US1 Fountain

The trailer:
1 yr old, HD axles, leaf spring tandem axle trailer, disc surge brakes all 4 wheels.

Whenever towing empty and coming to a stop, the trailer bucks so bad it about tears the back of the truck off. Only way to stop it from bucking is to give it just a bit of gas then try to stop again. It does it both at light and heavy braking.
I assume it is the trailer brakes coming on and slowing the trailer down enough till it disables the trailer brakes, then the coupler gets fully extended at which point it feels like it will bounce forward until the coupler activates the brakes again. This all happens in just a split second and cycles repeatedly. Not only is it embarrasing, but HAS to be harder than hell on the hitch! The only thing I can think of is that the dampener shocks are bad, but not sure if that is correct.
Trailer is pretty level. Have tried to lower the ball height, but a height adjustment of a few inches is really doing nothing considering the lenght of the trailer. BTW, didn't do this when I picked up the trailer last yr, or drove it from IN to OK to pick up the boat. Just started mid-summer last yr. With boat on the trailer it is fine.

Any ideas? Thanks

Iggy

I think you've figured it out.

Pure Energy

Can you adjust the breaks?

rjcardinal

Bleed the trailer brakes. You may have air in the line letting the surge coupler move more than is necessary.

If you have bled the brakes and you dont have any brake fluid leaks think about replacing the master cylinder in the coupler. If it is leaking around the piston it will act the same as if it needs to be bled.

Ron

Reed Jensen

Is there a small shock absorber in the hitch? near the master cylinder... if that is bad it will let the master cylinder come on quickly and then disengage... I've had to replace one in the past... I had a car trailer do the same thing .Part of the reason for the bucking... more braking than what you need for an empty trailer.. most tandem axle trailers only have brakes on two wheels... if you can't figure out how to make it stop bucking.. try disabling the brakes by locking them out while towing the trailer empty.. you certainly don't need the brakes when there isn't a boat on the trailer.

bn

I'm having the same problem with my 2002 triple axle Rocket trailer (aluminum trailer, torsion bars, drum brakes). I bought it new last spring, drove home from MD to NY - no problems.

Mid summer the problem started. When getting off the highway, something seems to engage the brakes and the whole thing shakes VIOLENTLY. It doesn't do it when I first leave my neighborhood. Only when I drive a distance, then everytime I stop after that.

Mine does it with boat on the trailer.

I had the brakes looked at last year and they couldn't find anything wrong with them. I talked to Rocket this year and they said to have someone else look at it. I am trying to get it into by buddy's shop. They are going to look at the shock in the actuator and maybe bleed the brakes.

Reed Jensen

One more thing... hydraulic trailer brakes have a single "leading" shoe... the slave cylinder is only "one sided" not two sided like automobiles.. the braking action is aided by the "servo action" of the shoes.. this dates back to the late thirties with what is called "bendix action" brakes.. Disc brakes don't get a servo action like shoe brakes do... one of the reasons that drum brakes don't grab while the brakes are new is because the "lead in" area of the shoes are " cut back". Any kid that worked in a brake shop years ago learned to cut back the leading edge of the leading shoe... you may want to take a die grinder ( wear dust protection ) and grind back about 1 inch of the leading edge of the leading shoe. This is done to reduce the "grabbing" of the leading shoe on the drum. The leading edge only needs to be cut back about 1/8 of an inch in depth and about 1 inch from the leading edge to the center of the shoe..

Reed Jensen

I worked in a brake shop over thirty years ago.. ( I hate to give my age away ).. and I learned that grabbing drum brakes were quite often caused by some other shop having put on too big of a lining on the leading shoe. If you were to look at the brake shoes on an old car... the leading shoe always has less lining on the shoe.... plus... it is a harder material... The material on the leading shoe has to be below the "fulcrum" area of the shoe... if the lining is too long and above the fulcrum area... the drum grabs the shoe and loads it up. Does any of this make sense to you guys? I can post some pictures if it helps...

US1 Fountain

Well, it would if I had drum brakes. hence the "disc surge" in the 1st line of my question. But I see what you are saying.

I had bleed them last yr when I replaced the 'el cheapo standard back up solinoid with the deluxe pressure relieving one. This was a problem before the solinoid change over. During that swap, I did remove and dissassemble the master cylinder to install the return relief line. Everything looked good there. Plus the brakes worked fine otherwise.

There are 2 of the dampner shocks, but do those things have enough resistance to actually hold the trailer back if they are good? Seems like ALOT of forward force those critters have to work against.
Got call into Eagle, waiting for a return call. Shall we place bets?

Reed Jensen

Sorry USA 1... I didn't see the disc notation in your first post... the small shock absorber just keeps the trailer from "bouncing" back and forth and surging...That is probably the problem.....