Home › Forums › Bass Cat Boats › Trailer Surge Brakes – Clunking at take off.
All, Let me just say, I am very mechanically and electrically inclined, but thought before I just tear into the surge system, Id get some advice. I bought my boat recently (03 Cougar) and when towing, It appears my trailer surge system is slowing the trailer just fine, I havent really noticed noise on slow down. But when I start from a dead stop, CLUNK! I keep thinking I hit something or someone hit me. I found the reservoir for the fluid, and not knowing how to check it, It appeared low so I added some….. Ok I filled it about half the distance to the top. Then tried with no improvement an filled it all the way up. ( and yes this didnt seem like the right thing to be doing but there was no fill reference line) Any suggestions on next steps to for troubleshooting and then where to get parts to fix the system?BTW, had the boat on a big lake this last weekend, and I am thrilled how well it does in big water. It was exactly why I wanted a bigger boat, that was better suited for our big water in the NW. Having fished in a ton of different boats, and for me, this ranks up there as one of the best at handling the big water we have here. Have to say the wife was pleased too with the smoothness of the ride. ….. and no… we had the kids along. ThanksSteve
Steve,The next time you launch I would thoroughly inspect the brake line (mine ran on the port side back then accross the axle to the stbd side). Look for any kind of damage or evidence of leaks. Check the line that goes right into the master cylinder… thats where mine broke and it seemed like a pretty common place to break. The rigid piece that was there has since been replaced in their design with a flexible line that wont break.You can order replacement parts from BCB.Its possible that you just have an air buble in the line in which case you will need to bleed the system. I believe there are instructions on how to do this in the FAQ but it is pretty straight forward. The only thing thats a little bit different is there is a tab on the toungue of the trailer that needs to be depressed and released to pump out the fluid. Let me know if you need me to explain it in more detail, I can help you out.When refilling, if you look really closely I belive yours should have a fill line… its about 1/2 to 2/3 up the resevoir.
More then likely you dont have a problem at all. I noticed the same thing when I first got my cat. When you come to a quick or hard stop the trailer will move forward on the hitch coupling a couple of inches. What you feel during take off is the trailer sliding back to its normal postion. A more gradual stop or take off you will hardly notice it.
OUR thoughts are it is either the hitch or the actuator suspension. BCB
Cape Fear wrote: More then likely you dont have a problem at all. I noticed the same thing when I first got my cat. When you come to a quick or hard stop the trailer will move forward on the hitch coupling a couple of inches. What you feel during take off is the trailer sliding back to its normal postion. A more gradual stop or take off you will hardly notice it.Agreed. I noticed the same thing when I got my PC which was my first boat. All I had to do was learn to make more gradual starts and the big CLUNK went away.
the first thing to do is check your break fluid, if its low it will slide up farther and snatch when you take off.
My 07 trailer has done that on a few times over the past year and a half, the culprit was the failure of the aluminum “s” shaped brake line piece that attaches directly to the brake housing. In my case I have replaced 3 of the 4 aluminum sections that failed and then re bled the brake lines and I am good to go. I actually carry two pre-bent pieces and plastic tubing for re-bleeding the brake lines and a bottle of brake fluid in the truck now so that if I am away on a trip I can “get r done!!”Last edited by BlackJack Baits on June 4th, 2011, 1:39 am, edited 1 time in total.
BlackJack, Have you spoken to Parts or Service about the line failure? They need to know these things? BCB Admin.
Call UFP and they will tell you its a bad actuator. Been there done that. Actuator slows the release on take offs. If its a light SOFT clunk you are fine. Big free slap its the actuator.C.O.D. Jr. III
© 2026 Bass Cat Boats

