Hi all,
was this magneto ever specified as original equipment? Reason I ask is I have D4 catalogs that cover the U-series and none of them reference this magneto. The only ones listed I can find are American Bosch. So, was this Wico a replacement part? And does any Cat literature refer to it?
My buddy's D4 Traxcavator's points spring is cooked (probably due to us hooking up what we thought was the ground wire, only to discover that someone previously had replaced the mag switch and turning it to off completes a circuit to 6V ...) and I would like to verify the correct parts numbers (points, condensor, rotor, distributor cover, coil), preferably both Cat and Wico. I don't actually see a reference list for Wico parts for this model
 

I installed new parts in the magneto today, fitted it to the tractor and tested its operation, which was fine. I replaced the points, condensor, distributor rotor, and distributor cap, with new parts from Standard Magneto. The fellow there said I should also replace the coil but I decided to continue using the current coil in case it was still good, which it was. So I have a spare coil if anyone needs on, at cost ($44).
The parts list is:
Part Cat# Wico# Price
Points 7M3894 1-5111 14.66
Condensor 2M2757 2-5007 9.63
Dist. Cap 5S5109 3-5025 55.72
Dist. Rotor 5M8036 4-5008 48.46
Coil n/a 5-5011 44.18

Things noticed - I needed to ream the bore of the points breaker arm as it was tight on the brass post, and I need to whittle the distributor cap as it was a bit too tight on the lugs that fit inside the magneto case for my liking.
The bearings in the magneto were tight and smooth so no other r-n-r was required other than cleaning and a new main gasket on the pony mounting surface

Looks like the magneto has become unreliable - will spark initially then after a few seconds of running (or maybe a minute) it will stop dead. After a minute or two I can get it to run again briefly. Condensor was new last summer. Does anyone have this mag lying around on the shelf? We need a new distributor rotor pedestal as ours is broken and glued back up badly