Farmall 300 brakes

Bkpigs · Mar 2, 2015

Still having problems with the left brake locking up on the left side. The distance from the mounting surface of the drum to the wear surface is 2.22 inches and the thickness of the pads is 1.00 inches when put together. Is that within the tolerances?
The pads have plenty of material left. I took the expander plates apart and they seem fine. No excessive build up or anything. I cleaned them and the balls up but still no dice. I don't want to get too crazy cleaning them up and take too much material away and cause more problems. As I am typing this I got to thinking if maybe the springs on the expander plates are a little weak. Would that cause this issue? Thanks in advance.

Janicholson · Mar 2, 2015

If the disks and expander are placed in the housing while on the bench, there should be no more than~.050" clearance to the top of the housing. if there is, the housing edge must be machined to that spec, or .030. Jim

300guy · Mar 2, 2015

Welcome to the club!! My 300 did the same thing even after replacing the disks, balls, springs and having the drum, and inside plate surfaced. The drum was surfaced to the correct tolerance but it would not stop and kept locking up. Everything was cleaned, lubed and cleaned again with all the rust removed three times. As a last resort, I replaced the actuator and so far that has solved the problem.

David G · Mar 2, 2015

Can you tell me what you mean by locking up? I had a disk brake on my MH engage on me coming down the road. It would not disengage, took it apart and found nothing wrong.

MikeJM · Mar 3, 2015

The mechanical disc brakes used in the 300, 400 and lots of other tractors into the 70's were of the self engergizing type, meaning that when you applied the brakes some of the rotation of the brake disc helped you apply the brake harder. The problem is when they grab like that and won't release you have to back up to get them to unlock.

We had the same problem on our 300, a new actuator solved the issue.

Bkpigs · Mar 3, 2015

(quoted from post at 06:00:04 03/03/15) Can you tell me what you mean by locking up? I had a disk brake on my MH engage on me coming down the road. It would not disengage, took it apart and found nothing wrong.

There is no gently applying the brake. It goes from free-wheeling to locked up when you push the pedal.

Thanks for the suggestions. I will look into getting new actuators.

Edit: That was untill I seen the price on those. I will give the new springs a try first.

jeffcat · Mar 3, 2015

On the actuator when you finally buy a new one you will see that the little "ramp" where the ball rides is worn. There is a hollow and that is the big problem. New springs could help and the balls should be SPOTLESS with no rust or shadows from rust. When everything is correct they work very nicely. Not quite air brakes but they stop pretty durn fast.

GordoSD · Mar 4, 2015

As Jim said check the space between the top disc and the drum edge , vertically when lying on the bench. If you have too much then those balls travel further down the ramps than they were designed to. Can also be result of the ramps being worn down too far.
Did you plane any off the drum edges. I start with .075 off an every brake job I do.

Bkpigs · Mar 4, 2015

I have .06 for clearance.

Janicholson · Mar 4, 2015

A little bit too big, I would take it down to .035". If the ball ramps are very clean and have no "dents" from wear, and the surfaces have been deglazed (A DA sander with 150 grit works well) it should be OK. Sometimes oil saturates the plates. heating them with a propane torch (gradually) can reveal if they have been saturated. If oil boils out, they will grab till you get the oil out (baking with a torch will work, do not char them. Jim

60 acre hillside · Mar 5, 2015

300 WITH BRAKES!? I know there were pedals, but brakes? Maybe I just drove the worn out ones.

Repair · Mar 5, 2015

Do you have any trans grease leaking in the brake assy?
are the brake disks in good shape? are they wore out.
Get 3 new springs for the actuator plates.
The surface that the brake disks will push on have to be clean, Inner & outer.
than adjust them.
You do have the springs on there that go to the brake pedal? Don't oil nothing in that housing.
I put a little amount of heavy grease on the 3 humps on the brake actuator, Don't get it on the brake disks!!
All the IH M's That have this type of brakes are stand on the peddle & hope for the best, Or just close your eyes!! Brakes.

mkirsch · Mar 5, 2015

.060" is too much clearance for the brakes to work properly. The actuator over-extends past where the springs can pull it back.

New disks may be enough to get it back near spec. You'll want new disks if you decide to have the drum machined anyway. No sense in taking too much off.

From the 656 on, IH got smart and added removable shims to compensate for wear on the brake surfaces. When it starts to lock up, you pop the cover plate off and remove a shim.

Farmall 300 brakes

Bkpigs

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Janicholson

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300guy

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David G

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MikeJM

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Bkpigs

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jeffcat

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GordoSD

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Bkpigs

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Janicholson

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60 acre hillside

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Repair

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mkirsch

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