Surge brake issue

[dpoff]

I`ve noticed that my 2011 Venture trailer surge brakes (disc) are bottoming out when coming to a stop. I havn`t found a leak at all and the resivor is full.Any ideas before I start pulling things apart?
Thanks
Dean

 

[tpenfield]

Are the pads OK?

 

[dpoff]

Havn`t pulled anything apart yet. Weekend project. Just looking for pointers, I will look at the pads for sure.Thanks.

 

[GA_Boater]

Also a bad shock could sound and feel like the master cylinder is bottoming.

 

[dpoff]

Thanks , but it is bottoming. I got out and looked after backing in the driveway and the tougue is pushed all the way in. Thanks again GA. I`m guessing bad master cylinder.

 

[GA_Boater]

Were you backing up hill, by chance? The reverse lockout, if the trailer has one, should stop the master cylinder from activating when backing up.

 

[dpoff]

Yes, I have the reverse lockout but I tried on the street and coming to a stop it bottoms out, then when starting off I feel it clunk when it pulls tight. I`ve ran a surge brake trailer for ten years but most of the time I`ve have this kind of problem it was an obvious leak. Think maybe I`ll be googling master cylinder issues in the a.m. before I start work on it! Then start from there lol!

 

[GA_Boater]

Sounds like it could be the shock. But if you don't see leaking juice, it may be an internally leaking master too.. Or both.

 

[dpoff]

When you say "the shock" are you talking about the tow vehicle? I`m thinking master cylinder. The fluid in there doesn`t look the cleanest.

 

[GA_Boater]

Item 4 below. This is for an Attwood and yours may be arranged differently, but all surge brakes have a shock absorber for dampening or the brakes would lock at the slightest braking of the tow vehicle. Item 6 is the master cylinder in this application.

Dirty fluid could mean the internal seals are worn.

 

[alldodge]

There are two types of bake release solenoids, ones which stop the flow of fluid and the other which divert the fluid back to the master cylinder reservoir (lets call then block and divert).

Block
If you have the block kind you need to have the solenoid turned on before you stop and start to back up. Failure to turn on before backing can have brakes applied prior to backing.

Divert
They can be turned on before or after because all pressure is released back to reservoir.

Master cylinder needs to have a hole in the forward check valve, this allows pressure to be released after pedal is released. Tie-Down disc needs this done to a master cylinder which use to have drums during retro fit

 

[dpoff]

Thanks for the clarification GA. I`ll be checking things out in the A.M.

 

[bruceb58]

It's usually the master cylinder although it would normally retract.

 

[dpoff]

This is the unit I have. As it turns out the shock will bottom out if the fluid is more than 3/8" below the filler top. Mine was about 1/2" below and I was thinking that was full enough, WRONG.
Took it on a road test and all is good.
Thanks for all the tips. I learned something about actuators during this ordeal.


This is from the manual,

"The built in dampening shock absorber retards the telescoping shock against
the hitch ball by depending on the brake fluid in the master cylinder. Low levels of brake fluid will signal the tow vehicle operator to add
brake fluid via hitch ball knocking"

 

[bruceb58]

You may want to bleed the brakes if you were that low. Also, changing the brake fluid every few years makes the master cylinder and caliper last much longer.

Looks like a Tie Down actuator. Not the best in the world. I have one. When it dies, it will get replaced.