Ammeter Gauge Question:

[Captain D]

Hi,

Just curious to ask a quick question with regards to the Mopar / B-Body 68-70' Charger ammeter gauge if we could:

On the very back of the cluster unit where the red wire eyelet connects to a threaded bolt, there is a nut that secures this bolt into place & keeps it tightly up against the rear backing of the cluster. However, this particular nut became loose & naturally so did the rest of the bolt itself in that by gently moving this bolt - you can actually move the face of the ammeter gauge at the very front of the cluster. I re-tightened this nut with a 3/8" wrench in the back & everything is now tight & secure.

However, my question is ~ by that bolt becoming loose & moving (and the gauge pivoting), could it have accidentally messed with the internal components or settings of the ammeter gauge itself as a whole in any way, by chance? The reason I ask is simply because I can't exactly see where the head of this bolt actually is inside the gauge & if it interferes with the internal mechanisms.

Probably nothing to worry about, I realize, but the mind can stew over misc. things while waiting for spring to arrive, 😉.

Thank you for any clarification...

[Nacho-RT74]

let's see... this is how an ammeter is built inside





if you look at it, the studs are pressed into the brass shunt, then an isolator sheet sits in between ammeter and cluster housing, then another isolation sheet ( the one visible from back ), a nut to keep it in place then the nuts to hold the wiring

Depending on working conditions along the years, this brass shunt could get stretched so the studs can get loosen from shunt, remember they are pressed in to the shunt. This makes a fire call due overheating being the contact somehow loosen between shunt and stud.

now, how is the movement you can see ? dunno. The ammeter should be tight to the cluster, but not to tight to break the isolation. They are tightened on factory. If they become loose could be for any of these reasons:

-shunt got stretched and stud is not making the correct contact anymore. This causes badfunction, incorrect charge rate and more overheating
-internal isolation sheet could be broken and now there is a play because the isolation missed. This could cause a short with housing.



so, in any case, I would dissasembly and check it.

[Nacho-RT74]

here is a guide to reinforce the ammeter in case of need it... Most of the pics are missed into photobucket world, so maybe you won't be able to see it, but the thread is pretty much clear

https://www.dodgetalk.com/threads/bullet-proof-your-ammeter-a-how-to.252130/

[Captain D]

Hey Nacho - I appreciate the pics,

Yeah, I believe the nut simply came loose on account that the entire bolt & edges (lack of a better term) all look clean / no deteriorating with cinge marks, etc. Besides, I just had the cluster out to have the speedometer gauge restored & the shop tested all the other gauges while it was there with everything working good.

Anyhow, thank you again for your time and info.

[nitrousn]

Probably nothing to worry about

That is the furthest from the truth. This is a problem area known for causing fires. Personally I would bypass it and install a voltmeter.

[Captain D]

One lap of the threaded stud seemed to be stripped a little. Without noticing it at first (being a tight / confined area) to back the final mounting nut off to examine everything, was when it was noticed that the stud became loose (due to the larger nut holding the stud in place up against the cluster). The Iarger nut was simply tightened up & was able to secure all connections, but I can always remove the cluster altogether to take it back to the shop to double-check to be safe.

As a side note, we did bypass the bulkhead connection altogether too (fleet bypass, I believe it is called).

[Nacho-RT74]

One lap of the threaded stud seemed to be stripped a little. Without noticing it at first (being a tight / confined area) to back the final mounting nut off to examine everything, was when it was noticed that the stud became loose (due to the larger nut holding the stud in place up against the cluster). The Iarger nut was simply tightened up & was able to secure all connections, but I can always remove the cluster altogether to take it back to the shop to double-check to be safe.

As a side note, we did bypass the bulkhead connection altogether too.

remember the terminals on studs must be tigthten them up between nuts, holding the nut againts the cluster with an open wrench while tighten up the top one, not simply tight the top one. That could make spin the stud and loose it inside or break isolations.

Probably nothing to worry about

That is the furthest from the truth. This is a problem area known for causing fires. Personally I would bypass it and install a voltmeter.

[John_Kunkel]

On the very back of the cluster unit where the red wire eyelet connects to a threaded bolt, there is a nut that secures this bolt into place & keeps it tightly up against the rear backing of the cluster. However, this particular nut became loose & naturally so did the rest of the bolt itself in that by gently moving this bolt - you can actually move the face of the ammeter gauge at the very front of the cluster.

I have always attributed the nut coming loose to shrinkage of the cardboard insulator.

[Captain D]

Thank you gents for the many replies + tips...much appreciated,  

Attached was a pic I was able to snag earlier today of the ammeter stud site (cell phone quality). As mentioned previously, the larger nut (pictured) came a lil' loose due to my trying to remove the smaller hardware assembly nut that, at the time, I hadn't realized that one of the loops along one of these threads were somewhat stripped. As you can see, this larger nut was tightened / snugged back up against the cluster and since then I re-installed the wiring eyelet as well as the tweaked mounting hardware to secure the ammeter wire firmly in place. Everything seems tight & good to go.

I did actually call the restoration shop today too to see if the technician wanted me to bring the cluster back up, but they said all that was needed was for me to snug up the larger nut up against the cluster (snug, but not overkill) and everything should be fine as long as I hadn't twisted the coil around 360 degrees to break it. With them having just tested all of the gauges a few days ago, including this ammeter, he said that he knew that everything was tight and clean at this site back there on the cluster.

Thank you again for the many tips as I appreciate everyone's time and pointers,