The International S series bus chassis was a conventional cowled chassis built from 1979 to 2004, first as the Schoolmaster and from 1989 as the 3800. Produced mainly for school buses, it was the longest-lived model line in International’s history and the last Navistar product developed while International Harvester still existed.
International S series bus chassis at a glance
| Maker | International Harvester, later Navistar International |
|---|---|
| Production | 1979–2004 |
| Type | conventional cowled bus chassis, also stripped chassis |
| Replaced | the Loadstar bus chassis |
| First generation | Schoolmaster, based on the S1700 and S1800 |
| Second generation | 3700 and 3800 from mid-1989, plus the 3600 of 1991 |
| Numbering | model numbers ending in 3 for buses; “23” for petrol and “53” for diesel |
| Replaced by | International 3300 in 2004 |
Based on one source (English Wikipedia).
History of the International S series bus chassis
The Schoolmaster
The S-series bus chassis arrived during 1979 alongside the conventional S-series trucks, replacing the Loadstar bus chassis and continuing the Schoolmaster name. Instead of being an adaptation of a truck chassis, the Schoolmaster was designed as a separate model line for bus use, with completely straight frame rails and a flat-back firewall so that body makers could mount their bodies with minimal changes. It changed little during its life; the main revisions were to the powertrain and to the badges as International Harvester became Navistar. For 1987 the grille was revised, with the International wording moved from the top to the bottom left and paired with the Navistar Diamond Road logo, and Navistar stopped using petrol engines.
Models and engines
The Schoolmaster was built as a version of the S1700 and the heavier S1800, the two ranges differing mostly in suspension capacity. Following International practice, bus model numbers ended in 3, with “23” for petrol engines and “53” for diesel. The S1723 used the International 345 V8 as standard with the 392, MV404 and MV446 as options; the S1823 used only the MV-series V8s; and the S1853 had a 9.0-litre V8 as standard with a DT466 or Caterpillar 3208 as options. For 1983 the S1753 brought diesel power to the S1700 chassis with a 6.9-litre IDI V8, enlarged to 7.3 litres in 1987. Four-speed manual gearboxes were standard on the S1700 versions and five-speed on the S1800, with a four-speed automatic optional. The S1823 was dropped after 1981 and the S1723 after 1986, when International stopped making petrol engines.
The 3800
In mid-1989 Navistar introduced the second generation of the S series, renamed the Class 6 trucks the 4000 series and gave the bus chassis its own designation: the S-1753 became the 3700 and the S-1853 the 3800, and the Schoolmaster name ended after ten years. The new chassis had a redesigned, lower hood with closer-fitting fenders, a new front bumper, a redesigned steering column and larger instruments. The 3700, equivalent to a 4700, had a 7.3-litre IDI V8 and hydraulic brakes; the 3800, equivalent to a 4900, had a DTA360 inline-six and air brakes. In 1991 a 3600 chassis was developed for the Thomas Vista semi-forward-control conventional, and the 3700 was dropped after 1994. For 1995 the 3800 received chrome hood badges and chrome International grille lettering, and the acquisition of AmTran by Navistar in April 1995 tied the chassis more closely to one body maker; in 2000 the conventional bus hood was redesigned as the International IC. Production of the 3800 ended in 2004, when the International 3300 replaced it after more than 25 years.
Design and features
- Purpose-built chassis: straight frame rails and a flat-back firewall made body mounting easy.
- Two generations: the Schoolmaster of 1979 and the 3800 of 1989.
- Diesel progress: from the 9.0-litre V8 and DT466 to the 6.9- and 7.3-litre IDI V8s.
- Numbers ending in 3: the last digit marked a bus chassis, with 23 for petrol and 53 for diesel.
- Longest-lived International: in production for over 25 years.
International S series bus chassis versions
- S1723: petrol-engined version on the S1700 chassis.
- S1753 (1983): diesel version of the S1700 with a 6.9-litre IDI V8.
- S1823: petrol version on the S1800 chassis, dropped after 1981.
- S1853: diesel version on the S1800 chassis with a 9.0-litre V8.
- 3700 (1989–1994): lighter version of the second generation.
- 3800 (1989–2004): the main school bus chassis, with the 3600 added in 1991.
The chassis was the bus version of the International S series and was replaced by the International 3300; the bodies came from AmTran and later IC Bus. More vehicles are in the International collection.
Sources
- International S series (bus chassis), English Wikipedia: models, engines, generations
