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-   -   Trailer brakes won't "firm up" after servicing (http://www.wakeworld.com/forum/showthread.php?t=795291)

fish6942 08-30-2012 4:40 AM

Trailer brakes won't "firm up" after servicing
 
I just installed a new swing tongue on my Boatmate trailer. The process included taking the UFP A-60 brake actuator from the old tongue and putting it in the new tongue.

The whole process went pretty smooth but now I can't seem to get the brakes to build proper pressure. I have a helper that's using a 2x4 as a lever to compress the tongue during the bleeding process and that's working fine. When I crack the bleeders there is a steady stream brake fluid with no apparent air bubbles.

We've ran about 1.5 pints of fluid through the master cylinder and still when we go to compress the tongue it travels all the way to the end of the stroke.

The trailer has disc brakes and they are on one axle only.

QUESTIONS:
1) The trailer has the reverse lockout solenoid. If that solenoid was somehow stuck in the energized (open) position, I wonder if I'd have these same symptoms???

2) Could I have screwed something up during the installation?

3) Would you expect that I'd need to run more that 1.5 pints through the system considering the M/C was uninstalled and reinstalled?

miljack 08-30-2012 5:52 AM

1. This is possible, but normally the solenoid needs to be energized to close.
2. are you sure the fitting for the flex hose to the hard line is not leaking?
3. Did you disconnect the brake line from the end of the M/c? 1.5 pints should be enough to bleed that system, I used about that much and I have tandem brakes.

Question for you, which swing away tounge do you have? Mine is a UFP and not all that happy with the amount of play in the pivots. Why did you replace the tounge?

thanks,

fish6942 08-30-2012 6:05 AM

Quote:

Originally Posted by miljack (Post 1779487)
1. This is possible, but normally the solenoid needs to be energized to close.
2. are you sure the fitting for the flex hose to the hard line is not leaking?
3. Did you disconnect the brake line from the end of the M/c? 1.5 pints should be enough to bleed that system, I used about that much and I have tandem brakes.

Question for you, which swing away tounge do you have? Mine is a UFP and not all that happy with the amount of play in the pivots. Why did you replace the tounge?

thanks,

1. Regarding the solenoid, I may be using the open/closed terms incorrectly. My understanding is that when the solenoid is energized (by the backup light wire), it somehow relieves pressure from the brake lines. Whether this is done through redirecting flow from the brake lines back to the reservoir or what I'm not sure.
2. I confirmed that this connection is not leaking.
3. Yes, that is where I disconnected the two.

The tongue was replaced due to a break in one of the steel plates that makes up the pivot assembly. It is a UFP tongue. See this thread: http://www.wakeworld.com/forum/showt...light=boatmate

tuneman 08-30-2012 7:10 AM

Sounds like you may not be bleeding the lines correctly. You don't need a helper with a 2x4. Just a flat blade screwdriver. You probably still have air in the solenoid and need to pump it out.

Go get one of those cheap bleeder kits at your local auto parts store (<$10). It's just a small bottle with a tube.
Attach it to the bleeder screw on the brake closest to the solenoid (likely the left wheel on your trailer).
Open up the screw and place the bottle on the frame above the screw.
Now go to the tongue and stick a flat blade screwdriver into the hole on the underside (next to the solenoid release lever)
Remove the cap on your reservoir
Pull the screwdriver forward until it locks into the compressed position
Release the solenoid by pressing the release lever
Repeat over and over until you no longer get bubbles coming up in the reservoir and you get clean, bubble free fluid coming out at the brake bleeder.
Tighten up the bleeder screw and repeat on other brake.
Never let your revervoir get too low, or you have to start over.

I hope this helps

fish6942 08-30-2012 8:05 AM

Quote:

Originally Posted by tuneman (Post 1779506)
Sounds like you may not be bleeding the lines correctly. You don't need a helper with a 2x4. Just a flat blade screwdriver. You probably still have air in the solenoid and need to pump it out.

Go get one of those cheap bleeder kits at your local auto parts store (<$10). It's just a small bottle with a tube.
Attach it to the bleeder screw on the brake closest to the solenoid (likely the left wheel on your trailer).
Open up the screw and place the bottle on the frame above the screw.
Now go to the tongue and stick a flat blade screwdriver into the hole on the underside (next to the solenoid release lever)
Remove the cap on your reservoir
Pull the screwdriver forward until it locks into the compressed position
Release the solenoid by pressing the release lever
Repeat over and over until you no longer get bubbles coming up in the reservoir and you get clean, bubble free fluid coming out at the brake bleeder.
Tighten up the bleeder screw and repeat on other brake.
Never let your revervoir get too low, or you have to start over.

I hope this helps

To be clear, what I'm referring to as the solenoid is the backup solenoid which is located behind and down stream from the master cylinder. It's controlled electrically by the reverse lights. What I believe you are calling the solenoid is the actuator for the master cylinder. Look at the second video from the left on this page to see what I mean by "solenoid": http://www.ufpnet.com/Actuators/tabid/54/Default.aspx

Before I started the bleeding process, I did use a screwdriver to push the actuator in and out a number of times while viewing the orifice at the bottom of the reservoir until no more bubbles surfaced. This was done with the bleeders closed and was done per the UFP manual.

Is there a reason that you suggest starting at the nearest bleeder? Nearly any brake bleeding process I've been involved in always starts at the most distant bleeder (this is also per the UFP manual).

Thanks!

tuneman 08-30-2012 8:40 AM

Geez, I need more coffee before I post in the morning! Sorry, I mixed up words and yes, should be furthest from mc.

fish6942 08-30-2012 9:52 AM

Quote:

Originally Posted by tuneman (Post 1779542)
Geez, I need more coffee before I post in the morning! Sorry, I mixed up words and yes, should be furthest from mc.

Yep, been there, done that. Appreciate you clearing that up.

I've never used these bleeder bottles. If you're able to keep the bleeder open while pumping the M/C, when the M/C actuator retracts and a negative pressure is created on the bleeder is the assumption that some of the fluid in the bottle will get sucked back into the brake caliper? I can always use a second person so I can close the bleede prior to retracting the M/C rod.

boardjnky4 08-30-2012 10:22 AM

I would bleed the brakes with a vacuum bleeder

jrichard 08-31-2012 8:11 AM

If the brakes won't lock up, you probably still have air in them (assuming your master cyclinder is good).

A couple of suggestions:

1. Actuate the master cylinder with a flat blade screw driver inserted through the small hole on the bottom of the A60. There are instructions/diagrams on the UFP site.

2. Make sure the tongue of the trailer is lower than the rear of the trailer so bubbles caught in the line make their way to the brakes

3. Depending on how your brake lines are routed, you can still have problems with bubbles getting trapped at high points.

4. You can always take it to a brake shop and pay them to power bleed. It doesn't cost much.

boarditup 08-31-2012 9:28 AM

I use an old-fashioned oiler (the kind with a trigger to pump the oil), available at NAPA) and a clear tube to the brake bleeder to force fluid from the brake caliper to master cylinder. Look for the absence of bubbles. Repeat a couple of times and you should be good-to-go. Drill a hole in the top of the oiler so you can keep the bottle full without removing the plunger from the bottle. It is quick, easy, and has never failed me yet.

miljack 09-04-2012 6:15 PM

@Karl, great tip on the oil can, haven't heard about that one! I used a Suckup oil pump vacuum on the caliper to get the majority of the air out of the system.
Best practice is to start with the longest brake line run from the m/c. Most trailers run the main line back to one side or the other, then the line(s) for the other side calipers are run across the frame/axle, start with the side that has the line run across the trailer.


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