Inductive pickup to drive a tachometer..

[R.O.R-2.0]

Heres one I put on my caddy today, did'nt want to copy yours so heres a little different version.
Sensor is 92 F-250 rear anti-lock. No welder needed for those without one. Works great even with a cheapo tach.


 

you got a VNT also? or just some other low mounted turbo?

[81 vw pu]

you got a VNT also? or just some other low mounted turbo?

It's the low mounted GT-15 (prothe's version)

[R.O.R-2.0]

you got a VNT also? or just some other low mounted turbo?

It's the low mounted GT-15 (prothe's version)

ok, that makes sense.

the GT15, and the VNT15/GT1749 look pretty similar on the cold side..

[burn_your_money]

Can someone tell me what year of Fords to look on for this crank sensor, and also where abouts on the engine it is located?

I know it's off a 4.0...

And if it's not too much trouble... also what tools are needed to remove it. I don't like lugging a lot of tools around the scrap yard

[81 vw pu]

The one I did was a rear anti-lock brake sensor from the rear diff housing on a 92 f-250.
You need a 10mm wrench and a pair of wire cutters.

[jimbote]

Kinda like my setup from a few years back ..... see post 29.... http://www.vwdiesel.net/forum/index.php?topic=3741.15 ....I guess you could have come up with it sooner, but it wasn't posted on here....

[jimbote]

tried this today....gonna keep posted on the workability....basically hooked up an 83 GTI tach to a battery and a ford V8 distributer....no coil no module....just the inductive pickup and trigger wheel....with my 750 rpm drill at full blast the tach registered just under 3K....and was smooth down to almost zero rpm....so I cut six of the trigger "arms" off of the wheel leaving two at 180 apart and buzzed the drill up to full speed...the tacho was smooth reading around 500 rpm....probably could be adjusted out with the pot.....I have already built a bracket to house an inductive speedo pickup from a late model ford tranny....it will be pointing at the four balancer bolts at the front of the crank....two of which will be spaced out so as to trigger the sensor only twice per rev....I'll be working this manana and I'll keep posted (with pics)  but looks promising so far

OK this works like a charm!!! .....for anyone not wanting to solder new caps or resistors on your tach this will work and give an accurate tacho signal with no mods to the tach or calibration of the tach for that matter.....some things I changed from my original idea of pointing the sensor at the pulley bolts was to use two 3/8 nuts welded to the outside of the crank pulley exactly 180 apart and have the sensor pointed at the nut facet with about .020 clearance....the old idea simply had too much bracket hanging over the sprocket add to that thrust clearance variance and it may have thrown off the gap and thus the reading.....good luck!!

[R.O.R-2.0]

great addition huh?

what tach you using?

if you have too big of a bracket, you end up with funky harmonics around 3000 revs from the crank..

it makes the bracket just start quivering, then it breaks in the end...

[jimbote]

factory MKI GTI gasser tach, the bracket I built was beefy with no strange harmonics....3/16 thick plate welded together and was still working great when I sold the truck over two years ago .... Was one of my favorite mods

[R.O.R-2.0]

factory MKI GTI gasser tach, the bracket I built was beefy with no strange harmonics....3/16 thick plate welded together and was still working great when I sold the truck over two years ago .... Was one of my favorite mods

well, maybe i just wasnt using a small enough air gap between the sensor, and the pulley..

i was running .060"... it drove my autometer tach just fine.. but not the mk2 gasser stock tach..

maybe i should re-install everything, and try a smaller air gap?

my second iteration of the bracket was 6061-t6 aluminum channel.. the last one was .100 sheet metal, and soft..

[burn_your_money]

I picked up what I believe to be a speed sensor off a 92ish F250 rear diff. My question is, do I have to weld onto the pulley, or would a pair of earth magnets excite the sensor?

[81 vw pu]

I picked up what I believe to be a speed sensor off a 92ish F250 rear diff. My question is, do I have to weld onto the pulley, or would a pair of earth magnets excite the sensor?

The sensor is the magnet. You just need to pass two pieces of metal spaced 180 degrees apart by the sensor.
Not sure on the magnet idea, but it would be easy to try with a dvm.

[burn_your_money]

I'm thinking that a magnet might give a stronger signal, which I need since I need to drive the stock tach (I think anyways)

[ORCoaster]

You might have to play with the magnets to get them to signal any thing.  Don't forget that they have two poles and passing two north or south past each other may not do diddle.  The north south combo might get the signal you want.

[92EcoDiesel Jetta]

factory MKI GTI gasser tach, the bracket I built was beefy with no strange harmonics....3/16 thick plate welded together and was still working great when I sold the truck over two years ago .... Was one of my favorite mods

well, maybe i just wasnt using a small enough air gap between the sensor, and the pulley..

i was running .060"... it drove my autometer tach just fine.. but not the mk2 gasser stock tach..

maybe i should re-install everything, and try a smaller air gap?

my second iteration of the bracket was 6061-t6 aluminum channel.. the last one was .100 sheet metal, and soft..

I can modify your mk2 gasser stock tach work with your sensor. PM me if interested.