posted 09-07-2010 08:57 AM ET (US)        

I picked up the boat on a Friday afternoon from my storage yard around 5 p.m. Due to road construction in the area, I had to drive home in rush-hour stop-and-go traffic, requiring very frequent application of the brakes. The trailer brake chatter was worse than ever, and nothing seemed to suppress it. It was time to look into the cause and remedy this problem.

Searching for some suggestions as to what may cause brake chatter on a boat trailer's brakes, one possibility was contamination of the brake drum surface with grease, likely from a leaking seal. I hoped that this was not the cause of my problem, as I did not want to tear down the wheel bearings and seals—a very messy job. Also, I had personally installed and greased all the seals and bearings on my trailer wheels, and I have not noticed any loss of grease, nor have I been pumping grease into the wheels via the BEARING BUDDY fitting on a continual basis. More searching found another suggested cause: one or more brake pads out of adjustment. This seemed like a more reasonable probable cause. I had adjusted the brakes when I installed them, but they had likely worn down some from the many thousands of miles we have towed the trailer on the highway.

The wheel that seems to be chattering the most from the sound of things was the left rear. I began my check of brake adjustment there. I jacked the wheel just off the ground and gave it a spin. The wheel rotated freely. (More on this below.) There was no sign of any brake pad drag, which meant the brakes were now too loose. It was time for some adjustment. This was actually a good sign for me, as it indicated that perhaps the chatter was being caused by poor brake adjustment, and not from grease escaped from the wheel bearings.

Drum brakes can be adjusted without tearing down the wheel by accessing a star-shaped adjustment wheel via a slot in the brake backing plate. There is a specialized tool that makes this adjustment easier. On drum brakes there is a bit of an oddity regarding this star wheel adjustment: it works differently depending on which side of the trailer the brake is installed. On one side clicking the wheel upward will tighten the brakes, while on the opposite side clicking the wheel upward will loosen the brakes. Fortunately, when I installed the brakes I made a few notes about which direction on each side produced tightening and loosening. I wrote the notes on the package that contains the adjustment tool. Also, there are two slots on the brake backing plate for access. The slots are normally sealed with a press-in pliable plastic plug. Only one slot accesses the star wheel adjuster. To help identify which slot was adjacent to the star wheel, I color coded the plastic plugs. Knowing where the star wheel adjusters were located and which direction to turn them was a big head start on the adjustment process.

Adjusting the brakes with the boat on the trailer is possible, but the access is a bit better if you can perform the adjustment without the boat in the way. Unfortunately, I had to work around the boat.

I gave the star wheel about ten clicks in the direction to tighten the brakes, then check the rotation of the wheel. I could feel a slight drag of the brake pads on the drum. This is the desired setting for a drum brake. The pads should be running just in contact with the drums. I moved on to the other wheels. I found them all to be running a bit loose, and I tightened them all a few clicks. Time for a test drive.

I took the trailer for a drive around the neighborhood, making a lot of stops. All sign of brake chatter was gone! The next day we took off on a 1,200-mile highway towing trip. The brakes worked well, with no sign of any chatter. The simple adjustment process had cured the problem.

posted 09-07-2010 09:14 AM ET (US)            

When I jacked up the trailer to spin the wheels to test for brake clearance, I only lifted the tires off the ground about 0.25-inch. When I checked the left-rear wheel, I gave the tire a spin, and it promptly came to a sudden stop when another portion of the tire hit the ground. I jacked up the trailer a bit more, and spun the wheel again. I could see that the tire was very much out-of-round, and there was an area of the tire that was protruding about 0.5-inch. The tire was a Goodyear MARATHON trailer radial, and it appeared that it had broken a belt.