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TACH signal from alternator

no, previus alternator was CS-130 (3 x CS-130 alternators in my Yucon story)

Then in 2012 I decided to install alternator with a better reputation for reliability and with more amperage
...and upgraded to AD244

new pulley 57mm for AD244 bought monday on ebay, i am waiting delivery .... ( 3-4-5 weeks :hungover:)

previus pulleys has 56mm OD to the groove, not to bad , but not the right distance seat for drive belt, AD-244 has a big housing case and need his pulley for make belt work in parallel with the other accessories, and not wear out the belt


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tell the truth, having chosen to go with OD 57mm, I also thought about installing a clutch pulley (with only 0.3mm backspace difference). has the advantage of further limiting vibrations but then I decided to not complicate my life further.
a fixed pulley has a very long life compared to clutch pulleys.


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Clutch pulleys are designed to thread onto the shaft and wouldn't work on these rigs.

not sure why they even invented those things. very troublesome. if I could get away from it and mount a regular pulley on the Jetta we have, I would have. the internal bearing went out and cause a severe vibration that destroyed the alternator on ours.
Clutch pulleys are designed to thread onto the shaft and wouldn't work on these rigs.

not sure why they even invented those things. very troublesome. if I could get away from it and mount a regular pulley on the Jetta we have, I would have. the internal bearing went out and cause a severe vibration that destroyed the alternator on ours.
what posted is a clutch pulley for AD244 17mm shaft, and it can be installed without problem

were invented to reduce vibration and extend the life of belts and accessories under severe conditions, the benefit is there, but they need to be replaced at regular intervals, say every 100k miles, if they don't have problems before

the problem that usually occurs is that they rust, and the system no longer grips the alternator shaft firmly, like a loose pulley, therefore no electricity production when this event occurs. in our diesels you should notice it immediately, voltmeter and tach are under your eyes, before discharging and ruining the batteries

as mentioned before, although these pulleys bring benefits, are another piece to maintain, so it's better not to complicate your life
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this instead https://www.dakotadigital.com/index...id=1192/category_id=694/mode=prod/prd1192.htm
is a system that allows you to calibrate the TACH from a signal coming from the alternator, it can also be used for other functions.

the price would be acceptable, affordable...compared to other expensive solutions
but it would be yet another accessory to be installed under the dashboard... it solves the problem, but I have no desire to drill, pass cables, make new connections,... when it would be enough to modify or replace the factory circuit board, it would be enough to find circuit board in some salvage yard


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for now I'll settle for a slightly altered reading from the TACH
this when 57mm pulley will arrive :banghead:

I will have to wait patiently for delivery as usual:depressed:

then a little luck would be enough, quite a lot 😂🤣😂 .... and find the circuit board
@alex1234 how do you remove the alternator pulley without distorting it? I've seen specific pulley pullers but don't want to buy a tool for 1 time use. I got my correct size pulley from a junkyard but had to break the donor alternator in the process, and would like to know if there is an easier method
on mine I just used an impact and socket on the nut. zipped it off and the pulley just slides off the shaft, onto the alternator I was using and then zip the nut back into place. no puller needed.

I have seen some of the rigs here at work where the pulleys get stuck due to rust. but I try to always add some never seize on the shafts when doing that kind of thing.
no puller pulley is needed
it is a simple slide in, if the pulley don't slide off, may be there is rust formed between pulley and alternator shaft, spay some wd40 or similar, a few taps with a rubber mallet and pulley should slide off.
there are cases in which rust is very resistant, so need time for soak, or a simple bearing puller is enoght, but you have to protect head alternator shaft with a metal disk.

an impact tool should not be used, but instead it seems to be a widely used practice, for convenience and time saving
think I have identified how to correct the odometer from miles to kms
the tach signal would been more complicated to correct

so a circuit board from a DIESEL 96-99 US MPH instrument cluster WITH AUTOMATIC TRANSMISSION will be fine for swap

found an used 97 circuit board online for $15....but unfortunately with unacceptable shipping costs

Does anyone want or need to go to some salvage yard, for give a try?


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There are almost no 6.5L diesel in the salvage yard anymore.
During one of the previous president (the name start with "O"), they have a program called "Cash for Clunkers".
During that time, a lot of these trucks were destroyed and pressed for metal.
every diesel truck I have found on my local pick a part yards here had all of the interior and dashes stripped down.

try looking on this site, maybe some of these guys will agree to ship at a reasonable fee. even if someone here knows the in's and out's on shipping carriers to get a discount rate could pickup for you and ship. I looked and there are several in various places with the price range $35 - $175 depending on condition and what not.

new 57mm pulley (part 24-1272) for AD244 alternator delivered and installed.
real groove diameter is 56.60mm, less than declared
this will increase the gap between RPM and tach reading from planned diameter and tach reading, some further gap that expected
Ooh, it's 0.4mm smaller than 57mm diameter? Perhaps the size listing is rounded up/down to the nearest mm? More importantly, who freaking cares!?!?

The error in needle width and the increment markings on the dial, combined with viewing angle, can easily be 50-75 RPM off from the actual engine speed, anyway! The tachometer on the 6.5's was mainly just to let you know if you were getting dangerously close/over the redline for the engine. It was NEVER intended to be dead on to the revolution accurate - if it was the input for it would have been taken off of the CPS output, NOT off of the alternator - not to mention that the tach display would have been designed much differently! I can NOT understand your almost OCD fixation on having such a dead accurate stock tachometer reading with what is not that precise of a factory dash gauge that has built in inaccuracy in its very design - needle width, face diameter, partial sweep, marking widths, increment spacing, etc.

You want dead-on accurate RPM readings? Then 1) Buy a Stewart Warner, AutoMeter or other high quality aftermarket large face (5" or larger), 270° (or greater) sweep electronic Racing Tachometer, OR a digital tachometer, AND 2) Then find a way to send an input signal from the CPS to drive it. The factory dash tachometer on the 6.5 (or gasser) was NEVER made or intended to be as accurate as you're try to get this one to be. If any part of the needle is touching any part of the increment marking for the RPM you calculate you should be running, consider it good and you've got the tachometer dialed in as accurate as its ever going to get.
for accurate reading have digital numbers from ECM on 8" screen with app, and not for TACH only...

it is well known a signal from alternator is not accurate also if you have the right pulley OD

but why not have an accurate tach reading, or more than now, without other tinsel...if it is possible?

if you don't agree, I'm sorry for you

ignore me, move on to something else you think is more interesting
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I know that there must be some way to catch the signal from the CPS. That would be about as accurate at it could get.
I know that the Too Kick trucks with the 8.3 diesel had the pickup sensor screwed into the bell housing and those were spot on.