Farmall M Disc Brakes

dhs

Member
I have a late M with disc brakes that I have problems with the brake discs glazing over. I take it apart and rough up the discs with sandpaper and the brakes work good for a short time. There is no oil leaking and the actuators, springs, and balls are all good and working. I swapped discs out of another tractor and that did not make any difference. The actuators are very smooth without any grooves or pitting.
 
The total space when the stack of parts are in the housing, and aligned where they should be, is .045 to .060" measured to the
mating surface of the housing to the tractor. way too much makes them either not work well, or work too well and lock up. Make
sure no trans oil is getting on them. Jim
 
(quoted from post at 17:14:04 09/12/20) The total space when the stack of parts are in the housing, and aligned where they should be, is .045 to .060" measured to the
mating surface of the housing to the tractor. way too much makes them either not work well, or work too well and lock up. Make
sure no trans oil is getting on them. Jim

I will check that clearance, thank you.
 
(quoted from post at 20:02:53 09/12/20) I had the discs sand-blasted lightly and it solved the glazing issue.


I have thought about blasting both the discs and the actuator plates.
 
If the clearance is wide, the wear is in all 4 friction surfaces. To make it right, the housing casting is machined so it sits
closer to the differential casting. Jim
 
(quoted from post at 21:38:12 09/12/20) If the clearance is wide, the wear is in all 4 friction surfaces. To make it right, the housing casting is machined so it sits
closer to the differential casting. Jim

What about the brake discs, how does their thickness affect the clearances? I don't see a minimum thickness spec in the IH manual.
 
New discs in a worn housing, expander, and differential carrier, will probably not be fat enough to be within the specs. I gave. I
use those numbers from experience, not a book. call Yesterdays Tractor and have them measure the thickness of one of their new
discs. They are friendly. If 3/4 thickness of new or less, replace them before machining the housing. Jim
 
(quoted from post at 11:59:15 09/13/20) New discs in a worn housing, expander, and differential carrier, will probably not be fat enough to be within the specs. I gave. I
use those numbers from experience, not a book. call Yesterdays Tractor and have them measure the thickness of one of their new
discs. They are friendly. If 3/4 thickness of new or less, replace them before machining the housing. Jim

One stack height is .045 to .050 and the other is .055 to .060. I did notice that the .050 side was trying to work a little and the .060 side was glazed smooth as glass. The brake discs are fairly new.
 
(quoted from post at 05:05:00 09/16/20) Why not sand blast that would bust the glaze even the steel you would have brakes that would stop now

That's just what I did. I blasted the outer housing, actuators and the discs. I cleaned up the inner wear services with 36 grit. The brakes work great. I don't do this yearly but I should if I want to keep the brakes working 100%. The reason for my original question is why do these brakes repeatedly glaze over? I have tried new discs and they are kept in adjustment. Everything in in good condition as this is a very low hour tractor. It does sit a lot and is only used about an hour per week for feeding.
 
So it takes a couple/few years for the discs to glaze over?

The way you made it sound originally was like it happened frequently, in the matter of hours or days.

Glazing over is the nature of the beast, especially if you use a light foot on the brake pedal and/or ride the brakes a lot. That just polishes and burnishes the surfaces to a perfect shiny glaze. Cleaning off the glaze is a maintenance item.

Clearances are only an issue if you run into the problem where the brake locks up.
 

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