Demco actuator free play

[GMjonn]

I have free play in my Demco 66 surge brake actuator. By that i mean you can push the coupler back towards the trailer more than a 1/4 inch before encountering resistance. In the picture you can see the pencil line i made showing how far in it can be pushed. when you pull it all the way forward the stud that comes out of the master cylinder with the spring, plate and nut does not touch the brace on the coupler however when i depress the master cylinder piston i get a good shot of brake fluid when i open the valve, and the wheel can not be turned when its jacked up and the system is pumped up. Hook it to the car and pull forward 3 or 4 feet and hit the brakes and the trailer runs the full travel and bangs into the coupler like the brakes are not working. Thoughts?

 

[bruceb58]

You first need to adjust the drum brake shoes so that they are just starting to hit the drum.

If that doesn't help, bleed the brakes and if that doesn't help, you likely need a new master cylinder.

 

[G_Hipster]

Agree, the brakes need to be adjusted

 

[Jcris]

+1 on above

 

[GMjonn]

The brakes are adjusted, I can hardly turn the drum and i hear it dragging against the shoes. Does Demco sell a complete master cylinder and how easy a install is it?

 

[bruceb58]

The brakes are adjusted, I can hardly turn the drum and i hear it dragging against the shoes. Does Demco sell a complete master cylinder and how easy a install is it?

Go to E Trailer. They have the master cylinder. [FONT=&quot]Item # 5650[/FONT]

 

[bruceb58]

You can also do a google search...3rd one down

https://www.google.com/search?q=565...7j69i60&sourceid=chrome&ie=UTF-8#q=5650+demco

 

[Lou C]

Sounds like you need a new master cyl. BTW, you should still be able to turn the drum, I think you have them too tight. I adjust mine so I can just hear a light scraping, not feel a drag. This will help prevent the shoes freezing to the drum when the boat is not being used due to moisture in the brake assembly.

 

[Grub54891]

I adjust the. Brakes out till I can't turn the drums easily, this centers the shoes in the drum. Then I back them out till I can turn it with very little drag, and a few more click's till the drag goes away. Never had an issue this way. Now it may not be the perfect procedure but it works fine for me. If the brakes don't apply properly after that, yeah there are other issues to deal with.

 

[GMjonn]

Ok, parts have been ordered, now i find something else to do till they show up

 

[GMjonn]

OK, new master cylinder has shown up. This one has a top to the master cylinder where the original unit just has a gasket that goes between the top of the actuator unit and the master cylinder. This one is also plastic, the original one is metal. My first problem is that I cant get the old master cylinder to come out. I have removed the cap and the 4 bolts on top that hold it place and I cant get it to wiggle or anything. Am I missing anything, or do I just need to whack it with a hammer and a block of wood?

 

[Jcris]

pic's please
Did you disconnect the cylinder?

 

[GMjonn]

No Title

Here are two pics, if you look closly you can see the cork gasket between the master cylinder and the top plate. I may just take the whole actuator unit off but i'm hesitant to do so because i dont know the torque values to tighten it back down.

 

[dingbat]

My first problem is that I cant get the old master cylinder to come out. I have removed the cap and the 4 bolts on top that hold it place and I cant get it to wiggle or anything. Am I missing anything, or do I just need to whack it with a hammer and a block of wood?

That's why I never repair actuators, always replace.

The time and effort spent replacing a component, only to find another problem, just isn't worth it.

 

[bruceb58]

Have you taken the front portion of the coupler out that slides in and out of the fixed portion? Not sure if that's needed or not.

You can always call Demco too if you need help
http://www.demco-products.com/our-company/contact-us

I have replaced the master cylinder in many actuators. The only time I replace the actuators is when the master cylinder is almost the exact same price as the whole actuatorsitself.

 

[GMjonn]

ok, done... took actuator off, confirmed nothing else held it in place and 3 good whacks with hammer and a block of wood and it came free! Just need to scrape old gasket off and new one should bolt up. stay tuned!

 

[Jcris]

Have you removed the drums and done an inspection?
You may find work work

 

[GMjonn]

I already did 2 new backing plates with all new brakes, so thats all taken care of.

 

[Jcris]

very nice
enjoy the long weekend