Does your trailer 'clunk ... ?

Casey · Posted: Sun Jan 12, 2014 8:17 am Post subject: Does your trailer 'clunk ... ?

Ok, I know this may be a silly question, but: Does your trailer 'clunk when you start-up from a stop?

We have a dual axle trailer with surge activated disk brakes. It tows fine (and we've done a LOT of towing). But whenever we come to a stop, when we restart, there is a momentary 'clunk (excuse the overly technical description), Every time.

I'm pretty sure it's only the surge actuator on the coupler shifting to its "drive" position, but I'm not sure. Should I try adjusting the mechanism? (Aside from the 'clunk, the trailer is working fine*, so I'm not inclined to mess-with-it.)

Best,
Clunky&Mary
PS: Now that the boat is in temporary storage we actually miss the clunking while driving the truck!
*Now that I think about it, at towing speeds over 90mph there does seem to be a slight reduction in gas mileage. Should I get the tires rebalanced? **
** RELAX ... I was only kidding about towing over 90mph. (no reduction in gas mileage) Smile

T.R. Bauer · Posted: Sun Jan 12, 2014 8:58 am Post subject:

Yes they can clunk and everyone I have had does from time to time. They work like this: As you stop your truck, the trailer brakes are applied by using the weight of the trailer/boat to move the actuator - it is like a brake pedal. The faster you stop your truck, the harder your trailer ball pushed on the actuator mechanism. The actuator mechanism does have a small spring that returns it to the normal position, but now there is some wiggle room forward and aft because the actuator had to move to apply the brakes. When you take off from the stop, the trailer ball moves back to it's old position when you were towing and you hear that clunk in the begining. Keeping everything lubed up helps a lot with this and I suspect it would probably go away, or at least nearly completely go away if you greased your ball. If your ball it all beat up, it wouldn't hurt to get a new one. While you are at it, it wouldn't hurt to check how smoothly your actuator is working too and grease it as needed.

NewMoon · Posted: Sun Jan 12, 2014 8:59 am Post subject:

My surge brake trailer has been clunking away for 15 years and almost 70,000 miles. Seems to do so more when the actuator needs a bit of cleanup and lube. I try to keep the actuator sliding back and forth easily with lots of that sort of TLC. If it's particularly gummed up with road grit etc the trailer brakes don't start working as easily, sometimes needing more agressive braking from the truck to engage them. The brakes don't release as easily when I start after a stop either, resulting in a louder clunk.

Chris · Posted: Sun Jan 12, 2014 9:29 am Post subject:

Surge brakes will give a little clunk normally...but if it is excessive it can mean the brakes need to be bled. There should be a small amount of travel in the actuater...but if the travel is approaching 100% it will really clunk...and the remedy is to bleed the brakes.

T.R. Bauer · Posted: Sun Jan 12, 2014 9:34 am Post subject:

Ron Cowan · Posted: Sun Jan 12, 2014 9:46 am Post subject:

I have observed the slightest clunk even pulling trailers without surge brakes. It does not matter which truck I am pulling with or which trailer I am pulling. Sure it is more pronounced on some but there on all. The draw bar is fairly tight but can be felt to have a little play. My assumption has always been that the draw bar rocks or moves slightly as the load is applied. Maybe you are hearing something louder tan I am but it is always there.

Spike · Posted: Sun Jan 12, 2014 10:34 am Post subject:

Yes they can clunk and make other noises from the brake system but check your trailer out. Mine was making a noise on starts and stops that turned out to be that I had two loose bolts holding the coupler on the main frame. Could have been a helluva mess had I not caught them.

ssobol · Posted: Sun Jan 12, 2014 12:03 pm Post subject:

Some of the clunking can come from the receiver at the draw bar. You can get receivers with dampers built in. I did this and it got rid of most of the clunking on my setup. Before this there would be clunking when starting and when going over bumps in the road.

Da Nag · Posted: Sun Jan 12, 2014 12:44 pm Post subject:

thataway · Posted: Sun Jan 12, 2014 12:51 pm Post subject:

Agree with all; part of a pre trip inspection for us, involves checking the brake fluid level in the coupler brake reservoir. A way to check the brakes is to back up with the lock out solenoid detached--again a good thing to do before starting a trip. If you have good brakes, then you will feel the resistance to rearward movement.

We also check the tire pressure, walk around the frame, check all fittings,springs, bunks, and put the motor in the trailering position--in the Caracal we have a "Transom saver"--the C Dory 22 a hard rubber block. We also make sure the motor is centered and that it is chocked to keep it from stressing the hydraulics as we do down the road.

The wheel bearings are greased before every major trip.

I just did all of the above, since we leave for the Keys in the AM.

localboy · Posted: Sun Jan 12, 2014 1:16 pm Post subject:

jimandlaurie · Posted: Sun Jan 12, 2014 1:25 pm Post subject:

It is what it is.

Larry H · Posted: Sun Jan 12, 2014 3:50 pm Post subject:

Excessive 'clunking' can also be caused by the brake shoes in drum brakes needing adjustment.

Will-C · Posted: Sun Jan 12, 2014 5:13 pm Post subject: Does your trailer 'clunk ... ?

Ours used to do that a little. The switching to electric over hydraulic fixed that problem for good.
D.D. Smile

Sunbeam · Posted: Sun Jan 12, 2014 8:31 pm Post subject:

I have surge brakes on the tandem trailer under my 22, with disc brakes on both axles. If I stop more "firmly" than usual (say a stale light changes and catches me), and then perhaps accelerate more quickly than usual, I can get a slight clunk from the coupler. However, under my usual driving conditions any clunk is either not there or nearly unnoticeable.

I can't remember for sure, but I think there was supposed to be something in my coupler to "dampen" the action. If so I guess it must be working. So it seems as if it is possible to have surge brakes with no major clunking.