Engineering:GM H platform (1986)

GM H Platform (FWD)
1986 Buick LeSabre
Overview
Manufacturer	General Motors
Also called	H-body
Production	1986–1999
Body and chassis
Class	Large car platform
Body style(s)	2-door Coupé 4-door sedan
Vehicles	Buick LeSabre Oldsmobile Eighty-Eight Pontiac Bonneville
Related	GM C platform GM G platform (FWD) GM K platform (FWD)
Powertrain
Engine(s)	Gasoline: Buick V6
Transmission(s)	4-speed THM440T4 automatic 4-speed 4T60-E automatic 4-speed 4T60E-HD automatic 4-speed 4T65-E automatic 4-speed 4T65E-HD automatic
Dimensions
Wheelbase	110.8 in (2,814 mm)
Chronology
Predecessor	GM B platform GM G platform (RWD)
Successor	GM G platform

The H platform, or H-body designates a General Motors front-wheel-drive full-sized automobile platform beginning in 1986. It is related to the C, G and K platforms. Many H-bodies used GM's Buick 3800 V6, and supercharged versions of this engine were available from 1991 to 1999. They originally came in both 2-door and 4-door versions, but the four-door sedans were dramatically more popular, and two-door models were dropped by 1992. Previously, the H platform designation was used for unrelated rear-wheel-drive compact cars.

According to one source, the H-body sedans were the next "big thing" for GM, and development cost more than $3 billion, which is on par with roughly how much Ford invested in the Ford Taurus. Both the H-body sedans and the Taurus (based on the D186 platform) were launched fully in 1986. Starting in 2000, all H-body vehicles moved to the G platform, however GM continued to call it the H platform. Most H-body cars had Buick's 3.8 liter (231 cubic-inch) V6 engine standard.

1986-1999 Buick LeSabre

The 1986 LeSabre was introduced on the new front wheel drive H platform, after departing from rear wheel drive on the GM B platform. Joining the LeSabre on the H-body included the Oldsmobile Delta 88 and the 1987 Pontiac Bonneville, which returned to full-size after a short-lived run as a mid-size on the G platform. One of the features of the LeSabre version of the H-body was a reverse clamshell hood - one that is hinged at the front (in the same fashion as that of the Buick Electra and Chevrolet Corvette of that era) instead of at the back near the cowl and windshield. The all new styling and implementation of front wheel drive ushered in a new era for the LeSabre, being of a flush aerodynamic design. The most radical change may have been the removal of Buick's long standing Ventiports from the front fenders. Most Buick LeSabre models from 1986 until 2005 were powered by Buick's 3.8 liter (231 cubic-inch) V6 engine. It started out with 150 hp (112 kW). It added balance shafts to become the famous "3800" V6 for 1988, with 165 hp (123 kW). This engine increased to 170 hp (127 kW) in 1991 with the addition of Tuned Port Injection. The 1986 model, however, featured the 3.0 liter (181 cubic-inch) V6 as standard.

This LeSabre was introduced in 1991 for the 1992 model year, and was redesigned along the same lines as the previous year's Park Avenue. The LeSabre was available only as a four-door ("family-style") sedan from this point forward until the car was discontinued in 2005. The headlights were streamlined with a separated amber turn signal strip wrapping around the lower front fascia. The rear fascia featured a wider trunk mouth and lower lift over height to ease loading baggage while the front was smoothed with simplified chrome molding and absent bumperettes. The LeSabre also featured GM's plastic body technologies, with high-stress plastic replacing traditional steel in the front fenders. The LeSabre's engine from 1992 to 1995 was the 3800 V6 (L27), which produced 170 hp (127 kW) and 225 lb·ft (305 N·m) The 3513 lb (1593 kg) car got 18 mpg (13.1 L/100 km) in the city and 28 mpg (8.4 L/100 km) on the highway, which was slightly better than the 1991 model. The car accelerated to 60 mph (97 km/h) in 8.9 seconds and could cover the quarter mile in 16.9 seconds at 80 mph (129 km/h). Top speed was electronically limited to 108 mph (173 km/h).

1986-1999 Oldsmobile 88

For 1986, the Oldsmobile Delta 88 switched platforms from the GM B platform to the smaller front-wheel drive H platform, with a wheelbase of only 110.8 inches (2,814 mm). The headlights changed from square sealed beam quads to integrated regular/high beam composite lamps in 1987. A few NASCAR teams built racecars with 1986 Delta 88 sheetmetal and ran them on the circuit in the 86–88 seasons, but only one victory (with Terry Labonte) was scored. The Oldsmobile Eighty Eight was redesigned for 1992, following the redesign of the Ninety Eight the previous year. This was the last Eighty Eight or 88 model from Oldsmobile (along with its performance LSS and Regency models) before being discontinued in 1999 and being replaced in 2001 with the Aurora. The 3.8 L Buick V6 was still the only engine, but output increased to 170 hp (127 kW) and 220 lb⋅ft (300 N⋅m) of torque.

1987-1999 Pontiac Bonneville

For 1987, Pontiac decided to change the Bonneville from the rear wheel drive G-body with the V8 to the more economical front wheel drive one-year-old H Body platform with the Buick LeSabre and Oldsmobile 88. Initially, a 150 hp (110 kW) 3.8 L V6 was the sole engine, mated to a four-speed Hydramatic 4T60 automatic and performance was adequate from this pairing. The new Bonneville was placed on Car & Driver's “10 Best” list for 1987, offering both a base model and LE model. For LE models, an SSE sport package was also available that featured a quicker gear ratio, sportier suspension and more standard features, as the Bonneville was intended to have a more sporty, European flavor than the LeSabre and 88.

The ninth-generation Pontiac Bonneville was unveiled on February 8, 1991, at the 1991 Chicago International Auto Show and launched in July 1991 for the 1992 model year; the interior and exterior of the car were completely redesigned. Developed over a ​4 ¹⁄₂-year period from 1986 to early 1991 under program director Dave Mitchell, styling work took place from 1987 to 1988, with a final design by John Folden being chosen in 1988 and frozen for production that same year. The first prototypes were built in 1989 and went into testing in mid-1989. In August 1990, production preparation began, with early production "builds" being constructed during late 1990. The first series production models were assembled in May 1991, with SE variants being launched in July 1991. The trims were redone once again, the LE trim (which had standard six-passenger seating) was removed, the SE was now the base model (the only model to offer six-passenger seating as an option), the SSE was now the mid grade and a new top of the line trim was now added, the SSEi, which received a standard passenger-side airbag. According to GM's Pontiac division, these trim acronyms have no implied meaning. The base and midlevel models were provided with Buick's basic 3.8-liter V6, while the SSEi received the hotter supercharged version. All engines came paired with a 4-speed overdrive automatic transmission. SSEi models got dual airbags and antilock brakes. SE and SSE models made due with a driver-side airbag and optional ABS. This generation hosted quite a few Bonneville firsts, becoming quicker and considerably safer. One of the most notable improvements over the previous generation was that the Bonneville SE now came standard with a driver airbag and was the first General Motors product equipped with a passenger airbag, while ABS was available as part of the sport appearance package. The SSE models came with standard ABS and traction control.

Vehicles

Years	Model	Previous platform	Next platform
1986–1999	Buick LeSabre	GM B platform	GM G platform
1986–1999	Oldsmobile 88/LSS	GM B platform	Retired
1987–1999	Pontiac Bonneville	GM G platform (RWD)	GM G platform

References

• List of GM VIN codes