VIDEO: An In-Depth Look Inside The New Detroit Assembly Complex – Mack Facility:

Take A Tour Inside The Home Of The New Jeep® Grand Cherokee L...

In February of 2019, Fiat Chrysler Automobiles (FCA) announced its plans to invest $1.6 billion to convert two of its smaller engine plants into a state-of-the-art assembly facility for its next-generation Jeep® Grand Cherokee (WL). The new assembly complex was part of a $4.5 billion investment that impacted five existing facilities in Michigan and aimed at creating 6,500 new jobs for the area. 

Detroit Assembly Complex – Mack plant, is home to the Jeep® Grand Cherokee L. (Stellantis).

While we got a sneak peek at the work behind the scenes at the new Detroit Assembly Complex – Mack, the first new automotive assembly plant in the city of Detroit in 30 years, the new plant is now operational and cranking out all-new 2021 Jeep Grand Cherokee L. The Grand Cherokee L is the first variant of the new fifth-generation Grand Cherokee to hit the market and is the first three-row offering on the most awarded SUV nameplate in history.

Stellantis, the newly formed identity between the merger of Peugeot S.A. (PSA) and FCA, is giving us an in-depth tour of its newest assembly plant in action. 

The body and chassis of the Jeep® Grand Cherokee L are married together on the decking line at Detroit Assembly Complex – Mack plant. (Stellantis).

With over 100 years of manufacturing done on the site, the new Detroit Assembly Complex – Mack facility started construction in the second quarter of 2019 and was complete in less than two years with an ongoing pandemic. The Mack facility is 3 million square feet of floor space on 266 acres of property. The plant is made up of three main production facilities (body shop, paint shop, and general assembly).

With a workforce of 4,900 people, the Mack facility has 2,100 Detroiters filling positions within the complex. Employees work three shifts, five days per week at the current moment to fulfill the demand of the new 2021 Jeep Grand Cherokee.

An employee at Detroit Assembly Complex – Mack plant uses a “happy seat” to work inside the body of a Jeep® Grand Cherokee L. (Stellantis).

According to Stellantis, the new plant has 770 inbound trucks per day, as well as 76 trucks and 95 railcars outbound per production day. It takes 36 hours from start to finish to build a new 2021 Jeep Grand Cherokee L.

Body Shop:

The Mack facility’s 650,000 square-foot body shop is made up of the former Mack Engine II plant, which was idled in 2012. The Mack Engine II plant was completed in 2000 and produced it produced the 3.7-liter V6 engine for the Dodge Ram 1500, Dodge Dakota, Dodge Nitro, Jeep Liberty (Cherokee), Jeep Grand Cherokee, and Jeep Commander.

The 650,000-square-foot body shop at Detroit Assembly Complex – Mack plant welds the body of the Jeep® Grand Cherokee L. (Stellantis).

Now, the facility houses 578 robots that can produce a body of a Grand Cherokee L and make sure it fits perfectly together in about 2 hours. 

A Jeep® Grand Cherokee L body moves through the framing cell in the body shop at Detroit Assembly Complex – Mack plant. (Stellantis).

A net form is created for the Jeep Grand Cherokee L to establish the perfect dimensional environment to hang panels, such as the hood, liftgate, doors, and fenders before the body is pierced. Robots measure the gaps and fit to ensure they are symmetrical. There are 26 robots in the cell.

Twenty-six robots in the Net Form and Pierce cell in the body shop at the plant measure the gaps on a Jeep® Grand Cherokee L. (Stellantis).

Radar technology is mounted on robots to measure hundreds of preprogrammed surface and alignment points to verify the build process. This 45-minute validation test is performed on a select number of vehicles across all three production shifts and complements the inline measurement system that measures every Jeep Grand Cherokee L coming through the body shop.

Paint Shop:

An all-new paint shop was build for the new Detroit Assembly Complex – Mack facility. The body shop measures 800,000 square feet and features five floors of space. It houses 124 robots that are fully automated thanks to a 100% robotic spray application, guaranteeing a perfect paint job every time. 

Twenty-one robots in the paint shop at Detroit Assembly Complex – Mack plant apply the color to the body of a Jeep® Grand Cherokee L. (Stellantis).

The 6 part process takes a total of 12 hours and the body shop can produce 11 different colors for the Grand Cherokee. The 6 part process includes the following steps…

  1. Phosphate E-Coat: Each vehicle goes through an E-Coat bath, giving the vehicle its first layer of corrosion protection
  2. Sealer: 28 robots apply 208 feet of sealer in each Grand Cherokee L to prevent leaks, corrosion, and wind noise
  3. Primer: 8 robots apply a smooth base layer that adds durability to the vehicle’s paint
  4. Base Paint Coat: 21 Robots (10 Painting and 11 “Opening”) paint the vehicle in up to 11 different exterior colors
  5. Clear Coat: The vehicle gets a clear coating to enhance the color and offers a protective coating for the paint
  6. Finesse & Polish: Workers identify and remove any imperfections in the paint, to ensure a smooth and flawless paint finish

General Assembly:

After the painting process is complete, the body is sent to the general assembly portion of the facility. Originally, the Mack Engine I plant, which built the Pentastar V6 engine family until December of 2019, the 1,000,000 square foot building now houses three stages of the assembly process (Trim, Chassis, and Final).

An employee at Detroit Assembly Complex – Mack plant installs the rear window glass on a Jeep® Grand Cherokee L. (Stellantis).

In the trim area, Grand Cherokee models receive things like the sunroof, wiring harnesses, major electrical components, instrument panel, windshield, as well as rear and half glass.

Skillets carry Jeep® Grand Cherokee Ls as they travel down the trim line at Detroit Assembly Complex – Mack plant. (Stellantis).

The chassis area performs engine dressing, engine and chassis marriage, body and chassis decking, hose and electrical connections, as well as filling all necessary fluids, and functionality testing.

Employees at Detroit Assembly Complex – Mack plant marry the body and chassis of a Jeep® Grand Cherokee L on the decking line. (Stellantis).

In the final assembly area, Grand Cherokees then receive their steering wheel, major components like doors, wheels, and tires, and electrical testing. After the final assembly area, conducts various checks like alignments, headlight aim, rolls, Automated Driver Assist System (ADAS) checks, before hitting the Buzz, Squeak, and Rattle (BSR) test track and inline water testing. After all the vehicles go through the certification line to make sure that the vehicle leaves the assembly line with no flaws.

Every Jeep® Grand Cherokee L during validation on the BSR test track at Detroit Assembly Complex – Mack. (Stellantis).

Each vehicle that is assembled at the Mack facility, is tested on the BSR test track. The test track consists of 2,000 feet of 11 different elements, which includes potholes, manhole covers, rumble strips, cobblestones, speed bumps, gravel, and a figure 8, to simulate real-world driving conditions. Each test takes about 3 minutes to conduct but insures if there are any BSRs detected, the vehicle will be fixed properly before being shipped.

A Jeep® Grand Cherokee L goes through the additional buzz, squeak, and rattle validation in the BSR Shaker. (Stellantis).

For additional validation beyond the BSR test track, vehicles can be sent to the BSR Shaker. The electro servo shaker is the first of its kind in North America and replicates the BSR test track in 2 minutes and 40 seconds, as well as additional testing like a pre-programmed profile of the more aggressive test roads at Stellantis Chelsea Proving Grounds in a 3 to 5-minute cycle, to make sure the vehicle is ready optimum customer’s satisfaction.

Every Grand Cherokee L is pounded with water by 600 nozzles in the inline water test at Detroit Assembly Complex – Mack plant. (Stellantis).

Every vehicle then goes through an inline water test, which takes 3 minutes to complete. The water test consists of 600 nozzles delivering water at 30 psi. Each vehicle is then checked for leaks before being signed off for final inspection. Vehicles can face additional validation performance in a Nine Position Water Test to simulate different terrain (hills and inclines) as well as other weather conditions.

An employee on the 400-foot-long Certification Line at Detroit Assembly Complex – Mack plant. (Stellantis).

After going through the certification line, each vehicle is then ready for shipping to a Jeep dealer. 

To keep up with everything surrounding the all-new fifth-generation Grand Cherokee, be sure to join our new WLJeepForum.com.


Robert S. Miller

Robert S. Miller is a diehard Mopar enthusiast who lives and breathes all that is Mopar. The Michigander is not only the Editor for MoparInsiders.com, 5thGenRams.com, and HDRams.com but an automotive photographer. He is an avid fan of offshore powerboat racing, which he travels the country to take part in.

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I watched this yesterday and it made me want a new Grand Cherokee really badly.

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Can't wait for these things to finally get the green light for sales :)

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GUILTY!! I am one of those who have too often complained at the pace of new product for many of the brands and models I favor, in particular Dodge and Chrysler. What I and others have overlooked or forgotten is the huge investments being made by Stellantis in manufacturing capacity, technology and quality. Mack Avenue is beyond impressive and the level of quality control points to world class product quality demanded in the global marketplace. This investment strategy will only translate into customer satisfaction and confidence, higher resale values and of course sales and profits. Sure, the wait for new product has been frustrating, but for the guilty amongst us, we have to see the whole picture. These video clips of Mack provide a sobering effect that clearifies things Mopar, not always obvious, that guys like me need to keep the faith. Hallelujah !!!

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