BMW throttle bodies Manual

Unload the two springs.

Take off the metal cap. Watch the video.

Unscrew both.

Pull the plate gently.

Take off the circlip and the nylon washer.

Pull out the throttle shaft.

Remove the plastic pulley.

Here both plastic sides connect throu 4mm hole. To remove it safely use 4mm drill and start drilling aprox. where the photo shows.

Now remove the rest of the plastic pulley.

Fit the aluminium pulley and mark the holes.

The accuracy of the OEM stainless steel plate is +-0.2mm. The tolerance of those OEM plates are relatively in big range. Why they don't chase great accuracy? The answer is simple, cheap and fast production. The OEM plate is formed on a press machine and after that melted plastic is squeezed around the plate to form the plastic pulley. The solution is light touch with keyfile to grind 0.1mm from each side. For reference the thickness of human hair is 0.1mm.

Punch each marking with center to avoid dislocation of the drill.

Also use two drills to avoid dislocating the holes. As it's suggested first use 2.5mm drill and second use 4mm drill. Drill the stainless steel on low rpm and lubricate! Start with a sharp drill and have it turning as slowly as your drill or drill press will allow. Set the drill press to its slowest speed or run the portable drill as slow as the trigger will allow. You need to exert pressure on the drill bit - as much as it will bear.

Stainless is actually a relatively soft metal, at least in its initial state. What stainless tends to do is “work harden” fairly quickly when heated, and drilling at high speed creates a lot of heat. When stainless steel work hardens, it becomes very hard and extremely difficult to drill.

Use sharp drills!

2.5mm drill.

4mm drill.

Clean all chips after drilling the holes

Done! Nice and clean.

Тighten all screws using threadlocker with high temperature properties or with greater properties. This is mandatory!

Check for drops of threadlocker and clean if present.

Return the shaft.

(Optional): Before placing back the shaft, clean the throttle body from fumes and oil debris using detergent for carburetors. Apply oil on both bearing.

Place the nylon washer and the circlip.

Return the throttle plate.

Fit the throttle plate without applying force! Nice and easy, it will fit perfectly.

Screw both.
(Optional) Use threadlocker low temperature properties.

Place back the metal cap. Use only rubber tools to place it back and load the springs!

First spring!

Done! Finished! Mission Complete! Enjoy increased lifespan and superior performance.