Disc Brake work on My Super M Farmall.Getting them to work !

Hi Guys,

I have recently replaced all 4 disc in my 1953 Super M.I have tried to adjust them in,but CANNOT get enogh slack out of the linkage to get the free travel in the pedals anywhere close to what the book is calling for.The pedals are REAL sloppy.
The expanders work,have good balls in them,NOT flat sided.

The surfaces inside that the disc rub against are smooth and NOT destroyed.

The brakes DO work,but ONLY at a FULL,harsh laying on them !!! One side "locks up/drags" after it is applied and will do so untill you back up and release it.(ME,thinking the expander is traveling PAST its full intened expansion capacity.)

I am thinking I have too much clearance total in between the brake hats/expanders and the disc???(In other words,the expanders are haveing to travell WAY outside their capacity to "scrub up against the disc.)

I was wondering if I could take the "hats"/covers to a machine shop and maybe have them milled down to tighten things up?

I know OEM works on disc brakes,But want WAY too much money to fix things !!!!

Also,since I will have the brakes apart,how much trouble is it to remove those pinions that the brake disc ride on ???? I know there is a seal behind them that is probably WAY overdue to be replaced?

Any help is appreciated. Thanks

Yes you can mill the"hats".take the 'guts' with you and measure with a syraightedge to find how much to take off.IFIRR,you should have about 20,ooo gap.then you will have to shim the bolt heads wth washers to take up the slack.

Mike I had same trouble on my 450. To get them to work I took a disk sander and polished the outer housing and the surface next to rearend. Once i got them cleaned up they worked fine.I also used new new expanders. Did you check the preload on the adjustment rods.

Are you meaning how tight the spring and ball shaped pivot "thing"that sits in the hole thru the pedal on the bolt is?

If you haven't already done so, pull the springs that hold the expander halves together. Take some sand paper, and by hand, sand the ramps that the balls ride in. The other area where they can "drag" and not allow a release is the three areas where the expander circumference touches the "hat". Sand the surfaces of the expander and of the "hat" where they touch. Don't know what others use for lube but I use a hi temp grease to lube the balls and ramps and where the expander touches the hat. Also lube all linkages. Yes the "hat" can be milled to tighten up the clearance, don't remember how much though.

Anyway, that is what I did for my 560 and the brakes work well and do not lock.

So,are you saying I need .020 gap TOTAL between all the brake cover/hat/brake disk/area against rear end housing(TOTAL CLEARANCE??? )Seems kinda tight to me?I dont know,I am just asking cause I dont know.

If you want those brakes to be amazing, sandblast all brake surfaces, the ball ramps and holes, they will work like you never imagined. Did this on alot of SMs 400s and 450s. Make sure to grease each ball and ramp, silicone the brake cover to. Moisture is the main killer of those types of brakes.

I would give it a little more than .020 clearance but not a whole lot more. The self adjusters in the larger tractors only move about .025 so it doesn't take a lot of room. Another thing I always do on that model and others with the spring cushioned adjusting bolt is to tighten the spring down tight. I feel it gives a better feel on the pedal. There is a spec on the compression of the spring but I don't go by it.

Yes, plane those covers. I've done 2 SH's, 1 SMTA, and 1 400 brake job. Once you plane one set of drums you will always do them. Take off.100 for a starting point.
Clean up the inner surfaces with a 40 grit flap wheel. Hit your discs with a rough rat tail wood rasp. Keep it flat across both sides.
Or a 6 inch floor belt sander is good with rough paper.

Hey Pete,

Are we talking TOTAL clearance of everything ???

If I measure the epanders from outside to outside surfaces, PLUS the width of BOTH brake disc.

Then I take that measurement and check the depth of the cover from the mounting surface to the surface where the disc touches.That measurement should be .020 + MORE than the disc and the expanders ???? I dont wanna screw this up!

.040" to.050" total clearance. Stack height of 2 disks, and expander when collapsed, subtracted from the depth of the space between the inside surface on the tractor, and the inner surface of the cover,
this puts the linkage in a great mechanical advantage, Like new< and leaves enough clearance to prevent draging. Jim

Have to remember, you probably have a quarter inch now (well, maybe not that much but a lot) so don't get too carried away machining it down. When you tighten things down good dimensions as close as .020 change. Better a little too much clearance than not enough. And like I said before and some one else mentioned, the pre load on the adjustment bolt, I tighten them down tight. No spring at all. They got away from that spring on later models.

I want to thank everyone who posted here.(I dont see email capability to reply to everyone.)I have the brakes working beutifully.


Thanks for all the input