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Thread: Headlight Adjuster Gears Revisited

  1. #1
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    Headlight Adjuster Gears Revisited

    In my past review ofthe posts on repairing the North American (NA) version of the E31headlight adjusters, I have never seen a discussion of why you maynot need to replace the missing gears. So let me add my comments tothis topic.


    The fact is that ifyour headlights were correctly pointed prior to loosing the adjustinggears, you donít need to replace them. Hereís why.


    The design of the NAheadlight adjusters requires the gears to perform two functions: 1.To provide the adjuster rotation that changes the headlight aiming,and 2. To hold the headlight unit in the resulting position withinthe headlight assembly. The use of a spline to connect the gear toits shaft can easily perform function #1, since it resists rotationalforces very well, but does terribly doing #2 because it cannot easilyresist axial forces exerted along the shaft axis. The result is thatover time those axial forces can cause the gear to slide off itsshaft, and the headlights droop.


    BMW partially fixedthis problem in a redesign of the gear by adding a set screw to addresistance to those axial forces. Since none of these gears areavailable today, except by stripping them off other cars, members ofthis forum have developed other solutions, such as Max Lumensí kitthat replaces the adjusters.


    The design of theheadlight unit suspension contributes to the problem because anydecelerations or vertical accelerations (bumps) impose axial loads onthe adjuster gears. Even lowering the headlights imposes those forceson the adjusters, the headlight shock absorbers (better calleddampers) slows those accelerations but doesnít prevent them. Sothis problem is unavoidable if you actually drive our cars.


    There is a solutionthat doesnít require full rebuilding of the adjusters. The goal isto isolate these axial forces away from the adjusters, that is useanother method to hold the headlight units rigid within the assembly.The simplest method is to wire the headlight units to the backheadlight assembly frame once the lights are aimed properly. Havingdone that, the gears are no longer necessary, at least until the nexttime you have to adjust the headlights.


    With the axialforces resisted by the wire mount, the spline gears work fine. I nowuse 3D-printed plastic replacement gears I made that press fit ontothe original spline shafts, and show no inclination to slide off.

  2. #2
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    Seems like a lot. My car is 23 years old with 150k on it and they just now broke. Putting a wire on my headlight to fix an issue that pops up once every 2 decades seems kinda dumb. Just replace the adjusters with Maxís kit and donít worry about it again.

  3. #3
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    Do you have any for sale? I still had the original metal adjusters that fell off, so I applied epoxy to the shaft then heated up the adjuster wheels to the point where they started to melt and pressed them onto the shaft. Let them cool down, dont think they will every be coming off again. But I like the idea of 3d made ones for people that dont have the adjusters any more.

  4. #4
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    Quote Originally Posted by dragon850 View Post
    Do you have any for sale? I still had the original metal adjusters that fell off, so I applied epoxy to the shaft then heated up the adjuster wheels to the point where they started to melt and pressed them onto the shaft. Let them cool down, dont think they will every be coming off again. But I like the idea of 3d made ones for people that dont have the adjusters any more.
    I'll have to check my spare parts box. They are in white plastic, if I have them, and can send for the cost of postage. I make them at the local comm. college, so can't honestly make a profit on them. If I don't have some, I'll have to regenerate the printer file, as the class files were deleted some time ago, and I did not keep a copy.

    Re the previous reply: My E31 has only 60K miles on it, and they had already departed the scene. You're lucky if they lasted that long, maybe you had the set screw model. I do find adjusting the original gears easier than Max's hex nuts as you can still access them from the std. location on top of the units.

  5. #5
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    If you can make more I would buy a couple sets.


    Quote Originally Posted by drphysic View Post
    In my past review ofthe posts on repairing the North American (NA) version of the E31headlight adjusters, I have never seen a discussion of why you maynot need to replace the missing gears. So let me add my comments tothis topic.


    The fact is that ifyour headlights were correctly pointed prior to loosing the adjustinggears, you don’t need to replace them. Here’s why.


    The design of the NAheadlight adjusters requires the gears to perform two functions: 1.To provide the adjuster rotation that changes the headlight aiming,and 2. To hold the headlight unit in the resulting position withinthe headlight assembly. The use of a spline to connect the gear toits shaft can easily perform function #1, since it resists rotationalforces very well, but does terribly doing #2 because it cannot easilyresist axial forces exerted along the shaft axis. The result is thatover time those axial forces can cause the gear to slide off itsshaft, and the headlights droop.


    BMW partially fixedthis problem in a redesign of the gear by adding a set screw to addresistance to those axial forces. Since none of these gears areavailable today, except by stripping them off other cars, members ofthis forum have developed other solutions, such as Max Lumens’ kitthat replaces the adjusters.


    The design of theheadlight unit suspension contributes to the problem because anydecelerations or vertical accelerations (bumps) impose axial loads onthe adjuster gears. Even lowering the headlights imposes those forceson the adjusters, the headlight shock absorbers (better calleddampers) slows those accelerations but doesn’t prevent them. Sothis problem is unavoidable if you actually drive our cars.


    There is a solutionthat doesn’t require full rebuilding of the adjusters. The goal isto isolate these axial forces away from the adjusters, that is useanother method to hold the headlight units rigid within the assembly.The simplest method is to wire the headlight units to the backheadlight assembly frame once the lights are aimed properly. Havingdone that, the gears are no longer necessary, at least until the nexttime you have to adjust the headlights.


    With the axialforces resisted by the wire mount, the spline gears work fine. I nowuse 3D-printed plastic replacement gears I made that press fit ontothe original spline shafts, and show no inclination to slide off.
    Hurt

    Current project working on the E31 rebuild.
    1992 BMW 850i, 1995 E31 840ci, 2008 E90 M3, 2008 750Li

  6. #6
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    Quote Originally Posted by drphysic View Post
    I'll have to check my spare parts box. They are in white plastic, if I have them, and can send for the cost of postage. I make them at the local comm. college, so can't honestly make a profit on them. If I don't have some, I'll have to regenerate the printer file, as the class files were deleted some time ago, and I did not keep a copy.

    Re the previous reply: My E31 has only 60K miles on it, and they had already departed the scene. You're lucky if they lasted that long, maybe you had the set screw model. I do find adjusting the original gears easier than Max's hex nuts as you can still access them from the std. location on top of the units.
    Great! i would be very happy to pay postage, please let me know if you find more!

  7. #7
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    Quote Originally Posted by drphysic View Post
    I'll have to check my spare parts box. They are in white plastic, if I have them, and can send for the cost of postage. I make them at the local comm. college, so can't honestly make a profit on them. If I don't have some, I'll have to regenerate the printer file, as the class files were deleted some time ago, and I did not keep a copy.
    Me me me... thanks
    '91 Dinan 860 Stage III (soon to be Dinan TT 6L)
    '91 850i 6sp (mint)
    '91 850i 6sp (getting there)
    '90 Dinan 750iL TT stage III
    '94 850 CSi (being restored to factory perfect)
    '96 850Ci, The George Carlin car
    '94 840ci (4 short - obvious parts car), '91 850i parts car
    '73 3.0 csi, '08 535i, '95 318i
    ...and a few other non BMW cars

  8. #8
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    I would like my name added to the list wanting/needing these gears. My '97 also has ~60K miles, but probably a lot of bumpy potholes in MA and NJ by it's two previous owners. Let me know what I owe you. Payment via USPS or PayPal, You can communicate directly via: kittyandgary 'at' verizon 'dot' net
    Please put e31 headlights in Subject line.
    THANKS for posting this and for making the gears.

    My address is:

    Gary Knox
    979 Centennial Drive
    West Chester, PA 19382
    Last edited by Gary Knox; 02-11-2018 at 01:19 PM.
    Gary Knox
    '74 BMW 3.0 CS
    '97 BMW 840 Ci
    '03 MB SL55 AMG
    '07 Audi A8
    '90 MB 560 SEC and '94 Porsche 928 GTS recently departed but long enjoyed
    50 or so others over the past 67 years of driving

  9. #9
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    or you can share the files and we can build our own

    (not intruding on anyone's business model - but if it's easier to share that way instead of printing them yourself and shipping out at cost...)

  10. #10
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    I will be in my class this Thursday, and will look at re-generating the CAD file that makes the gears. I used an example loaned to me by Wuffer to take the measurements, but will be able to take them off my existing copies. I'll get back to folks on Friday to report on the progress.

  11. #11
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    Would love to have a copy of the CAD file if you're able to recreate and share. TIA.

  12. #12
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    Quote Originally Posted by rockytt View Post
    or you can share the files and we can build our own

    (not intruding on anyone's business model - but if it's easier to share that way instead of printing them yourself and shipping out at cost...)
    I was going to do that too. In fact, there are many services that if you send them the appropriate file, they will print them for you. You can even get them printed in metal for a price...

  13. #13
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    In fact, there are many services that if you send them the appropriate file, they will print them for you. You can even get them printed in metal for a price...


    vibranium would be nice...

  14. #14
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    One a these dudes bout to get your file and start sellin em on eBay lol

  15. #15
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    I discovered that the school reassigned the licenses to the Inventor software, and so I have 2 options: get a new computer whose graphics are capable of running the Autodesk software (my machines, all Linux but one old Win10 laptop won't run the software), or find a computer somewhere at the school that has the running software. Will find out more on Monday.

    I don't care if someone wants to make some $s on these, if I can get a working file that can be used to print the gears... I am a woodworker and am working on clocks right now.

  16. #16
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    Of all the dudes that inquired about a shared file, I can personally vouch for them that they're not out to make a quick buck off of someone's hard work. These guys are stand-up guys. This forum is full of folks who genuinely doesn't think twice to offer extremely helpful advises to a fellow e31 enthusiast so he/she can have the car on the road and enjoying it.
    Thanks in advance for offering, DRPhysic.

  17. #17
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    I already have a 3D model of this part that I used to machine new ones. My buddy and I couldn't come up with a way to make them economically (6 hours machine time each on his 3 axis), but I'll be more than happy to share the file

  18. #18
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    If the part does not have to do the double duty, it seems to work fine as a 3D-printed plastic part. If you could email me the file, I can see if can be used to drive the printers.

    BTW, I am in the process of installing Win10 on my Linux desktop using a "virtual machine" interface, will see how that works today. Fusion 360 works within a browser, but seems limited, so could run the full version with this capability.

  19. #19
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    posted in a new thread with some pictures of the file and the resulting parts

  20. #20
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    Quote Originally Posted by Spandrel View Post
    posted in a new thread with some pictures of the file and the resulting parts
    I just added photo of the printed parts in the new thread: https://www.bimmerforums.com/forum/s...s-3D-CAD-files

  21. #21
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    For those of you following this thread and not the other, let me know via PM if you want me to print you up some of these, with contact info, and I'll start sending them out when production starts again.

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