Isuzu Bellett 1600GTR (1969)
Publication: Car Graphic
Format: Road Impressions
Date: December 1969
Author: Shotaro Kobayashi
Road testing the Isuzu Bellett 1600GTR
When Paul Frere first came to Japan, he said that his favorite of all the Japanese cars he test drove was the Bellett 1600GT, which had been tuned to be low and stiff. He also suggested that the Bellett GTX, which was active in touring car racing with a twin-cam engine from the 117 Coupe, should be made commercially available. The manufacturer seemed interested in this idea, and almost immediately, the car was released under the name 1600GTR (Tokyo price, 1.16 million yen). The general outline of the GTR, compared to the GT, is that its suspension has been lowered and stiffened to a standard similar to that of Isuzu’s existing Stage I sports kit (for gymkhana), radial tires have been fitted, and it is equipped with the same DOHC four-cylinder engine as the 117 Coupe.
Although the 117 and the GTR use the same engine, it is clearly evident from their body styles that the 117 is a Gran Turismo that runs gracefully on the highway, while the GTR is designed for performance and is “hot” enough to participate in gymkhana straight from the factory. However, it is not an unruly horse, and is extremely easy to drive.
The powertrain is the same as the 117, using the same engine, clutch, and gearbox, and the standard 3.73 final drive ratio is the same as the 1600GT. This twin-cam engine is already well-known for its quick acceleration and smoothness up to high rpm. Unofficial overtaking times (all taken in fourth gear) show that strong average torque is maintained up to at least 140km/h (above which air resistance increases suddenly). Since there is power to spare, consistent acceleration is available no matter at what rpm the throttle is opened. The top speed of 190km/h in the catalog data is likely to be achievable without exaggeration.
The test car ran roughly at around 2500rpm due to poorly adjusted carburetors (twin Solexes, double choke), but it was smooth otherwise and revved well up to 7000rpm (the yellow zone is marked from 6500rpm, the red zone from 7000rpm). There was little mechanical noise even at speeds over 100km/h, and the loudest noise was the muffled exhaust sound, which was evident from the sudden silence when the clutch was depressed. The exhaust resonance started to fill the cabin at around 4000rpm (120km/h), then became quiet again around 4500rpm. Also, a whirring noise from the tires (Yokohama GT Specials) was clearly heard up to about 100km/h, but after switching to Bridgestone radials, this disappeared completely.
The engine is a little rough at its idling speed of 900rpm, and there is a lot of buzzing vibration. The very short shift lever protruding from the floor tunnel is a feature unique to Isuzu vehicles. Its action has a nice “click” to it, but it takes quite a bit of force to operate. The clutch engages cleanly and smoothly.
One of the car’s greatest strengths is its outstanding maneuverability. This is largely due to the stiff and low (10mm lower than the GT) suspension. As mentioned above, it is tuned to be close to Isuzu’s Stage I sports kit, and the spring constants are much higher compared to the standard 1600GT (5.3kg/mm vs 3.1kg/mm for the front coils, 3.5kg/mm vs 0.9kg/mm for the rear transverse camber-compensator leaves, and with three leaves instead of one). The stabilizer and rear coil springs remain unchanged, but the dampers have been strengthened both front and rear.
The rack-and-pinion steering feels a little heavy at low speeds, but the response at high speeds is sharp and almost completely free of play. It has excellent straight-line stability, so you can drive it without worry even when taking your hands off the wheel at high speeds.
This feeling is especially noticeable when speeding down a winding road. There is almost no body roll even in fast cornering, and the radial tires have good grip. This allows you to maintain a deceptively rapid pace, as I once experienced while driving on a winding section of the Metropolitan Expressway. The traffic around me seemed to have suddenly slowed down, and it was not until I glanced at the speedometer that I realized I was going at a quite a high speed. The stiff suspension demonstrated outstanding handling for a swing axle layout, and although the slight initial understeer turned into final oversteer at the limit, the tail slide was easily controlled with delicate application of the throttle.
Although the handling is excellent, it is inevitable that ride comfort is sacrificed to some extent. The stiff springs and stiff tires pick up the unevenness of the road surface clearly, and the steering is rough in its kickback, though the leather-wrapped wheelrim absorbs it to some extent to isolate it from your hands.
The springs also feel stiff on unpaved country roads, where there is some bouncing, but it’s not enough to upset your stomach, and the ride quality isn’t so bad as to be a cause fpr concern. The Bellett has always had a good ride on rough roads, and while the kickback, noise, and vibration give a bad initial impression, this probably won’t be a big deal for people considering buying a GTR. On gravel roads, the differential lock is effective and prevents one-wheel spin. This differential lock was previously an option on the GT.
The brakes are a front disc/rear Alfin drum combination, with highly fade-resistant pads. These type M33S pads (M59 on the GT) require more pedal effort, and a vacuum servo has been added to compensate. A pressure control valve has also been added to prevent the rear wheels from locking too early under sudden braking, improving their dependability at high speeds. In city driving, the pedal effort is still heavy, but the stability at high speeds and the smooth, progressive braking feel are excellent. The front-to-rear balance is also good, and there is no servo lag. The floor-mounted handbrake is also easy to use.
Next, regarding the interior, the front seats have a unique backrest that extends up high and doubles as a headrest, the fore-and-aft seat slide travel is more than sufficient, and the bucket-type seats provide excellent lateral support. However, the headrest integrated with the backrest impairs the view over the shoulder when backing up. The steering wheel is a sporty three-spoke design wrapped in leather, as mentioned above, and the slightly thick grip feels great to the touch.
The driving position is unique to the Bellett GT series, with the seat mounted low and the steering wheel and dashboard positioned high. When you adjust the seat to fit the steering wheel and shift lever, you realize that the pedals are too close. It would be better if the brake and clutch pedals were a little further away, so that their position when fully depressed was their normal resting position. There is also a big difference in height between the brake pedal and the accelerator, so heel-and-toeing is not so easy. The dashboard is basically the same as the 1600GT, and the instrument panel is finished in black. The wipers and bonnet are painted matte black to prevent reflections, but if this is the intention, then the chrome rings around the gauges should also be removed.
By the current standards of the class, the Bellett has small body dimensions, and the GT’s rear seats are only auxiliary in their accommodations. For tall people, even if you slide the front seat all the way forward, the knee room and head room are extremely limited, and in the GTR, the front seats integrated with the headrests make forward visibility poor, creating an unavoidable feeling of being crammed into a small space. Therefore, this car is a three-seater at best. Some of the small accessories that stand out are the heated defogger wire in the rear window, the windshield washer that works simultaneously with the wipers, and standard halogen fog lights (which also light up the gauges and tail lamps).
Finally, the fuel economy was 9.2km/l on average for a 300km round trip to FISCO on the Tomei Expressway and driving around Tokyo, which is a relatively good figure for this type of vehicle. Although this article only provides a brief impression of the 1600GTR, we are planning to conduct a full-scale road test at a later date, so please look forward to it.