"Caddie" Ideal daily driver.
**Unfortunately Caddie was totaled on Wednesday evening 9:30 PM 11/09/2005, at 236,000 miles on the odometer, on a back road in Easton, CT. The driver (my son) lost control, clipped off a power pole, the car landed on its side and was completely destroyed. He walked away with bruises (thank you Cadillac) but the car did not. See photos page 2.**
1991 Cadillac Seville STS. The now famous STS Cadillac Touring Sedan. And the last year of the compact body style. Consequently the 1991 STS is a rare car with a unique combination of Seville style, excellent fuel economy, great power and performance suspension.
Below is a photograph of the "Cadillac" emblem just above the glove box handle and directly in front of the front passenger.
Fully a Cadillac in styling, luxury leather interior and amenities the STS also has firm performance suspension, tighter performance steering, better gearing and more engine power, now the standard for all STS Cadillacs. Below is a photograph of the "STS" emblem on the trunk exterior (if it doesn't have this, it isn't).
Looking back now, the early eighties were an extremely difficult period for the American automotive industry. Fuel prices were hovering around $1.20 a gallon and it was generally accepted that fuel prices would triple by the mid-eighties. All manufacturers were seeking more fuel efficient alternatives to their still big cars. Unfortunately, fuel prices had only risen by a little in 1986 (to around $1.50 per gallon) when Cadillac introduced their two new smaller cars with smaller engines and Seville sales plummeted from 39,755 to 19,098 units. Seville production would hover around 22,000 units for the next couple of years.
In 1989 in a move to make the Seville more attractive to the younger audience, and capture the BMW and Audi market, a larger engine and sportier appearance was introduced and 33,128 units were produced.
In 1991 the Cadillac Seville was further modified with the addition of a larger engine (4.9L), advanced sport/touring suspension, de-chromed details, stronger styling and labeled as the "STS". The 1991 STS is a rare combination of luxury, performance and economy.
Base pricing on both the Seville and STS were over US$40,000. Sticker price of my 1991 STS (build in November 1990) was approximately US$60,000 in September of 1991 and included premium sound, 16" alloy wheels, performance tires, moon roof, and all options available.
STYLE - BODY AND TRIM APPEARANCE
Solid and strong lines from the wide profile tires, low suspension, long hood and compact body give strong appearance and solid performance. The STS was equipped with the firmer ride and handling of a touring suspension package. It included 23mm front and 16mm rear stabilizer bars, special 16-inch forged aluminum wheels with standard Goodyear Eagle GT4 P215/60R16 tires). I have upgraded to V rated performance tires Hankook K106 225/50R16 92V. The ubiquitous "Cadillac” wreath hood ornament found on most Cadillacs has been replaced in the 1991 STS with the Cadillac grill emblem.
Dual stainless-steel exhaust from front to back are finished with and square exhaust tips and provide a pleasant and powerful exhaust note. The 1991 Sevilles also received a new taillamp treatment and neutral density back-up lamps. The rear suspension featured a novel single transverse leaf spring like the C4 Chevrolet Corvette.
Trunk emblem (photo below) rotates to reveal manual key lock (which is seldom used because of the keyless radio signal key fob). Most remote access packages used infra-red signals which can be blocked by glass, buildings or other vehicles. The radio remote access package can be operated from indoors and greater distances.
Many of the same components and design features from the 1991 Corvette are used in the 1991 STS. Consequently the performance of the 1991 STS is similar to the Corvette of the same year although the STS is slower due to the higher mass of the sedan (4 door) configuration.
WHEELS AND TIRES
Adding solid footing to the solid appearance the 1991 STS came with special 16-inch forged aluminum wheels. These wheels added strength as well as light unsprung weight thus increasing suspension performance. The 1991 STS came equipped with Goodyear Eagle GT4 P215/60R16 tires.
The forged alloy wheels feature beveled slots and silver polished surface. The aluminum hubcap covers the 5 standard 19mm lug nuts. This was the only year to feature the aluminum hubcap, all subsequent years featured plastic hubcaps with the same general appearance.
I have upgraded to V rated performance tires Hankook K106 225/50R16 92V. The Hankook K106 is a high performance radial designed for serious driving excitement. The radical v-shaped tread pattern efficiently disperses water without compromising speed or handling. Rated at "92" provides for a load rating of 1389 lbs (630 kg). Rated as "V" provides for speed rating of 149 mph (240 km/h) for Sport Sedans, Coupes & Sports Cars. This tread pattern added a significant amount of road noise, a definate buzz-whirr at highway speeds and higher. This is unfortunate because this car was typically extermely quiet at standard highway speeds and is no longer so with these tires. Added note: After considerable consideration, I now believe the reason the car was totaled (see page 2) was that these tires did not hold in the cold-damp road environment, and let go of adhesion without warning. The manufacturer used a slightly harder coumpound to gain longer wear, but sacrificing cold-damp adhesion.
INTERIOR
The STS exclusively featured high-gloss elm burl wood in all door panels, instrument panel and console.
In addition to redesigned seats, new full Beechwood leather front bucket seats included six-way power seat adjusters, power recliners and power lumbar support for driver and passenger.
There was also a full-width rear leather seat with integral headrests and rear passenger lighting (opera lights).
In later models the rear console was eliminated to accommodate a third center rear seat passenger. That was unfortunate because the older style (as in mine) provided "bucket seat" feel for the two rear passengers (particularly useful when driving in a spirited manner with passengers). Notice the luxurious and "plump" leather throughout. It is not vinyl with leather patches like in my Mercedes, but full leather coverings. Look cloesly at the stiching and one can observe leather in both connecting surfaces.
Spacious trunk is carpeted and includes a pad useful if one must change a tire or perhaps as a picnic blanket. One can see the rear speaker housings covered in carpeting just below the back window. The trunk pull down latch was a weak point in the system and would break if the trunk was slammed. Once one got used to it's proper use, it worked very well.
The keyless access feature includes an electronic trunk release and a trunk pull down feature. I have recently learned that the new STS do not have the trunk pull down feature. The trunk pull down is a special latch for the trunk. With a slight pressure from the operator the trunk lid will cose and latch, then a motor takes over and pulls the trunk lid down aginst the gaskets making a tight seal.
ENGINE
The 1991 Seville is powered by a 300 cubic inch (4.9 L L26 HT4900 SFI) V8 transverse mounted with intergral transmission. This engine debuted in 1991 and features a square 92 mm bore and stroke. Power was the same as the 4500 at 200 horse power (149 kW) but torque was up slightly to 275 ft.lbf (373 Nm). The 1991 STS had even further enhanced power with the early Northstar engine. This power is far above the 4.1 L LT8 HT4100 V8, 130 horse power engine in previous Cadillacs.
The engine features port fuel injection (PFI) (spray into each cylinder), normally aspirated (cold air though throttle body), and high voltage electronic ignition. This engine was produced for other Cadillacs until 1996 and was replaced in the STS by the all aluminum Northstar engine in 1992. Cadillac was the first automobile maker to mass produce a V8 engine. The company has produced eight generations of V8s since 1914, and today is the only General Motors division to retain its own V8 design.
Front wheel drive final drive ratio for the Seville sedan was 2.97:1 while the SLS's was 3.33:1. I do not recall the final ratio for the STS but it is geared for a quick start and still retains a very high top end.
PERFORMANCE
Cadillac style, luxury and performance, and high fuel economy. This car appeals to the late 1980s market demand for more precise and compact European styling. The STS overall body size and wheelbase was increased in 1992 resulting in more mass and a slower and less efficient car.
With 225,000 miles it is still running strong. I recently (Aug 2005) took a trip on the New Jersey Turnpike and was able to record average highway fuel economy performance. Data was taken after 30 minutes of steady cruise control operation on moderately level highway, air conditioning off, open windows and ambient temperatures in the high 80s. The output of the car computer (indicated average fuel economy in MPG) was plotted versus the average cruise control speed setting (cruise settiing and indicated speed MPH) below. One may notice variability in the data increases with increasing speed. One may observe that the slower you go, the steadier the foot on the gas, the better the economy, the lower the engine wear, up to about 40 MPG at 50 MPH.
One can observe average fuel economy using the on the "on board" computer. In this photograph 31.8 mpg at 65 mph is indicated. One can also see the Bose Gold 8 speaker CD AM/FM stereo system.
SPECIFICATIONS
BODY
Overall Weight 4,595 lbs. GVW (2.3 US tons)
Weight Front 2,569 lbs.
Weight Rear 2026 lbs.
Weight ratio 56% Front / 44% rear
Height 53.2 in. (1351 mm)
Width 72.0 in. (1829 mm)
Overall Length 190.8 in. (4846 mm)
Wheelbase 108.0 in. (2743 mm) (15.9 feet)
Standard Tires 215/60R16
Upgraded Tires 225/50R16
Fuel Tank 18.8 gal.
1992 STS (new body style - for comparison)
Wheelbase 111 in
Overall Length 203.9
ENGINE
Type 90-degree overhead valve V-8
Block Aluminum block
Cylinders cast iron cylinder liners
Head cast iron cylinder heads
Displacement 300 cu. in. (4.9 liters)
Bore & Stroke 3.62 x 3.62 in.
Compression ratio 9.5:1
Bhp 200@4100 rpm
Torque 275 lb.-ft.©3000 rpm
Lifters Roller hydraulic valve lifters
Injection Sequential port fuel injection
Transmission
4T60-E electronically controlled four-speed automatic with overdrive (includes viscous converter clutch)
Steering
Power-assisted rack-and-pinion
Front Suspension
Fully independent McPherson strut with coil springs. Strut-type shock absorbers, integral-in strut and Computer Command Ride and heavy duty stabilizer (sway) bar.
Rear Suspension
Fully independent transverse mono leaf with automatic level control and Computer Command Ride and rear heavy duty stabilizer (sway) bar.
Brakes
Power assisted front disc and rear disc with Bosch Il ABS anti-lock braking system.
Body Construction
Integral body-frame
FF frame
K body
In automobile design, an FF, or Front-engine, Front wheel drive, layout places both the engine and driven wheels at the front of the vehicle. This layout is typically chosen for its compact packaging - that is, it takes up very little space, allowing the rest of the vehicle to be designed more flexibly. In contrast with the FR layout, the FF layout eliminates the central tunnel needed to accommodate a driveshaft taking power to the rear wheels. Like the RR and MR layouts, it places the heavy engine over the drive wheels which aids traction. As the steered wheels are also the driven wheels, FF cars are far superior to FR cars in conditions such as snow. However, powerful cars rarely use the FF layout because weight transference under acceleration unloads the front wheels and reduces grip. As a rule of thumb 150hp is the limit for a FF car of average weight; electronic traction control can avoid wheelspin but largely negates the benefit of extra power.
Early cars using the FF layout include the Citroën Traction Avant, Saab 92 and the Mini. In the 1980s, the traction and packaging advantages of this layout caused many compact and mid-sized vehicles to adopt it. Because the transversely-mounted engine does not require a bevel gear to change the direction of the final drive, coastdown losses are reduced by approximately 2-3% of flywheel power and hence overall efficiency is slightly higher than with a FR design.
The front wheel drive K-body was used for full-size Cadillacs from 1979. K-bodies were sedans; coupes used the identical GM E platform.
Unlike most GM platforms, the K was not shared by multiple divisions (though the E was). Technically, though, the architecture was shared under a different name: the GM G platform was based on the K and produced at the same time.
The K platform was updated in 1997 with improved suspension geometry. The Seville was replaced with the rear wheel drive GM Sigma platform Cadillac STS for 2005, but the DeVille's replacement, the DTS continues on the K-body.
REFERENCES:
Cadillac forum
Cadillac Classified Advertisements
View other cars in my garage by clicking on "twombly" (upper left).
