Grounding 101

Post by **Linda** » Sun Dec 18, 2005 7:51 pm

Some questions for the experts on grounding and overall wiring protection:
Can a ground cable go fron neg battery to frame and another overlap from frame to engine, (off the same bolt) or should the two grounds be separated?
Is a ground strap better than a battery cable?
Does the clock draw enough power to run down the battery?
What is the best thing to use to clean wires inside terminals, like the one from the starter?
Where does the noise suppression part hook up to?
Is there another place for a good starter to frame ground other than the lower starter bolt hole?
What are fusible links exactly, do you make them or buy them and what size and how do they connect? I know that the alternator should have an extra ground too, is that just to the frame?
If the horn doesn't work is there a ground point to check or is that likely a fuse?
Auto electrics seem kind of tricky.
Thanks,
Linda
68 1600

datsunrides · Post by **datsunrides** » Sun Dec 18, 2005 10:38 pm

I'll give it a go. I will give my thoughts in the order asked.
It really doesn't matter as long as you have a good battery to frame and engine to frame connection.
A ground strap is basically a flat battery cable, it doesn't take a large strap to properly ground the engine to the frame, just make sure one is there or your throttle and choke cables will act as a ground (don't ask

)
Only over a long period of time,assuming your battery is in good condition.
I would cut the end off and install a new terminal. Soldered is best but crimp terminals work good too.
Usually noise suppression is installed in the charging circuit.
The starter does not necessarily need to be grounded directly to the frame. The engine to frame connection should suffice.
Fusible links are a wire section designed to "melt" when too much amperage passes through the wiring. Basically the same as a fuse blowing. They are easily purchased at auto part stores and are sized like fuses ( 5amp, 10amp, 15amp, etc...) They are installed inline on the positive side of the circuit you wish to protect.
Some alternators have a ground to the field (I believe). Most just ground through the case to the engine.
The horn issue con be a lot of different things. Blown fuse, bad relay, worn / dirty contacts, bad ground, bad horn itself. If you push the button and hear a clicking sound, that should mean your system is working up to the relay and the problem is at or with the horn itself. If nothing happens, then it's troubleshooting time. The horn circuit is a easy one to start learning how to diagnose electrical problems. A test light and multi meter are your best friend for electrical work. If you can find one, there is a test light that also can supply direct power and ground in addition to being a test light. The name is slipping my mind right now, but I have a couple of these and absolutely love them. And the cable is long enough to reach from the battery to anywhere on the car. Auto electrics are tricky, but with some basic tools and a bit of knowledge (and common sense) most electrical issues on our cars are easily solved. Especially with some help from the members on this forum. There are some really bright, articulate people here.

OK, now to go get a beer!

Mark

Post by **dbrick** » Sun Dec 18, 2005 11:09 pm

I'm no expert, but I'll give it a try

The grounds can originate from anywhere to anywhere as long as the connections are clean and the cables large enough. There are some who believe all grounds should come back to the same point, but a 200 pound steel frame makes a good bus bar. the body frame and engine should each have more than one connection to each other, and all connection points should be cleaned/sanded to bare metal. An anti corrosion coating after bolting the cables on is good too. I have a 2 gauge cable from the batt neg to the engine block and a 2 ga jumper from the same bolt on the engine to the frame and then a 1o ga from that point to the body. There is a 2 ga wire from the starter bolt to the frame. and there is a 10 gauge wire from the batt neg to the body and another 1o ga wire from the alternator to the frame. I like overkill. There are probably a few more factory ones in back by the tail lights.

Straps more flexible and maybe cheaper, but conductor size and connection quality determines how well they work.

I don't know how much the clock draws, but it could eventually draw down the battery.

To clean connections, I disconnect and use a spray cleaner to remove all the gunk. scrape of any crusty stuff and re assemble. At work (Fire and security alarms) I use Radio Shak contact cleaner with great success. It leaves a thin film of mineral oil after cleaning. About $10.00 a can. Make sure all power is disconnected. I don't know if these cleaners will make the plastic brittle. Dean sells a reasonably priced kit with new plastic plug bodies and metal terminals, they are not hard to replace, just painstaking..

Don't know about the supressor

I think I used the upper starter bolt.

Fusable links are a calculated section of undersized wire, like 4 inches of 18 gauge on a 12 gauge circuit. This creates a spot that will burn out under an overload. The longer and thinner the fusable link wire, the lower the amperage that it will burn up. In most cases you can buy a replacment piece specific to the application. Fuses or circuit breakers work better, IMHO.

Mine goes from a bolt on the alternator body to a screw on the frame with a 10 Ga wire. In therory, if the body frame and engine are properly grounded and bonded together, it doesn't matter where you ground it.

The horn circuit generally has constant + power to the horn relay and the horn button grounds the ground term of the relay to the steering column when the horn button is pressed. When the horn relay is activated, it sends + power to the horn, which is chassis grounded. If the relay is clicking, it's not the horn button.

Auto electronics are prety simple if you treat each circuit seperatly and work from one end to the other. You need a good test light, and an autoranging multimeter. Sears has a great meter , reg $29.99, usually on sale for $19.99 once a month. A good test light with a long lead and a nice big ground clip should be less than $20.00.

GooRuck!!

Victor_laury · Post by **Victor_laury** » Mon Dec 19, 2005 10:41 am

Nissan wasn't shy about grounds. In a stock high windsheld car the - terminal connected to the engine on the 10 mm air pump bracket bolt. With it, there were 2, 10 gauge Black w/ yellow stripe wires, one connecting to the frame (1/4'' nf bolt) and 1 connecting to the body at the Voltage regulator bolt. I don't know if the infamous starter ground cable was original (anybody got a parts book handy?) But, it's become at least SOP to run a 10 gauge wire from the 10 mm bottom starter bolt (thats 3/8 nf to those with a 66 SPL) to the 1/4 nf frame bolt

Victor_laury · Post by **Victor_laury** » Mon Dec 19, 2005 11:04 am

With our 35 + year old cars, terminal cleaning is good practice! I use a contact cleaner to flush out the connector AND THEN a ridiculously expensive product called Caig (manuf) "DeOxIt". Ok. I can't REALLY tell you if this stuff works or is just high priced snake oil, but, I don't like melted fuse boxes, slow wipers/blowers and turn signals that dim everything each cycle. http://www.caig.com

Please note that I flush first with cheaper over-the-counter contact cleaner first to be able to use less of the $$$$ special snake oil!

Doing this even makes the connectors look better! Especially those amber plastic coated bullet connector become clearer and newer looking. I got into this habit because of the 240Z. Electrical woes are far more endemic on those cars than roadsters. Recently I bought a 71 521 truck and ran thrught it quite thoroughly. I don't know how much I improved the elec. system, but I can say that the systems seem to work flawlessly (may be they did BEFORE my treatment as well).

excalibur · Post by **excalibur** » Mon Dec 19, 2005 4:13 pm

Another option for cleaning electrical parts is using acetic acid. (BE CAREFUL with this stuff tho-it is acid. My father who owns a commercial boat repair fauciltiy always keeps a plastic tub of the stuff around. You just dip your dirty/corroded pieces in and about 1 min. later they come out looking just like new. I would be cautious to try this on the connector pieces, as the acid would probably eat the plastic insulator. This is also a awesome way of cleaning fuse blocks. The copper and fiber board are un-damaged, but the dirt and corrosion just melt away. You won't even need to scrub.

A good protector after cleaning (just spray it on and walk away) is corrosion block (commercial fishermen swear by it). It will also help in cleaning the contacts as well as is a awesome penetrating oil. Find it at: http://www.nocorrosion.com/corrosion-control.htm

Just my ten cents..

datsunfreak · Post by **datsunfreak** » Mon Dec 19, 2005 6:04 pm

Pretty common SOP in the 510 world to vinegar dip all the connections, and the fuse box. Works fantastic.

And on the last two cars I built, I removed all the stock wiring and started over with one of these. Every Datsun I build from now on will be done that way...

Post by **dbrick** » Mon Dec 19, 2005 6:48 pm

After the vinegar, you can dip in baking soda and water solution to neutralize, and the bubbling is cool.

Another funny one I picked up by mistake...I'm a fire alarm tech by trade, and when the batteries go bad they leak acid all over the terminals. I also have a bad stomach, so I have Alka-Seltzer at all times in the truck. It was late at night, I ran out of new terminals.....So I figures why not try it Well, Plop Plop Fizz Fizz and dip the corroded battery terminal in for 30 seconds, all the corrosion is gone, nice bright copper. The customer wasn't half as amazed as I was.

Works for car battery terminals too. Use Extra strength Alka Seltzer for racing only.

Conner · Post by **Conner** » Mon Dec 19, 2005 9:09 pm

So John, when you used the Hot Rod wiring harness, where did you get all the connections to build your replacement wiring harness? Did you re-use the old ones, did new ones come with the harness, or did you get new ones somewhere?

datsunfreak · Post by **datsunfreak** » Mon Dec 19, 2005 9:25 pm

Didn't really use stock style connectors on anything. I did use the stock taillight pigtails/connectors, then bought new pigtails/connectors for the headlights. Everything else is new. Got all new switches (aircraft type) and gauges (Auto Meter), etc.

I seem to be developing a habit of replacing everything but the sheet metal and glass when I build a Datsun with newer/better stuff...

datsunfreak · Post by **datsunfreak** » Mon Dec 19, 2005 9:28 pm

Also, if you shop around on the web a bit there's plenty of places to buy male/female connectors and bulkhead connectors you can use to replicate a stock type harness. Your local GM dealer is also a good place to get these, and as a bonus you can get nice weather-proof connectors there also, for things exposed to the elements.

Post by **Linda** » Mon Dec 19, 2005 11:34 pm

Here'a a post I found on that "other" Datsun list about grounding
http://www.team.net/html_arc/datsun-roa ... 00633.html
by Tom Walters
Linda
8 1600