International Harvester S-Series (bus chassis)

International Harvester S-Series "Schoolmaster"
Late 1980s International S-1800 (retired)
Driver's compartment of a typical 1980s International S-Series school bus (Wayne Lifeguard body pictured)
Overview
Manufacturer	International Harvester Navistar International
Also called	International Harvester S-1723/S-1753
Production	1979–1989
Body and chassis
Body style	Cowled chassis School bus Commercial bus Stripped chassis (1853FC)
Platform	International Harvester S-Series
Powertrain
Engine	Gasoline International Harvester 345 cubic-inch V8 (1979–1986) International Harvester 392 cubic-inch V8 (1979–1986) International Harvester MV-404 6.6 liter V8 (1979–1981) International Harvester MV-446 7.3 liter V8 (1979–1981) Diesel International Harvester D-150/170/190 9.0 liter V8 (September 1978 – December 1979) International Harvester 9.0L V8 (January 1980–1987) International Harvester IDI 6.9 L (420 cu in) (1983–1987) International Harvester IDI 7.3 L (444 cu in) (1986–1989) International Harvester DT466 7.6 L (466 cu in) (1979–1989) International Harvester DT360 5.9 L (360 cu in) (1986–1989) Caterpillar 3208 10.4 L (636 cu in) (1979–1981)
Transmission	5-speed manual Allison AT545 4-speed automatic Allison MT643 4-speed automatic

International 3800
2000–2001 International 3800 (Carpenter Classic 2000 body)
Driver's compartment of a typical 1990s International 3800 school bus
Overview
Manufacturer	Navistar International
Also called	International 3700/3800
Production	1989–2004
Body and chassis
Body style	Cowled chassis School bus Commercial bus Front-engine stripped chassis (3900) Rear-engine stripped chassis (3000)
Platform	International Harvester S-Series
Powertrain
Engine	Diesel Navistar DTA360 I6 (1989–1994) Navistar DT408 I6 (1994–1995) Navistar DTA466 I6 (1989–1998) Navistar DT466E I6 (1996–2004) Navistar 7.3L IDI V8 (1989–1994) Navistar T444E V8 (1994–2004)
Transmission	5-speed manual Allison AT545 4-speed automatic Allison MT643 4-speed automatic
Chronology
Successor	International 3300

The International Harvester S-Series "Schoolmaster" is a Type C (conventional) bus chassis that was manufactured by International Harvester and then Navistar International from 1979 to 1989. In 1989, the S-Series was updated and renamed the International 3800. It was used primarily as a cowled chassis for both school bus and commercial bus applications; it also was the basis for the front and rear-engine stripped chassis that International uses for bus applications as well.

Introduced in 1979 to replace the Loadstar bus chassis, the S-Series was produced in two distinct generations. In 1989, all versions of the S-Series were updated; both versions were offered that year. The 3800 was produced until 2004, outliving other versions of the S-Series/4000-Series by three years. In production for 25 years, the S-Series bus chassis was the longest produced model ever made by International; it was also the last designed by International Harvester before the transition to Navistar.

The Schoolmaster used powertrains and components from the S-Series medium-duty trucks. Two models were available: the S-1700 and the heavier-duty S-1800.

The Schoolmaster changed relatively little over its production run. Many of these changes reflected the transition from International Harvester to Navistar. In 1987, an updated International logo was added to the grille and the steering wheel. Also, in an industry first, all gasoline engines were dropped from the S-Series bus chassis powertrain lineup.

In 1989, Navistar redesigned the S-Series medium-duty conventionals for the first time since 1979; the medium-duty trucks were renamed the 4000-Series. As part of the redesign, the school bus chassis was given a more aerodynamic hood that better integrated the front bumper. On the inside, a two spoke-steering wheel was introduced along with a new instrument cluster. For the first time, the school bus chassis received a separate model designation; the S-1703 was replaced by the 3700; and the S-1803 was replaced by the 3800.

As with its predecessor, the 3800 would change very little over its 15 years of production. In 1991, the 3600 semi-forward control variant was introduced; this was a chassis designed for the Thomas Vista. After 1994, the lower-GVWR 3700 was discontinued. For 1995, along with all other International medium-duty trucks, the 3800 received chrome hood badges denoting the model series and its engine type; the grille badging changed from red to chrome.