Cadillac CELESTIQ - Powertrain and Suspension
It has been a while since we’ve talked about the upcoming Cadillac flagship, the CELESTIQ.
We’ve talked about the shopping experience as well as the engineering.
But, under all the fancy styling and bespoke interior and exterior styling and features is GM’s Ultium platform’s suspension, battery, and motors.
Like GM’s other Ultium-based cars, the CELESTIQ has a long, low battery pack forming the center of a ‘skateboard’ chassis. At each end of the pack are mega castings that hold one drive motor per end as well the independent suspension components.
In the case of the CELESTIQ, the battery pack has 111 kWH of capacity (up from the LYRIQ’s 100kWH pack). The combined motor output works out to 600hp and 640 lb*ft of torque. Combined, these provide an estimated 300 miles of range with a 0-60 time around 3.8 seconds.
Cadillac has been known for decades for their high-performance suspension systems. Conventional suspensions have just one level of damping (resistance to movement of the wheel) which means that it is common for the suspension to fall flat in certain edge cases on the road or track.
Cadillac’s performance suspensions of the 90’s would adjust between at least two different damping profiles based on sensor input. Initially, these Road Sensing Suspensions (RSS) could read the road conditions every 15ms. This meant the suspension was able to read road conditions nearly every foot at 60 mph. Ever since, Cadillac has advanced their road-sensing technology and shock absorbers to get better and faster to enabled their cars to drive better and more responsively without sacrificing comfort.
In 2002, Cadillac pioneered use of magnetorheological fluid that replaced adjustable shock absorber valving with fluid that could be electrically changed in viscosity (thickness). This greatly increased the capability of the suspension system to adjust to performance demands. This system is marketed under their “MagneRide” name.
The latest Blackwing CT4-V and CT5-V debuted a new version of MagneRide (version 4) which will lead directly to the technology in CELESTIQ. Unlike the early RSS systems which could read the road and respond once every 15ms, which worked out to 67 times per second…the new 4th generation MagneRide reads conditions 1000 times per second. So, unlike reading the road nearly once per foot at 60mph, the new system can read the road once every inch. Then it can quickly change the thickness of the fluid in the shocks to allow them to either stiffen and hold the body and wheels in place or relax and allow tires to follow the road contours without disturbing the body. This undoubtedly will allow the CELESTIQ to ride like the most comfortable ultra luxury cars on the market while also being capable of attacking the tight turns of your favorite canyon road.
Combined with the magnetic shocks, CELESTIQ also has a 5-link suspension that uses adaptive air springs to replace traditional coil springs that further can combine isolated ride as well as high-performance handling.
There is one other component of a suspension system that is needed for performance handling that can compromise ride and comfort. In order to drive fast around curves, it is important for the car to stay flat (parallel to the road’s surface). Soft ride normally comes with a boat-like characteristic that would have the car rolling towards the outside of the corner. This roll is uncomfortable for passengers and also unloads the inside tire and reduces the ability to stick to the road.
Preventing this roll are the aptly named ‘anti-roll bars’ that connect the suspension of the car from side to side and fight this rolling of the body. Unfortunately the downside to this anti-roll feature is that bumps more easily transfer force into the body (shocking the passengers when one tire encounters a bump or dip in the road. In the CELESTIQ, Cadillac has developed ‘active roll control’ to lend the big sedan flat cornering while not unduly transferring bumps to the cabin. They aren’t clear on how this technology works, but a search of GM’s patents does suggest the use of electronics and motors to alter how much roll resistance is included in the suspension - allowing for soft ride over bumps while also resisting roll during performance driving. This sounds like another example, much like the MagneRide system to allow comfort and agile handling in one car.
Another way that Cadillac is striving to make this big flagship a driver’s car is via the addition of rear steering. Most cars steer exclusively with the front tires. Rear tires just track straight forward. In the CELESTIQ, Cadillac has added a rear steering system that can add 3.5 degrees of rear steering in the opposite direction (out of phase) of the front. This causes the car to rotate faster than it would otherwise making the big car handle like a much smaller vehicle. At higher speeds, when this sort of counter-steering in the rear would feel less stable, the rear steering will steer in the same direction as the front (in-phase) to help enhance stability. The result should be a car that handles small and nimble on twisty roads while being stable and comfortable on high-speed highway driving.
That isn’t the only steering trick announced for the new Cadillac flagship. CELESTIQ’s electric power steering comes with a variable steering ratio. Based on speed and driving scenario, the steering will change the number of turns of the steering wheel necessary to change the front tire’s angle from center. Imagine only needing to turn the steering wheel a small amount to navigate a parking lot, while the rate changes to make the car more stable on the open road and you have the general idea.
It is by bringing all of GM’s latest engineering and technology, that they plan to make the most impressive Cadillac ever sold. While being loaded with design and technology, it may be with their powertrain and suspension prowess that Cadillac’s CELESTIQ really impresses the most.