1925 Buick battery voltage 6 or 8

[KEK]

Hi everyone -

 

I finally got around to installing a nitrophyl float in my Marvel carburetor as Hugh recommended (that material is super easy to work with. I had to sand and form it to match the old float). Anyway when I tried to start the car to give it a test drive the motor generator would not motor. I have the 6 v battery on a tender so it seemed the battery was sufficiently charged. A few voltage checks indicate erratic voltage so I put the big charger on it and fully charged the battery. It then motored just fine.

 

That got me to thinking about my problem with chewing up the sliding starter gear. The starter gear was changed but it still hits hard when I press the starter pedal.  My question is if the voltage is relatively low will the motor generator motor at a lower RPM and cause the sliding gear not to mesh as smooth as a faster motoring RPM? So I was wondering if I could install a 8 v battery to increase the motoring RPM?

 

Thanks 

Ken

[Terry Wiegand]

The speed of the armature in the Starter/Generator unit when it is 'motoring' has absolutely nothing to do with the sliding reduction gear.  The reduction gear does not go to work until you step down on the starting pedal.  If it were me, I would check and then check again the electrical cable connections for the negative (ground) and positive (battery) and make sure that they are good and tight as required.  I would also check the lubrication points in the system and make sure everything is as it should be.  Electrical current can be a funny thing at times.  It needs good connections to travel properly.

 

Terry Wiegand

South Hutchinson, Kansas

[KEK]

Hi Terry - Good advice to check electrical connections. In doing so I found a couple terminals on the starter-generator that look like they are about to fail so I am going to replace all 3 of these wires.  

 

The battery cables are probably ok but they are really old so I am going to make some new ones and replace both battery cables.  

 

I found that after charging my battery the SG would motor but it didn’t have enough power to engage the starter. As soon as the sliding gear engaged it stopped turning. I eventually figured out the battery has failed and could not produce the amps needed.

 

I remember reading somewhere that the motor generator should spin at about 200 or 250 RPM. I figured this rate was required so the pinion gear meshes smoothly with the sliding gear. If my SG is motoring too slow I was thinking an 8 v battery would have plenty of amps to motor at the high end of the 250 RPM. Since I am going to replace the battery anyway that is why I was thinking about using an 8 volt. Has anyone done this or is an 8 v battery too much for the 6 v system? Bad idea?

[Matt Harwood]

8V batteries are not a solution, they are a crutch. Good connections, big cables, and clean grounds will offer a big improvement. Get those parts right and you won't need more voltage. It started reliably when it was new, it can be made to start reliably today. Do a search on this forum for hard starting and you'll find you're not alone and the answer is always the same: big cables, good grounds, clean connections, strong battery. 

[Brian_Heil]

18 minutes ago, Matt Harwood said:

8V batteries are not a solution, they are a crutch. Good connections, big cables, and clean grounds will offer a big improvement. Get those parts right and you won't need more voltage. It started reliably when it was new, it can be made to start reliably today. Do a search on this forum for hard starting and you'll find you're not alone and the answer is always the same: big cables, good grounds, clean connections, strong battery. 

Add to that good brushes with good spring load, clean commutators (both) lubed brush engagement large pin and well adjusted starter linkage. 

[Rod Wise]

KEK

It is not the RPM of the generator that meshes the gears.  The motoring of the generator and the starting of the motor( when you press the starter pedal )  are two separate circuits.  When you turn the ignition on, the generator  turns  slowly,( motors ) This is to align the gears so they will mesh properly.  When you press the starter pedal,  the motoring circuit is disengaged and the starter circuit is engaged,  As the others have said you need larger cables for a 6 volt circuit than a 12 volt circuit as it is carrying a higher amperage

Edited August 20, 2020 by Rod Wise (see edit history)

[Hubert_25-25]

I would recommend an Optima red top dry cell battery.  I have had no issues with mine and there are no battery gasses to deal with.    Hugh

[Robert Engle]

Don't forget to have a battery with a high CCA (cold cranking amps) rating. I prefer the sealed batteries so there is no outgassing to corrode terminals and cable connecters.

 

Bob Engle

[Marty Roth]

On some of our 6 Volt cars, I use a pair of Optima Red Tops in Parallel,

so still 6 Volt, but Double the Amperage.

Even the later models 1937 Roadmaster and 1941 Cadillac, and also the 1915 Hudson and 1930 Packard spin over just fine on 6 Volt,

but heavy cables (I use "000" - Triple Aught), and clean connections make all the difference !

[KEK]

Great input everyone - I will stick with 6v and run heavier wires on the battery and replace the 3 ignition wires. I never would have thought that you would need a 000 gage for the short battery cables. Looks like the old cables are 1 gage. I will use Hugh’s spreadsheet for wire gage for the 3 ignition wires.  If this doesn’t do the trick then it sounds like I need to think about pulling the SG and have someone go through it. When I had it out of the car I noticed there were new brushes and rollers so I thought it was rebuilt but maybe not completely.

 

Thanks for all of your help. Hope this works.

Ken

 

Edited August 21, 2020 by KEK
Correct gage size (see edit history)

[KEK]

I replaced the battery cables, ignition wires and a new battery. Turns over very slow.  I never had this problem until last week when the old battery died.  The car starts and the amp meter shows the generator is charging.  Does it sound like I need to rebuild the SG?

 

Ken

[Terry Wiegand]

What did you replace the battery cables with?  As was mentioned earlier, the heavier the cables the better it is.  Electricity travels on the surface of the wiring - not through it.  So, the bigger the gauge of wire the more surface area you will have and more current flowing.

 

Terry Wiegand

South Hutchinson, Kansas

[Morgan Wright]

1 hour ago, Terry Wiegand said:

What did you replace the battery cables with?  As was mentioned earlier, the heavier the cables the better it is.  Electricity travels on the surface of the wiring - not through it.  So, the bigger the gauge of wire the more surface area you will have and more current flowing.

 

Terry Wiegand

South Hutchinson, Kansas

 

Electrons travel from one copper atom to another, through the mass of the copper, not just on the surface. What matters is the cross section area, which goes up with the square of the diameter. So a 1/2 inch wire conducts 4 times more electrons than a 1/4 inch, everything else held equal.

[KEK]

I replaced the battery cables with “00” gage. I think I have a short in the SG that is drawing a huge load. That explains why my old battery went dead and could not recover. It also explains why the starter was slow with a new battery and cables. I checked the battery after I got the car started and back from a short test drive. It was at 60%. Just the little time the new battery was connected to the SG drained it down so it barely turned over the engine when I started it.

 

So I started looking for a short. I disconnected the wire from the SG to the amp meter. I left the + side of the battery cable connected to the SG. I then disconnected the cable from the + battery terminal and connected my volt meter between the + terminal on the battery and the battery cable connected to the SG. I read 6+ volts. 

 

Doesn’t this indicate a short in the SG? I was surprised to measure full voltage at the lug on the SG. I was expecting no voltage. Do I understand this correctly?

 

Ken

 

[Terry Wiegand]

Ken,

I sent you a PM

 

Terry Wiegand

South Hutchinson, Kansas

[Hubert_25-25]

Ken, 

   With the cover off the starter generator you can have someone push the Starter pedal in and you can watch the starter generator operation.  Leave the ignition switch off and the transmission in neutral.  You can use a wooden stick to gently push on the upper starter brush when it engages to see if they are pushing down enough on the armature.  Does it make any difference with cranking speed.

You also have several grounding areas that you need to be sanded clean for a good ground.  Lightly sand with 100 grit paper - no paint or rust.

- Start with checking the ground on the lower brushes first.  2 screws hold them in place.  When you remove the lower brushes,  check that they spring return freely.   There should be no paint on the housing in that area, and no paint on the inside of the brush holder.      

- To check the Starter Generator ground,  you would normally need to remove the SG unit.   Remove the 3 mounting bolts.  Make sure the unit will not fall.  Create a small gap between the SG and the block mounting.  Fold the sandpaper over a putty knife and sand both mounting surfaces.   Maybe you can see if there is rust or paint between.  If you do remove the SG unit, You can bench test it while it is out.      Hugh

[KEK]

Hi Hugh -

 

I pulled the SG last year to check the pinion gear on the end of the generator and at that time I saw that it had new brushes and new rubber rollers. The 2 wires (from the field coil?) were old so I put some shrink wrap on both of them. I also made sure there was no paint in the area that you mentioned based on some of your photos that you posted at that time. I replaced the SG and it turned over fine but still did not mesh well with the sliding gear. 

 

Normally when I park the car I put a battery tender on it but alway disconnected the ground cable until a couple weeks ago when I left the cables connected. Then when I tried to start it the battery was completely dead so I replaced it with a new 600 CCA battery and the new 00 cables. The shop manual says to use 00 so I figured that would work. But before I started the car the new battery discharged to 60% so the engined barely turned over. It turned over just fast enough that I could start it.

 

I then charged the new battery back to 100% and it now turns over much faster. It still seems a little slow but I think these old starters are that way. So it looks to me like I have a serious short that is draining the battery . To test for a short I disconnected the wire from the positive side of the SG to the amp meter so the only electrical connection is the positive battery cable to the SG. I then placed my voltage meter between the positive side of the battery and the SG + lug and measured full voltage. That’s a lot of voltage that is going somewhere which would not take long to drain a battery. This seems to me that it indicates a short in the SG. Maybe the SG is different than modern starters and that its not indicating a short. Do you know if it is normal if the amp meter wire is disconnected to isolate the SG electrically to see full voltage at the SG + lug?  When I wired my 1930 Model A street rod with a modern harness before I connected the battery cables I did the same test. Zero voltage is safe to connect but any voltage is indicative of a short. I am a little concerned about testing the SG if there is a short in the system so I think I need to remove it again and look it over and then bench test it. What do you think?

 

Ken

[Hubert_25-25]

Ken, 

   Count the number of teeth on the gear on the end of the starter generator motor, and also on the sliding gear.  Someone put a Master gear  on my Standard motor  (Standard is 13 tooth and Master is 12 tooth) and it drove me crazy until that one was resolved.  

I never disconnect the ground while using a battery tender.  It should draw 0 voltage when the key is off.  Anything greater than 0 is a short or something is on.  If the key is off and you touch the ground wire to the battery there should be no sparking.  Check this with the lights off in a dark garage if necessary.  Start removing wires until you can figure out where the problem is coming from.  It could be coming internally from your starter generator.   

 

Spare Starter Generators are out there.  I suggest that you keep an eye out for one.  I keep a working spare.  I won't do a lot of troubleshooting of this on the car.  Easier to just swap them out and then do bench testing.  

Hugh  

Edited August 22, 2020 by Hubert_25-25 (see edit history)

[Rod Wise]

Ken

 Looking at the wiring circuit for the starter motor.  When the wire to the ameter is disconnected,  the only circuit is from the main S/G terminal through the field coil to the upper starter brush.  The top  brush only comes into contact with the comutator when the starter pedal is depressed.  So a  current  should only be passing through the starter circuit when the starter pedal is depressed.  If the brush is not touching the commutator, there should be no current flow.  In the comutator end of the S/G there a many insulators separating the two different circuits,  if any of these are old or broken a short can accurr. There is a small insulator roller which is involved when the brushes are raised and lowered. which often breaks causing a short ( you can see it to the left of terminal A in the diagram ) To find a current flowing in a wire I suggest getting a clamp meter which wraps a round the wire and shows the amperage passing through the wire.

[Rod Wise]

Arrow showing insulated roller

[Hubert_25-25]

Ken, 

    The shrink wrap is not my first choice for "recovering" those old wires.  I don't think it can handle much amperage load.  See this yellow fiberglass insulating sheathing.  I think this is much better stuff.  As you can see I used both.  (first photo with 2 photos)

 

There are actually 3 insulators.  One at the base of the starter spring,(photo2) .  On the arm there are 2 rollers (photo 3 from Kevin Roner).   Hugh 

 

 

 

 

Edited August 23, 2020 by Hubert_25-25 (see edit history)

[KEK]

Hugh -

 

I touched the ground cable to the negative battery post and it lit up like a match.  So I think it confirms I have a serious short in the SG. No other electrical circuit was connected so the SG was isolated.  I am going to pull it out and examine it on the bench.  Probably end up sending it off to be rebuilt. 

 

I have a non working spare SG of the same model No. 283 for a 1925 standard and also a spare non-working model 268 which is for a Master. Both have pinion gears. The pinion gear on the 283 is the same as the pinion gear that is on the car, i.e. 13 teeth. I replaced the sliding gear and that helped a little but didn’t solve the gear grinding. I am thinking after I get my SG working properly It might solve the problem?

 

By the way, that is a great diagram you posted that shows the front of the SG. I have never seen that one before. Thanks for posting it.

 

Ken

[Daves1940Buick56S]

On 8/21/2020 at 6:27 PM, Terry Wiegand said:

What did you replace the battery cables with?  As was mentioned earlier, the heavier the cables the better it is.  Electricity travels on the surface of the wiring - not through it.  So, the bigger the gauge of wire the more surface area you will have and more current flowing.

 

Terry Wiegand

South Hutchinson, Kansas

Terry:

 

If it's AC you are correct. We can calculate "skin depth" as a function of frequency. The higher the freq, the closer it all is to the surface. DC, though, does use the whole conductor. In a copper line the skin depth is about 8.5 mm at 60 Hz.

 

In high power RF transmitters at fixed stations, the transmission line is sometimes just a hardline consisting of 2 concentric copper pipes with inner supports to maintain a constant impedance. No point in using expensive solid center conductor since the RF only rides the surface.

 

Cheers, Dave

Edited August 24, 2020 by Daves1940Buick56S (see edit history)

[KEK]

I replaced both cables with “00” that is what the shop manual says to use so it should be sufficient size. I’ll have the SG off today and can look it over on the bench. I am pretty certain there is a short that is drawing most of the current away from the starter motor resulting in it turning over slow. Hugh thanks for the explanation of the wiring circuit. That is where I will start looking.

 

Ken

[KEK]

I found the short. The arm on the upper brush came off the insulated roller. See pic. The spring on the arm held it down tight on the SG on the casting providing the short.

 

I talked to Rex at Precision Power and he has never seen this problem with the brush arm coming off. He also has not had a SG causing the sliding gear mesh problem I am having. However, the brush arm came off for a reason and perhaps there is a timing issue that could be causing the gear mesh. In any case the SG needs to be looked at to figure out why the arm came off.  I don't want this to keep happening so I am off to build a shipping container 😃

 

Ken

 

 

[Frank DuVal]

On 8/21/2020 at 6:27 PM, Terry Wiegand said:

Electricity travels on the surface of the wiring - not through it. 

 

Only in high frequency applications. In 60 Hz AC and DC, current flows in the whole crossection. That is why AWG is based upon crossection and not circumference. i.e. doubling of crossection doubles current capacity. Now once you get bigger than 400 MCM (aka KCMIL) then skin effect might be an issue, but nowhere does an antique car need that size wire!

 

 

[Rod Wise]

Ken

That arm does need to go back on the round insulator.  That insulator does not turn,  the groove only holds the arm in place.   Technicaly,  the starter motor  is not involved with the meshing of the gears,  ( but it does turn slowly to assist meshing of the gears).  It is the gears  in the housing   that slide backwards to engage with the flywheel and the starter gear that do the meshing.  If the starter motor turns slowly when you turn the ignition on,  ( motors )   it is working correctly.   If, when you press down on the starter  pedal  it is hard it is most likely the starter pedal and gears need oiling.  There are a number of points that require oiling in what I call the tower ( don,t know the proper name )  and the gears in the flywheel housing.  as well as the tapered shaft that raises and lowers the brushes.  If the gears in the flywheel housing are not oiled  and are not turning freely,  they will not mesh properly. Sorry for the poor photoes  could not get the camera to focus properly. Arrows show places requiring oiling.  as well as the shaft the gears slide on.

 

Edited August 25, 2020 by Rod Wise (see edit history)

[Rod Wise]

When you push down on the starter pedal,  the gears in the housing are moved backwards,  The larger gear at the front engages with the starter motor gear and the other  gear engages with the flywheel.  There is an over riding clutch in the front gear to prevent damage to S/G when the engine starts.  My 25 Master starter motor gear has 12 teeth.  There is a grease nipple behind the S/G to grease the shaft.  Yours would be easier to get to  without the stearing box on the right side. If there are new rollers and insulators in your S/G and it was motoring properly and starting the engine before, I don,t feel this is your problem.  The lever that moves the tapered rod back and forward is fixed by a lock nut.  The timming of the raising and lowering of the brushes is not adjustable.  If it were me,  I would oil everything well,  get all the gears and linkages  moving freely  and see if that makes a difference.

Edited August 25, 2020 by Rod Wise (see edit history)

[Hubert_25-25]

Ken, 

    I think that arm either came off during the Starter generator rebuilding process, or the pointer operating the arm lifted just a little too much and let the slot come off of the insulator.   If the insulator roller that rides on the pointer is a little too large it could do the same thing.   My suggestion is to put the slot back on the insulator, put the SG unit back in the car, and have someone work the starter pedal while you observe the operation.  I am afraid that without watching how the operating pin is contacting this arm, a rebuilder will not see the problem.  It could be that the roller installed that rides on the pointer is bigger diameter than it should be (so maybe cut the roller diameter down just a little with a file), or maybe you can make a minor adjustment inside the housing.  You do not need to hook up any electrical wires, just set the unit back in and see if that arm comes off again and make adjustments to fix it.  I do remember during the rebuilding of mine that I had knocked mine out of that slot at one point.  

 

Hugh  

[KEK]

Hugh -

 

I started the car at least a dozen times over the last year and the roller was not a problem. That just happened a couple weeks ago. I drove the car a couple miles to gas it up and during the drive the car died a couple times because I am still having flooding issues so I had to restart it several times to get it back home. I then parked the car and the next time I tried to start it the battery was dead due to the short cause by the arm coming off the insulator during one of the times I had to restart it.  

 

I am going to do the test you suggest when I get it back from the rebuilder. Perhaps it has the wrong size roller on it or something else. At least it should be rebuilt to original specifications and then that is one thing I can eliminate.  I am also going to go back through the lubrication points that Rod mentions above to make sure everything is clean and lubricated. I did clean the replacement sliding gear and greased it so I know that is okay. I didn’t realize that the pointed rod that the roller rides on needs to be oiled. So I will make sure it is clean and lubricated before I run the test.

 

Thanks

Ken

[Hubert_25-25]

Ken, 

   It never hurts to have a second set of eyes go thru the starter generator.  Motoring helps with the initial alignment.  Once the gears are aligned, the starter pedal should  move easily in it's full travel.  If you remove the floor pedal assembly from the top of the bell housing, you should be able slide the gear assembly by hand in and out of the gears with no trouble.         Hugh

[KEK]

Hi everyone -

 

I got my rebuilt starter generator installed on the car today. No more grinding the sliding starter gear!  The starter engagement is smooth and quiet. Problem solved!  I thought I would post this update in case anyone else has the same problem with their sliding starter gear self destructing.

 

Thanks everyone for all your tips and guidance that ultimately lead to a solution. My next steps are to solve my carburetor problem and complete the electrical wiring then I should have a car that is drivable. I am beginning to see some light at the end of the tunnel - finally.

 

Ken

[KEK]

Just when I thought I had the problem solved another one has surfaced. My sliding gear is grinding again.

 

Yesterday I tested it 4 or 5 times and it worked perfectly. This morning after I installed the distributor and tried to start it I noticed the grinding problem. Apparently the ‘motoring’ stops before the sliding gear is engaged.

 

If you slowly press the peddle down about one inch the motoring stops. Then when I continue to depress the peddle you can feel it engage what I think it the pointed rod that starts to lift the brushes off the generator then after that the sliding gear and starter is engaged. Clearly the motoring stops well before the sliding gear is engaged. Is this a problem I need to talk to the rebuilder about or is this timing of the brushes something I can adjust?

 

Thanks,

Ken

 

 

 

[Hubert_25-25]

Ken, 

    There really is no apparent adjustment for when the generator stops turning and the starter takes over.  Clearly the generator spinning helps with gear engagement.  The wear item is the rubbing block that the pointer engages with.  Did they replace that when your Starter Generator was rebuilt?  See the photo of the worn rubbing block.  With a worn block, the starter will engage earlier. 

And that could damage the teeth on the sliding gear because the starter is putting a load on the teeth before they are fully engaged.  I have seen these rollers replaced with several different materials.   

 

[KEK]

Hugh - 

 

They did a complete rebuild so I suspect the roller was replaced. I will call him and confirm tomorrow. 

 

Isn’t the purpose of the motoring to help sync the sliding gear with the pinion gear on the starter? In my case the motoring completely stops before the starter takes over.

 

Ken

[Hubert_25-25]

Ken, 

   So I suspect the length of the brushes will also effect the engagement and disengagement time of the starter and the generator.  Not sure if the new brushes are identical to the old or are reproductions that are close. 

 

From the shop manual. 

The first movement brings the starter gears into mesh with the gears on the flywheel.  The slow rotation of the armature which begins when the ignition switch was turned on overcomes the probability of the ends of the teeth striking and failing to mesh.  

 

As the starter pedal is pushed further down the upper generator brush is lifted and the circuit between the storage battery and the generator winding of the motor generator are broken.

Upon the last movement of the starter pedal the upper brush is brought down on the motor commutator closing the circuit between the battery and the motor windings on the motor generator.  

 

So if your gears are worn off on the end from previous problems, the sequence of events may not be occurring at the correct moment.  

Perhaps disconnect the battery.  Remove the sheet metal cover on the starter gear, remove the 4 bolts on the starter pedal, and remove the cover on the backof the SG unit.  This will allow you to slide the gear back and forth and you can observe when the brushes are lifted and dropped to determine if you need to make any modifications. 

My thoughts:

The generator brush should be disengaged only after you are on the starter gear at least 1/4 of the way.  Maybe this is hard on the generator to be meshed with the engine with power on it, but the time should be short as the brush will be disengaging soon.   

The starter brush should not be engaging until very late and the teeth are at least 3/4 fully meshed.  This would prevent grinding of the gear teeth.      

 

I have not removed my sheetmetal to observe when meshing is occuring if I were to slowly push the pedal down, and then to see when the starter took over, but just reading thru this I think that is how it works.

 Hugh

[Oldtech]

Main thing here is that the generator brush has to be lifted BEFORE the starter brush touches down.

[KEK]

The new brushes the rebuilder installed are NOS. He said he rebuild the unit back to factory specs. 

 

Hugh you said that the generator brush should be disengaged only after you are on the starter gear at least 1/4 of the way.  I agree with that. I think my problem is that the generator brushes are being lifted up before the gears are engaged and before the starter brushes touch down.  In fact I think the generator brushes are being lifted up too early and before the starter gears are brought into mesh with the gears on the flywheel. From the first sentence in the shop manual that you posted above says... The first movement brings the starter gears into mesh with the gears on the flywheel.  But when I just barely press the starter pedal down about an inch I can feel the pointed end of the operating pin engage the generator brush mechanism and at this moment the motoring stops. I think the tapered end of the pin is just barely engaged with the insulated roller before the motor stops but the sliding gear and pinion are not yet engaged. So then when I continue to press the pedal down further the gears don’t get meshed because the generator is not motoring.

 

Quoting from the manual it seems that the motoring should continue after the gears are meshed and until the pedal is pushed down further... “As the starter pedal is pushed further down the upper generator brush is lifted....“  When I press my starter pedal down its the same effect as if I didn’t turn on the ignition, i.e. no motoring during gear meshing. I think I have a timing problem with the first movement.

 

Hugh - have you ever pressed your starter pedal down with the ignition off? If so did your gears clash when the starter motor engaged?

 

Ken

[Hubert_25-25]

Ken,

   It does appear that your generator brush is lifting too early.  

 

On my car I turn the ignition, and it begins motoring.  As I push on the pedal, It sounds like a roller coaster car as the gears are engaging.   A clinking noise of the gears engaging.  The starter taking over does not happen until I push the pedal further.  

 

I can crank my car with the ignition off.  If I try to make the gears mesh without motoring, they do just clash into each other, but nothing is turning, so it just does not engage.  After several attempts at trying this, the gears will mesh and then the pedal will travel low enough and it begins to crank.  Sometimes you get lucky and it goes straight in and begins cranking.  

 

Attached is a drawing and write up to help you.    Hugh

 

 

Edited March 8, 2021 by Hubert_25-25 (see edit history)

[KEK]

Hugh - That is a great explanation of the timing. And thank you for verifying the operation with you car. If my operation shaft with the tapered point is too long would that cause the generator brush to lift early?