1.08 steradians, the windshield is 0.641 steradians, and the wiper’s wiping range is 0.46 steradians, wiping 64.9% of the visible area. The rear visible range is 11.7 steradians, which is natural for this type of car, but the overall field of view is slightly below average.
Magazine: Thank you all very much.
Postscript: Story Photos
