Positive ground

[daveboy]

Well, I got my new taper roller bearings in this past weekend to replace the old ball-bearings in my '52 half-ton. Getting that inner race off was a bear, but after applying a lot of heat it slid off. Seems that it was installed with some type of adhesive because once I got it off there was a film of some type on the spindle that I removed.

I thought that I would do a little routine maintenance on her (I've only had her a short time), and inspecting and cleaning battery terminals was on my list. I was rather surprised to see that this truck has a positive ground. Can anyone shed some light on this for me? My questions are:

1. Did this truck originally come with a positive ground? ('52 Chevy half-ton)
2. What are the advantages/disadvantages to a positive ground?
3. Heaven-forbid if I ever needed to jump it, but would it still hook the cables positive to positive and negative to negative, or should I reverse that?
4. What would happen if I hooked the positive terminal on the battery to the starter and the negative terminal to the frame?

Inquiring minds want to know.

Thanks
daveboy

[_Ogre]

loctite green is made to secure loose bearings
if, after cleaning the spindle up, your new bearing is loose, you can reapply green loctite to hold it securely

check your wiring again, to the best of my knowledge a 52 chevy is 6 volt, neg ground

[mechanixman]

Yeah
All trucks had a negative ground.
Positive was fed to the starter stud, and all the electrics stemmed off that.

I've had an iffy connection when using cables, the best place to get a connection, is negative on the ground strap from the frame to the engine block. and positive on the same place on the starter

[OrrieG]

No. some early 50's GMCs are positive ground. I found that out trying to put a stero in my Dad's 57 GMC hunting bus...cost me $35 1965 dollars for a new radio.

[mechanixman]

Really?
Well I stand corrected. Sorry about that.
My cousin has a 48 chevy and a 50 chevy. Both those and mine are all negative ground.
I guess that's what led me to believe all 47-54 trucks were negative ground. Maybe it was just chevrolets?

[daveboy]

Well, I was a little surprised too. But, yep, no question about it...the positive terminal on the battery is connected straight to the frame and the negative terminal is connected to the starter.

But, previous owners have done some rather strange things to this truck and that is why I was curious if this was like this from the factory. The truck has been kept as close to original as possible. I can't imagine why anyone would purposely change it. But, I also notice that my ammeter is wired backwards. When the generator is charging, the meter shows discharge and vice-versa. That got me to wondering if the battery is just installed backwards. I would think that would cause all sorts of problems. I know it would with modern electronics, but just not so sure about these old trucks.

daveboy

[1project2many]

Here's the deal with old vehicles and positive ground. I have run into plenty of old positive ground cars that have been reversed accidentally. When I was younger I thought it couldn't work. But it does. The starter design forces the starter to rotate in the correct direction regardless of current flow so the engine will still crank. The points and coil will still create a spark although the spark voltage and duration are likely to be affected, But the engine will run. You might run into a problem with the generator. Generators have to be polarized, which is a way of introducing a magnetic field so they will produce current that flows in the correct direction. But a generator can be "re-polarized" in the opposite direction so it will charge. Light bulbs don't care what direction current flows so they will still light. And tube type devices such as very early radios won't care what direction current flows so they may also work. Electric fans, such as the heater fan, will turn backward so you won't have a defroster. Also, the ammeter on the dash will show a discharge whenever the system is charging. But it is possible for the battery to be connected wrong and the truck still run.

When connecting jumper cables be sure to connect plus to plus and minus to minus. Any other connection will cause big sparks.

If the truck is originally negative ground, and you are not trying to keep the truck original, negative ground is a better path. Positive ground cars tend to corrode faster as the positive charge on the steel tends to attract oxygen atoms to form rust.

[daveboy]

Thanks for the info so far. Can anyone shed any light as to whether this truck originally came with a positive ground? That is interesting about it making a difference as far as the generator is concerned...not sure I understand that though. The thing I was concerned about was the starter, and I guess that questioned has been answered. I haven't checked the fan motor to see what happens there, but I will do that.

daveboy

[wood1]

Originally Posted by OrrieG

No. some early 50's GMCs are positive ground. I found that out trying to put a stero in my Dad's 57 GMC hunting bus...cost me $35 1965 dollars for a new radio.

Yes. GMC was positive ground '39-'59.

[meter swinger]

1project2many summed it up. My 55 dodge wagon is 6V positive ground, but dodge did strange stuff. You probably need to hunt down a wiring diagram to know beyond a doubt.
They can be jumped. I have jumped mine a few times with a 12V battery. I turn off the car that has the 12V battery in it, and make sure everything on the dash of the 6V car is off.
One day ill just be done with it and swap to 12V neg. ground.
Posted via Mobile Device

[1project2many]

I said

If the truck is originally negative ground, and you are not trying to keep the truck original, negative ground is a better path.

I meant to say, "If the truck is originally positive ground..."

[Wrenchbender Ret]

It definatly came out with neg. ground. Every thing is neg. ground when they changed to 12 volts. The starter is fine. The gen. can be polarized. If the regulator was changed to pos. ground, you will need a neg ground reg. Check the coil connection. If it is going to run on neg. ground the wire from the ign. switch should go to the Plus side.

[daveboy]

Well, the original wiring diagram that I have shows a negative ground. So, it seems that maybe we have some confusion on how these things were originally wired? I just can't, for the life of me, figure out why someone would have taken a negative ground (from the factory) and turned it into a positive ground. I can understand going the other way though.

I am not going to change it, because it works fine the way it is. I was just wondering if that's how it left the factory.

daveboy

[_Ogre]

no

[tttuba]

My 47 gmc was positive ground 6 volt and it is now negative ground 12 volt with an alternator not a generator. Truck will be as original as possible but I think this is an upgrade that has safety implications so I can justify it. If anyone ever wants to go back it is not a big deal to do it.

[tttuba]

And also the wiring has been replaced so the cloth covered wire ...which was deteriorating...wont create a fire.

[OrrieG]

Originally Posted by meter swinger

They can be jumped. I have jumped mine a few times with a 12V battery. Posted via Mobile Device

I had a 47 Ford pickup with 6v flathead. compression was so bad that if you were not parked on a hill so it could build up I had to use a 12v battery to get it to crank fast enough to start, they switched it over to the 6v to run. Luckily for me I broke an axle after only driving it for a few months before I electrocuted myself. The stuff we put up with when we are young and broke...

[mr48chev]

Originally Posted by daveboy

Well, the original wiring diagram that I have shows a negative ground. So, it seems that maybe we have some confusion on how these things were originally wired? I just can't, for the life of me, figure out why someone would have taken a negative ground (from the factory) and turned it into a positive ground. I can understand going the other way though.

I am not going to change it, because it works fine the way it is. I was just wondering if that's how it left the factory.

daveboy

I would have to think that someone who was used to six volt positive ground systems changed it or someone swapped a GMC generator and regulator on it at one time. Checking the tag on the generator (if it has a Delco tag on it) might shed some light on that if the part number is a GMC part number.

There and still are some guys who are hard core in thinking that a positive ground system works better than a negative ground system and can cite theory for hours on end to back their concept up.

[dwcsr]

I suspect that someone in its lifetime swapped the grounds for whatever reason and left it that way. That explains your amp meter going to discharge when you rev it up. I wouldn't change it until you do major work on the electric system. As said before GMC and others worked that way for years.

[Russell Ashley]

Originally Posted by OrrieG

I had a 47 Ford pickup with 6v flathead. compression was so bad that if you were not parked on a hill so it could build up I had to use a 12v battery to get it to crank fast enough to start, they switched it over to the 6v to run. Luckily for me I broke an axle after only driving it for a few months before I electrocuted myself. The stuff we put up with when we are young and broke...

Orrie, My first old truck was also a 47 Ford, back in 1970. It had a 50 Mercury flathead engine that I later swapped for a 307 Chevy.

[daveboy]

Well, that is my plan for now. I will keep it as is. I am sure that somewhere way, way down the road, I will convert to 12V but I will do it kicking and screaming. Thanks for all the insight.

daveboy

[mr48chev]

Yep, if it isn't broke and works there isn't much need to "fix" it at this time.

Back in my late teens I had a Nash Metropolitan ragtop and when the Lucas generator went out we converted it to a Chevy generator and regulator and switched it to neg ground.

I blew the engine and traded the body to a guy who had wrecked his metro ragtop but had a good engine. He put the Delco generator back in but hooked the battery up positive ground and in no uncertain terms informed me that my Chevy generator was junk and he had swapped the car back to a Lucas generator. He wasn't too happy when I asked him if he had hooked the car up Negative ground like I had set it up after he had thrown a four month old generator in the junk.