Vintage Mustang Forums banner

1 - 17 of 17 Posts

·
Registered
Joined
·
832 Posts
Discussion Starter #1
Hey y'all!

Fighting through some wiring after I recently dropped my 289 in. I've just put the alternator in, and I've run into a problem; I'll present it as I see it, and if there's anything wrong with what I'm assuming is right, please correct me.

The alternator has a grounding strap (two black wires with red stripes taped together?) that is supposed to be grounded on the engine at the front passenger side (under cylinder 1). Is that right so far?

Additionally, it is grounded with the negative battery cable. Still correct so far?

The problem I have is that the connector piece, that fits over the bolt, is too small; the bolt does not fit into the little circle on the connector (sorry I can't describe it better-- I've attached a photo of the same style so you can figure out what I'm saying :D). So my question is, what should I do about this? Should I file the connector a little wider so it fits over the grounding bolt? Find a different place to ground elsewhere on the engine? Change out the connecting piece for a larger one? It worries me that an alternator made for my application has this issue, so I was hoping to get some other opinions on it.

Thanks all and an early Happy New Year!
Alex
 

Attachments

·
Registered
Joined
·
57 Posts
Go to the hardware store and buy a bigger diameter ring terminal. My Ace hardware carries the Noble brand which are way better than the auto parts store Chinese crap. Manufacturers make that alternator for multiple cars, so no way to guarantee that everything will fit without modification.
 

·
Registered
Joined
·
3,245 Posts
Make sure you also have a ground strap from the engine to body. Very important.
This is generally done from the passenger side back of the motor to the firewall.
 

·
Registered
Joined
·
35,838 Posts
Hey y'all!

Fighting through some wiring after I recently dropped my 289 in. I've just put the alternator in, and I've run into a problem; I'll present it as I see it, and if there's anything wrong with what I'm assuming is right, please correct me.

The alternator has a grounding strap (two black wires with red stripes taped together?) that is supposed to be grounded on the engine at the front passenger side (under cylinder 1). Is that right so far?

Additionally, it is grounded with the negative battery cable. Still correct so far?

The problem I have is that the connector piece, that fits over the bolt, is too small; the bolt does not fit into the little circle on the connector (sorry I can't describe it better-- I've attached a photo of the same style so you can figure out what I'm saying :D). So my question is, what should I do about this? Should I file the connector a little wider so it fits over the grounding bolt? Find a different place to ground elsewhere on the engine? Change out the connecting piece for a larger one? It worries me that an alternator made for my application has this issue, so I was hoping to get some other opinions on it.

Thanks all and an early Happy New Year!
Alex
Go to the hardware store and buy a bigger diameter ring terminal. My Ace hardware carries the Noble brand which are way better than the auto parts store Chinese crap. Manufacturers make that alternator for multiple cars, so no way to guarantee that everything will fit without modification.
^ ^ ^ This. Buy an UNINSULATED one, solder the wire to it, and shrink wrap the joint.
 

·
Registered
Joined
·
832 Posts
Discussion Starter #6
Thanks guys, I went and picked up a new terminal and all is well now after replacing it. Appreciate the help!
 

·
Registered
Joined
·
832 Posts
Discussion Starter #7
This is generally done from the passenger side back of the motor to the firewall.
I have two leads from the motor to the outside; one that is the negative battery terminal and the other goes to the alternator. Am I missing one?
 

·
Registered
Joined
·
3,245 Posts
I have two leads from the motor to the outside; one that is the negative battery terminal and the other goes to the alternator. Am I missing one?
Yes, there is generally a grounding strap from the rear passenger cylinder head (I think) to the firewall.
 

·
Registered
Joined
·
35,825 Posts
^ ^ ^ This. Buy an UNINSULATED one, solder the wire to it, and shrink wrap the joint.
By far the best way to do it.
Yes, there is generally a grounding strap from the rear passenger cylinder head (I think) to the firewall.
Yes, invariably. All Mustangs had this.
 

·
Registered
Joined
·
1,566 Posts
I run a ground in the same spot (head to firewall), but added an additional ground cable from the grounding location on the block to the chassis/sub-frame. I connected it at the sway-bar mounting fastener.

741628
 

·
Registered
Joined
·
35,838 Posts
For those wishing to add a secondary engine to chassis ground, I recommend using a braided strap, which will handle the movement and vibration much better than stranded copper wire and stamped terminal ends.

 

·
Registered
Joined
·
1,566 Posts
I can understand your thinking, but why is the stranded copper wire used for the secondary ground any more susceptible to damage than the similar cable used from the battery to the engine block?
 

·
Registered
Joined
·
35,825 Posts
I can understand your thinking, but why is the stranded copper wire used for the secondary ground any more susceptible to damage than the similar cable used from the battery to the engine block?
Actually about the same.

In mid 1970, a change was made to the battery ground wire. It still went to the engine block, but in the middle it was screwed to the shock tower. This eliminated the need for the extra wire at the back end.

 

·
Registered
Joined
·
1,566 Posts
Great info! I do remember seeing a lot more braided grounds used back in the late 60's and early 70's. Actually, most of the cars i remember seeing them on were probably 50's models.
 

·
Registered
Joined
·
996 Posts
As grounding issues are one of the most common electrical problems mentioned here, I wouldn't skimp on ground cables/connections. I plan to add a few this winter when the interior is out for insulation, such as a wire from the battery (or ground cable connection to the engine) to the instrument panel.
 
  • Like
Reactions: Huskinhano

·
Registered
Joined
·
35,838 Posts
I can understand your thinking, but why is the stranded copper wire used for the secondary ground any more susceptible to damage than the similar cable used from the battery to the engine block?
Because the main ground cable is a) big and b) long.
 
1 - 17 of 17 Posts
Top