Need failed Speed sensors | Page 3 | FerrariChat

Need failed Speed sensors

Discussion in '308/328' started by Rich in Panama City, Oct 16, 2014.

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  1. Rich in Panama City

    Aug 29, 2013
    124
    Panama City Beach FL
    Full Name:
    Rich Roesch
    Adrian: Congratulations! It works! Calibration also good against GPS. Speed indication did drop out a few times for just a second or two, perhaps too much gap, might want to put a touch of glue on the back side of the sensor to the board to steady it since I had to blindly fit it into the oring seal piece and that might push the sensor back a bit when it is only supported by the 4 wires. Heads up, the "window" in the oring seal end piece is only .017" thick, very brittle, and mine was evidently cracked and then failed while I was assembling so I made a new window from a small flashlight lens and glued in on to the oring seal end piece. I had to ground the board to the sensor body with a wire long enough too allow assembly after soldering. I have lots of pictures and other lessons learned so please check for a pm. I am thinking I should send you this first board back so you can see the modifications I made. Rich
     
  2. alvaroagm

    alvaroagm Rookie

    Jul 7, 2011
    5
    Really good news!!
    Thanks a lot Adrian and Rich for your tests.
     
  3. Crowndog

    Crowndog F1 Veteran
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    Jul 16, 2011
    7,042
    Fairfield,Pa
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    Robert
    Wonderful progress guys, thank you.
     
  4. alhbln

    alhbln Formula 3
    Consultant Owner

    Mar 4, 2008
    1,749
    Berlin, Germany
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    Adrian
    #54 alhbln, Jan 11, 2015
    Last edited by a moderator: Sep 7, 2017
    Rich,

    i can think of two reasons why the speedo signal drops out, 1. the distance between the sensor and trigger wheel is too large, e.g. the distance between the sensor top and body end is more than 1 mm (see drawing below), or 2. the sensor has movement inside the body so the distance between the sensor and trigger wheel distance changes due to vibrations etc.

    Try potting it into the sensor body, the circuit board shape was designed for an easy install without additional parts. I've added some photos i did with clear epoxy to show the installation/placing. If you need to remove everything you can still heat up the body and push out the epoxy/circuit board.

    Good luck,
    Adrian
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  5. Rich in Panama City

    Aug 29, 2013
    124
    Panama City Beach FL
    Full Name:
    Rich Roesch
    #55 Rich in Panama City, Jan 11, 2015
    Last edited by a moderator: Sep 7, 2017
    Adrian: I think you are correct, too much gap. I should be home later today to check but I think it is less than 1mm but also, for my testing, there is a window I glued to the oring seal end piece and in front of your sensor that might interfere. Your sensor was a perfect fit into that oring piece so this method was benefical for testing since it allowed me to easily assemble, disassemble, etc., in anticipation of applying lessons learned for testing with the second board. Can't judge the gap from this picture but you can see how your sensor fit into the oring seal end piece after the intermediate piece was removed and you can see pieces of the original window in the background. Agree potting is best for a final version since that also solves resealing issues at the connector end and to easily ground the board to the body when installed but before potting.
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  6. rbrandes

    rbrandes Rookie

    Jan 12, 2015
    2
    Alhbin,
    Rich just stopped by with his parts. I am going to make some sensor bodies for him to play with. I can do 6061T6 aluminum and anodize it. Do you see any problem with it not being brass?

    Regards, Ray Brandes
    Panama City Beach (Is in which country?)
     
  7. Rich in Panama City

    Aug 29, 2013
    124
    Panama City Beach FL
    Full Name:
    Rich Roesch
    Ray: why anodize? Remember we need a ground path. Also, some owners may want brass since the original is brass.
     
  8. alhbln

    alhbln Formula 3
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    Mar 4, 2008
    1,749
    Berlin, Germany
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    Adrian
    Ray, welcome!

    i am not a specialist in mechanics/materials but as long as the 6016T6 has a similar thermal expansion characteristics as brass, then it should be fine. Maybe the bodies can be anodized in a yellow/orange color to look similar to the original brass bodies?
    A small area should be milled out on the inside after the anodization to allow soldering in a ground connection. Soldering a wire to the inside of the body should not be a problem if you heat up the area and then scrape off the oxidation while you are applying tin.

    My favorite would be brass though to make everything look as original as possible.

    Rich, what do you think about doing the potting with a PU compound? PU is more flexible than epoxy, so no issues with a different thermal expansion behavior and easy to remove/replace too.

    Cheers,
    Adrian
     
  9. rbrandes

    rbrandes Rookie

    Jan 12, 2015
    2
    No luck finding brass at the scrap yard. I think it would be best to stay with brass. I don't think the cost difference justifies the material savings.

    Rich, I have reverse engineered the housings. You can pick them up any time.
    Regards, Ray
     
  10. Rich in Panama City

    Aug 29, 2013
    124
    Panama City Beach FL
    Full Name:
    Rich Roesch
    Adrian and Rich would like to continuing testing of Adrian's new board for the Type 2 Speed Sensor (1980-1999, Veglia #68 0517, Ferrari #116987; see:Veglia Borletti Speedo Sensors 68 1005, 68 1041, 68 0517) and read the recent Fchat speed sensor discussions.
    Please contact the appropriate person (Adrian in Germany/Europe and Rich in Florida/US) if you have a suspect sensor and would like to participate in this testing phase. We will respond with instructions to remove and send us your broken sensor body for repair then send your sensor back with instructions to reinstall. Note that to R&R the speed sensor may require a slotted or deep 32mm or 1 1/4" socket, the slot or deep socket allows removal without damage to the wire and connector and the speed sensor is easily accessed from under the transmission. We appreciate funds to cover shipping costs. Please be patient, since this testing phase is a volunteer effort to help our fellow Fchatters and to keep our Ferraris on the road. Your obligation will be to install, drive your cars with an eye on your speedometers and report your experiences, failures, successes, recommendations and comments. We are also testing Adrian's new boards with newly-made brass sensor bodies. This is an interim effort to get enough testing that we feel confident about the reliability and accuracy of Adrian's board; and the viability of this owner-installed approach across several owners so we can decide if we should keep up production, outsource production, or publish all the documentation for a 3rd party to continue this effort. We really appreciate your participation and comments. Rich, and for Adrian
     
  11. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    Adrian
    BTW, this is the final replacement Sensor, potted in PU (the red stuff in front). The front surface of the Hall sensor (PCB image, right side) is about 0,5 mm below the red surface, e.g. the potting just covers the sensor which is flush with the brass surface.

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  12. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    SanFrancisco BayArea
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    1983 US 308 GTS QV
    Upon receipt of my sender board, my speedometer immediately began functioning properly again. Since the speedometer has, on occasion, dropped to indicate half speed or drops out altogether, I guess it still makes sense for me to change the darned thing.

    I am doing other work on the car so now is a good time to install the new speedometer sender. I have a couple of questions:

    1.) Are there photos or instructions somewhere as to how to disassemble the stock sender? It appears to be pretty tightly sealed.

    2.) Once apart, I read that I need to solder a ground to the outer brass casing. Is there any recommended way to do this in such a tight environment?

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  13. Ferraridoc

    Ferraridoc F1 World Champ
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    Jun 20, 2012
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    Patrick
    Hi Brian
    You have to peel/grind/machine off the brass ring that crimps in the board (shown in your pic), and then press the whole thing out from the other side. I used a vice and two different sized sockets. Once the seal is broken, it moves quite easily.
     
  14. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    There were concerns about the possible degradation of the epoxy potting material due to differential thermal expansion. Did these problems very materialize?
     
  15. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    Given the small volume and minimal thermal expansion i would not expect any issues. I am using PU for such applications though which stays a bit flexible anyway.
     
  16. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    Another question: Can the sensor be exposed at the bottom of the casing? That is, rather than the 0.5mm to 1.0mm recommended distance between the sensor top and body end, can the distance be 0 mm (or even + 1mm)?
     
  17. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    The distance can be 0mm (flush), but it should not extend outside of the brass enclosure as the air gap is quite small.
     
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  18. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    #68 Brian A, May 25, 2023
    Last edited: May 25, 2023
    Enough is enough. My existing sensor continues to work okay most times and only seems to go goofy when the engine gets very hot (... I think, maybe...)

    I recently got a second broken sensor which I've now disassembled and have commenced installing the new board into it. I am going to install it in the car as soon as possible.

    - I am still unclear how I ground the board to the casing. Are the "ears" the four metal rectangles in the four "corners" of the board? Do I solder a wire within the casing itself?

    - I cleared out all material from the casing. When I inserted the new board, I could not get the Hall Sensor to come within the 1 mm max spec. It was at 2 mm. I filed the board a bit (timidly) and filed the casing a bit but still couldn't get it within tolerance. I finally had to bend the 4 connectors to the Hall Sensor to lengthen the board. It is now actually flush with the bottom of the casing. It would be better if there was some adjustability where the Hall Sensor could be extended beyond the housing. That way it could be set at 0 mm just by balancing the housing on a flat surface and the two top corners of the board Super Glued to the housing to hold it in position during potting.

    - Your photo on post 54 looks like you did not reuse the top plastic housing cover. I would prefer to just fill the housing with potting epoxy and not bother with the cover. Any problems with doing this?

    - Any source for the black harness connector? My wires are extremely brittle and it would be nice to replace the connector and wires as well as the board.

    These sensors are now extremely rare. Anyone who buys one is going to have to pay big bucks for it. Your boards are a great alternative; the installation is a little intimidating because potting electrical components is not something most of us (at least me) have ever done, but it seems to be straightforward now that I am into it.
     
  19. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    Hi Brian,

    for creating the ground connection you can either directly sold one of the ground pads to the enclosure at the thread side of the body or (easier method) solder a wire to the enclosure inner side and one of the ground pads.

    Direct soldering connection between body and ground pad:

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    The PCB has been designed to be a perfect fit, but i did only test this on a handful of casings/enclosures, there might be differences in manufacturing. Gently pushing the sensor/bending the sensor wires forward to adapt is the preferred method.

    The cover is not required anymore in the conversion.

    The black harness bullet connector is kind of a standard component, i found some prewired ones on ebay some time ago but forgot the type name.

    Good luck,
    Adrian
     
  20. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    Thanks for the quick reply. I will put a touch of solder on the board corner to ground the board.

    I bent the sensor wires with great trepidation. I’m glad you officially approve. :) Whew. I will pot the board with the sensor at 0 mm.

    Regarding the connector, I am just going to reuse mine. I’ve soldered on 100 mm pigtails and covered the joints with heat-shrink tubing.

    There is a common two pin connector referred to as a 2-Way Flat Connector that is used for trailer connections and such. It is slightly bigger than the one for the speed sensor though. Pins are slightly farther apart and slightly larger diameter. I wonder if it is an SAE vs metric problem.
     
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  21. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    I went with this method. I have second thoughts that maybe I should have used a wire since I could have tested the connection before potting the board. Oh well; too late now.

    My biggest worry is that my solder joints for the ground are "cold" considering how big a heat sink the brass casing is.

    Anyway, its done. Just now waiting the 24 hours for the epoxy to set.

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  22. alhbln

    alhbln Formula 3
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    Looks good!
     
  23. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    I am sorry to report that my upgraded speed sensor lasted 12 miles before it went dead. It was 12 happy miles.

    I suspect I made a poor ground connection by attempting to solder the board directly to the inside of the brass casing. The brass is a huge heat sink and the joint may have stayed "cold".

    If that is the problem, the connection may have broke because of thermal expansion of the brass case as the engine heated up pulling the solder away from the brass. I regret not heating the case. soldering on a ground wire to the inside of the case, letting it cool, and only then soldering the board connections and installing and potting the board.

    Is there now a way to remove the board and potting compound from the inside of the case to try again? I used this stuff:
    https://www.amazon.com/gp/product/B073JNDRXJ
     
  24. alhbln

    alhbln Formula 3
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    Mar 4, 2008
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    You could try heat up the brass case with a heat gun to around 200º, then you should be able to push out the epoxy including the board by applying force from the sensor side of the brass enclosure.
    Remove enough of the epoxy from the core you just pushed out to get to the boards ground connector, reinsert the epoxy core and try to create a better ground connection by using a larger soldering iron. It helps cleaning the brass area where you want to solder with contact cleaner.
     
  25. Brian A

    Brian A F1 Rookie

    Dec 21, 2012
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    It worked! Got the sensor out and the epoxy off.

    Will re-solder the ground.

    Have ordered another tube of potting epoxy. 3 days delivery time (Friday).
     

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