The Ford Barn - View Single Post - Extra Ground Strap 51 Merc. Engine to firewall

rotorwrench · 03-21-2026, 12:41 PM

The early 6-volt voltage regulators were rubber mounted to the firewall and had a jumper to ground the case to the firewall. One of my 51 Merc cars is Banning blue on the lower body just like that. My two early 51 cars have a lot of grounding between the different drive train and body parts so I've never added any bonding straps and everything works OK. the battery is bonded to the engine and the engine is bonded through the mounting bolts & bushings. The rubber acts as a cushion but the bolts make physical contact. The generator is bolted on plus it's well connected to the VR so it bonds through as long as the VR is bolted to the firewall.

A lot depends on condition of all the interconnection points to electrical equipment. If a car has a lot of corrosion, it will get to be problematic at some point. Bonding jumpers are sort of a band aid to an underlying problem but I would never tell a person not to do it if it solves an immediate problem.

03-21-2026, 12:41 PM	#9
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 18,018	Re: Extra Ground Strap 51 Merc. Engine to firewall The early 6-volt voltage regulators were rubber mounted to the firewall and had a jumper to ground the case to the firewall. One of my 51 Merc cars is Banning blue on the lower body just like that. My two early 51 cars have a lot of grounding between the different drive train and body parts so I've never added any bonding straps and everything works OK. the battery is bonded to the engine and the engine is bonded through the mounting bolts & bushings. The rubber acts as a cushion but the bolts make physical contact. The generator is bolted on plus it's well connected to the VR so it bonds through as long as the VR is bolted to the firewall. A lot depends on condition of all the interconnection points to electrical equipment. If a car has a lot of corrosion, it will get to be problematic at some point. Bonding jumpers are sort of a band aid to an underlying problem but I would never tell a person not to do it if it solves an immediate problem.