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Joined
Aug 13, 2010
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Location
Conway, S.C.
My Car
1972 MACH 1
2019 F150
My 72 Mach has a cluster w/tach. However the harnes is for non tach cluster. Can I direct wire the tach to the distributor to make it work? And I also need a new circuit board the old one is bad. Do I need a standard cluster with warning lights type board to work for the dash lights to work. The circuit board seems to be a common failure with age, should I just buy a new board or try to get a complete used cluster.

What's the best way to go?:dodgy:

 
For the 71-73's the only solution for the tach cluster is a tach harness as far as I know. However, there may be a means of converting the existing harness. For my '69, the process was to re-pin the plug by moving pretty much every wire around to a new location and then splicing into the pink resistor wire off the switch. There were instructions for this at www.boss302.com for my '69, so it was a do-it-myself type job. For the 71-73's I do not know of such a document to walk someone through it. But, there is a poster at the Vintage Mustang Forum called "Midlife" who rebuilds and repairs harnesses as a side job. He might be able to do the 71-73 conversion for you. If you are a member there, PM him and ask.

Regarding the circuit board--if you can find a reasonable priced new one, I would buy it. I would imagine the standard cluster and tach cluster boards are different--so if you haven't found a tach version it is a gamble.

 
HemiKiller 'Dennis' posted a good write up on modifying the harness slightly to convert a non-tach car over to a tach car.

there is a bad one on the net that shows you how to cut up your harness to make it work, don't follow that.

the best way would be removing the non-tach harness and replacing it with a tach one. i know that is not a great option since it would cost you a few hundred dollars.

another option, instead of making it look stock behind the dash, you could run a set of wires into the engine compartment, i believe it needs ground and the Distributor side of the coil to make it work.

http://www.mustangsandmore.com/ubb/RichPajzerGauges.html <-- i think this is the 'bad idea' version.

i know a lot of guys that keep the idiot lights on the left side of the instrument cluster with the clock, and then run a A-piller gauge pod with a tach and oil and vacuum gauges to avoid dealing with the center gauge cluster also.

going the replacement route swapping harnesses can be dangerous to your wallet. I found out that there are at least 7 slightly different harnesses per year for all the different options ford offered. differences exist between sportroof and mach 1 and 71-early 72 cars and later 72 cars and 73s are very different, so you REALLY have to research what car the harness came out of and what options the car had.

here is a good difference that cost me 100$

71 cars included the underdash lighting and map lights on the main harness even if you didn't get them as an option.

early 72 kepted the underdash lighting plugs, but ditched the map light part of the harness and moved it to a daughter harness that was sort of spliced in with plugs. Well i bought a map light for my car, DOH!!!

73 they totally removed the underdash lighting plugs and map light plug if it wasn't ordered with it.

The V4 and V2 harness is different slightly if you had the seatbelt warning lights its different.

you would have to find a car similar to yours from the same year and if possible the same plant that made it to have a really good fit.

That is why a lot of guy either forget about converting it, or go aftermarket.

one thing i don't like about mounting a A-pillar gauge is you drill holes in the A-pillar cover. the A-pillar cover is REALLY rare depending on your body style (sportroofs) and once you cut it; It will cost tons of money if you ever want to restore it back.

 
As part of my transformation of "Ice" (my '73 Grande), I swapped out the 302 for a 429-based 472. As part of that effort, I also removed the "gauge cluster" (including Tachometer and console guages from a '73 Mach I parts care) and installed them into the Grande.

I know my "limitations", so I got a neighbor (who is an electrician) assist me in the wiring effort. I ordered the "with/Tach" circuit board (as Don stated above, they are different) for a 1971 429 mustang and using the '71 and '73 wiring diagrams (both now here on the site), we wired up the tachometer (and everything else). I was EXTREMELY pleased with the results.

Hope this helps.

BT

 
HemiKiller 'Dennis' posted a good write up on modifying the harness slightly to convert a non-tach car over to a tach car.

there is a bad one on the net that shows you how to cut up your harness to make it work, don't follow that.

the best way would be removing the non-tach harness and replacing it with a tach one. i know that is not a great option since it would cost you a few hundred dollars.

another option, instead of making it look stock behind the dash, you could run a set of wires into the engine compartment, i believe it needs ground and the Distributor side of the coil to make it work.

http://www.mustangsandmore.com/ubb/RichPajzerGauges.html <-- i think this is the 'bad idea' version.

i know a lot of guys that keep the idiot lights on the left side of the instrument cluster with the clock, and then run a A-piller gauge pod with a tach and oil and vacuum gauges to avoid dealing with the center gauge cluster also.

going the replacement route swapping harnesses can be dangerous to your wallet. I found out that there are at least 7 slightly different harnesses per year for all the different options ford offered. differences exist between sportroof and mach 1 and 71-early 72 cars and later 72 cars and 73s are very different, so you REALLY have to research what car the harness came out of and what options the car had.

here is a good difference that cost me 100$

71 cars included the underdash lighting and map lights on the main harness even if you didn't get them as an option.

early 72 kepted the underdash lighting plugs, but ditched the map light part of the harness and moved it to a daughter harness that was sort of spliced in with plugs. Well i bought a map light for my car, DOH!!!

73 they totally removed the underdash lighting plugs and map light plug if it wasn't ordered with it.

The V4 and V2 harness is different slightly if you had the seatbelt warning lights its different.

you would have to find a car similar to yours from the same year and if possible the same plant that made it to have a really good fit.

That is why a lot of guy either forget about converting it, or go aftermarket.

one thing i don't like about mounting a A-pillar gauge is you drill holes in the A-pillar cover. the A-pillar cover is REALLY rare depending on your body style (sportroofs) and once you cut it; It will cost tons of money if you ever want to restore it back.
I think I'm going to use my standard harnes and run wires from the tach cluster to the distributor. Less to modify and easier way to go. I like the stock tach look.....Thanks for options to everyone

 
OK - so school me on the tach. I have the 'clock/fuel/speedo' cluster and would prefer a 'tach/fuel/speedo' cluster. All of my gauges and plastic are in great shape, so I would be interested in swapping in a factory tach.

Is it possible, considering the circuit board on the back and are the gauges modular enough to allow simply finding a tach and swapping it with the clock and performing a little rewiring trickery? (I'm not as concerned with the wiring looking stock - I'm restoring mine to drive, not to win Concours de' Elegance.

I'll be reading the write-ups the links are posted to. Thanks in advance.

 
To answer your question, Eric...Yes, that is what I did. Rewired the stock tach and used a tach circuit board.

See my post above.

BT

 
OK - so school me on the tach. I have the 'clock/fuel/speedo' cluster and would prefer a 'tach/fuel/speedo' cluster. All of my gauges and plastic are in great shape, so I would be interested in swapping in a factory tach.

Is it possible, considering the circuit board on the back and are the gauges modular enough to allow simply finding a tach and swapping it with the clock and performing a little rewiring trickery? (I'm not as concerned with the wiring looking stock - I'm restoring mine to drive, not to win Concours de' Elegance.

I'll be reading the write-ups the links are posted to. Thanks in advance.
I make tachometer that uses the warning light cluster and matches the speedometer. It is a modern three wire hook-up so if you're running an MSD you won't need a tach adapter. You can see it here: http://www.rccinnovations.com/Mustangs.php just scroll down to the M7123S tachometer.

b67gqu.jpg


Bob

 
I make tachometer that uses the warning light cluster and matches the speedometer. It is a modern three wire hook-up so if you're running an MSD you won't need a tach adapter. You can see it here: http://www.rccinnovations.com/Mustangs.php just scroll down to the M7123S tachometer.

b67gqu.jpg


Bob
I'm very interested in this.

Do you make the new gauge face from scratch, and if so how close does the coloring/surface texture match original? (looking at the picture it looks pretty close!)

Three wires; does that mean one ground, one positive, and one to the coil and that's all? Will it work with a Pertronix ignitor and Flamethrower coil?

Are they really that easy to "drop in"; what work is involved with doing this? I'm assuming it uses the original globes for the idiot lights?

Thanks

 
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I use the original warning light cluster and jewels. The new face is an overlay made from the same material (my old employer) used to make modern clusters for OEMs and applied with 3m adhesive. There is a slight difference in pointers - mine is slightly thicker. It is not readily noticeable, but it is different.

Wiring is the same as any aftermarket tach, as you stated: 12V+, 12V- and a signal from coil- or MSD tach out.

It uses the original lighting.

Installation is a snap:

- remove the cluster

- remove the bulbs (twist out)

- remove the CVR ( one screw)

- gently remove the printed circuit from the warning light cluster

- remove 3 screws around edge

- remove warning light assembly

- send me the assembly as a core

reassembly:

- place new tach assembly into cluster

- install screws around edge

- put printed circuit back in place, routing wires for tach through (factory) hole in printed circuit

- install bulbs

- install CVR

- wire tach to power and ignition

- install cluster assembly

I try to make all of my stuff bolt in and with a factory OEM look.

Bob

 
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I use the original warning light cluster and jewels. The new face is an overlay made from the same material (my old employer) used to make modern clusters for OEMs and applied with 3m adhesive. There is a slight difference in pointers - mine is slightly thicker. It is not readily noticeable, but it is different.

Wiring is the same as any aftermarket tach, as you stated: 12V+, 12V- and a signal from coil- or MSD tach out.

It uses the original lighting.

Installation is a snap:

- remove the cluster

- remove the bulbs (twist out)

- remove the CVR ( one screw)

- gently remove the printed circuit from the warning light cluster

- remove 3 screws around edge

- remove warning light assembly

- send me the assembly as a core

reassembly:

- place new tach assembly into cluster

- install screws around edge

- put printed circuit back in place, routing wires for tach through (factory) hole in printed circuit

- install bulbs

- install CVR

- wire tach to power and ignition

- install cluster assembly

I try to make all of my stuff bolt in and with a factory OEM look.

Bob
Thanks for the specific information Bob, I really do want one of these. I'm in Australia and don't want to have my car sitting around for too long with the instruments out of it while waiting out the longer postage time-frame. I see you have a higher price option for "I don't have a core" - does this mean if I choose this option you will send over all the parts I need to do the job without me having to send anything to you? (forgive my ignorance, but I'm actually not quite sure what a "core" actually consists of either.....)

 
You are correct - I look for cores at swap meets and on-line or people contact me directly when they have something they think I might be interested in. This way I can supply the parts needed from another cluster and send it to you ready to install and minimize your downtime. Once replaced you can opt to send me your old unit for a refund of the core charge, sell it outright or keep it.

In the case of this tachometer I would need the entire left cluster - the plastic back, metal front, red warning light jewel (also called the lens) and the center piece on the pedestal. You can keep the bulbs, bulb holders, blue bulb covers and hardware.

**Where in Australia are you? I have a good friend in Melbourne and quite a few customers down under.

 
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I like the idea of sending the parts back for a refund.

I changed the globes in the instrument cluster to LEDs not too long back and found it impossible to disconnect the plug from the back of the instruments, so in the end I just left it hanging there while I changed the globes - is there a trick to loosening the plug? (I couldn't really see it so I was working by feel)

Also, I bought a digital "Glow Shift" tacho off ebay recently but didn't install it because during my test connections I couldn't get it to read the right revs, here is a post I put on this forum about it: http://www.7173mustangs.com/thread-new-glow-shift-tachometer-dodgy?highlight=tachometer

Obviously after that failed attempt I'm a still a tiny bit hesitant in spending a lot of money on something if there is the possibility it won't work. I was wondering if it was something to do with my Pertronix setup. Would you anticipate that there would be no problems using your tacho with Pertonix and Flamethrower coil?

 
As far as I know there is no real trick to getting the cluster out - remove screws, disconnect speedo cable and unplug main wiring connector. I believe that the cable and connector are held in with a plastic clip that you need to feel around for and depress to release. Unfortunately I do not have a main connector to get a picture of.

Your Glow-shift tachometer appears to have an electrical issue. My first response was to check the cylinder count setting but I see you did all that. Not having any experience with those I hate to guess, but since you have no odd ignition bits such as an MSD or HyFire I would put my money on a bad tach.

I have been selling my tach conversions for over 6 years now and the only problem I ran into (once) was a noisy system that made the tach needle jump & twitch. In that instance the customer had to install an SN20 inline filter that cost about $20.

My tachs have been hooked to single points, dual points, Pertronix, Duraspark, Mallory Hi-Fire and MSD systems with no issues. My Cougar tachs are the same electrically and are sold by West Coast Classic Cougars and Mustangs Unlimited direct to the customer so Lord knows what else they have been hooked to that I never heard about. If an Autometer or VDO tach will work on it mine will.

 
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