48 Business Coupe Electrical Questions

[Mike Claar]

I'm new to this sight.  I just bought a 48 Business Coupe.  Got some electrical question.  I'm sure a lot of fingers have touched this thing over the years.  I'm wanting to make a reliable driver out of it.  So here goes.  I know it was a 6V positive ground when new.  Someone has put a one wire 12 alternator on it with negative ground.  It starts and runs.  Anything I should be looking for to make sure this was done correctly?

[MarcDeSoto]

There are a lot of things you are leaving out here.  What car do you have?  Has the car been converted to 12 volts?  Does it have a 12 volt battery, and is it negative grounded?  Does the ammeter do anything odd when you drive the car?  

[OUTFXD]

Check and make sure that all  the light bulbs have been changed to 12v bulbs.  Also any STOCK Gauges, radio, Heater Blower motor, Fuel gauge sender will need 12v to 6v Voltage reducers/

[Mike Claar]

It's a 1948 Business Coupe.  It has a 12V Battery and a 1 wire GM alternator, it is setup as a negative ground.  The ammeter does seem to act strange when you rev the motor.  The gas gauge seems to go up as I rev the motor.  The Blower, radio, and horn doesn't work. I assume they have been disconnected.  The wipers work but run fast, I know the starter is still a 6V starter, and the turn signals seem to blink fast.  Most of the outside lights work, but no dash lights.

[DJK]

My solution would be to go back to 6v pos ground with a 6v pos ground alternator. Howard Enterprises Iola,Ks. 620-228-1477

[Sniper]

 

A 1948 Business coupe doesn't tell us what you have. 

 

I converted my 51 to 12v negative ground.

 

All bulbs got replaced, there are 12v versions of them all.

 

Blower motor got replaced with a 12v version http://www.yourolddad.com/blower-motor

 

Had to swap the two wires on the ammeter to the other post.  Fuel gauge use a Runtz Resistor, the rest are mechanical.

 

Wiper motor, had to build myself a current regulator to slow it down.  Your 48 may have a 12v aftermarket replacement 

 

 

 

 

 

 

[Merle Coggins]

On 11/29/2021 at 11:45 PM, Mike Claar said:

It's a 1948 Business Coupe. 

 

Plymouth? Dodge? DeSoto? Chrysler? Ford? Pontiac? Packard? ... 

[Dave72dt]

Brand and model are irrelevant.  The basics of swapping to 12V neg are the same.  Every component of the electrical system needs to be checked for correct voltage and polarity or voltage reduction where you need to use the OE 6V component.  You might want to consider swapping out the ammeter for a volt meter.   Most gens didn't produce much more than 30 amps and the alternator can produce much more than that.  Starter and wires will survive as is but I'd still have the starter checked for bushings and brushes.

[Sniper]

33 minutes ago, Dave72dt said:

Brand and model are irrelevant.

 

I strongly disagree.  Many things are specifically make and model relevant.  For example, my link to the 12v heater blower motor swap is not likely to be relevant to anything not Mopar.  How the earlier Mopar fuel gauges work are unique to Mopar as far as I know.  The 12v wiper motor setup someone mentioned is likely to be different as well.

 

You think Chevy, Ford and Mopar all use the same bulbs in the same locations?  No, they do not.  

[Dave72dt]

Somehow a 6v heater blower motor needs to be addressed when in a 12 v conversion.  It doesn't matter the brand or where it's at in the car.  It still needs to be addressed.  Fuel gauges need to be addressed, does not matter brand or how it works, just needs to be addressed. 6v bulbs are 6v bulbs, no matter where they are on the vehicle.  Maybe I'm nitpicking the op 's question, but he didn't ask for a solution for a particular item.  If for a particular item, then yes, make, model and year.  If I were working on a Ford or Chevy with 6v and converting them to 12v, I'd still have to address the heater, bulbs and gauges.  The solutions may be different but I'd still have to address them.  

[Sniper]

If that were so the OP could have just googled a generic answer and not come to a site the sort of specializes in specific makes and models.

 

Got a friend with a 51 Chevy he wanted help converting to 12v, I googled that and found a very detailed list with part numbers and how to's.  Because, to be very frank here, if you can't figure out the generic needs of converting to 12v all on your own then you don't have the skill set to do the conversion to begin with.  These cars are not rockets and don't need rocket scientist to work on them.

[desoto1939]

ok so lets cut the poster some slack. As you can see he is more knowledgeable of 12 volt cars just by what he posted that he currently owns,  So he just got the 48 MoPar.  So might not have alot of knowledge on this car and also what was done to the car. He knows that there is a 12 volt conversion that was partially done by a previous owner and not sure of how it was done and apparently not  done to completion.

 

So he is asking for some help from the more experience members that have done 12 v conversions.  So lets provide some positive suggestions to help him complete the conversion and retain another MoPar Owner and car.

 

The nit picking just puts a dampener on this guy and then also puts a sour tone towards his questions.  When we all started out in theis hobby we did not know all of the answeres. Some of us were lucky that fellow car owner provided us with guidance and help.  Our job is now to pass along the info so that another guy can enjoy his car and keep the hobby alive and growing.

 

I have been in the hobby 35 years and i am still learning everyday.  I read the issues that members post and the replys  to how to address the issues . This is what we all should be doing and this helps all of us get better at diagnosing issues.

 

Rich Hartung

desoto1939@aol.com