A Hidden Electrical Fault Question
Reproduction Model A firewall terminal boxes have been made overseas for a long time and many have a hidden electrical fault that can be very difficult to locate; the fault could be disastrous and actually cause a fire. Below shows the back side of the terminal block which attached directly to the firewall with four screws.
JB Weld fills the entire cavity or covers screw (stud) heads. This prevents stud heads from backing out.
NOTE THE GEAR TEETH DESIGN OF THE 4 CORNER BRASS THREADED INSERTS THAT PREVENT ROTATION WHEN SCREWS ARE TURNED TO TIGHTEN.
Stud heads are molded into the terminal box. Both left and right views are form the Model A
The original terminal boxes were constructed such that the two terminal studs were molded into the base of the box during the manufacturing process and there is no way they could touch the firewall and thus short out. The reproductions, however, were manufactured by forming two holes in the molding and inserting two studs into the holes from the back. The two studs are threaded to receive a nut on the end of each stud which is supposed to keep the studs in place. “Hot” wires are attached to the ends of the studs and held tight by two additional nuts. The two studs can loosen and easily back out, touch the firewall, and thus cause a short. Both studs always have battery power on them making them “HOT” all the time, so there would be an out-of-sight electri- cal short circuit if the stud touches the firewall. It’s prudent to inspect and modify any re- production terminal block with this faulty stud assembly before installing it. First, apply a little
Loctite to the threads of the two studs just outside the molding where the nuts meet the molding. Securely tighten the nuts over the Loctite (don’t over-tighten!) Next, fill the hole behind each stud head with JB Weld. This will prevent the stud from backing out and shorting.
INTERIOR OF REPRODUCTION TERMINAL BOX BASE INTERIOR OF ORIGINAL TERMINAL BOX BASE
Two nuts are recessed into the box; the upper nuts – secure wires.
The studs are molded into the box, not buts are needed here (the upper nuts are not shown)
With the box’s cover off this is what you see from the engine compartment.
