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Playin' In The Dirt Again
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Discussion Starter #1
Hello Forum.

Today I was tilling some soil and noticed a screeching sound coming, I think, from the general area of the left rear wheel of my JD-750. It is a high frequency, downright shrill sound that comes and goes as the wheel turns. If I make a hard left I hear very little of it. If I make a hard right I hear more of it. If I use neither brake and just go forward, I hear it. If the tractor goes faster, the rate of the coming and going of the sound goes up.

Wondering if a brake was stuck or something, I checked to see if the tractor would pull to the left on its own, given a chance on flat terrain. It just went straight when I let the steering wheel go.

The left brake pedal is a little lower at rest than the right one. But it has been this way since I got the tractor in February, as best as I can tell. The brake pedals are not strapped together, as I use them separately a lot, and did today.

I looked underneath the tractor and did not see anything caught that could make the sound.

Any ideas what may be causing this mysterious screeching/squeeling sound?

Many thanks.

:Tractor2:
 

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On my 855, I've had them stick before after pressing them. I would push down hard on the pedal a few times and go forward and back and it would release. Doesn't do it very often, hasn't done it this year yet, but I remember it doing it twice last year. They don't screech or anything, but maybe your brakes are wore more.
 

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Playin' In The Dirt Again
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194 Posts
Discussion Starter #3
On my 855, I've had them stick before after pressing them. I would push down hard on the pedal a few times and go forward and back and it would release. Doesn't do it very often, hasn't done it this year yet, but I remember it doing it twice last year. They don't screech or anything, but maybe your brakes are wore more.
Thanks, Roush.

I discovered the problem. It was a stuck brake just as you suggested. Unfortunately, it would not release altogether no matter what I did. It just continued to squeak in the left rear wheel brake assembly.

I removed the left and right brake assembly covers. These contain the brake shoe assemblies on their undersides. This removal operation was somewhat troublesome. You see, the brake pads (left and right) were not relaxed and in their normal rest positions. They were instead extended, and were dragging the drums on both left and right. But worse on the squeaky left side. It took some careful, well positioned hammering to get the covers off, dragging the unwilling shoes out of the drums.

There is a shaft which goes through these covers, and which has a cam on its end. Turning this shaft and its cam shaped end causes the brake pads to separate, and press against the spinning drum, slowing or stopping the associated rear wheel, left or right. Those shafts were almost frozen, taking a lot of force on the pedal to engage the brakes. And the return springs between the shoes were not strong enough to overcome the stuck shafts.

On each brake assembly, the outside end of that shaft has a lever welded to it. And that lever is connected to the brake pedal by way of an attached rod.

Again, those shafts (both left and right) had almost completely frozen inside their pipe-shaped cylinders going through the brake cover plates, from outside the tractor to inside the brake housings. This was true on brakes left and right, but was somewhat worse on the left side, the squeaking side.

The shafts had to be punched out with a sledge hammer of five pounds.

I used a bit of light oil (PB Blaster) and back and forth hammering, out then in then out then in then out.... until it got looser and could finally be punched all the way out. I used a deep well socket of appropriate diameter as a punch for the sledge hammer to hit. When I finally got the shafts out of their collars/cylinders/tubes I cleaned the insides of the tubes with emery cloth dripping wet with mineral spirits. I cleaned the removed shafts with the wire wheel end of a bench grinder motor.

Once shiny smooth and clean, I coated the shaft and its cylinder walls with Red 'N Tacky general purpose grease (Lucas). After reassembly, the brakes work normally.

Problem solved.

I would recommend that folks with these tractors check and verify the proper function of those levers going into the brake shoe housings. It's quite difficult to remove the covers when the shoes are stuck in the braked position by reason of a frozen/rusted cam control shaft.

:Tractor2:
 

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I Love All Color Tractors
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22,321 Posts
Here is a diagram of what you are describing:



Nice write up about what happened and what you did to correct it.

On the larger 850, 950, and 1050 tractors, there is another bolt with another cam on it on the other end of the brake shoes that will adjust the shoes. That one has a lock nut on it that will sometimes loosen and go out of adjustment too.

Anyway, nice write up and glad that you got it fixed. :thThumbsU
 

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Playin' In The Dirt Again
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194 Posts
Discussion Starter #5
Thanks, DJ.

That diagram is really convenient to have in the thread. I appreciate your having put it here.

:Tractor2:
 

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Playin' In The Dirt Again
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194 Posts
Discussion Starter #6
Adendum:

When I was done fixing the frozen brake shoe housing covers and their control shafts, I noticed that the brake pedals could not be adjusted to be equal in position, even though both were indicating top of travel at rest, up against rubber bumpers underneath the footrests.

Being a newbie as I am, when I first got the tractor in late February I did not realize that those two pedals being on different planes actually meant something was out of order.

Evidently, what had happened was that the previous owner had stood on the left brake to make it work when it was almost frozen in that shaft that controls the cam that pushes the left side's brake shoes apart. That excessive pressure from standing on the left pedal had bent the tubular steel connecting the pedal to the underside brake control mechanism of the tractor.

Here's what I did to bend it back to its rightful position, next to the right pedal:

I chocked the wheels. Then I put a small block of wood between the upper side of the bent tubing and the underside of the footrest. This was to distribute upward force that would be applied to bend the tubing back upwards and straighten it out.

Then I put a piece of scrap wood, 2X12X18, on the gravel covered ground beneath the tractor, directly under where that tubing begins to curl upward towards the foot pedal. Then I put an automotive scissor jack onto that piece of wood. I cranked the jack up about 1/3 of its travel and noted the remaining distance between it and the bottom of the curved end of the tubing that needed bending upward. Then I cut a piece of 4X4 to that remaining length, 11-1/4 inches. Then I connected the 4X4 between the jack and the tubing's underside, as forward on the tubing as it could go without slipping. Then I cranked the jack up slowly. As I cranked it up, the tubing bent back to its original shape. When the two foot pedals rested at the same plane I stopped the jacking motion.

After that I readjusted the turnbuckle linkage between brake pedal control levers and brake housing levers on both sides. I made it so that the travel and pressure required for each brake was approximately equal to the other's. About two to three inches to achieve full braking pressure either side.

The brakes work well now. I noticed that I can drive the tractor without the steering wheel now, just pressing the brakes individually. Amazing. I also noticed that when I push in the clutch that the tractor continues rolling. Those frozen brakes had been dragging all along since I had gotten the tractor, causing it to stop fairly quickly anytime I pushed in the clutch.

:Tractor2:
 

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I Love All Color Tractors
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22,321 Posts
Nice catch and nice fix. :fing32:
 
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