Model 70 Starter Drive Failure

Carls70

Member
Hello Everyone,

I've noticed recently that occassionally when attempting to start the 70 when the starter button it would spin up but not crank over the engine. The next time the starter was engaged it would crank normally. Well... This week the starter would spin but the engine would not crank over at all. The ring gear on the flywheel looks decent all the way around, I rolled it over by hand to check the whole gear and all the teeth are there...

I didn't think to take a picture of the pinion engagement but it looked pretty good. The pinion gear turned freely without dragging on the over-running clutch so I expected a failed clutch.

The starter appears to have been gone through recently but I don't really know much about the history on this tractor.

So I ordered up a new drive, pulled the starter to find the pinion gear appears to have broken away from the inner clutch sleeve, it freely rotates and slides up and down about 1/8" inside the drive.

The starter is a Delco #1108981 and according to the parts book uses a #1924589 drive assembly. This is a 1954 Year #15523

I ordered one locally (using the Delco #) and so far it looks compatible.

My concern is putting in the new drive to have the same failure occur. Anyone else have a similar starter drive failure?

The new drive looks beefy enough but only has 3 spline teeth inside vs 6 on the old unit, should I even be worried about this?

Is there a source for a heavier duty drive that someone can point me to? this one ran $28 and online I found one that was over $60. (Standard Motor SDN233)

Here are the pics I took after disassembly. Thought/opinions anyone?

Thanks! Carl

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That fork is worn pretty bad where it contacts the drive. Might be worth the time to weld it up and grind it back to profile with a dremal. Unless someone sells new ones ? Make sure your distrubitor advance is free and working properly and your timing is set to spec. if too advanced on starting it can kick back and break things like drives and starter noses.
 
Looks like the new drive is more heavy duty than the old one . The 3 spirels reduce and drag for engagement. Also looks like the starter has low voltage due to the lead sparkles and brass sparkels . The Windings show heat and guessing thats where the solder came from Also looks like the center bearing is worn out . Mike M is right on with his diagnoses .
 
Thanks for the replies guys, I was wondering about the wear on the forks too. The last guy that -tinkered- with this machine had hooked up the batteries (2 - 6v) in parallel with shop made clamp on cable ends and #6 awg coarse strand cable. Said he played with it quite a while trying to get it to start.

One of the first things I did was to get rid of that mess and dropped in a group 27 interstate cranking battery. It fired right off on the first try @ 12th but he must have charged and drained those 6v batteries several tikes trying to get it started on 6v...

I was worried about the solder by the commutators and the melted insulation on the field winding lead too...

I haven't put a timing light on it yet but it sounds like that is a good next step. The points 'look' new and the distributor is clean inside but I neglected to check the advance weights.
 
Update: Thanks Mike M for the advice, I welded the barrels up on the engagement fork, and ground them back round(ish) with a small carbide burr on the little grinder. Seems to have taken quite a bit of slop out of the equation after final assembly.

Thanks DONMYEIL for mentioning the center bearing, I stuck my finger in there and the remnant of the middle bushing was wiggling loose inside the bearing plate. The parts man at the local Deere dealer was able to get one from Vintage Parts out of Wisconsin and Deere still has the small bushings on the ends of the armature available.

After installing the new nose cone bushing and midbearing, I took some brake cleaner to the brush holder area and blew all the nasties out with air afterwards, however one of the grounded brush wires was pushed lightly against the insulated brush connecting bar during this step and I failed to notice it until after the starter was reassembled and i attempted a bench test... Lots of current draw, no rotation, what the???

After noticing the glowing wire and separating the shorting wire/link it seemed to spin normally. Whoops...

Well anyhow, now the starter is reassembled, bench tested, and reinstalled in the tractor. Hoping to test out after the weekend.

Hope you enjoy sharing my adventure. Thanks for your time & help!

Carl
 
check the ignition advance while cranking . If the weights are stuck or the initial is too advanced . She will kick back and over stress the starter .
 
Thank you for the guidance B&D, I am planning on checking the distributor and timing next.

I have noticed a what sounds like a knock under load climbing uphill and have been wanting to check the crank & flywheel out also.

I picked up a set of new flywheel bolts/washers/nuts when I was at the dealership for the starter parts. Will probably post about that this week if I can get to looking at it.

I put a dial indicator on it when reinstalling the starter and the crank end play is currently about .009" with the engine at room temperature. The manual says .005" -.010" but I have read some archived posts referencing closer to .015" (maybe that was for a diesel though) guess I will cross that bridge when I get there.

Carl
 

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