Very nice!!
Beautiful, Adrian I think re-using the old brass bodies would probably be the easiest route - just need to glue in the plastic plug at the back somehow, as the brass lip will be gone.
Patrick, reusing the old brass bodies would be quite feasible, but wouldn't it be easier (and more scalable) to fabricate new brass bodies to create a batch of new speedo sensors? No plastic plug required with the new setup I plan to use a cable support sleeve (see drawing, on the left side) which is potted in with the circuit board . The orange color shows the potting material. If the electronics should ever fail, you can heat up the brass body to 200-250ºC and push out the old sensor assembly, then install a new board with epoxy/PU. Rich, what do you think about the brass body fabrication, would that be rather costly/time intense or is it easy? Image Unavailable, Please Login
Adrian: let me ask the machine shop guys but I think Patrick is correct and expect reusing old bodies to be more feasible since there would be no material, labor or machine time costs. Besides then you could provide a board to go into a persons existing body. You are way ahead on the electircal side - my EE's have to fit in fun projects. I have realized a broken wire on the end of my board but there maybe other issues.
Per this chat, Adrian and Rich, along with Patrick's help are working on our first functioning prototype speed sensor replacement. We believe it will be very economical and hope to provide complete instructions and/or perhaps replacement units. This is part number 116987. Please respond if you have a failed speed sensor to contribute to our cause. Thanks, Rich
Quick update, i am expecting delivery of sensor components next week for building the physical prototype.
Sourced a good hall sensor chip for the circuit board and did a quick 3D print (red) of the new board to see if everything fits into the sensor body - it does Next step is to build a circuit boards for testing. Image Unavailable, Please Login
Rich, how about i send you one of the first circuit boards when they are ready, so you can try out potting it into the sensor body you have, and do some test drives?
Adrian: either way is fine with me. Glad to do my fair share since you are doing all the brilliant work!
I made a quick CAD model of the casing and sent it out to one of my favorite machine shops. The quote came back at $65/ea for quantity 20.
Rich this is David you have been by my shop on PCB a few times but i seem to miss you every time, I have the speed sensor off my 308 and it looks way different than yours. it works most of the time but because im selling the car i need it to work all the time, stop by when you get a chance and look at mine,
Fantastic! My only concern is the end not having a pressed in plastic 'window' like the original. The gearbox oil gets hot and is also under a bit of pressure, not much but enough that over time it may work the potting loose thru thermal cycles. How much heat and vibration can those components take? you'd be surprised at the vibration occurring in the drive-train. Excellent work, not picking on your work at all, just want to make sure parts like these are available and will also survive the environment it's subjected to. That sensor sits upside down in the bottom of the pump housing, if it fails by having the potting come loose then all the oil in the gearbox will get drained out fairly quickly.
The components are specified to work at 125º/150ºC and the potted SMD components should be able to take quite some vibrational load (at least considerably more than the wire through parts on the original sensor), so that should be fine. Thanks for pointing out about the potting/upside down position, i'll think about how to lock in the epoxy core, as example by adding a small brace soldered into the end of the brass housing.
David Steele: Been out of pocket and just saw your msg. I will stop by your shop again but we are gone much of the time over the holidays. Rich
I've got an early 348 and have also had the sensor fail issue. I searched far and wide and eventually purchased one from a generous f-chat brother. I still have the original and would be interested in repairing it if these boards become available
Adrian: per my PM and this picture, ditch the original intermediate part and reuse the end piece with the oring (after a new oring is installed) to seal on the sensor end of the body, fit the board into the backside of this end piece with a bit off the board ears beside the sensor. Plan to assemble and test soon. Will send pics of the board after trimming, hopefully with test results. Comments? Image Unavailable, Please Login
Adrian: tested but no speed indicated. Before I try second board please comment on the mods I had to make to fit the first board. I had to trim the "ears" off each end of the board, at the sensor end to fit it into the OEM oring seal end and it appears there may have been a connection from those ears to the sensor? If so I may be able to trim less or put a grouve into the oring seal end to accept the ears on the second board. On the connector end I had to trim a bit of the ears to fit in the original cap. I dont think there was any consequence but I did not ground the board to the body so please let me know if that is also necessary. Attached is a picture that shows how much I trimmed on the sensor end of the board showing a bit of the wires that may have gone to the sensor. I have more lessons learned but wanted to check before I proceed. Image Unavailable, Please Login
Rich, there is no connection from the "ears" to the sensor itself, the ears are only for the ground connection to the sensor body. Grounding the sensor board via one of the "ears" to the sensor body is necessary for the sensor board to work. Make sure that the distance between the top of the sensor and the front edge of the sensor body is not more than one millimeter to ensure the distance between the sensor and tooth wheel is small enough. Good luck, Adrian
