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-   -   Surge brakes pulsating or "machine gunning" (http://www.mastercraft.com/teamtalk/showthread.php?t=47717)

kgrove 05-19-2012 06:45 PM

Surge brakes pulsating or "machine gunning"
 
'08 X15 with stock MC trailer. I had the master cylinder on my surge brakes replaced, and afterwards when I brake, the surge brakes pulse on and off as the trailer slams into the hitch, releases, slams in again, and keeps doing this over and over. I was told this is called "machine gunning", though i dont know if that is a universal term or just the local dealer's internal term. They thought it was a bad shock or dampener so that when I braked, the trailer would slam the master cylinder causing the brakes to engage to hard and/or make the trailer rebound backwards ands start a vicious cycle. They replaced the dampener and it's still doing it, although not as often or severely.

The obvious answer is to take it back and make them fix it but they just as obviously are not sure what's wrong or they would have fixed it already. Any ideas? What else could cause this if I have a new master cylinder and shock/dampener? I will be taking it back to make them fix it, but I'd prefer giving them some suggestions as to what to look for since they've done what they know to do.

petermegan 05-19-2012 07:35 PM

Wonder whether it was bled properly. Air in the system could compress and cause an intermittant application of the brakes. Only guessing, never experienced it.

thatsmrmastercraft 05-19-2012 07:55 PM

I'm no trailer brake expert, but I agree, it sounds like air in the lines.

mikeg205 05-19-2012 09:12 PM

I had the same problem... #1 make sure bled correctly, #2 make sure shock in actuator ok, #3 - there are wear cushions that need to be periodically replaced. Mine was pulsating side to side...spoke with pacific trailers where I get my parts. Bought $25 bucks of parts - problem solved...do y ou have the UFP-A60 Actutor?

kgrove 05-21-2012 03:33 PM

I have no idea what kind of actuator I have - whatever was standard on 2008 MC stock trailers. I'll suggest they check the lines were properly bled and have no air. After that I'm flummoxed.

mikeg205 05-21-2012 06:30 PM

Take a picture and put it up here...I'll most likely be able to identify.

kgrove 05-21-2012 09:29 PM

Will do, but it will be a few days before I see my boat.

Stutsman230 05-21-2012 09:48 PM

I have been told that there is an orifice in the actuator. The old orifice may have been smaller. Talk to Jim at Arizona Luxury Marine about your problem.

rgardjr1 05-21-2012 10:24 PM

Quote:

Originally Posted by Stutsman230 (Post 841846)
I have been told that there is an orifice in the actuator. The old orifice may have been smaller. Talk to Jim at Arizona Luxury Marine about your problem.

I'm in the process of replacing the Reliable actuator on my 2006 trailer with a UFP actuator. I can confirm that there was a fitting that came off my old master cylinder and connected to the brake line that had a much smaller orifice than the brake line would. I haven't got everything put back together yet, but I will take a picture of the of the fitting tomorrow and post it here tomorrow. I would be nice to confirm that this fitting is needed before I put mine back together and bleed the brake lines.

mikeg205 05-22-2012 08:54 AM

Quote:

Originally Posted by Stutsman230 (Post 841846)
I have been told that there is an orifice in the actuator. The old orifice may have been smaller. Talk to Jim at Arizona Luxury Marine about your problem.

It's critical to have the brakes bled properly. If you have the UFP A60 or any UFP master cylinder it also has to be bled - according to UFP tech. Two holes in UFP master cylinder from UFP in the M-cylinder I have. Also, a shock absorber in the actuator will cause the piston in the master cylinder to move quicker on the rebound when trailer slows down.

I had my issue upon light breaking....You can easily see the actuator bucking forward and backward and causing the chattering sound...per UFP - new shock, wear pads and properly bled lines.


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