Cub Eating Up Starters

[kajun]

Folks:

My tractor seems to have eaten a Chinese knock-off starter and also eaten my OEM starter that was fully rebuilt a month ago by a professional shop. Both have "failed" this way : pulling the starter-reach-rod results in starter doing nothing at all most of the time . I thought the problem was in saddle-starter-switches but brand new switches on both starters helped nothing . A couple days ago with both starters on a "test block " and connected by jumper cables directly to positive terminal and to ground I found that sometimes starters do not respond at all ,but by rotating the drive shafts on each of them both of the starters will run wide open . In other words , now they work , now they don't . Two questions :

1. What is causing starters to fail in the same way ? [ Cub was outfitted with 12 volt system in late 2011 ; problem developed in summer of 2018; Chinese knock off starter was placed on tractor in summer of 2018 and failed ,in time , as described ]

2. What is fix ?

So sorry to be always asking for help.

Kajun

[Lt.Mike]

One thing that comes to mind is the state of tune to the tractor and how long do you crank that starter to get it fired up?
Even the best starter doesn’t like cranking more than a couple of seconds. Continuous cranking will heat it up and eventually burn it out.
Are your cables good? Connections clean? A weak battery or weak voltage from the battery will kill a starter in time.
Make sure all those are correct first.
The starter a Cub uses isn’t put together with the technological voodoo today’s automotive type of electrical equipment is made.
I took apart and rebuilt my cubs starter myself using parts available on eBay and it was pretty basic. Got impressive results. I figured it’s already broke, can’t break it any more.
There was a certain amount of satisfaction there too.
That starter worked great for years till this past summer when I over cranked it.
What can I say? Should have known better.
Mike

[Scrivet]

.....but by rotating the drive shafts on each of them both of the starters will run wide open . ........

That tells me the brushes and commutator are not making good contact. I would be looking at cleanliness, wear, brush spring tension, etc.

[brewzalot]

my OEM starter that was fully rebuilt a month ago by a professional shop.

I would take it back, describe your issue, and see what they say.

[Gary Dotson]

Your symptoms describe an armature with an open circuit (dead spot) (starter doesn't run until you turn it a bit, then seems to run normal). Take the original back to the shop that rebuilt it and have them check it out. Not saying there was any problem with the rebuild but they will have equipment to check an armature properly.

[kajun]

Thanks , men.

Yes the OEM starter is going back to the rebuilder . Yes battery is good ; I believe the leads to be good too.

I was wondering about some other thing that could be causing serial failures . How about oil on the brushes and commutator as Scrivet mentioned ?

This tractor has suffered repeated rear-main-seal failures despite using TST-supplied seals and giving the mechanics his installation instructions. There was a little oil at the face-plate where starter mounts when I took it off . But , contrast that to this . So far as I can recall I never had starter failure in the years that I just kept topping up with oil due to rear seal and leaving a trail of oil wherever I went. Seems like I would have had starter failure(s) then .

Your thoughts ? Again sorry to be dense.

[Don McCombs]

This tractor has suffered repeated rear-main-seal failures despite using TST-supplied seals and giving the mechanics his installation instructions.

How are they failing? Bearing spinning? Just leaking? If so, where is it leaking? Give us a little more to go on.

[staninlowerAL]

Gary Dotson's answer: Ditto. BTDT!! Unless you can find a good used armature, you can replace the whole starter for about the same cost as a reman one.

[lowgearfarm]

I've had a "dead-spot" in my Delco 1109610 starter for the last few months. So yesterday I went to replace the brushes. Unbolted the end cap, pulled the armature from the case, but couldn't get enough access to the brush retaining bolts. Considered unbolting the field coils and pulling the whole guts from the case, but the field coil retaining bolts are so seized into the case that I decided not to take that route. I got discouraged and just put the whole thing back together - the old brushes didn't look too bad anyway. Maybe the dead-spot was just that loose wire going to the solenoid anyway. But I'm left wondering - how does one get access to the brush retaining bolts?

[Glen]

Hi,
The 6 volt Cub starters I have worked on, you have to loosen the screws holding the inside wires to the brush mountings, through the slotted holes, after removing the band.
When the wires are disconnected, then the end will come off.
They always had screw heads, on the ones I have seen. If they are rusted or frozen, it could be hard, they would have to be soaked loose with penetrating oil.

You have to work through the holes to connect the wires again.

I think Jim B. or someone has said the big screws holding the magnets on the case are usually tightened lots, and hard to get loose.

Clean the commutator where the brushes run, sand it with fine sandpaper, and wipe off all sanding with a clean rag.
Look at the large part of the armature, if it has any rub marks, the 2 bushings at the ends of the starter need replacing.

[lowgearfarm]

OK. What you say (above) all makes sense. The screw heads on the brushes don't appear to be rusted, so I'll give those a squirt of penetrating oil and cross my fingers. It's good to hear that they can be reconnected through the square side holes when putting it back together.
Sort of related: The long "thru bolts" wanted to shear off when I took them off - I ended up turning them by their shanks with vise grips rather than twisting the heads off. I can't located replacement bolts on line, so I was thinking of making some up with threaded rod (32 pitch, I think).
Thanks for your help - my kindergarten grandson was no help at all - although he was pretty interested.