Which battery is correct for pony electric starter

Yes welcome back , You need perfect connections and good cables with 6 volt , but the starters do seem to go lazy rather than pack up completely , people put on a 12volt battery and they work ok ish for a bit longer , I've just sent two starters for rebuild after comparing them to a known good one .. they turned over the same pony motor but only just and were drawing a lot more current than the good one... someone was selling brush bush and spring kits on ebay but its like all these jobs hopefully someone who rebuilds this stuff for a living will know what repair to do for the best results...

The most difficult part will be finding someone who still rebuilds starters, alternators, and generators. We actually used to rebuild them at the GM dealership I started out at, and it was no big deal.

A new set of brushes and bushings will have it working like new.

If you have bad luck you may need to turn the commutator.

OK I'm not the Cat expert but there are certain things that are common to all IC electric start engine.

Most starters have powered field winding to put the magnet part in the starter and of course the armature. The powered windings are the reason you can convert a 6V+ ground system to a 12V- ground without having to do anything to the starter.

The most common problem with starters is power. That's bad connections or weak battery most often. Then next is either bad bushings that allow the armature to make contact with the field windings or bad brushes that fail to make good contact.

So all connections clean tight and bright! No exceptions. If you have the repair type cable ends that means taking them apart and cleaning them. You may have to go as far as removing the starter and cleaning the surface area where the starter mounts and starter body. Correct size battery cables. 6V systems like 0 or 00 cable to pass the needed amperage. The smaller cables like is on your car are not sufficient in size for a 6V system. Then of course a fully charged battery.

Now internally the brushes and bushings. For most people changing these items are a little to involved for them so a reman is in order. Sever good youtube vids on the process. As was pointed out the commentator may need to be turned.

Nothing wrong with converting to 12 volt. Where the problem comes in is that most people are covering up another problem and the conversion becomes bandaid. With the exception of the charging system (because that's going to be replaced) everything else should be in top condition before a conversion is made. No sense in covering up a problem.

RIck

Those symptoms sound like the result of either a bad starter bendix and/or slower than normal starter cranking speed. Very likely that your starter would benefit from a complete going-through. For what it's worth the last starter bendix I replaced on a 5U D2 was Standard brand part #SDN17, but check the model and serial numbers on your unit to make sure this part is correct for yours.

The best investments I ever made for doing my own starter and generator work is a growler and an armature lathe with undercutter attachment. Beyond those special tools about the only other thing you'd need is a standard multimeter to do voltage and continuity checks. There really isn't much to the old starters and generators of this era, crazy simple really once you're familiar with them and the tests to do to them to see if all the components are in good condition. Now that I'm set up with the tools I need, I do all my own and as long as the case windings and armatures are in good condition, my rebuild cost per unit is less than $25 for new brushes, bushings, plus the paint I put on the outsides when I'm done. Tooling up do do your own is the best way to go in my opinion, my tools have paid for themselves a couple of times over already with the money I've saved by not having to hire the jobs out. I'll post a couple of pics I have up over on the ACME board of a Ford 8N generator I just rebuilt-

Growler testing for armature shorts

[img]http://i802.photobucket.com/albums/yy310/TRNelson/116_zpsuvzoixfs.jpg[/img]


Armature lathe to turn the commutator back true-

[img]http://i802.photobucket.com/albums/yy310/TRNelson/117_zps9gqbojbu.jpg[/img]



Undercutter for taking down the Mika based insulating material from between the commutator bars-

[img]http://i802.photobucket.com/albums/yy310/TRNelson/118_zpsnvzjwskn.jpg[/img]

[quote="oldtanker"]OK I'm not the Cat expert but there are certain things that are common to all IC electric start engine.

Most starters have powered field winding to put the magnet part in the starter and of course the armature. The powered windings are the reason you can convert a 6V+ ground system to a 12V- ground without having to do anything to the starter.

The most common problem with starters is power. That's bad connections or weak battery most often. Then next is either bad bushings that allow the armature to make contact with the field windings or bad brushes that fail to make good contact.

So all connections clean tight and bright! No exceptions. If you have the repair type cable ends that means taking them apart and cleaning them. You may have to go as far as removing the starter and cleaning the surface area where the starter mounts and starter body. Correct size battery cables. 6V systems like 0 or 00 cable to pass the needed amperage. The smaller cables like is on your car are not sufficient in size for a 6V system. Then of course a fully charged battery.

Now internally the brushes and bushings. For most people changing these items are a little to involved for them so a reman is in order. Sever good youtube vids on the process. As was pointed out the commentator may need to be turned.

Nothing wrong with converting to 12 volt. Where the problem comes in is that most people are covering up another problem and the conversion becomes bandaid. With the exception of the charging system (because that's going to be replaced) everything else should be in top condition before a conversion is made. No sense in covering up a problem.

RIck[/quote]

+1 to everything Rick posted, when it comes to contacts/connections there is no such thing as TOO clean. An area that even some rebuilders overlook is the case-to-endplates surfaces, I like getting these down to bare metal and even lightly coating them with a good electrical grease to help continuity and keep them cleaner longer. And the bigger battery cables for 6V - pretend your battery cable is a garden hose and one volt equals 1 psi water pressure. To spin your 6V starter under load at a similiar cranking speed as a 12V starter, you need to be able to flow as much of your 6V current as you can with as little as possible restriction as you can manage (or electrically speaking, resistance). 6V systems dont have the ability to push current through smaller cables or dirty connections quite as well as 12V, so by putting bigger cables on your 6V battery and starter you're effectively increasing the diameter of your "garden hose", giving you the ability to flow the volume you need even though your supply has less "water pressure" (voltage/amperage).

Any lathe can be used for armature cleanup.

Grind off the round end of a hack saw blade (on a diagonal) and it can be used as a manual 'undercutting tool'. Just 'scrape' out ~ 1/16" of the mica insulation after cleaning up the commutator.

Daron

Starter commutators do not need to have the mica undercut and is detrimental to do so. Commutator does need to be round so a light lathe cut may be required.
The down side to running the 6v starter on 12v is that it is hard (may break) on the drive spring. Conversion to the barrel type drive will prevent that.

[quote="Old Magnet"]Starter commutators do not need to have the mica undercut and is detrimental to do so. Commutator does need to be round so a light lathe cut may be required.
The down side to running the 6v starter on 12v is that it is hard (may break) on the drive spring. Conversion to the barrel type drive will prevent that.[/quote]

Sorry for the confusion, OM is right in that starters do not need to be undercut - the pics I posted are of a generator armature. I've read that the higher amounts of current that starters deal with can cause excessive arcing and damage to the commutator, even dragging some of the copper material until it shorts across the bars if there is an undercut. But as long as we're on the topic I do want to ask this question: I've heard a lot of differing opinions about undercutting generator armatures, and if so how deep to go. I've been taught that the benefits of undercutting a generator include longer brush life and more even wear of the commutator bars since the Mica has a different wear rate. The undercuts are also supposedly able to give the worn brush material a place to sift into and find their way out of the commutator easier. Since a generator turns a ton more than a starter and generally copes with less electrical load, undercutting is necessary. So, (1) does anyone have info that would disprove those points regarding generators? And (2) how deep is generally considered an appropriate undercut on this era of units? I usually go around 1/32" deep, has always worked great but I'm always open to hearing other opinions.

1/32" undercut is correct on the generators. Undercutting is required because the soft carbon brushes will not wear down protruding mica. Starters have hard copper impregnated brushes that are cable of wearing down the mica and the commutator at equal rates. Both generator and starter commutators should be trimmed if they are 0.002" out of round. This minimizes bouncing and arching at the brushes.