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Throttle Body Resurection by brandon

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  • Throttle Body Resurection by brandon

    I have ulterior motives for copying Brandon's awesome throttle body DIY here - I plan on doing this myself shortly and this guide will be invaluable when the time comes! This post was being buried (somewhere on page 5 or 6 of the general chat section) and I thought it deserved to be here. All pics and text are Brandon's - directly copied from his original post - totally without his permission but certainly with respect for his abilities - hopefully he wont mind!

    First, if you're removing the TBs from your car, be very careful with your E10 socket on the nuts holding the TBs to your head. Go slowly and stay on them as straight as possible or you could risk stripping. These guys are about $14 EACH, so be careful!

    A couple of the E10 bolts holding the mount blocks to the TBs didn't want to come loose and had to be drilled/extracted.

    So I started with this mess of 46mm throttle bodies that looked like they spent some time at the bottom of the Hudson River

    Muck accumulation everywhere.

    First 12mm bearing was totally shot

    Second 12mm bearing seal gone

    The 8mm butterfly shaft bearings weren't in much better shape

    Before cleanup

    After cleanup


    Disassembled parts

  • #2
    A few of the new parts. You can buy everything new from BMW save for the bearings and throttle plate screws. The only NLA part (as of mid 2016) is the linkage piece with the ball joint rod end bearings piece without the springs shown below. The CO2 adjustment screws are "available" but are totally wrong (way to pointy) and do not work. I sent these back and just cleaned up my originals. Seriously, BMW Classic - pull your heads out of your asses.

    Some initial clean up with the Dremel:

    Powder coating:


    Don't forget powder coating involved heat and that heat will melt the small nylon/plastic bushings on this piece of linkage. Powder was stripped, mess cleaned up and the part was coated again. I ended up buying some thin Teflon washers with the correct shaft size. Cut a slot in the washer and slide it on to the shaft because the piece is riveted on.


    New 12mm bearings: INA HK1210 purchased from Amazon for about $6 each. Buy German FAG, INA or SKF brands, not cheap Chinese crap. Unfortunately the double sealed INA 12mm bearings from McMaster-Carr are much thicker than the originals and do not fit in the required locations.

    I opted for double sealed 8mm bearings. They're 2mm thicker than the originals (HK0810 vs HK0812) because of the seals, but this did not impact re-installation - plenty of space in the recesses.

    I bought those from McMaster Carr: (again, the 12mm double sealed are too big and do not fit)

    They're pretty easy to press fit into either side of the butterfly shaft openings. I gently tapped with a rubber mallet and the went in with minimal force. Not too easy - they aren't going anywhere.

    The 12mm bearings required a high tech and complicated apparatus as such. You have to be careful when getting them started, but once in, they seat easily.

    Grease all bearings liberally with Dow Molykote 44, or your white lithium grease of choice. Wipe off excess so as not to attract any dirt. Molykote is made for long-term bearing lubrication and is resistant to washing out if you're the kind of weirdo who rinses off his engine now and again. I bought it on Amazon for about $22 for a tube that will last me a lifetime.

    Making those throttle plates shine:

    Things are starting to take shape. I realized after this photo the lever arm was on backwards, so I flipped it around.

    Random pre-assembly shot of two sets of 46mm and one set of 48mm


    • #3
      New linkage detail

      Finall assembly:




      Here are the S14 and S38 TB setup and calibration/sync procedures:

      https://<a href="http://home.insight...rottle.htm</a>

      Link to another M88 TB refurb write up, though they didn't go through fill disassembly/reassembly.

      https://<a href="http://6-city.blogs...35csi.html</a>

      Small update on 12mm double sealed bearings that recently came in the mail.

      On the throttle body actuator shaft bearings (that's what I'm going to call the large 12mm bearings), I managed to find a European source that sells the double sealed version (HK121614-2RS). Shipping for two units from France was about $14


      This is a suitable replacement for the factory double sealed bearings (F-83416) that are the correct width, but are no longer available. I originally bought the HK1210, which is the proper width, but unsealed. I had a set of original F-83416 that were in good shape, so I used those in the 46mm TBs I just rebuilt (because the HK121614-2RS just came today in the mail).

      The standard HK1210 in the middle has no seals. The F-81416 (right) has seals and is 10mm wide. The 2RS (right) has seals, but is 14mm wide.


      The 2RS seem to fit the most exposed/unprotected location on the throttle bodies without issue.





      You're probably fine with a standard unsealed HK1210 (or good F-83416) at the other end because you have washers providing protection to either side.



      Thanks to Brandon for his awesome write-up!


      • #4
        Glad to help. Small typo in the first sentence though... the fasteners are E8 and not E10. :^) Please let me know if you have any questions and remember that after you complete a rebuild/refurbish, you will need to calibrate the fine measurements, such as the default TB openings and stop screws. Then you will need to set the base idle and sync the TBs with the car running.

        Here is a good reference and start point: (page 53 of 94)
        Alles Beste!

        B. Wheaton
        1989 E30 M3, Owner since June 2000
        2008 E61 535xiT - The DD and work horse

        Register your E30 M3!


        • #5
          That's petty cool. Thanks!

          Disclaimer: Remember, I know absolutely nothing, but it doesn't prevent me from having an opinion or suggestion. :


          • #6
            I assume you have everything put back together and up and running. I have a questions about the "throw" of those pillow ball linkages.

            I'm getting a new bowden cable but I was able to tighten up the one I have enough to right before holding the throttle open (maximum tightness without opening the throttle).

            I wanted to see how far it would actuate those 2 ball mount fittings DOWN. Turns out that then end up about flush with the plane of the fuel rail.

            I got out of the car and manually pushed the ball joints downwards to match where I had seen it from pedal actuation. I then continued to push them down PAST where my pedal could get them.

            I had a good 1.5-2 inches left of travel.....

            How much play should there really be?


            • #7
              I was going back and reviewing this as I plan to tackle it over the winter. Research tells me that it is a challenge to find replacement screws that hold the throttle plates to the shaft.

              Did you end up replacing them? If so do you mind sharing a source of where you found the screws with the proper taper?

              Saved the page as a PDF as reference, than you for documenting!


              • #8
                Is it just me that can't see the pictures or have they gone?


                • #9
                  I can't see the pictures either.


                  • #10
                    same here- pictures are no longer available


                    • #11
                      The technical manual procedure is archived here:


                      • #12
                        Darn, I should have downloaded his photos.


                        • #13
                          The original thread is here: