Trailer brakes not always releasing

[Darol Wester]

The trailer is under an approximately 5500 lb. boat. The axles are three years old and have disc brakes. They have about 2000 miles on them. When returning from the coast last weekend, we found them really hot at our stop. So hot that the grease was squirting out the rubber caps for greasing the bearings.

I relieved the pressure at one of the bleeders and continued down the road with no problem. It did this 2 more times before I made it home but not nearly as hot.

The unit consists of the hitch actuator to the brake cylinder and behind that there's a reverse lockout unit.(Tiedown)

With several possibilities, what would be my best bet?

 

[vfrkent]

Re: Trailer brakes not always releasing

Well first were all four brakes hot? if so then most likely it has to do with the master cylinder to effect all four, if only one or two out of the four then I would be looking at the pistons being seized in the cylinder.

Regards,
Kent

 

[dockwrecker]

Re: Trailer brakes not always releasing

Has it always had disc brakes? Did you recently change the master cylinder? The master for disc brakes should have a pressure relief hole in the end of the piston. Maybe it's gummed up, or maybe you have a drum brake master. Who made the brakes?

 

[jeffnick]

Re: Trailer brakes not always releasing

If the bleeder squirted fluid it could be the coupler. If it dribbled out more likely trouble at the brake. I had the same problem with disc brakes and found that backing off the spindle nut one flat helped. This allows for a slight rotor wobble that encourages pad/rotor clearance.

Personally, I prefer electric boat trailer brakes.
http://72land-n-sea.blogspot.com/2011/05/trailer-tires-brakes.html

 

[Darol Wester]

Re: Trailer brakes not always releasing

The first time it got hot, it was all 4 wheels. The next couple times they were all hotter than normal, but the right rear was hotter.

When we installed the new axles and disc brakes, we changed the master cylinder to fit the disc system. Who makes the brakes I'm not sure of. My partner took care of that and he died, so I'm short on that info at the time.

When I released the pressure, it squirted out maybe 3 inches quickly, then dropped off in an instant.

I'll check and see how much wobble I have already and see if backing off the nut might work. Worth a try. I'll also dig into the master cylinder and see what I find.

Thanks guys. Much appreciated.

 

[Darol Wester]

Re: Trailer brakes not always releasing

Just out of curiosity, now that I think a little more, we did put in a new master, but this project was in the hands of my friend and I'm assuming it was the correct one. If it wasn't, what would be the tell tail signs. We did use the same hitch/housing if that means anything. I've got the master cylinder out. What should I look for as far as the correct part?

 

[Darol Wester]

Re: Trailer brakes not always releasing

If this works, it's a photo of the master cylinder.

 

[dockwrecker]

Re: Trailer brakes not always releasing

The difference isn't visible on the outside. It's on the end of the piston inside of the cylinder. There's a nylon washer on the end of the piston that for disc brakes has a small hole drilled in it to relieve pressure. The washer is solid for drum brakes. You can easily drill a small hole in it if it doesn't have one, problem solved. It would appear that you have a disc master given that it has the return hole for the reverse solenoid, but I'd pop the piston out and have a look.

 

[haulnazz15]

Re: Trailer brakes not always releasing

You do have an electric trailer brake controller on the vehicle right?

 

[Darol Wester]

Re: Trailer brakes not always releasing

No electric controller. It operates off the hitch actuating.

Any idea what master this is, so I can get a new gasket for it?

 

[dockwrecker]

Re: Trailer brakes not always releasing

That's an Atwood master. Call these guys for the gasket.
http://www.championtrailers.com/atwood_brake_coupler_parts.htm

 

[dingbat]

Re: Trailer brakes not always releasing

I am not convinced that you have a problem with your brakes.

Disc brakes run hot. It?s not unusual to see disc temps up in the 600-700 degrees F range. Throw in a hot summer day and your typical trailer grease with a drop tempature of 350 degrees turns to liquid. If you?re using bearing buddies, the spring pushes the melted grease out the pressure relief vents and you end up with a big mess.

Make sure you?re using a grease rated for Disc brake service. The higher the drop temp the better. I use grease with a drop temp of 550 degrees and still get some seepage on my grease caps from time to time in the summer.

 

[lncoop]

Re: Trailer brakes not always releasing

Do the rubber caps perchance look like this?
http://www.trailerpartsdepot.com/itemdesc.asp?Ic=02486

 

[Darol Wester]

Re: Trailer brakes not always releasing

Do the rubber caps perchance look like this?
http://www.trailerpartsdepot.com/itemdesc.asp?Ic=02486

That's the ones. No bearing buddies with springs. The hubs got hot enough that while we were standing there, the caps started popping off and big globs of grease fell out on the rim below. I'd think that's too hot.

As far as the correct grease, ???? we used marine grease. Wasn't aware of disc grease till now. I'll assume it would be a great idea to run some of that through all 4 hubs and push out what's there?

Also, what does drop temp mean?

Thanks

 

[lncoop]

Re: Trailer brakes not always releasing

I'm not saying your hubs didn't get too hot because I'm no expert and I wasn't there. However, I will say that grease escaping from that little rubber plug isn't necessarily indicative of a problem. You'll find that they have cracks/slits in them and that's why the grease is escaping. They just need to be replaced at a couple bucks apiece.

 

[dingbat]

Re: Trailer brakes not always releasing

As far as the correct grease, ???? we used marine grease. Wasn't aware of disc grease till now. I'll assume it would be a great idea to run some of that through all 4 hubs and push out what's there?

Also, what does drop temp mean?

Thanks

There is no such designation as "marine" grease. Marine greases are marked as being water resistant. What grease isn't? Note that no where in this explaination of grease types ,etc. do they mention marine grease.

http://www.reliability.com/industry/articles/article66.pdf

 

[guy74]

Re: Trailer brakes not always releasing

I have always been told that "Marine Grease" isn't to be use in high speed, high heat aplications. It is designed to not wash out, and to help prevent water intrusion on slow moving, low temp, low pressure application. A disc-brake hub would not be a good place for that type of grease. I use a lithium based #2 EP grease in wheel bearings on everthing from the boat trailer to the semi trailers. I've never had any issues with it.

 

[Darol Wester]

Re: Trailer brakes not always releasing

Well...I'm gettin educated and that's why I came here. We always thought that the "marine grease" we were using was the right thing. Now, up until this boat, we've always had a much lighter boat thus never having the issues I'm having now I'm guessing.

So, do you think I'll need to tear down each wheel, clean it and re-pack them, or will I be able to run the proper grease through till the other is flushed back out at me? Door # 1 I would imagine.

I really appreciate you bringing this to my attention. Lord knows we don't need any problems when we're havin fun.

Do you guys have a favorite brake fluid to use also?

 

[guy74]

Re: Trailer brakes not always releasing

I think you can probably flush it back out at you, I have "sure lube" hub on my stock trailers, they seem to do a good job pushing most of the old out. But if the trailer is new to you, and you haven't been though the bearings yet, it might be a good time to take it apart and replace the seals while you are at it. I use the kind of grease I do mainly because all our equipment requires that grade, so we buy it 40 tubes at a time. As far as brake fluid, a good DOT 3 or DOT 4, normally whatever brand is availible, works for me.

 

[bruceb58]

Re: Trailer brakes not always releasing

I use sta-lube marine grease with my disc brakes and have never had a problem. I do have an electric/hydraulic actuator so I don't have a problem with the brakes being applied going down hills.

Does this happen after you are coming down a long grade? Is the trailer level? Is an equilizing hitch being used?