Proper way to make ground connections?

Distribution block is good.
You could also coat the ground connection with paint after it is hooked up. That way you still have metal to metal connection under a protective layer.

I usually grind clean an inconspicuous spot, affix my ground, then shoot over it with some rattle can paint to keep the rust away.

I've done the distribution block method. Seems to work pretty well but it does involve a lot more wires. If you're using modern engine management, you will want to keep your power and sensor grounds separate. I don't think a cabureted Bug is going to be too sensitive.

But I've also noticed that my bare metal ground points don't seem to corrode, and it's not like you're going to be driving this thing in the winter. So I'd stick with that method myself.

You could tap a hole and put a bolt through one or more O-connectors. That's how it's done from the factory.

Weld a stud of decent size somewhere, then use a re-purposed battery cable affixed to it to ground a distribution block for all your grounds. You can paint everything but the last bit of threads. Cover those with grease.

Once I've got a ground bolted down, I usually shoot it with a spray of Permatex battery protector and sealer.

Just remember to keep the total current in mind if you consolidate a lot a grounds at a single point.

Based on some aircraft experience, it's also worth considering whether or not the structure you are grounding to can be sacrificed or not if something goes wrong and you end up attempting to pass a lot of amps through a high resistance connection. If you burn up the ground point, it might be nice if it's something that you can either easily replace, or won't miss if it's gone.

rollins111 wrote:

Keith Tanner wrote: I've done the distribution block method. Seems to work pretty well but it does involve a lot more wires. If you're using modern engine management, you will want to keep your power and sensor grounds separate. I don't think a cabureted Bug is going to be too sensitive. But I've also noticed that my bare metal ground points don't seem to corrode, and it's not like you're going to be driving this thing in the winter. So I'd stick with that method myself.

Just a note that I'm doing a Subaru EJ25 swap with an aftermarket EMS Stinger ecu so it's carbureted no longer... Is there any reason why power and sensor grounds don't play well together? Does the power signal somehow interfere with the sensors?

Yes, you can get a bit of leakage that make your sensors a bit less accurate. I'll bet your factory EJ25 ECU has multiple ground wires in the harness that go to different grounding points for this reason.

If there is anything that will screw up a DC system it is poor grounds. I used the distribution blocks. I used three, one for under the hood (headlights, turn signals, horn, electric fan etc), one under the dash (gauges, switchs, etc) and one in the trunk(brake, turn signal, running lights, fuel pump, etc)The one under the hood hooked to the negative battery cable to the starter which was daisy chained to the one under the dash and then daisy chained to the one in the trunk. It does use more wire but is neater, keeps from having to grind off paint and will be easier to trouble shoot if there are any issues with electical systems in the future.

If you ground to a frame or sheet metal a star washer between the ground lug and clean metal is a must. In the old days a missing star washer could turn a car into a lemon. To protect the clean metal I would use die-electric grease after it is tight.

Having seen MG and Ford heater cables melt due to bad grounds and since I still have VW wiring flashbacks and nightmares, I treat grounds with at least as much respect as I do anything that carries battery voltage. Running a wire from each component to a common ground then grounding that does eliminate multiple ground points but it adds weight and complexity, it's a trade off.

Stacking grounds can lead to another problem: each time two connectors are stacked there's the potential for voltage drop, this can get worse over time as the surface of the terminal oxidizes (first step in corrosion). Something like this will get around that.

On the ECU connections on my latest project (13B turbo) some of the sensors which use 5v reference ground back to the ECU without being grounded to anything else so those of course are isolated from the body and engine. Then there are some which also use that same 5v reference and ground not only to the ECU but to the body/engine, I daisy chained those. One end is grounded to the body, the other end to the engine. I used the same point on the engine to run a 10 gauge ground wire back to the ECU case, the ECU case is grounded to the body both through the wiring connectors and an external ground strap and in addition there's a ground strap from the engine to the body.

Solder and shrink wrap wherever possible, if not I discovered that Harbor Freight now sells butt connectors with shrink wrap quite reasonably. They seem as good quality as the Wurth ones I got a new arse torn for.

In reply to Curmudgeon:

We've used those bus bars in a couple 'glass hotrods, they work great.

To the O.P. whatever way you go, remember the rule: Clean, dry and tight for ground terminals.

Shawn

The ground for 5v reference is really important due to the low voltage involved. A bulb with 12v can work with a half assed ground, it might not be as bright though. OTOH, that 5v reference works this way: the ECU uses the amount of voltage as its signal to do certain things. Crappy ground = a voltage signal that's incorrect = an ECU that has no idea what's happening.

Curmudgeon wrote: The ground for 5v reference is really important due to the low voltage involved. A bulb with 12v can work with a half assed ground, it might not be as bright though. OTOH, that 5v reference works this way: the ECU uses the amount of voltage as its signal to do certain things. Crappy ground = a voltage signal that's incorrect = an ECU that has no idea what's happening.

This is very good info. I helped a friend figure out a non running car and it was due to a rusty ground on the ECU, so none of the 5v signals were correct.

i took a ground bar for a home electrical panel and mounted it up under the dash. i used that to ground everything from the cabin. then engine stuff was grounded to block. i grounded the headlights and tails near them. my ground cable goes to the frame, then i have a ground cable up front from engine block to frame, and from that point to body.

Karacticus wrote: Just remember to keep the total current in mind if you consolidate a lot a grounds at a single point.

A lot of people forget that there is still current on the ground side. The pressure (voltage) is gone, but the current is still flowing. I would consolidate grounds, but not to a big extent mainly to keep wire runs down and to prevent having lots of current through one ground. Just drill and tap, or self-tapers and star washers. Then paint or undercoating if you want to. You don't have many grounds on that car, so you should be able to get away with one under the front hood, one or two in the rear, and one in the cab.

I see the OEMs grounding everything to one spot, so I do the same. I've never had noise issues grounding all sensors and the engine computer itself to the same location.

The OEM's care only about 1) cheap 2) will it get through the warranty period.

Curmudgeon wrote: The OEM's care only about 1) cheap 2) will it get through the warranty period.

And even then, cheap is #1. They anticipate warranty costs and if it's still cheaper to do it shoddy, they'll do it shoddy.

I like to use ring terminals with a star washer. The threads of the screw make excellent contact. As long as you have good contact between the ring terminal and the head, you're good. Before you torque it down the last 1/4", squirt a little drop of clear silicone under the head. That will cover any bare metal

Go to mcmaster and snag some weld tabs that are threaded, tack them on. Then screw in a button head stainless machine screw. Works well for me. Got a picture around here somewhere.