Looking to run a 60-2 trigger wheel and optical pickup off the crank instead of CAS with my PNP. I was speaking with Matt Cramer today, and he believes all I would need to do is make some software changes. Anyone have a clue where I need to start? Thx

 

Do you think the CAS isn't accurate enough with the MS, and you need to run a trigger wheel?

Why?

 

Speaking from recent observations, the CAS isn't accurate enough even with the stock ECU. This has nothing to do with my recent trigger trouble- it's a universal problem. The CAS is driven by the timing belt, and the timing belt has some degree of slack in it by design. As you rev the engine, the CAS jumps around slightly relative to the crank.

Ben, I am *very* interested in this. What do you have in mind with respect to mounting the wheel, and where are you getting it?

 

*need*? No. But I think it's a good idea.

Joe, I got it second hand from Frank who's pulled out his 1.8 and motec in favor of an LS1. Actually, it's in transit and I won't have it until next week. I understand that Vishnu originally offered the items for use with the TECII. Will know more in a few days.

 

Are you sure about this? Nearly every car made today comes with a cam-mounted position sensor, and I know the amount of work that OEM's put in to get a clean signal from the position sensor. I have myself seen several SAE papers about the subject.

 

LOL, don't you think there's a reason why mazda went to a crank trigger in 96?

 

32-tooth crank trigger in my OTM..

Good luck with this Ben, keep us posted!

 

This is new information, I thought even the NB's came with a cas?

 

They have a cam position sensor to identify #1 TDC (this is a totally different unit from the NA CAS), however the primary firing trigger is on the crank. A little jitter doesn't matter on the cam reference.

Most modern cars are like this.

Ben- keep me posted, I'm primarily curious about how it attaches to the crank pulley. I do have a lathe that can turn up to about 3" (limited by the chuck at the moment), however drilling accurately spaced holes around a circle can be a bit of a challenge. If I can't come up with a new CAS soon, I may make the leap to a crankwheel as well.

 

Could one of the wheels DIYautotune is currently offering possibly work? I need to research crank triggers, I know nothing about the MS side of using one nor why you need certain numbers of teeth or spacing.

http://www.diyautotune.com/catalog/t...eel-p-181.html

 

It is the Vishnu piece--was offered as part of the Tec3 kit actually. The wheel is an Electromotive wheel mounted to a custom hub that bolts to the four crank pulley bolts and has a big hole through the center. The sensor is mounted to a T-shaped dealie that you can kinda see in the photo.

Note that I tossed the 3/8 sensor as EM deemed them unreliable and made a new 1/2" sensor mount out of square aluminum tubing.

 

Pretty much any wheel will do. Tooth config looks pretty easy. The trick is mounting it properly- with a sensor gap of 0.7mm - 1mm, they have to be really concentric. I was hoping maybe Ben had found a source for pre-fabricated adapters.

I found one wheel in particular that really looks slick. Go to this webpage and scroll down to "5.75" lightweight trigger wheel": http://trigger-wheels.com/store/index1.html The 1.5" center hole and pre-cut slots should make it uber-easy to install and adjust. Just gotta figure out what to do in terms of a center hub...

 

ATI damper

 

If only that wasn't a $500 option. Unless FM has them marked up an extra $400 that probably wouldn't be my preferable option.

 

There has to be a way to make an aluminum adapter that bolts into the space in the center of the crank pulley and provides a surface for the wheel to mount on. If it weren't for the diameter required, I'd turn one myself...

 

Joe, you can't reverse the jaws in you lathe to turn larger stock? Every lathe I've ever seen had reversible jaws.

 

His lathe is pretty tiny, like super tiny, i bet that max diameter he is talking about is with the jaws turned around.

 

Even if so, does it have provisions for a faceplate? If so you can use support the work on centers and use a lathe dog to drive it.

 

not bolted but pressed:


https://www.miataturbo.net/forum/sho...highlight=edis

 

My lathe has a 7" swing, but the chuck I have in it presently will only accommodate a maximum 3" stock, and that with the "outside" jaws installed and fully extended- from a practical standpoint it'll only hold about 2.5" with anything resembling decent clamping force and stability. A 5" chuck with plate is only $100, I should probably buy one...

I think a more practical approach however would be to have the pieces made by a small-run prototyping shop. I just did an ultra quick-n-dirty sample drawing with the emachineshop software, and it quoted me $39 ea in qty 10, $27 each in qty 25. So if a group buy came together, it would be pretty darn affordable. The trick would be to make sure we have a design that'll fit both the 1.6 (long & short) and the 1.8 pulleys. I'm thinking of a mushroom-shaped piece that replaces the flat washer-like thing that holds the pulley on, and is retained by the same four bolts. It would also probably be specific to a particular wheel, so we'd have to agree on that. If we could find something domestically like the one I linked to above (with the slots) that would be cool- or we could have those custom-made too...