Bucking trailer!!!!!!!!!!!
 

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

I think you've figured it out.

Can you adjust the breaks?

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

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... :crazy: 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.

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.

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..

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... :eureka:

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?
:rolleyes: :D

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.....

30 years ago, or in the 1930's, Reed? :D:D:D

30 years ago.... you know the 1970's... discos.. bell bottom pants... bad hairdo's..... platform shoes..... kind of like the **** kids wear today.... :D ... In the 1930's... I was just a throb in my Daddy's pants!.....:cool:

We see this occationally and after bleeding the brakes the situation clears up.

Why would bleeding correct this? The brakes work fine otherwise. Wouldn't it be even more noticable when towing with a load?
Thanks

Re: Bucking trailer!!!!!!!!!!!
 

TTT

Just did a check and going to run it past you experts.
BTW, coupler model is a Titan 20=HD chit!

I engaged and locked in the break away lever. By doing this, it moves the master cyl. away out of the equation and allows for free movement of the coupler.
I can push/pull on the coupler fairly easy a couple of inches, not a wham bam sloppy seconds thing, but easier than what I would expect from having 2 shock absorbers inside. In other words, not a slow steady resisted movement. Question is, how much force should these things resist? Also, can I just remove the 3 rear large 'slide' bolts and pull the coupler out of the box tube w/o disturbing the brake assembly? Thanks

Re: Bucking trailer!!!!!!!!!!!
 

bn, any success?

Re: Bucking trailer!!!!!!!!!!!
 

US Fountain: Did your trailer ever have Drum brakes? If it did and you did not modify your actuator you MAY be experiencing a issue with that. Let me know and I can forward you to a fix (if that is the case).

Jon

Re: Bucking trailer!!!!!!!!!!!
 

Jon,

No, ordered with disc.
Thanks though.

Re: Bucking trailer!!!!!!!!!!!
 

US1 no luck yet, I have not been able to get it in to anybody for service. I do have an appointment at a Camper/RV service place for Tuesday. I figure they probably deal more with surge brakes on trailers more than marinas do.

I have the same brand actuator as you - hmmmmm.

Titan
Model 10
Pat No. 3241639
10k Gross
800 Tongue

I will let you know what they come up with after they look at it.

Re: Bucking trailer!!!!!!!!!!!
 

I agree with Reed on the damper issue (the small shock). If that is bad, the master cylinder will be actuated too quickly, then release too quickly, and set up an oscillation. That's the shutter. Hey Reed, I'm quite impressed with your knowledge of the old drum brake systems. They were also called "self energizing brakes". Not many people know that stuff any more. I've been into muscle cars since the late 70's, and learned a lot of that stuff along the way. Actually I'm impressed with most of the stuff I see you post. I'm knowledgeable enough to know that you know what you're talking about. Just figured I'd shoot that out to you.

Paul

Re: Bucking trailer!!!!!!!!!!!
 

Acording to the travel trailer shops I questioned, they never deal with surge brakes as campers use electric. Either way, keep me posted if they find a cure.

Thanks

Re: Bucking trailer!!!!!!!!!!!
 

Im having the same problem as BN now and my trailer is only 3 months old. I picked it up in Austin and drove to Nashvlle in April and it did great, now 3 out of 5 times I get a lot of loud noise when the surge engages. Sometimes I get a bad vibration, it still stops, but something isnt right. Suggestions?

Re: Bucking trailer!!!!!!!!!!!
 

The "dampning shocks" are like a gas filled shock for car/truck in that they should go to the full extend position when the trailer is in "idle" position. When you locked the emergency stop lever, how easy was it to push in on the ball coupler. There should be enough resistance to keep this "cycling" of the brakes from happening. That's where I would look first. I thought I was the only one that had, "Damn, we ain't never seen that before" kind'a problems.
Robert

Re: Bucking trailer!!!!!!!!!!!
 

It was fairly easy to move by hand. Not like there was nothing there, but not enough that I could see it doing any good. I'm thinking both of mine are shot. Sure would have thought that they both would have lasted longer than a few months.

Somehow I don't see Eagle Trailers stepping up to the plate now. ;)
Thanks

Re: Bucking trailer!!!!!!!!!!!
 

I'm not a fan of surge brakes to start with, and this has always been a problem with them. The "cycling". I personally like the vacuum over hydraulic set up with drum brakes, but it is EXPENSIVE. I've heard too many times of the pistons in the calipers seizing up for me to go to disc brakes yet, but I will always stay with the vacuum over hydraulics, they are too good.

Robert

Re: Bucking trailer!!!!!!!!!!!
 

Ok, my trailer is finally fixed. Took the boat and trailer to a local place that works on 18 wheelers. (never went to the camper place)

They said that the wheel bearrings were on too tight (they had to use a breaker bar to take them off) and the wheel hubs were leaking. They think that water was getting in the wheel hubs some how.

So they replaced the wheel bearrings, wheel hubs, put new brake shoes on, and machined the drums.

Works GREAT NOW!!! :)


Now I am waiting to see what Rocket will do for me. I hope that they stand behind their product.

The bill was $845 and I bought the trailer new last year. This problem started last year - well before any warranties were up.

Re: Bucking trailer!!!!!!!!!!!
 

bn, glad to hear it. Sure would have thought if the bearings were that tight, you would have seen flames coming from the wheels, or at least been sitting on the side of the road.

I just replaced both of my dampner shocks other day. Haven't tried it yet. The old ones were not as stiff as the new ones when I pushed/pulled them steady. They felt preety good in that regards, but when I would pull them out and then quickly push/pull them in short quick strokes, they had no resistance and moved freely.
Crossing my fingeres.

Re: Bucking trailer!!!!!!!!!!!
 

Thanks Paul.... I work on antique cars for a living.. so I have workshop manuals dating back to early 1900's... so "self energizing brakes" were cutting edge back then... plus it helps to want to know what the parts you are changing do... rather than just replacing parts until the problem disappears.I'm one of the few people around that still know how to work on mechanical brakes.... now I really am making myself look old..... :eek:

Re: Bucking trailer!!!!!!!!!!!
 

UPDATE
Dampner shocks did not fix it. So rebleed the system......still does it.

With a brain storm of an idea, had the wife pull the trailer while watching from the side lines. It's all in the design of the spring and shackles on a tandem axle with brakes on both axles. In short, the front axle will lift up and skip on the pavement shaking the trailer to smitherings. Only cure is to: never pull empty, or lock out the coupler. Not comfortable with no brakes.

Any suggestions? Thanks

Re: Bucking trailer!!!!!!!!!!!
 

very interesting topic. You stated that if you lock out the coupler, then you have no brakes. I dont know how long your trailer is, I imagine even if it were galvanized, a decent tow vehicle shouldnt have that much trouble stopping an empty trailer. Just my two cents. Brakes on a trailer assist due to the increased weight load of the tow vehicle itself and of course the load you are pulling. Doubling the workload of the vehicle with half the braking capacity it is originally equipped with doesnt equate well with Newtonian physics.

Re: Bucking trailer!!!!!!!!!!!
 

The trailer is for my 32' boat. It is an all steel Eagle. Heavy as chit. Truck is a Ford 250 SD. When I say 'lock out, what I did was to energize the bleed off back up solinoid with a jumper wire to my parking lights. So any braking pressure was relieved and dumped back into the master cylinder. I just towed it around the block that way and I can tell it is back there. You know about giving the Ins Co. any reason to refuse settlement if the occasion ever happened..........

Ideally an electric brake setup would be the fix since the braking pressure is adjustable. But for the 6x/yr of towing unloaded, will just have to put up with it.