bherder
05-06-2009, 10:09 AM
HOW TO ‘BULLET-PROOF’ YOUR AMMETER
(Sorry about some of the fuzzy pics … My camera aint the greatest…)
Ok …. All us Mopar guys know what a freekin disaster-zone the ammeter circuit is in our beloved ol’ Mopars. It’s almost like The Dodge Boys went out of their way, to set themselves up for failure. Instead of making it ‘right’ OR switching over to a volt meter (As they finally caved in and did..) …. It’s like my 80+ year-old father would say … About so MANY things …”Damn it! It’s worked for 50 years! I’m not changing anything!”
So, in a nutshell… This is how our ‘full-flow’ ammeters work.. (Pay attention, because you’ll need this to understand later why things don’t work right and what you should/shouldn’t do..)
Also, these instructions are specifically geared towards the 72’ thru 80’ ammeters. The 80’s ammeters are pretty much the same thing, and the same principals can be applied, but the pics and specs may not be applied verbatim.
The ‘BATT’ output goes directly through the ammeter and then gets distributed throughout the rest of the system, including amperage back to charge the battery. This is ‘full flow’ … And also why, if ANYthing goes wrong, it’ll KILL all power … To anything.
Or catch fire.
(Mmmmm…. Well, you may get lucky and have enough juice in the batt to get you home …)
I’ve noticed that (Don’t know exactly what year) that The Dodge Boys changed over to a ‘shunted’ ammeter. This is (From what I’ve examined and taken apart) basically worthless. This was a ‘Lets hope it works and not set anything else on fire’ kinda fix.
Your ammeter has two magnets. One little-bitty one on the mechanism that the needle pivots on. There is another bigger horseshoe magnet that is sandwiched in between the faceplate and frame. The two magnets play off each other (Like if you were playing with two magnets and opposite poles ‘attract’ while ‘like’ poles push each other away..)
OK now … The magnet on the needle is ‘fixed’ … The magnet (The big one) is the one that the current runs past. As we all learned in 4th grade science … Whenever voltage/current is in close proximity to a ferrous metal, it will change the magnetic properties of that metal.
So here’s what we’ve got … Current from the battery connection on the alternator runs directly past the larger horseshoe magnet. If it’s plus/minus, this will slightly alter the magnetic field of that magnet.. That magnet, will in turn, play off the little-bitty magnet that is attached to the needle. This is what makes the needle ‘swing’ (Plus or minus)
OK, we’re all together on this now, right?
HERE IS WHERE THE DODGE BOYS SCREWED UP.
1.) They ‘hung on’ to Grandpa’s design, and only gave up after being dragged out the door kicking and screaming. (I’m sure that safety issues and complaints helped)
2.) They used a ‘full flow’ gauge. (Later ‘shunted’ but still junk)
3.) They ran ALL the juice from the alt, to the ammeter and back out again, through a crappy bulk-head connector.
4.) Their construction of the ammeter itself was quick/easy (GARBAGE)
5.) They switched in the mid-70’s to a plastic basket which, if anything went wrong, quickly snowballed to disaster.
LEGAL STUFF
NOTE…. Although SOME of these ‘repair hints’ will work on a METAL instrument cluster basket, THIS IS INTENDED FOR THE PLASTIC BASKETS, WHICH HAVE THE MAJORITY OF THE PROBLEMS!!
I will make note where needed. If YOU should happen to screw up and set your rig on fire, I am in NO WAY responsible.
HOW TO FIX IT.
If you really feel the need.
But like I say, it bothers me that I ‘had’ a dead gauge. That’s just me though.
First thing is, you must ABSOLUTELY by-pass the crappy (And neglected) bulk-head connector on the firewall. Personally, I drilled a ½” hole in the fire wall … Rubber grommet on that …. And ran 6 gauge wires, to/from the ammeter. Yeah, over-kill, but that’s just me. I wouldn’t go with anything less than 10 gauge however…
When you run your new wires …. Use COPPER LUGS and make SURE you solder the connections! I can’t stress ‘soldering’ over ‘crimping’ enough!!
ONE major hurdle covered ….
The next is the fact that the ammeter was put together cheaply. The fact that any of the ‘continuity’ of it, stays of any quality, is because ONLY of nice clean/tight contacts. Well, we know what happens when that doesn’t happen…
I’ve taken apart/repaired literally dozens of these. The ammeter itself is put together very crappy, which is the second major wrench in the gears.
Here you can see where one of the lugs got so hot, it cooked the fiber board insulator and it broke.
http://i163.photobucket.com/albums/t304/bherder/damage.jpg
http://i163.photobucket.com/albums/t304/bherder/discolor.jpg
You can also see where the heat discolored the brass. You can also see where the lug is rusted right where it makes contact with the frame. Not a good thing.
The ‘frame’ of the ammeter is brass. OK, that’s good … Has some strength and copper in it. The MAJOR weakness is the lugs connecting to the frame and the wires (Back of the cluster basket) Brass is fine, hardly corrodes, but the lugs are steel and problems with them will come up much quicker.
The lugs themselves are CRIMPED into the frame with a little piece of fiber-board for insulation on the back. Well, this is garbage, and (Like anything else that’s ‘crimped’) will loosen over time. I’ve seen 30+ year old meters where the lugs were fine, but I’ve also seen them about ready to just fall out. Either way. The connections always seem to be at least slightly corroded..
So what we need to do, is ‘bullet-proof’ the lug connections on the gauge. However this means taking the gauge apart. Not a big deal, if you’re careful. You must take special care NOT to damage the needle when everything is apart.
First thing, is look at the gauge from the back, and mark rhe back of the horseshoe magnet. I use a Sharpie and draw a little dot on it. This is important, because if you reinstall it backwards, you’ll have to do it over again, because the gauge will either not work, or read backwards.
Drill out the little rivets and take the faceplate and magnet off.
http://i163.photobucket.com/albums/t304/bherder/rivets.jpg
I usually give the gauge frame a good squirt of electrical cleaner at this point.
Now what we’re gonna do is solder the heads of lugs to the brass frame. This is another reason for disassembling the gauge. You must get everything quite hot, and as we also learned in 4th grade science, heat can destroy magnetism. (The only gauges I’ve not been able to fix, were ones that go so hot, it destroyed the magnetism of the magnet. I’ve only ever had that happen a couple times though.) … I hold the lugs in a vise that I have a pair of wooden jaws for… A) so it doesn’t screw up the threads, and B) so it won’t act like a heatsink.
You’ll need a 100 watt soldering gun. BE PATIENT as it’s a fairly sizable chunk of metal we’re trying to heat up. You want to run a good bead all the way around the lugs. This is what you should end up with..
http://i163.photobucket.com/albums/t304/bherder/solderedA.jpg
OK, we’ve taken care of a Micky-mouse connection and make it a rock solid one. Next thing I do is clean the lugs off and run a 10-32 die up and down the threads.
http://i163.photobucket.com/albums/t304/bherder/tap.jpg
OK, now is where you guys with a metal instrument cluster basket will have to skip the next step. Unless you go through extraordinary measures to insulate the lugs from the metal. I’ve done it, but it’s a major PITA.
OK, now we know that copper is a much better electrical conductor than steel. So what we’re going to do is ‘sleeve’ the steel lug with ¼” copper tubing. Now you ‘plastic basket’ guys don’t really need the little piece of fiber board on the back. This was from the metal basket days, to center/insulate the gauge. So use a small pair of needle nose pliers to carefully break off the fiber board. You’ll probably find some corrosion there, so clean that all off. Cut a couple of pieces of copper tubing about the length of the lug. OK, two things…
You’ll notice that the I.D. of the tube is slightly too small to slide over the lug. It’s just big enough though, to run a 10-32 tap through. This actually turns out to be a good thing as it will hold the tubing firmly to the back of the gauge frame. So run your tap through the tubing.
Now, you’ll also notice that the steel lug fits through a square hole on the gauge frame and the clip Dodge used to hold everything together keeps the tubing from butting up against the frame. So take a small pair of wire cutters and make 4 little snips on the edge of the tubing, 90 degrees apart. Use needle nose pliers to pull the edges out slightly. (If you have a flaring tool, you can also do it that way also)
http://i163.photobucket.com/albums/t304/bherder/copperA.jpg
You should be able to thread the tubing on and have it but-up to the gauge frame.
OK, now put that aside for a minute.
Since having the copper tubing sleeve on there doesn’t do much good without it coming into contact with the wires on the back of the cluster, we need to modify the plastic housing a bit. What we want, is for the tubing to come completely through the housing and PCB. So we’re going to drill 9/32” holes through everything. (I use a small drill press to make sure everything is square..) Drill from back to front. The copper tubing should be able to pass through completely now.
Now… If your plastic basket had no damage (Not melted) you’ll have to bevel the inside front of the holes a bit, so that the gauge sets level and flat with the rest of the gauges (You’ll have the flair on the tubing holding it up higher a bit) If you have a bit of a melted plastic problem you’ll have to shim up the back of the gauge with some washers so the gauge sets flat and level. Make sure you get this all right, because it affects what we do next.
Insert the gauge back through the holes, and where the copper tubing comes through the PCB, make a mark with a scratch-awl on the tubing right at the surface of the back of the PCB. Take the gauge out… Unthread the copper sleeves … And using a tubing cutter, cut off the excess leaving about an extra 64th of an inch on your sleeves. If you did it juuuust right, with the gauge back in the holes, you should have just a hair of copper sleeve sticking out the back of the PCB …. It should look like this..
http://i163.photobucket.com/albums/t304/bherder/backofcluster.jpg
(Now after everything is done, when you put your first set of nuts on the lugs, the copper will crush slightly, and then you’ll have a good solid connection…)
OK, pull your gauge back out …. Now, were going to solder the copper sleeves to the backside of the gauge frame. (Again be patient) It’ll look something like this…
http://i163.photobucket.com/albums/t304/bherder/backsoldered.jpg
So now, what we’ve ended up with is, a gauge frame with rock-solid soldered connections on both sides, with copper as the electrical conductor… It ain’t gonna get any better than that!
OK! Lets Put The Gauge Back Together Now!
You probably noticed the little-bitty rivets Dodge used to hold everything together when you first took it apart.. Well, you won’t find anything that small at your local hardware store. So you’ll have to step it up a size bigger. I use 1/8” x 1/8” aluminum (Non-magnetic) pop-rivets. You’ll have to drill out the gauge frame holes, the gauge face, and hog out the indents on the horseshoe magnet. Drilling the holes is the easy part.
http://i163.photobucket.com/albums/t304/bherder/drillholes.jpg
For hogging out the indents, I use a small jewelers file (Like a little rat-tail) so as NOT to heat up the magnet any more than possible. (Yes, you can use the edge of a cutting wheel on an angle-grinder, but you risk heating the magnet, or missing the indent and taking a chunk out of the magnet where you didn’t intend..)
Once you’ve done all that, you should be able to put the rivets through the gauge face … Slide the magnet back on … and put the rivets through the holes in the gauge frame .. All should be an easy fit.
TRIPLE-CHECK yourself that you got the magnet in the right way. OK, ‘pop’ your rivets!
(BTW … The rivet heads may ‘look’ big, but after everything is assembled and the dash bezel is back on, you’ll never see them)
Also, if you haven’t already done so, now would be a good time to repaint your needle(s) … They’re more than likely ’yellow’ from baking in the sun for 30+ years…. You can buy fluorescent poster paints from any artsy crafts store … Five and dime … Michael’s …. Make them nice and orange again, or whatever color you like!
We’re almost there!!
Put your ‘1,000 times better than new’ gauge back into the basket.
If you haven’t thrown away the steel nuts that Dodge used, throw them away now. Use brass/copper nuts on the lugs to tighten up the gauge rock solid. You can use either loc-tite or copper lock washers. Remember to tighten them up several times, because here is where we’re trying to ‘crush’ the copper sleeve.
It should look something like this..
http://i163.photobucket.com/albums/t304/bherder/nuts.jpg
Now, when you’re ready to reinstall the inst cluster, there should be enough ‘post/lug’ left over for your wire lugs, AND the other pair of brass/copper nuts/lock washers …. So you’ll end up with one pair of nuts/washers holding the gauge in …. Wire lugs …. Then another pair of nuts/washers.
And there ya have it. You’ve got an ammeter that should be able to take .50 caliber machine gun fire!
Enjoy!!
(Sorry about some of the fuzzy pics … My camera aint the greatest…)
Ok …. All us Mopar guys know what a freekin disaster-zone the ammeter circuit is in our beloved ol’ Mopars. It’s almost like The Dodge Boys went out of their way, to set themselves up for failure. Instead of making it ‘right’ OR switching over to a volt meter (As they finally caved in and did..) …. It’s like my 80+ year-old father would say … About so MANY things …”Damn it! It’s worked for 50 years! I’m not changing anything!”
So, in a nutshell… This is how our ‘full-flow’ ammeters work.. (Pay attention, because you’ll need this to understand later why things don’t work right and what you should/shouldn’t do..)
Also, these instructions are specifically geared towards the 72’ thru 80’ ammeters. The 80’s ammeters are pretty much the same thing, and the same principals can be applied, but the pics and specs may not be applied verbatim.
The ‘BATT’ output goes directly through the ammeter and then gets distributed throughout the rest of the system, including amperage back to charge the battery. This is ‘full flow’ … And also why, if ANYthing goes wrong, it’ll KILL all power … To anything.
Or catch fire.
(Mmmmm…. Well, you may get lucky and have enough juice in the batt to get you home …)
I’ve noticed that (Don’t know exactly what year) that The Dodge Boys changed over to a ‘shunted’ ammeter. This is (From what I’ve examined and taken apart) basically worthless. This was a ‘Lets hope it works and not set anything else on fire’ kinda fix.
Your ammeter has two magnets. One little-bitty one on the mechanism that the needle pivots on. There is another bigger horseshoe magnet that is sandwiched in between the faceplate and frame. The two magnets play off each other (Like if you were playing with two magnets and opposite poles ‘attract’ while ‘like’ poles push each other away..)
OK now … The magnet on the needle is ‘fixed’ … The magnet (The big one) is the one that the current runs past. As we all learned in 4th grade science … Whenever voltage/current is in close proximity to a ferrous metal, it will change the magnetic properties of that metal.
So here’s what we’ve got … Current from the battery connection on the alternator runs directly past the larger horseshoe magnet. If it’s plus/minus, this will slightly alter the magnetic field of that magnet.. That magnet, will in turn, play off the little-bitty magnet that is attached to the needle. This is what makes the needle ‘swing’ (Plus or minus)
OK, we’re all together on this now, right?
HERE IS WHERE THE DODGE BOYS SCREWED UP.
1.) They ‘hung on’ to Grandpa’s design, and only gave up after being dragged out the door kicking and screaming. (I’m sure that safety issues and complaints helped)
2.) They used a ‘full flow’ gauge. (Later ‘shunted’ but still junk)
3.) They ran ALL the juice from the alt, to the ammeter and back out again, through a crappy bulk-head connector.
4.) Their construction of the ammeter itself was quick/easy (GARBAGE)
5.) They switched in the mid-70’s to a plastic basket which, if anything went wrong, quickly snowballed to disaster.
LEGAL STUFF
NOTE…. Although SOME of these ‘repair hints’ will work on a METAL instrument cluster basket, THIS IS INTENDED FOR THE PLASTIC BASKETS, WHICH HAVE THE MAJORITY OF THE PROBLEMS!!
I will make note where needed. If YOU should happen to screw up and set your rig on fire, I am in NO WAY responsible.
HOW TO FIX IT.
If you really feel the need.
But like I say, it bothers me that I ‘had’ a dead gauge. That’s just me though.
First thing is, you must ABSOLUTELY by-pass the crappy (And neglected) bulk-head connector on the firewall. Personally, I drilled a ½” hole in the fire wall … Rubber grommet on that …. And ran 6 gauge wires, to/from the ammeter. Yeah, over-kill, but that’s just me. I wouldn’t go with anything less than 10 gauge however…
When you run your new wires …. Use COPPER LUGS and make SURE you solder the connections! I can’t stress ‘soldering’ over ‘crimping’ enough!!
ONE major hurdle covered ….
The next is the fact that the ammeter was put together cheaply. The fact that any of the ‘continuity’ of it, stays of any quality, is because ONLY of nice clean/tight contacts. Well, we know what happens when that doesn’t happen…
I’ve taken apart/repaired literally dozens of these. The ammeter itself is put together very crappy, which is the second major wrench in the gears.
Here you can see where one of the lugs got so hot, it cooked the fiber board insulator and it broke.
http://i163.photobucket.com/albums/t304/bherder/damage.jpg
http://i163.photobucket.com/albums/t304/bherder/discolor.jpg
You can also see where the heat discolored the brass. You can also see where the lug is rusted right where it makes contact with the frame. Not a good thing.
The ‘frame’ of the ammeter is brass. OK, that’s good … Has some strength and copper in it. The MAJOR weakness is the lugs connecting to the frame and the wires (Back of the cluster basket) Brass is fine, hardly corrodes, but the lugs are steel and problems with them will come up much quicker.
The lugs themselves are CRIMPED into the frame with a little piece of fiber-board for insulation on the back. Well, this is garbage, and (Like anything else that’s ‘crimped’) will loosen over time. I’ve seen 30+ year old meters where the lugs were fine, but I’ve also seen them about ready to just fall out. Either way. The connections always seem to be at least slightly corroded..
So what we need to do, is ‘bullet-proof’ the lug connections on the gauge. However this means taking the gauge apart. Not a big deal, if you’re careful. You must take special care NOT to damage the needle when everything is apart.
First thing, is look at the gauge from the back, and mark rhe back of the horseshoe magnet. I use a Sharpie and draw a little dot on it. This is important, because if you reinstall it backwards, you’ll have to do it over again, because the gauge will either not work, or read backwards.
Drill out the little rivets and take the faceplate and magnet off.
http://i163.photobucket.com/albums/t304/bherder/rivets.jpg
I usually give the gauge frame a good squirt of electrical cleaner at this point.
Now what we’re gonna do is solder the heads of lugs to the brass frame. This is another reason for disassembling the gauge. You must get everything quite hot, and as we also learned in 4th grade science, heat can destroy magnetism. (The only gauges I’ve not been able to fix, were ones that go so hot, it destroyed the magnetism of the magnet. I’ve only ever had that happen a couple times though.) … I hold the lugs in a vise that I have a pair of wooden jaws for… A) so it doesn’t screw up the threads, and B) so it won’t act like a heatsink.
You’ll need a 100 watt soldering gun. BE PATIENT as it’s a fairly sizable chunk of metal we’re trying to heat up. You want to run a good bead all the way around the lugs. This is what you should end up with..
http://i163.photobucket.com/albums/t304/bherder/solderedA.jpg
OK, we’ve taken care of a Micky-mouse connection and make it a rock solid one. Next thing I do is clean the lugs off and run a 10-32 die up and down the threads.
http://i163.photobucket.com/albums/t304/bherder/tap.jpg
OK, now is where you guys with a metal instrument cluster basket will have to skip the next step. Unless you go through extraordinary measures to insulate the lugs from the metal. I’ve done it, but it’s a major PITA.
OK, now we know that copper is a much better electrical conductor than steel. So what we’re going to do is ‘sleeve’ the steel lug with ¼” copper tubing. Now you ‘plastic basket’ guys don’t really need the little piece of fiber board on the back. This was from the metal basket days, to center/insulate the gauge. So use a small pair of needle nose pliers to carefully break off the fiber board. You’ll probably find some corrosion there, so clean that all off. Cut a couple of pieces of copper tubing about the length of the lug. OK, two things…
You’ll notice that the I.D. of the tube is slightly too small to slide over the lug. It’s just big enough though, to run a 10-32 tap through. This actually turns out to be a good thing as it will hold the tubing firmly to the back of the gauge frame. So run your tap through the tubing.
Now, you’ll also notice that the steel lug fits through a square hole on the gauge frame and the clip Dodge used to hold everything together keeps the tubing from butting up against the frame. So take a small pair of wire cutters and make 4 little snips on the edge of the tubing, 90 degrees apart. Use needle nose pliers to pull the edges out slightly. (If you have a flaring tool, you can also do it that way also)
http://i163.photobucket.com/albums/t304/bherder/copperA.jpg
You should be able to thread the tubing on and have it but-up to the gauge frame.
OK, now put that aside for a minute.
Since having the copper tubing sleeve on there doesn’t do much good without it coming into contact with the wires on the back of the cluster, we need to modify the plastic housing a bit. What we want, is for the tubing to come completely through the housing and PCB. So we’re going to drill 9/32” holes through everything. (I use a small drill press to make sure everything is square..) Drill from back to front. The copper tubing should be able to pass through completely now.
Now… If your plastic basket had no damage (Not melted) you’ll have to bevel the inside front of the holes a bit, so that the gauge sets level and flat with the rest of the gauges (You’ll have the flair on the tubing holding it up higher a bit) If you have a bit of a melted plastic problem you’ll have to shim up the back of the gauge with some washers so the gauge sets flat and level. Make sure you get this all right, because it affects what we do next.
Insert the gauge back through the holes, and where the copper tubing comes through the PCB, make a mark with a scratch-awl on the tubing right at the surface of the back of the PCB. Take the gauge out… Unthread the copper sleeves … And using a tubing cutter, cut off the excess leaving about an extra 64th of an inch on your sleeves. If you did it juuuust right, with the gauge back in the holes, you should have just a hair of copper sleeve sticking out the back of the PCB …. It should look like this..
http://i163.photobucket.com/albums/t304/bherder/backofcluster.jpg
(Now after everything is done, when you put your first set of nuts on the lugs, the copper will crush slightly, and then you’ll have a good solid connection…)
OK, pull your gauge back out …. Now, were going to solder the copper sleeves to the backside of the gauge frame. (Again be patient) It’ll look something like this…
http://i163.photobucket.com/albums/t304/bherder/backsoldered.jpg
So now, what we’ve ended up with is, a gauge frame with rock-solid soldered connections on both sides, with copper as the electrical conductor… It ain’t gonna get any better than that!
OK! Lets Put The Gauge Back Together Now!
You probably noticed the little-bitty rivets Dodge used to hold everything together when you first took it apart.. Well, you won’t find anything that small at your local hardware store. So you’ll have to step it up a size bigger. I use 1/8” x 1/8” aluminum (Non-magnetic) pop-rivets. You’ll have to drill out the gauge frame holes, the gauge face, and hog out the indents on the horseshoe magnet. Drilling the holes is the easy part.
http://i163.photobucket.com/albums/t304/bherder/drillholes.jpg
For hogging out the indents, I use a small jewelers file (Like a little rat-tail) so as NOT to heat up the magnet any more than possible. (Yes, you can use the edge of a cutting wheel on an angle-grinder, but you risk heating the magnet, or missing the indent and taking a chunk out of the magnet where you didn’t intend..)
Once you’ve done all that, you should be able to put the rivets through the gauge face … Slide the magnet back on … and put the rivets through the holes in the gauge frame .. All should be an easy fit.
TRIPLE-CHECK yourself that you got the magnet in the right way. OK, ‘pop’ your rivets!
(BTW … The rivet heads may ‘look’ big, but after everything is assembled and the dash bezel is back on, you’ll never see them)
Also, if you haven’t already done so, now would be a good time to repaint your needle(s) … They’re more than likely ’yellow’ from baking in the sun for 30+ years…. You can buy fluorescent poster paints from any artsy crafts store … Five and dime … Michael’s …. Make them nice and orange again, or whatever color you like!
We’re almost there!!
Put your ‘1,000 times better than new’ gauge back into the basket.
If you haven’t thrown away the steel nuts that Dodge used, throw them away now. Use brass/copper nuts on the lugs to tighten up the gauge rock solid. You can use either loc-tite or copper lock washers. Remember to tighten them up several times, because here is where we’re trying to ‘crush’ the copper sleeve.
It should look something like this..
http://i163.photobucket.com/albums/t304/bherder/nuts.jpg
Now, when you’re ready to reinstall the inst cluster, there should be enough ‘post/lug’ left over for your wire lugs, AND the other pair of brass/copper nuts/lock washers …. So you’ll end up with one pair of nuts/washers holding the gauge in …. Wire lugs …. Then another pair of nuts/washers.
And there ya have it. You’ve got an ammeter that should be able to take .50 caliber machine gun fire!
Enjoy!!