4020 starter 24v changed to 12v

Tx Jim · Dec 8, 2009

On a 4020 24V starter that has been changed to 12V,does one have to change to 12v field coils along with armature? Starter just returned from repair shop.
Reason I asked is I'm working on a 4020 that cranks slow,has new batteries & cables and starter has a stud for ground cable. Batteries test 12.7V with engine not running and drop to 7V when starter button is applied. I'm looking for an amp meter to check amp draw.

I've never seen a ground stud on a 4020 12V starter as one normally grounds negative cable to frame or engine block.

Thanks,Jim

tim s · Dec 8, 2009

I have "never" seen a 24 volt starter successfuly converted to 12 volt, there have been a couple of starter shops around here attempt it, but they never worked out, I'm sure someone on here has made it work, but I don't waste time and money trying,some the newer starters do have a ground terminal on the starter frame, I run a short cable to a mounting bolt..

Douglas01 · Dec 8, 2009

I had a similiar problem with my 4020, engine would not roll over very fast and on cold days it would not crank. After burning up 2 starters and replacing batteries, what I found was the batteries I was using did not have enough cranking AMPs, replaced with new Interstate batteries and now, I have no problems cranking, even in cold weather.

John T · Dec 8, 2009

I dont know beans about new gen or those starters but Id think changing the fields IS A MUST for 24 to 12 volt conversion. I CAN SAY a voltage drop from 12 all the way down to 7 IS TOO MUCH indicative of a starter or other serious problem. Also the old 24 volt were NOT case frame grounded starters so thats another important change. My old friend Gerald J is good on these type of questions, maybe he can help..

John T

4020_1966 · Dec 8, 2009

The Delco 12v starter specs Deere has listed say it should be 8.4V when cranking over. 7 is to low for cranking.

Anonymous-0 · Dec 8, 2009

From what I've heard the good 12 volt starter is a NipponDenso probably geared from later JD tractors. Its reputed to be far superior to the Delco starters made for 12 volt diesel starting.

There are two sizes of the long skinny batteries, a 3EE and 3ET. One has more cranking amps than the other but neither has the cranking amps of a more modern rectangular battery. The connecting bars have to be too long in the long skinny battery. For my gas 4020, I made an enlarged left step and sat a side terminal battery right next to the starter with SHORT heavy cables. That with a bigger battery should work for diesel with the Denso starter too.

Make sure the battery cables after the conversion from 24 to 12 are SUBSTANTIAL. 12 cranking takes at least twice the current of 24 volt cranking and so twice the cable size at least. Larger only hurts if the cable is stronger than the battery post and rips off the post instead of bending.

Gerald J.

tim s · Dec 8, 2009

Yes, the Nippendenso starters are far better than the Delcos, they are my starter of choice(even thou they are made in Japan), it seems that the bushings are better which keeps the armuture centered better for a longer life, the cables are just as important as good batterys, and as always every thing needs to be in "harmony" for a cold morning start up.Lack of all these 'modern' electrical advances is what made the old Pony engines shine in there day...

Dale in IN · Dec 8, 2009

Jim:
Go get you a starter off of a 4320. It will fit right on where your 24 v starter was. It is 4" longer than the orginal 24 volt case. And it has a lot more tork. I tried converting mine years ago with no luck. Then a John Deere Dealer Machinack told me to do that and it solved my problem. I could hardly believe how that 4320 would spin that engine.
dale

buickanddeere · Dec 8, 2009

It appears the chassis return end of the field winding was connected to the old + terminal. Instead of being bonded to the starter's case internally.
The starter may operate better if that old terminal is connected back to the battery (-) post.
Given the same size starter body, it's possible to push more volts X amps through the windings with 24V rather than 12V. To compensate the windings and therefore the starter body. Have to be much larger on a 12V starter to make the "same power".
The 4230 may have used the mighty Delco 37MT or 42MT starter. Even with 12V if used with two 1000CCA batteries and 2/00 cables with swagged ends. Those starters will crank a 4020 to near idle speed.A 37MT will make approx 9HP on 12V if memory serves.

Anonymous-0 · Dec 8, 2009

If a motor makes a particular horsepower rating on 24 volts at a specific speed the design need only half the turns of twice the wire cross section to make the same horsepower at the same speed and fits in the same case.

That being said, the 4020 starters were not oversized, but if anything were smaller than needed for reliable starting so a bigger starter is a benefit if it fits.

Gerald J.

buickanddeere · Dec 8, 2009

You double the voltage on the same sized wire then the magnetic field will be four times stronger if the magnetic path doesn't become saturated.

M w J · Dec 8, 2009

I just put an 8000 series gear reduction starter on a 4440. The nippondenso is a good starter But the gear reduction starter is smaller in size and turns twice as fast and is $20 cheaper $403. We forgot to plug in the 4440 last night to run an auger and it started this morning at 7 degrees.

Mike M · Dec 8, 2009

I had one done for a JD500 and wasn't happy. Got a late 4020 12V starter and it was better ?
This was before all the other choices of starters out now.

I ended up putting it on our gas 4020 with a starter drive change.

Anonymous-0 · Dec 8, 2009

But so will the wire heating that destroys the insulation. It will also be four times greater at twice the current and twice the voltage. Tends to lead to smoke and shorted turns in the windings.

Gerald J.

buickanddeere · Dec 8, 2009

A little cross referencing through the Delco parts book will show the some of the same windings used with different voltages.High torque applications for example.
I should have said four times the power, not four times the magnetic field strength.
It takes some math but the cross sectional size of wire doesn't change by 1/2 or doubling to carry the same amount of power. When the voltage is doubled or 1/2'd.

Anonymous-0 · Dec 8, 2009

Does if you are going to use the same current density and wire heating. At least that's the way I designed motor windings and transformer windings.

Gerald J.

Anonymous-0 · Dec 8, 2009

Check and see if your nose cone on that gear reduction is aluminum. Dealer talked me into one for a friends 3010. Year and a half later I was prying the nose cone and pieces out of the clutch housing, yep broke off, wasn't much of a deal after all. Has a Nipp. from a 4440 now like I wanted in the first place. chris

Tx Jim · Dec 9, 2009

Thanks for all replies. I'll tell him again he needs a starter. When I first went to look at tractor I told my neighbor he needed to get a Nippodenso starter but he had already tried the cheap way out.

JDemaris · Dec 9, 2009

You cannot use 24 volt field coils in a 12 volt system. The wires are too small and the windings are wrong. In most cases, the higher the voltage, the smaller the wires.

That's why 6 volt starters work fine on 12 volts. They are overbuilt for the job. You can go up but you cannot go down.

A 12 volt starter can't be made to work on 6 volts and neither can a 24 volt starter on 12 volts.

M w J · Dec 9, 2009

Yep it is aluminum I would say if 1 broke there had to be a reason. We have a 3020 that has broke a cast starter . If it was a gas and backfires they will break if the starter is engaged with the flywheel still turnin slow they can break .JD has been useing these starters for long enough now if the aluninum parts were a problem they would not still be using them.

Tx Jim · Dec 10, 2009

JDemaris
I was thinking that because the field coils had a stud through them and the case that the re-builder tried to change the starter from 24V to 12V.

Is there a better place to purchase a Nippodenso starter than JD?

Will a starter off a 466 fit a 404?

JDGnut · Dec 10, 2009

Tim,
They are still using the 3 bolt pattern for the starters.. any of them will possibly fit.. The only issue you have watch out for is which intake it has on it.. if its got the round intake that curves down, they will not let it fit.. (same for the gear reduction starters.) I wish I had writen down the part numbers for the starters I have used.. but I think it was usually the Nip starter others have talked about..
You can try ebay...
JDGnut

Drop me an email, I tried to sent you and email, but it came back..
Thanks,
Bryan
[email protected]

4020 starter 24v changed to 12v

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