Author Topic: Inductive pickup to drive a tachometer..  (Read 26575 times)

Reply #45December 21, 2012, 01:49:19 pm

8v-of-fury

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Re: Inductive pickup to drive a tachometer..
« Reply #45 on: December 21, 2012, 01:49:19 pm »
I have still yet to do this.. Might have to in this upcoming few weeks.

Reply #46December 22, 2012, 02:06:48 pm

R.O.R-2.0

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Re: Inductive pickup to drive a tachometer..
« Reply #46 on: December 22, 2012, 02:06:48 pm »
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.

no offense, but if i cant do it myself, its not happening..

now, if you feel like telling me how to do it, im down.. but im not gonna pull my car apart, and send you pieces of it.. i just dont feel right letting someone else work on my car..

its like letting someone have sex with your wife.. it just doesnt happen.

im sure you ARE capable of the mods..

i would just rather you share your info with the forum, rather than keep it to yourself and charge for it..
92 Jetta GLI - Black, 1.6D w/ GT2056V turbo..
86 GTI - 4 Door, Med Twilight Gray, Tow Machine..
86 Audi Coupe GT - Tornado Red, All Stock.. WRECKED.
89 Toyota 4Runner - Dark Grey Metallic, LIFTED!

Turbo: exhaust gasses go into the turbocharger and spin it, witchcraft happens and you go faster.

Reply #47December 23, 2012, 12:59:21 am

8v-of-fury

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Re: Inductive pickup to drive a tachometer..
« Reply #47 on: December 23, 2012, 12:59:21 am »
While it would be nice to share, he is not forced to by-law or anything ;)

Reply #48December 23, 2012, 01:38:29 pm

ORCoaster

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Re: Inductive pickup to drive a tachometer..
« Reply #48 on: December 23, 2012, 01:38:29 pm »
Knowledge is power and with power comes money.  Yes, it would be good to share but that kind of kills the spirit of invention, patented parts and competition.  All things that made US great.  Buy one, take it apart and you will know what he does. 

Does Microsoft produce Open Source code?  Do other large corporations share their R&D results with Popular Mechanics?  Nope!  Gotta pay the man, to be on equal footing.  Sorry Dude.


Reply #49December 23, 2012, 03:59:21 pm

burn_your_money

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Re: Inductive pickup to drive a tachometer..
« Reply #49 on: December 23, 2012, 03:59:21 pm »
Let's talk about inductive pickups instead...
Tyler

Reply #50December 26, 2012, 12:21:35 pm

92EcoDiesel Jetta

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Re: Inductive pickup to drive a tachometer..
« Reply #50 on: December 26, 2012, 12:21:35 pm »
I thought I was offering a valuable service. Seems there's lots of idi's out there without a tach and many of those owners would love to have a tach. You do not have to send me the entire cluster, just the tach and the mag pickup. I will mod it and take a video of it working on the bench before sending it back to you.

I do not have any gasser clusters at the moment. If I get more, I will convert them to a diesel cluster with either a W terminal tach or mag pickup tach (pickup included) and offer it it the parts for sale forum

Edit:
For anyone interested in this and do not feel like paying for it, maybe we can work something out in trades for parts?

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.

no offense, but if i cant do it myself, its not happening..

now, if you feel like telling me how to do it, im down.. but im not gonna pull my car apart, and send you pieces of it.. i just dont feel right letting someone else work on my car..

its like letting someone have sex with your wife.. it just doesnt happen.

im sure you ARE capable of the mods..

i would just rather you share your info with the forum, rather than keep it to yourself and charge for it..
« Last Edit: December 26, 2012, 12:24:36 pm by 92EcoDiesel Jetta »

Reply #51March 16, 2013, 09:33:28 pm

hillfolk'r

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Re: Inductive pickup to drive a tachometer..
« Reply #51 on: March 16, 2013, 09:33:28 pm »
Haha drill the bell housing and install an mpu like a generator they run off the flywheel teeth. I installed a few before on i drilled bell housings its no biggie.
Throttle cables ftw

Reply #52March 16, 2013, 09:41:14 pm

hillfolk'r

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Re: Inductive pickup to drive a tachometer..
« Reply #52 on: March 16, 2013, 09:41:14 pm »
Its easier to put in a w lead in an alternator thats a 1.5 hour project for an average. Im sure vdo still makes the diesel tach i got too. Its kinda small 2 inch but the sw i recently dug out is a little bigger
I had it adjusted close at idle but up at 2k it was readin 2200. It still needs further calibration
 I've never had any slippage issues or bounce with any w lead powered tach. Well unless your belt is loose but duh tighten your belt then!




« Last Edit: March 16, 2013, 09:45:48 pm by hillfolk'r »
Throttle cables ftw

Reply #53May 26, 2014, 01:22:47 pm

libbydiesel

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Re: Inductive pickup to drive a tachometer..
« Reply #53 on: May 26, 2014, 01:22:47 pm »
This last weekend I worked on installing a tachometer into my '91 ALH Automatic Vanagon.  Due to this being an mTDI there is no ECU and so no engine speed signal generated.  Some folks use the alt W-signal (unrectified A/C signal) but pulley size differences can cause calibration issues and also mess with the dynamic oil pressure warning system function.  To that end I decided to stay with a gasser tach and to generate the necessary 2 pulses per rev to drive it. 

Here are the fabbed components I came up with:




They fasten to the engine like this:



I replaced two of the four crank bolts with studs and coupling nuts and then installed a short bolt into the open end of the coupling nuts in order to read off the flat face of the bolts.  The bracket was designed so that I could still access the main crank bolt for rotating the engine by hand:




I had a little concern about crank thrust changing the air gap, but it doesn't seem to be an issue.  Tach operation is solid.  On another install I might be tempted to rotate the sensor so that it is perpendicular to the crank axis and then install two longer bolts into the coupling nuts in order to read off the shanks of the bolts but this works fine for this install.  The sensor that I used is part number XR3Z-7H103AB (as provided by Jimbote in the other thread) and retails for approx $25.  On my setup, it generates approx 1.9v A/C.  I found that it would not drive the stock '91 vanagon gasser tach (arghhh....) but that it works well with an early mk2 gasser tach.  I tested the system with a mk1 rabbit tach and it works fine there as well.  Oddly enough I have two early mk2 gasser tachs and only one would work with the system.  I'm not sure if the one that didn't work was because of a fault with the tach or a difference in design.  Although I had to disassemble the instrument cluster to install the mk2 tach, I did not make any changes to the wiring.  The probe has two interchangeable connections and one goes to ground and the other goes to the green wire that was previously connected to the WBX ignition coil.  I have considered installing magnets instead of the two bolts in order to bump up the signal output in order for it to work with the stock vanagon tach.  I'm curious if anyone has any other suggestions.

Reply #54May 26, 2014, 02:11:32 pm

theman53

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Re: Inductive pickup to drive a tachometer..
« Reply #54 on: May 26, 2014, 02:11:32 pm »
No suggestion, but I think what you have done is awesome.

Reply #55May 26, 2014, 09:18:36 pm

ToddA1

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Re: Inductive pickup to drive a tachometer..
« Reply #55 on: May 26, 2014, 09:18:36 pm »
^^^ Agreed ^^^.   I bought that sensor over a year ago and haven't done anything with it, other than look at it.

Any reason you want to make the pick up read off the shank instead of the head?

-Todd

Reply #56May 26, 2014, 09:58:50 pm

libbydiesel

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Re: Inductive pickup to drive a tachometer..
« Reply #56 on: May 26, 2014, 09:58:50 pm »
Any reason you want to make the pick up read off the shank instead of the head?

Radial movement of the crankshaft is less than the thrust motion and so reading perpendicular to the axis will give a more consistent air gap than reading parallel to the axis of the crank.  Regardless, the way it is currently set up works fine, so I will not be changing it.