Starter/Alternator on a "B"...
Printed From: Unofficial Allis
Category: Allis Chalmers
Forum Name: Farm Equipment
Forum Description: everything about Allis-Chalmers farm equipment
URL: https://www.allischalmers.com/forum/forum_posts.asp?TID=195167
Printed Date: 21 Aug 2025 at 9:08pm
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Topic: Starter/Alternator on a "B"...
Posted By: LBOW
Subject: Starter/Alternator on a "B"...
Date Posted: 15 May 2023 at 9:43pm
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This tractor has been converted to an alternator 12v so now it's negative ground. Does that negatively affect the starter in any way besides turning faster? I've been hand cranking but I'm going to want to add a starter soon. Thanks
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Replies:
Posted By: SteveM C/IL
Date Posted: 15 May 2023 at 10:23pm
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I don't know how a B starter compares to a WD 45 starter but my 45 has been on 12V for 42yrs doing fine. It's a 6V starter.
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Posted By: steve(ill)
Date Posted: 15 May 2023 at 10:27pm
i have converted several "B" to 12v... Starter dont care one bit.
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Like them all, but love the "B"s.
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Posted By: HudCo
Date Posted: 15 May 2023 at 11:11pm
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i ran my 6v starters on 12 v for years but i have changed allmy starters to 12v now much much better no more slamming in hard now and then . when i do a 12v alternator on somenes tractor i always change the starter to 12v does not matter what color the tractor is
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Posted By: PaulB
Date Posted: 16 May 2023 at 6:50am
As said the starter will work just fine as is, however because of it spinning much faster as you have noticed it just might possible destroy the flywheel ring gear in time. This is not as much of an issue with the tractors with larger engines and flywheels, although the B,C & CA tractors are prone to this, however some will not, why this is, I can't say I myself have a CA that has been just fine on 12 volts for many years and others have needed a couple gear replacements. If your ruins the ring gear, the best thing to do is have the starter rebuilt as a TRUE 12 volt starter, this will slow down the starter speed and prolong the ring gear life.
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If it was fun to pull in LOW gear, I could have a John Deere.
Real pullers don't have speed limits.
If you can't make it GO... make it SHINY
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Posted By: DSeries4
Date Posted: 16 May 2023 at 4:06pm
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Positive or negative ground - the starter does not care.
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'49 G, '54 WD45, '55 CA, '56 WD45D, '57 WD45, '58 D14, '59 D14, '60 D14, '63 D15D, '66 D15II, '66 D21II, '67 D17IV, '67 D17IVD, '67 190XTD, '73 620, '76 185, '77 175, '84 8030, '85 6080
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Posted By: Steve in NJ
Date Posted: 16 May 2023 at 9:06pm
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I always tell our customer's if they're switching over to 12 volts, it's always a good idea to flip the Starter to 12 as well. Bent drives, cracked nose cones and damaged flywheel ring gears are just a few of the common problems when running 12 volts through 6V field coils. This tends to make the starter violent. Besides, who wants to split the Tractor to install a ring gear if you don't have too.... I do a lot of converted Starters for our customer's if interested.
Steve@B&B bb-customcircuits.com
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39'RC, 43'WC, 48'B, 49'G, 50'WF, 65 Big 10, 67'B-110, 75'716H, 2-620's, & a Motorhead wife
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Posted By: Les Kerf
Date Posted: 17 May 2023 at 7:48am
These starters are series wound, meaning the entire current flows through the field and then through the armature; in order to reverse the rotation you need to reverse the polarity of either the field or the armature, but not both. This is not readily done on these units.
Changing from positive ground to negative ground effectively changes the polarity of both field and armature, therefore the rotation remains the same.
On a permanent magnet type starter, switching polarity does cause the starter to run backwards unless you also could turn the magnets around.
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