47 m cracked rear case

Gents,

I've got a crack in the underside Of the rear case of the tractor. Can you Weld cast or can you fix it with j b weld? The tractor is leaking Rear End fluid. Has anyone experienced this problem before

I thought most M's had cracks in the rear end. Isn't it from when inside axle bearing gives out
& a ball gets wedged between the bull gear & the rear end case? Mine has a patch welded on the bottom side of the rearend housing. Very professional repair job long time ago. At least 50 years ago.

Yes, a GOOD welder can weld cast! Ask around and find out who is the best welder in your area and go talk to him/her.

The rear case of my M cracked when a bolt broke in the differential and got wedged between the case and the bull gear.

I suggest that you try to find out what caused the crack. You can lift the cover using the bolt holes that hold the seat on. BE SURE to put a block between the lid and the case when you are investigating the cause of the crack.

If the crack is new, it is most likely the ball bearing issue mentioned below. If it is old and has been operated for many years and the axle is nt loose, it may be OK. I would still do the following if it is an old issue.
Lift the side of the tractor that on which the crack appears. Lift on the axle housing and block the housing with cribbing to assure safety.
Lower the oil level in the case by removing the plug till at least all oil in that chamber is removed. (10 gallons is likely.)
Remove the PTO unit from the rear.
Through that hole you can feel around in the bottom of the case to retrieve parts if any. Use a magnet pickup tool to get everything. Have a helper with a 2X4X8 pry on the tire and wheel while you feel inside to determine if the bull gear is moving up and down any. A few thousandths is OK a quarter inch is not.
If it moves a bunch, the top will need to come off, and the the bull gear and axle housing taken apart to change the bearing. I think the best plan would then be to weld the case from inside and out to repair the crack. A 1/4" deep V groove, and cold welding with Ni rod (short 1/2" beads. then hammer peening with a pick hammer, then more weld, never letting it get hot, 20 minutes of cooling for 30 seconds or less of welding. Will make a permanent repair. If ground and finished on the outside the repair will disappear. Best of luck Jim

What Jim said will work well. I"ve seen some interesting ones where a patch was riveted or bolted instead of welded.

Most, I think not. Have layed under a few though and put a patch on them. Not the right way to do it though. I would strip the case, clean it until no oil is left in crack and then clean it a couple more times. Then take it to someone who will repair it to look like new.

Pretzer is right the inside axle brg goes out and the bull gear wears on the case and cuts a groove the width of the bull gear and if a ball goes through it pushes out the bottom. As a young feller the dealership where I worked removed many of the cases and had a good machine shop weld them up. Farmall had a lot of tranny rear end trouble it seemed in those days Maybe the other makes did also but didn't work there to know. later JOhn