This splitter DIY guide will walk you through the install process using our Buildjournal Quick-Release Splitter Brackets for the E46 / M3. Splitter mounting to your chassis can be difficult, but not anymore. We’ve developed a 100% bolt-on chassis mounted bracket that uses a skeleton frame to support the rear of the splitter, which is new for our latest version enhancement. Quick-release is even quicker now. A huge evolution over our old V1 brackets.

If you have your own rear mounting solution we also offer the front brackets by itself without the skeleton brace. This splitter DIY will cover the installation for the Full Kit with Rear Support.

1.1 Jack up the car.

1.2 Remove and discard the OEM plastic undertray.

1.3 Locate the 3 factory holes located on the front reinforcement plate which holds the plastic undertray.

1.4 Using the supplied hardware, mount the rear bracket to the 3 holes on the front reinforcement plate – hex bolt side down. Do not tighten it down just yet. This will help with the splitter alignment in the next steps.

2.1 Use the picture here to assemble the bracket. Each side of the bracket is made with 3 main parts: main bracket, adjustment plate, splitter feet. It’s important the orientation is set correctly otherwise you will have alignment issues with the skeleton brace and rear bracket. Pictured on left is the left/driver side.

3.1 Remove your front bumper and Kevlar/aluminum bumper beam. If you have the aluminum bar, you need to also remove the bumper shocks. For now, leave the bar and bumper off. Notice how the splitter feet lines up with the rear bracket.

3.2 Use the OEM nuts to hold the front brackets in place, but do not tighten all the way down. This will help with the splitter alignment in the next steps.

4.1 Insert the quick-release pin into the feet/adjustment plate and tighten down the thumb screws. This is important for the alignment. Your front brackets, adjustment plates and rear bracket should be loose.

4.2 Temporarily install your bumper back on to set the the splitter height.

4.3 Rest the jack on your splitter and jack up to the desired height. Make sure the frame is in place.

4.4 Once the splitter height is set, carefully remove the bumper.

4.5 Tighten the front brackets and adjustment plate. Your front brackets are now set.

4.6 Secure the frame to the feet with the holes aligned and use a clamp to hold it in place while you adjust the rear bracket.

4.7 Make sure the rear bracket and frame are in contact with each other or else you’ll experience some back and forth deflection. Tighten down the rear bracket. Now your frame should be all set. Test for any play and adjust if necessary.

5.1 With the splitter still in position, mount the bumper back on and visually align the splitter to where you want it to mount.

5.2 Remove bumper once splitter position is set.

5.3 With the feet aligned with the frame holes, mark your drill points on the splitter. I put some ink on a Q-tip and marked the holes straight down using the first and last holes on the feet. Splitter mounting requires a minimum 4 mounting points from the feet to the splitter.

5.5 Drill the marked holes using a 1/4″ bit.

6.1 Use the supplied hardware to mount the splitter through the frame and onto the feet.

6.2 If you are using our Splitter Brace, you can install that during this step. This brace adds support for the front of the splitter for those not wanting to run splitter rods outside on the exterior of the car. It also doubles as a splitter skid plate.

6.3 If you are using our Splitter Rods with Shocks, you can install them now.

6.4 Your install is complete. Check for play and adjust if necessary.