Farm Equipment - off color MM GUYS- Ground question

Print Page | Close Window

off color MM GUYS- Ground question

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=8193
Printed Date: 18 Jan 2025 at 9:30pm
Software Version: Web Wiz Forums 11.10 - http://www.webwizforums.com

Topic: off color MM GUYS- Ground question

Posted By: Anthony
Subject: off color MM GUYS- Ground question
Date Posted: 16 Feb 2010 at 3:21pm

I have a 1951 U LP and a 1955 MM U LP, where any of these U's positive ground.......what would happen if I tried it like that would it fry my electrical wiring?

As always many thanks

Anthony

Replies:

Posted By: Gerald J.
Date Posted: 16 Feb 2010 at 3:52pm

Check the battery connectors and the battery posts. They are fat and thin for that reason to make it less convenient to connect the wrong polarity. Unfortunately if the cables or connectors have been replaced, all bets are off. You need to polarize the generator to the battery before starting the engine. Another check is the coil polarity should be the same as the battery, + to points for positive ground, + to ignition switch for negative ground. The coil polarity should match the battery polarity for the best ignition. An alternator and a solid state radio are absolutely unforgiving for reversed polarity. A solid state regulator too. A vibrator type regulator can be not too forgiving giving short life with the wrong polarity because of the different metals chosen for the points. Lights and starter don't care about polarity in the vintage tractor. A modern tractor with permanent magnet starter fields cares about polarity. The starter will run the wrong direction with the wrong polarity, but the bendix won't engage all the way probably.

Gerald J.

Posted By: Matt (Jordan,MN)
Date Posted: 16 Feb 2010 at 5:43pm

I have 4 U MM's and they are all Pos. ground. I belive that all MM tractors were Pos. ground until the 60's

Posted By: Anthony
Date Posted: 16 Feb 2010 at 7:19pm

If you hook the battery up wrong will it still spark at the points

Posted By: norm [ind]
Date Posted: 16 Feb 2010 at 7:49pm

most all tractors up to the 60's were positive grd. regardles of color

Posted By: Anthony
Date Posted: 16 Feb 2010 at 8:35pm

Thanks Norm, does that inlcude my Allis WD, it must have been change because ever since I bought it I have been running it with negative ground

Posted By: Anthony
Date Posted: 16 Feb 2010 at 8:36pm

it seems to run fine, just has some charging problems, my voltage regulator went out and I couldnt find another one to replace it, or maybe battery was hooked up wrong, what will your amp gage do if it is hooked up wrong will it show that it is charging

Posted By: Roger A. NY
Date Posted: 17 Feb 2010 at 3:42pm

All tractors regardless of color WERE NOT POSITIVE GROUND. Case SC, DC and LA's were all negative ground from the factory. V series and VA series were posotive ground from the factory