The original Wireless Lego Race Car was built with the hacked motor and gearbox with axle that I took out from small toy R/C car, and modified LEGO Plates to be used as a servo mount.
Later on I designed new three new hardwares to be used with custom design LEGO vehicles or robots:

3D printed motor housing for 24mm diameter 9V motor. See details in R /C LEGO® "The Bull" Buggy, Step 1: 3D Printed Motor Housing.
3D printed servo mount for 9g Micro Servo (Tower Pro SG92R, and T Pro SG90). See details in "12 Thumbs" R/C LEGO Dragster, Step 1: 3D Printed Servo Mount.
Palm Arduino Plus, an Arduino Compatible Board which included motor controller IC (L293D/SN754410) on the PCB. See details in Palm Arduino Plus.

So, I no longer have to hack or modify anything any more. Now it is a lot more convenient, when I have a new custom design LEGO vehicle or robot to build, I just order the 3D printed motor housing and servo mount (since I do not own a 3D Printer!)

Even though this was a "redux" or a rebuild of Wireless Lego Race Car, there are some changes on the parts. But the shape of the car is still the same.
I am going to show you how to build this car step by step all over again just like we tear the model apart and rebuild it.

Disclaimer:
_{LEGO®, TECHNIC, are property of The LEGO Group of Companies (http://www.lego.com), which does not sponsor, own, authorize or endorse this creation.}

Step 1: Parts & Tools

Following is the list of Lego Technic parts that I used for building this Wireless Lego Race Car Redux.

If you want to do this project you could use the differenct color for the car.

Note: The number in the bracket is the Lego's Design ID.

Lego Components

2 nos. - 1x16 Technic Brick (#3703), Red Color
2 nos. - 1x12 Technic Brick (#3895), Red Color
2 nos. - 1x10 Technic Brick (#2730), Red Color
6 nos. - 1x8 Technic Brick (#3702), Red Color
5 nos. - 1x6 Technic Brick (#3894), Red Color
2 nos. - 1x4 Technic Brick (#3701), Red Color
6 nos. - 1x2 Technic Brick (#3700), Red Color
2 nos. - 1x2 Technic Brick (#3700), White Color
1 no. - 1X2 Technic Brick with 2 holes Ø4,87 (#32000), White Color (Not shown in the photo)
2 nos. - 1x1 Angular Bricks (#4070)

3 nos. - 2x8 Technic Plate (#3738), Red Color
2 nos - 2x6 Technic Plate (#32001), Red Color

2 nos. - 1x10 Plate (#4477), White Color
2 nos. - 1x8 Plate (#3460), White Color
9 nos. - 1x6 Plate (#3666), White Color
2 nos. - 1x4 Plate (#3710), White Color
4 nos. - 1x2 Plate (#3023), White Color
4 nos. - 1x1 Plate (#30008), Yellow Transparent
2 nos. - 1x2x2 Corner Plate (#2420), Red Color
1 no. - 1x4 Flat Tile (#2431)

10 nos. - Connector Peg with Friction (#2780)

4 nos. - Connector Peg 3M (#32556)
2 nos. - Connector Peg with Knob (#4274), Grey Color
4 nos. - Connector Peg/Cross Axle (#6562)
2 nos. - Connector Peg (#3673) or 1 1/2 Connector Peg (#32002)

1 no. - Cross Axle 12M (#3708), Black Color
3 nos. - Cross Axle 6M (#3706), Black Color
1 no. - Cross Axle 2M with Groove (#32062), Black Color
1 no. - Cross Axle 3L with Stud (#6587)

10 nos. - Bush for Cross Axle (#6590)

2 nos. - Lift arm 1x2 thin (#41677), Red Color
2 nos. - Lift arm 3x3 (#32249), Red Color

1 no. - Panel Fairing #5 (#32527), Red Color
1 no. - Panel Fairing #6 (#32528), Red Color

2 nos. - Slanted Brick1x6 (#2744), Red Color

Steering Kit and Gear Kit

1 no. - Steering Gear Holder (#2790)
1 no. - Steering Rack (#2791)
1 no. - Steering Rack Top (#2792)
1 no. - Steering Rack Bracket 1x 8 Plate (#4262)
1 no. - Steering Arm Drop Link (#4261)

2 nos. - 8-Tooth Gear (#3647)
1 no. - 24-Tooth Crown Gear Type III (#3650)

Wheels and Rims
Front
2 no. - Tire size 30.4 x 14 VR (#6578)
2 no. - Rim, Wheel size 30.4 x 14 VR (#2994)

Rear
2 no. - Tire size 43.2 x 22 ZR (#44309)
2 no. - Reinforced Rim with no pin holes 30.4mm D x 20 mm (#56145)

Rear Wing Flap
1 no. - Panel Fairing #5 (#32527)
1 no. - Panel Fairing #6 (#32528)
2 nos. - Lift arm 3x3 (#32249)
2 nos. - Lift arm 1x2 thin (#41677)

Servo
Servo horn glued to LEGO Cross Axle 3L with Stud (#6587)
9g Micro Servo (Tower Pro SG92R, or T Pro SG90)
3D Printed Servo Mount
(NOTE: The STL file for the servo mount (V01) is available for download here, for latest version (V06) that I used with this Wireless R/C Race you can view the model or have it made at Shapeways, here.)

Motor
2mm Shaft Adapter for Lego Wheels (Pololu part #1001)
(or Modified Connector Peg/Cross Axle (#6562) to fit the shaft of DC toy motor.)
24mm diameter, 9V Motor
3D Printed Motor Housing
(NOTE: The STL file for this motor is available for download here, or in case if you do not have a 3D printer, you can view the model or have it made at Shapeways, here.)

Arduino and Motor Controller IC
Arduino or Arduino compatible (I used Palm Arduino Plus in this project.)
L293D (or SN754410) motors driver IC

Wireless Radios
Palm Arduino Plus has three options of wireless radio modules,

XBee module, RN-XV WiFly module, and Bluetooth module.

RN-XV WiFly module
Xbee breakout board (for RN-XV WiFly module, I used XB-Buddy Basic Kit, Jameco's Part no. 2163680)

Tools
Super Glue
Sand paper
Files

Step 2: Car Frame

Following are the photos show how to assemble parts:

Photo 1 Two 1x12 Technic brick (#3895)

Photo 2, 3, 4 Four Connector Peg 3M (#32556) and Two 1x12 Technic Brick (#3895)

Photo 5, 6 Two 1x8 Technic Brick (#3702)

Photo 7, 8, 9, 10 Two 1x4 Technic Brick (#3701), Four Connector Peg (#3673), and Two Connector Peg with Knob (#4274)

Photo 11, 12, 13, 14 Four Connector Peg (#3673) and Two 1x8 Technic Brick (#3702)

Photo 15 Turn the frame upside down.

Photo 16, 17 One 2x8 Technic Plate (#3738)

Photo 18, 19 One 2x8 Technic Plate (#3738)

Photo 20, 21 One 2x6 Technic Plate (#32001)

Photo 22 Turn the frame upside down.

Photo 23, 24 One 1x4 Flat Tile (#2431)

Step 3: Steering System

Following are the photos show how to assemble parts:

Photo 1, 2 Steering Gear Holder (#2790) and Steering Rack Top (#2792)

Photo 3 Steering Rack (#2791)

Photo 4, 5 Two Connector Peg/Cross Axles (#6562) and Two Steering Arm Drop Link (#4261)

Photo 6 8-Tooth Gear (#3647)

Photo 7 Servo horn glued to Axle 3L with Stud (#6587).
See details instruction in R/C Lego Car: Step 4

Photo 8, 9 One 1/2 Bush (#32123)

Photo 10, 11, 12 Connector Peg/Cross Axle (#6562) and Two Tire (Balloon) size 30.4 x 14 VR with rims (#2994)

Photo 13 Now we have part of the steering system done.

Next, we are going to create the decal.

Photo 14, 15, 16 Connector Peg with Friction (#2780) and Two Slanted Bricks 1x6 (#2744)

Photo 17 Instructables Robot sticker.

Photo 18 Mark the cutting line, make the width the same as the width of two slant bricks. Then, draw the number 1 along the cutting line.

Photo 19 Use the X-acto knife to cut the sticker along the marked line.

Photo 20 Remove number 1 from sticker pad, and place on the slant. Then, remove the robot from the sticker pad, and place the robot on top of the number one as shown.

Next, we are continuing on to install the steering system and the front of the car.

Photo 21, 22 1x 8 Steering Rack Bracket Plate (#4262)

Photo 23, 24 Intall the nose with the decal.

Photo 25, 26, 27 Snap the bracket to the steering system.

Step 4: Servo, Battery Compartment & Motor Housing

New parts:
3D Printed Motor Housing. See design details in Step 1 of R/C LEGO "The Bull" Buggy.
Modified Connector Peg/Cross Axle (#6562) to fit the shaft of DC toy motor. (or used Pololu part #1001, as I used in this project.)

Following are the photos show how to assemble servo mount:

Photo 1, 2 Remove the front 2x6 Technic Plate (#32001) from the car body.

Installs 9g servo into 3D Printed Servo Mount.

Photo 3 9g Micro Servo (Tower Pro SG92R) and 3D printed servo mount.

Photo 4 Insert the cables from the servo into the top opening of the servo mount.

Photo 5 Slide the servo into the 3D printed servo mount.

Photo 6 Push the servo in until the mounting area flush with 3D printed servo mount.

Photo 7, 8, 9 Four 1x4 Plate (#3710)

Photo 10, 11, 12 Place the assembled servo in place, as shown in the photo.

Photo 13, 14 Two 1x2 Plate (#3023)

Photo 15, 16 Two 1x1 Angular Bricks (#4070)

Photo 17, 18, 19 Place the removed 2x6 Technic Plate (#32001) back to it place.

Photo 20, 21 2x6 Technic Plate (#32001)

Photo 22, 23 Two 1x2x2 Corner Plate (#2420)

Photo 24, 25 Two 1x6 Plate (#3666)

Photo 26, 27, 28 Four 1x1 Transparent Plates (#30008)

Photo 29, 30 Two 1x6 Technic Plate (#3666)

Photo 31, 32 Two 1x8 Technic Plate (#3460)

Photo 33, 34 Two 1x8 Technic Brick (#3702)

Photo 35, 36 Two 1x2 Technic Bricks (#3700)

Photo 37, 38 Rechargeable 7.4V 500mAh LiPo Battery power supply for motor.

Photo 39. 40 Rechargeable 3.7V LiPo Battery power supply for Arduino and XBee/RN/XV WiFly or Bluetooth module.

Photo 40, 41 Assembled 3D printed motor housing with 24mm diameter 9V motor.

Step 5: Rear Wheels

New Lego parts:
24-Tooth Crown Gear Type III (#3650)

Following are the photos show how to assemble parts:

Photo 1, 2 Cross Axle 12M (#3708), and 24-Tooth Crown Gear Type III (#3650)

Photo 3, 4 Bush for Cross Axle (#6590)

Photo 5, 6 Two 1x6 Technic Bricks (#3894)

Photo 7, 8 Two Tires (Balloon) size 43.2 x 22 ZR with rims (#56145)

Photo 9, 10 Two 1x6 Technic Bricks (#3894)

Photo 11, 12 1x6 Technic Bricks (#3894)

Photo 13, 14 Installed the wheelbase to the main body of the car.

Step 6: Rear Wing Flap

Following are the photos show how to assemble parts:

Photo 1, 2, 3 Cross Axle 6M (#3706) and two Lift arm 1x2 thin (#41677)

Photo 4, 5, 6 Two Lift arm 3x3 (#32249) and Cross Axle 2M with Groove (#32062)

Photo 7, 8 Two Bush for Cross Axle (#6590)

Photo 9 Two Cross Axle 6M (#3706)

Photo 10, 11 A Panel Fairing #5 (#32527), A Panel Fairing #6 (#32528), and two Connector Peg (#3673)

Photo 12, 13, 14 Two Bush for Cross Axle (#6590)

Photo 15, 16 Two 1x6 Technic Bricks (#3894)

Photo 17, 18 Install the flap to the car from previous step.

Step 7: More Car Frame

Continue from the previous Step (7):

Photo 1 Car from previous Step.

Photo 2, 3 Two 1x2 Technic Bricks (#3700)

Photo 4, 5 2x6 Technic Plate (#32001)

Photo 6, 7 Two 1x2 Technic Bricks (#3700)

Photo 8, 9 Two 1x10 Plates (#4477)

Photo 10, 11, 12Palm Arduino Plus with Bluetooth module installed, and Two 1x6 Plate (#3666)

Photo 13, 14 Two 1x2 Plate (#3023)

Photo 15, 16 Three 1x6 Plate (#3666)

Photo 17, 18 1X2 Technic Brick with 2 holes Ø4,87 (#32000)

Photo 19 And we have the car! Bravo!

Step 8: User Interface and Control

From this point on, everything is the same as what I did in original version of Wireless Lego Race Car from Step 10 to 12.

Step 10: User Interface Design
Step 11: RN-XV Module Configuration
Step 12: PHP and Apache on Mac OSX

If you want to try out using XBee module instead, please see the the details in R/C Lego Car, Step 9: Processing UI & Arduino Sketch.

For the Bluetooth connection, see the details of how to configure the Bluetooth at this site:
Setting up a Wireless serial connection with your Wiring hardware using Bluetooth and
BlueSMiRF Installation Tutorial by James Frye.

Since both XBee and Bluetooth communication are Serial Comm. you could use the same codes that we used in with R/C Lego Car (& Redux) with the minimum change of codes.

To used bluetooth you need to change the Baudrate to 115200 in both Arduino Sketch and Processing Sketch, instead of what we set for XBee. (As shown below.)

In Arduino Sketch

... void setup() { Serial.begin(115200); ... }

In Processing Sketch

... void setup() { // Windows // change the portName and Baudrate accordingly //port = new Serial(this, portName, 115200); // Mac String XBeePort = Serial.list()[0]; port = new Serial(this, XBeePort, 115200); // Setup the screen for output. size(480, 320); speed = 0; ... }

You can use the same code that is used with LEGO R/C Car Redux, and can be downloaded in Step 11: Processing UI & Arduino Sketch.

Step 9: Conclusion

Photos and Videos

Below are some photos of finished Wireless LEGO Race Car Redux, and videos shows the bench test of Lego Race Car with XBee module.

Videos

- Test Servo