Speed Signals - what are you guys using for speed signals as inputs to ECU's? I CAN use the stock ABS sensors with a mag - > Hall Effect converter however I CANNOT for the life of me get my hands on a set of sensors short of buying new ones. New sensors of old technology plus converters are turning out to be the most expensive option. Mounting a Hall Effect sensor is the easy part, it's just getting a trigger wheel is turning out to be a bitch. The stockers will not work, the teeth are of the wrong orientation, so, what have other people done? I need them at all four corners and this is for an FC.

 

In my setup (MoTeC M4 + TC Mux) I used the stock abs setup (27 tooth? wheel and sensor) with a MoTeC DMC-D convertor per axle. This converts the stock signal mag (sine wave) to a hall effect (square) input for the TC Mux's ground speed input. From bench testing with the car on jack, it provides a reliable signal down to approximately 5 MPH. Link to MoTeC DMC (series) Spec Sheet is provided.

An alternative I looked at early in the install was tapping into the transmission's speed sensor output for the rear wheels signal. In the FD, I seem to recall it feeds the speedo or odometer with a feed-through to the ECU. If you really need it, Aaron (2+ron) has my Technical Highlight notes indicating the signal type/count in my schematics binder back at Yaw Power. Not sure what the FC's tranny speed-to-speedo signal looks like, but it might be a start.

Trying to understand what you're looking for. How is the tooth configuration on the FC? Does it use a missing tooth? If it's a regular interval, that is software configurable. Subscribed.

 

Well Carlos, since you subscribed, I guess I better update this

The FC, first, not using a stock tranny anymore. When I was I bought a thread in Hall Effect sensor from speedometersolutions that worked great all last year. Today actually, I'm going to pick up a hybrid 6-spd that I built from 2 different trans that bolts up, uses a stock clutch and hydraulics, and the shifter fits where it's supposed to; and Dave @ KDR cryo'ed the whole thing, resynced it, and put a few new bearings in.

The tailhousing on that trans had the provisions for a speed sender, but the mainshaft that I used didn't have the machined recess for the gear. Since I wanted to do traction control and have 4 speed inputs for it, not having a driveshaft speed sensor wasn't a big deal in the least. Actually wasn't planning on using it; was going to run 4 signals through the TC Mux. The M820 has four dig inputs but I'm using 2 for low fluid level inputs. I just have one hole to fill in the tranny, pretty straight forward.

For speed signals, I had originally purchased 2 DMC-D's and was going to use the factory sensors and rings. Finding the rings was pretty easy, the FC uses a 90 tooth ring front and rear. Finding the sensors without buying new proved really difficult. After 3 months of looking, literally, I started to give up hope. New sensors are $180 through MazdaComp. That makes them the most expensive sensor I could find.

So one day I grabbed a front hub, rear hub, brake rotors, reluctors and went up to my local MoTeC guru to bumble around with the sensors that he had instock. What we discovered is that the GT101DC fit's in the factory hub in the rear. The sensors mounting bolt needs to be tickled out ever so slightly to use the stock M8. I suppose you could drill and heli-coil the AL hub and use a 1/4-20, but I think boreing out he sensor would be pretty quick and painless.

In the front.... Mazda decided to use a different sensor; it's a hex shape instead of a circle. If you're using factory ABS front knuckles, then all you need to do is blast a 3/4" cobalt step bit through the hub and viola, tickle the sensor's mounting flange a touch and the sensor bolts in. I suppose you could drill and heli-coil the hub and use a 1/4-20, but drilling and tapping the front's cast iron would definately be more time consuming that tickling the AL bushing in the GT101DC.

If no front ABS knucles are available, a very simple AL bracket is all you need. From what I've seen, ALL FC rear hubs have the provision for the sensor. At least the 7 that I've collected all have it.

So, we have good hall effect sensors mounted, time to get it a signal.

Billy Waits (ReSpeed) came through for me with a base .dxf file, and with alot of help from Limbar85, actually all the help, we tweaked the file a few times until we were happy with it. Hardest part was reverse engineering the factory mounting bolt patterns. Measuring it out I came up with 94.8m radius in the front and becuase that didn't make much sense, I asked to have it made @ 95mm x 3. I sent out the file to be bid at three different places and a waterjetter down south won it. He cut them yesterday actually, and I should have them on Friday. It's a 24 tooth count wheel cut from .25" mild steel. With 15* of wheel rotation between signals, it should be very accurate down to very slow speeds, and react very quickly when it does let loose. The teeth measure .7" in depth, with a gap of .7" as well, the diameter of the sensor so there should be no double triggering. Here's the first drawing pic.

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I've got the MoTeC and the TC Mux wired up, just waiting on the triggers. Once I have them on the car and tested, Limbar is getting a set as is Paul Yaw. I'll probably order two spare sets just so I have them, there are 2 other FC's that I'm looking at purchasing, why I have no idea but I am, and I'm hoping that they'll fit my FD project as well that I'm going to start on as soon as I return from DGRRX. That would be awesome but we'll see.

So, a plan has been set and excecuted, now it's just time to test it. The car is still basically a shell with a little wiring left to do on the rear harness, full interior install, I need to install Pauls ID725/2000 injectors, a set of Bosch coils, and basically install everything from the firewall forward. I'm praying to have her running Monday/Tuesday.

 

Well, apparently you still can't link to www. rotary car club dot com , so if you want to see the pic, head over there, in the lounge there is a thread titled, I need a .dxf file.

 

WOW, someone's been busy since the first post. Thanks for the comprehensive update. Your follow-through is impressive. Anyways, sorry I was "too little too late." At a minimun, I hope my info may be of some future value for your FD build.

I am however curious about the watercutting provider you used. A link might come in handy in the future.

Cheers,
Carlos

 

Yeah, very busy, thrashing like hell to get her done in time for DGRRX.... you're attending correct?

I'm sure the info that you provided will come in very handy with the FD build.

The waterjetter that I used is atlanta water jetting. Jim is a great guy, upfront and follows through with what he says he will do. I've got a friend out in SD that may get the next batch with lazer cutting though. He MAY be able to do it cheaper, time will tell. Gotta get the proto-type's on and tested before I order a few more sets.

 

Will very much look forward to seeing your handiwork in person at DDGRR! More MoTeC groupie chatting then. ;-)

Please keep us advise on who ends up with the final order for cutting services. It's a capability I'd like to learn more about in the future.

Cheers,
Carlos

 

YES! We must get a few of us all "grouped" together yacking EUC's. Looking forward to meeting you @ DGRRX - Silver FC, black ceramic coated 13B-RE, REW twins, CT plates

The wheels arrived today. Lined them up with the factory reluctor wheels and the fit looks PERFECT. So I'll press out the rear hubs, bolt them on F&R and measure for the spacers I'm going to need. Order those Monday, get them Tuesday, put them on Wed, hopefully driving the car Thurs.... we'll see though. Waking up tomorrow and starting on the car and not stoping until it's time to go to sleep Sunday night.... 36 hours I outta be able to make some kickass progress