From the Ground Up – Building a BMW E36 M3 for Performance Touring C

It’s not often when a shop gets a chance to build a fresh racecar from the ground up. It’s often quick and dirty matter of welding in a roll cage, fabricating mounts for the racing seat, bolting on the safety goodies and suspension bits and turning it loose on the track.

This 1998 BMW M3 coupe is a different story. In the Doghouse Garage took it down to the bare shell, then sent it to Jim Pierce Motorsports in Torrance, Calif., to be fitted with a roll cage and seat mounts. Pierce reinforced the rear subframe where it attaches to the body by incorporating the mounting points with the roll cage. It’s enough of a problem on these cars that the factory floor pans buckle with the loads.

“It will become more rigid,” said In the Doghouse Garage owner Patrick Orozco. “It will tie in with the subfame. The subframe won’t move as much. With the cage attached, the floor pan won’t move as much.”

When they got it back, Orozco used dry ice to remove all the sound-deadening material from the floor pans. Check out this month’s “Toolshed Engineer” to see how that process works. In the end, it was worth the time and effort it took to remove the material, Orozco said.

“It’s not as easy as they say, and it’s not as cheap as they say,” he said. “It took a lot of dry ice to do job. But it took out some weight. It took about 20 pounds out of it.”

In the Doghouse Garage stripped the car bare and sent it out to have cage installed at Jim Pierce Motorsports in Torrance, Calif.
In the Doghouse Garage stripped the car bare and sent it out to have cage installed at Jim Pierce Motorsports in Torrance, Calif.
The car also had all the sound-deadening material removed and was fully seam welded for added structural integrity.
The car also had all the sound-deadening material removed and was fully seam welded for added structural integrity.

At that point it was ready to go to J&D Auto Body in Oxnard, Calif., to have the 2002 “Laguna Seca” blue paint applied. The color was originally used on 2002 BMW E46 M3’s. The car arrived back at the Doghouse and the crew began putting it back together, beginning with the suspension. It’s going to be a lot car for PTC, but Orozco and the owner have done the math and it should end up on the sweet end of the rule set.

“We have a lot of little goodies that I really can’t say that were putting into the car because I signed a nondisclosure agreement,” Orozco said. “The owner doesn’t want us to reveal a lot of the stuff that’s going into the car. It’s going to be set up well.”

What follows is part one of the build process we’ll be following in Speed News over the next few issues.

The cage includes NASCAR bars on the driver side and a lateral brace that ties the two sides of cage together.
The cage includes NASCAR bars on the driver side and a lateral brace that ties the two sides of cage together.
All the glass and wiring harnesses were removed to allow for a more complete paint application process.
All the glass and wiring harnesses were removed to allow for a more complete paint application process.
The NASCAR bars tie into the lower bar that connects the front upright of the cage with the main hoop at the B pillar.
The NASCAR bars tie into the lower bar that connects the front upright of the cage with the main hoop at the B pillar.
The rear of the cage features an X brace with four reinforcements that tie into where the rear subframe attaches to the car. It’s a known problem on these cars that the floor pan can flex and crack with subframe movement.
The rear of the cage features an X brace with four reinforcements that tie into where the rear subframe attaches to the car. It’s a known problem on these cars that the floor pan can flex and crack with subframe movement.
The cage features all the triangulated bracing to strong.
The cage features all the triangulated bracing to strong.
The rear of the cage features an X brace with four reinforcements that tie into where the rear subframe attaches to the car. It’s a known problem on these cars that the floor pan can flex and crack with subframe movement.
The rear of the cage features an X brace with four reinforcements that tie into where the rear subframe attaches to the car. It’s a known problem on these cars that the floor pan can flex and crack with subframe movement.
The whole interior was painted to match the exterior. The sunroof was replaced with a carbon fiber panel.
The whole interior was painted to match the exterior. The sunroof was replaced with a carbon fiber panel.
Here you can see how the front half of the cage ties in with the key supports in the rear half of the cage.
Here you can see how the front half of the cage ties in with the key supports in the rear half of the cage.
The hood is made of fiberglass topped with a layer carbon fiber.
The hood is made of fiberglass topped with a layer carbon fiber.
The extractor vents on top of the fender relieve aerodynamic pressure in the wheel arch and the open rear flanks extract heat,
The extractor vents on top of the fender relieve aerodynamic pressure in the wheel arch and the open rear flanks extract heat,
The circles are used to point out dimples in the finish on the carbon fiber sunroof-delete panel. They will be fixed before the car is race ready.
The circles are used to point out dimples in the finish on the carbon fiber sunroof-delete panel. They will be fixed before the car is race ready.
Like the hood, the deck lid is made of fiberglass, with top layer of carbon fiber.
Like the hood, the deck lid is made of fiberglass, with top layer of carbon fiber.
In this shot, you get a great look at how the cage was built to reinforce the rear subframe mounting points.
In this shot, you get a great look at how the cage was built to reinforce the rear subframe mounting points.
The paint work extended to under the hood and under the chassis.
The paint work extended to under the hood and under the chassis.
You can see where the cage mounting points attach to the rocker panels, one of the strongest portions of the chassis.
You can see where the cage mounting points attach to the rocker panels, one of the strongest portions of the chassis.
Orozco moves the car around the shop on dollies, which makes things easier.
Orozco moves the car around the shop on dollies, which makes things easier.
The D2 suspension package is the next project for the E36 M3.
The D2 suspension package is the next project for the E36 M3.
Headlights were removed but the car will use its factory brake cooling ducts.
Headlights were removed but the car will use its factory brake cooling ducts.
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Image courtesy of Brett Becker