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Brake chatter: Prevention and remedies

Michael J. Thomas for Progressive Dairyman Published on 05 August 2016

Many of us have experienced a growling chatter emitting from the brakes of our tractors when we apply either brake independent of the other or both together. I had been having this trouble on an older 510 industrial John Deere backhoe and finally broke down and took it to the shop.

I contacted a good friend who happens to be a very good tractor and machinery mechanic from Twin Falls, Idaho, Jake Jackovac. He instructed me to start by pulling a hydraulic fluid sample. The sample revealed that the fluid contained excessive moisture and sludge.



At this point, Jackovac asked me if I had ever changed the fluid to a high-performance tractor hydraulic fluid (THF), or was I still using the 303 THF that was recommended for the backhoe when it was manufactured? I had to admit that I had never changed it from the original recommended fluid.

“The problem with THFs such as 303 and other similar older hydraulic fluids is that they are manufactured using processes more than 30 years out of date,” said Jackovac.

“When these fluids were originally recommended, the recommended change intervals were more frequent, and the load demands on the internal parts of the system were not as high as they are today. Today’s high-performance THF has special additives to improve viscosity, reduce wear, and inhibit water and corrosion.”

Jackovac said, “The physical action that causes the chatter may be the result of ‘stick-slip.’ This happens when the friction disk sticks to the steel plate, then breaks loose in rapid succession. This results in a stutter or ‘chatter’ in the brakes. This creates the noise you hear and the stutter in the brake pedal."

"Often, this problem is related to the hydraulic fluid being contaminated with water or sludge. It can be a mechanical issue if the disks are worn badly and rusted.”


As I did a little more digging, I learned that John Deere had dropped its specification on 303 in the 1970s and began to make advancements in THF formulation.

Jackovac provided me with the name of a service representative, Darby Johnson, with Dillon Implement in Dillon, Montana. Johnson explained more of the details involving the differences between 303 and the high-performance THFs available today.

While 303 THF is cheaper initially, maintenance costs and loss of performance offset this savings over time. Manufacturers of 303 use cheaper, heavier base oils to thicken the fluid rather than viscosity-modifying additives.

These heavier oils do not provide the proper viscosity at varying operating temperatures, which contributes to excessive wear of internal components of the hydraulic system, hydraulic pump starvation and brake chatter.

Johnson cautioned that there is no industry standard for hydraulic/transmission fluid, and equipment manufacturers set the minimum requirement for their own equipment but do not test competitors’ fluids that claim to meet requirements.

He told me that many of the additives currently used in high-performance THF – viscosity modifiers, anti-wear additives, anti-corrosion additives and friction modifiers – were not added to 303 THF and are not required to be added to generic or store brands that claim to meet manufacturers’ requirements.


When Johnson learned that I was still using 303 THF in the 510 backhoe, he asked if I had noticed a difference in the performance of the machine between summer and winter.

“The sluggish response in the hydraulics for the first half-hour to an hour on a cold day is due to the hydraulic fluid being too thick to be picked up and pumped through the system efficiently until the oil temperature rises to a degree that allows the system to work correctly without starving the pump,” he said, then added, “Without the moisture inhibitors added to modern high-performance THF, the hydraulic filters in the system collect sludge more rapidly, also contributing to a sluggish system.”

When I asked Johnson if the trouble I had been having with the backhoe not cranking fast enough to start after the backhoe had been run for an extended period on a hot summer day could be related to the 303 THF, he said, “If you are having to manually disengage the hydraulic pump to start the hoe when the fluid is hot, it is very likely associated with the THF failing to provide proper lubrication to the pump or the relief valve.”

Johnson said modern high-performance THF also contains anti-wear additives to prolong the life of bearings and gears. These fluids leave a high-pressure film on the components of the system to prevent metal-on-metal wear.

“The absence of anti-wear additives in the 303 THF are contributing to problems such as the hard starting of your backhoe on hot days,” Johnson said.

High-performance THF also contains anti-corrosion and erosion additives to prevent rust and pitting of the internal parts of the system. Johnson said, “It is likely that you will find the moving parts of the system, valves, brake parts and components of the pump are pitted with rust, and that may be contributing to both the brake chatter and hard starting in the summer.”

Johnson explained that the job of modern high-performance THF is very complex. In addition to all of the lubrication, anti-wear and proper viscosity requirements of the fluid, it also must provide the proper amount of friction for wet clutches to absorb shock without excessive slipping and provide the proper amount of friction for the brakes to provide maximum stopping power with little or no chatter.

After determining that I had moisture in the hydraulic system of the 510 backhoe, Jackovac drained the fluid and removed the transmission/hydraulic system filters. He then cut the filters in half, and we looked at the debris within the elements. The filters were filled with a heavy sludge and rust flecks. Jackovac drained the THF from the hydraulic/transmission system and refilled the system.

After refilling the system with a J20C-rated THF, Jackovac started the backhoe and tried the brakes again. The chatter was reduced but still present enough to be troublesome.

“There is one more thing to do before breaking into the backhoe and checking the condition of the brake disks and other components,” Jackovac said. “There is a good noise- reducing THF out there that we can substitute for J20C (Hy-Gard).”

We again drained the hydraulic/transmission system and filters. After refilling the system with J20C noise-reducing THF, we again tried the brakes. The brake chatter was all but completely eliminated, but Jackovac did have to replace the electric relief valve to correct the issue with difficulty starting the backhoe on hot days.

As Jackovac put away his tools to leave, he said, “Just treat your older tractors as if they were newer models and replace that 303 THF with high-performance THF, and you will save yourself a lot of trouble and downtime.”  PD

Michael J. Thomas is a freelance writer from Salmon, Idaho.