1943 Farmall M: Rear Axle Overhaul

Notes taken while overhauling the rear axle in on my 1943 Farmall M.

Some things are taken from my direct experience. Other stats are taken from various online and offline sources. No guarantees. Any prices listed here are for my own research. Things change.


Securely block up the tractor and remove the rear wheel(s). But before further disassembly, grab the outer end of the axle shaft and try to lift it. If there is play, one or both of the bearings may be bad. Even if you do not feel play, you will want to carefully clean and inspect the bearings. I had an inner bearing that seemed tight, but one ball was fractured.

Bull gears

Unbolt the bull gears and slide them off the axle shaft splines.


Unbolt and remove the rear axle housings (carriers).

Remove the inner bearing retainer and outer bearing cap.

To separate the axle shaft from the carrier, put some boards on the ground (to prevent marring the spines). Stand it up on the splined end. Then lift the carrier by the “ears”, and drop it a few inches repeatedly until it separates.



Scrape out the accumulated crud (grease and dirt) from the bottom of the axle carrier. I suggest standing it on end and flushing with brake cleaner so that you are sure you aren’t pushing old dirt into new bearings.

The carrier caps have an overhang covering 34 of the top side of the axle, with a groove along the inside. This is to keep dirt away from the seal, yet allow it to fall to the ground if some does get in there. However, both of my caps had the grooves packed hard with dirt. Dig these out.

While the caps are off, push some clean grease through the grease zerks.

Locating parts

Complete overhaul of the transmission and axles rear axles (replacing all wear parts with new) may run approximately $750, if you pay the asking price.

Price shopping, finding new-old-stock (NOS) parts, and better cross-referencing of aftermarket parts can get it under $500. If your inner bearings are still good, it will be much less.

Typically, farmallparts.com has competitive prices, but browsing the site doesn’t always lead me to the part. I’ve found that searching on google for the part number with the “site:” qualifier works well. For example, I found the inner bearings by searching for “st223 site:farmallparts.com”.

Surprisingly, for several parts the Case IH dealers are cheaper. Don’t overlook the dealer when price-shopping. (Some parts are OEM-only, so in an attempt to be comprehensive, I suspect that some shops source and resell OEM at a 20-25% markup.)

Direct interchange bearings may be cheaper, but know the manufacturer, and count the number of balls. Some IH bearings were “maxi-fill”, meaning they notched the race to fit another ball in, for additional load capacity. I don’t yet know of any of the Farmall M’s were considered “maxi-fill”, but I have noticed that some current CaseIH replacement bearings have fewer balls (example is ST-223 which had 16 balls; replaced by 84330092 with 15 balls). I am curious if current processes are improved enough to compensate, or if this is a cost-savings measure.

Ball vs Roller Bearing

(To be verified)

The letter series tractors used ball bearings for the axle shafts. The hundred series (at least, 460 and 560) used roller bearings. The roller bearings are likely stronger since there is a larger contact area.

Need to research compatibility.

Parts breakdowns

Rear frame cover gasket

Rear Frame Cover Gasket - M, MD 49056DA, 358843R1, 1981227C1

Rear axle carrier

  • Rear axle carrier cap gasket 48950D → 1981232C1
  • Rear axle felt washer 45085D
  • Rear axle seal 48776D → 377788R91 ID 2.750; OD 3.756; width .5 Cross-reference:
    • 360457R91
    • 358780R91
    • 358819R91
    • 377788R91
    • ABC1565
    • UT3216
    • Timkin 455004
  • Axle carrier gasket (“kidney gasket”) 47670DB
  • Cap 6727DBU


Drive shaft

Original is 52089DA; replaced with a 52089DC.

  • drive shaft 52089DA
  • smaller bearing ST-239
  • spacer
  • larger bearing
  • inner roller bearing
  • inner roller bearing retainer
  • gasket 48730D → 1342400C1
  • driving shaft seal 43359D → 71871C1
  • driving shaft gasket 48730D → 1342400C1

Counter shaft

  • (3) woodruff keys 88745

Slider shaft

Inner rear axle bearing

Original ST-223 (16-ball version) → 8433009 (15-ball?).

This seems to be one of those times when it’s cheaper to go the dealer and buy the newest version.

Cross reference: - Timken 1214AG $115 - Fafnir 214W (open)

Outer rear axle bearing

Original was ST-310 (11 balls, sealed one side) or in later models ST-310A (10 balls, sealed one side). I removed New Departure 3214 (11 balls, sealed on one side). Don’t know if that was factory original.

These are somewhat difficult to cross-reference and locate currently. CIH wants $135 for ST-310.

Other bearings fit, but have no shield. The shield is intended to keep grease and oil separate. I prefer to stick with this original design, even though other open bearings physically fit (ST-675, ST-223, L-270, L-265, …?)

My old bearing has stampings “New Departure 3214 / Shield Bearing Number 7514”. Based on the “New Departure Handbook”, Sixteenth Edition, published May 1943, (available free on Google Books, or multiple paper copies on eBay), the “3214” number means no shield. “7514” is one shield, and “77514” is two shields. Apparently my bearing with both “3214” and “7514” is an amalgamation and therefore I should order 7514.

New Departure 3214 / 7514 are available on eBay and Amazon for $55 / $75 shipped (respectively), via locatebearings or now it seems to be locateballbearings. Supposedly new even

Cross reference: - ST-310 (11 balls, shielded) - ST-310A (10 balls, shielded) - New Departure 7514 (11 balls, shielded) - Nachi 6214 ZZE (shielded) - ST-253 (OD 125mm ID 70mm W 24mm) - PC-270 (11 balls)


flat belt pulley; 4 bolt; 10.5” diameter; 49248-D

Updated December 21, 2014