Cadillac used the body-frame interface of the 2021 Escalade to mitigate “cabin boom” on the 2021 Escalade, GM lead upper structure engineer Jeff McCormick said recently.

McCormick’s presentation to the virtual 2021 Great Designs in Steel on May 21 highlighted this region and a couple of other areas where GM improved ride or sound quality using the vehicle structure.

The discussion gives collision repairers a sense of what they might encounter and have to restore when working on the popular luxury SUV.

McCormick called the 2021 Escalade’s dynamic fuel management system a hurdle for engineers due to the prospect of cabin boom. The feature, which involves the Escalade shutting off up to seven cylinders automatically to save gas, operates at high amplitudes across a broad frequency range.

He said Cadillac dealt with this issue two ways. It improved body stiffness, and it focused the interface between the new vehicle body and frame.

Presenting the following slide, McCormick noted how Cadillac was “very careful” to align the frame mounts with the center of the sections.

The OEM connected the components with throughbolts, something it had done in the prior-gen 2020 Escalade. However, McCormick said GM improved the design for the 2021 Escalade with great success.

He said the front three cabin mounts seen in the slide were “critical” for cabin boom, and the Escalade’s architecture improvement and stiffness have produced “some nice results.”

Cadillac achieved a 2-3 decibel decrease in road noise sound pressure density, a “very nice improvement” related to the stiffer structure. However, the structure also lets the OEM “soften the isolators” and produce an approximately 2 dB decrease in sound pressure, he said, calling it an “additional benefit for our customers.”

Cadillac also managed cabin boom higher in the body structure. New bows reduced the effect in the roof, while baffles in the quarter panels stiffened the structure and cut airborne noise, McCormick said. Stiffer hinge and latch reinforcements reduced the liftgate’s ability to intensify cabin boom, he said.

Meanwhile, the rear floor panel has been designed to stave off exhaust-related boom. “It is robust to those inputs,” he said.

Such efforts contributed to a 6 dB drop in the primary boom range for low-speed coarse road noise. It also yielded a 10 dB cut in 1,350-1,650 RPM powertrain noise, which amounts to “nice improvement there as well,” McCormick said.

The interface area and stiffer body structure also contributed to what a slide called “the exclusive Cadillac experience.” McCormick related this concept to feel and handling.

The stiffer body, new frame-body interface shear mount design, new independent rear suspension and a better “body response at key occupant to body interfaces” played a role in that performance, according to the slide.

“Every mount was increased in stiffness from 30 to a hundred percent,” McCormick said. The largest improvements can be seen in the three frontal mounts described above.

McCormick said vertical stiffness matters the most for cabin boom, but the stiffness of all three directions (vertical, lateral, and fore-aft) affects ride comfort.

He presented a slide showing how driver rear inboard seat track response fell 6 dB fore-aft, 6 dB laterally and 3dB vertically “Something very nice for our customers,” he said.

Overall, the 2021 Escalade’s lateral stiffness improved 10 percent from the prior-generation SUV, with the integrated front-end structure the largest contributor, according to McCormick. Global bending stiffness increased 28 percent, and global static torsion grew 46 percent.

More information:

“2021 Cadillac Escalade”

General Motors at Great Designs in Steel, May 19, 2021

“2021 CADILLAC ESCALADE STRUCTURE REVIEW”

General Motors at Great Designs in Steel, May 19, 2021

Official GM OEM repair procedures

Images:

The 2021 Cadillac Escalade is shown. (Provided by Cadillac)

Cadillac used the body-frame interface and body stiffness to mitigate “cabin boom” on the 2021 Escalade, GM lead upper structure engineer Jeff McCormick told the 2021 Great Designs in Steel. (General Motors slide provided by Great Designs in Steel)

Cadillac used the body-frame interface and body stiffness to mitigate “cabin boom” on the 2021 Escalade, GM lead upper structure engineer Jeff McCormick told the 2021 Great Designs in Steel. McCormick noted how Cadillac was “very careful” to align the frame mounts with the center of the sections. (General Motors slide provided by Great Designs in Steel)

The stiffer body, new frame-body interface shear mount design, new independent rear suspension and a better “body response at key occupant to body interfaces” on the 2021 Cadillac Escalade played a role in “the exclusive Cadillac experience.” GM lead upper structure engineer Jeff McCormick related this concept to feel and handling. (General Motors slide provided by Great Designs in Steel)

“Every mount was increased in stiffness from 30 to a hundred percent” on the 2021 Cadillac Escalade body-frame interface, GM lead upper structure engineer Jeff McCormick told the 2021 Great Designs in Steel. (General Motors slide provided by Great Designs in Steel)