Fixing dragging trailer brakes

[Dave M.]

I may have posted this on the old site, but it is gone, so I will post it here. I have resolved the issues with the help of my Sea Ray dealer and the manufacturer. But I wanted to post photos describing what can go wrong and pointing out maintenance you may want to do.

The problem started not long after I got a new heavier duty trailer for my 270. I noticed the wheel assemblies would be hot after driving, and tracked it to dragging brakes. Then it got bad enough I could detect it while pulling, and could not fully release the brakes without jacking up the hitch to take weight off the ball. My Sea Ray dealer is 200 miles away, so finding the problem myself was my goal.

This all happened last year, and it turned out I had two problems. One was lack of lubrication, the other was a manufacturing tolerance thing causing parts to drag. I will write about the lubrication issue here.

Here is a picture of the coupler/surge brake assembly, taken today. In the picture, I have labeled the front rollers, the rear rollers, and the sliding front section. The actual rollers are not visible here, but one can see the through bolts acting as axles for the rollers.

The sliding front section needs to be able to slide in and out to actuate and release the brakes. The front rollers are just sleeves that go over the through bolts. The bolts are rigidly attached to the housing, and the front section, when there is weight on the ball, pushes up against the rollers to carry the ball weight. The rollers are on the outside of the tube of the sliding front section, so push down on the outside of it. Since the through bolts are outside of the sliding front section, they do nothing to restrain the forward and back movement of the sliding section when working properly.

The rear rollers are inside of the sliding front section. Bolts go through slots in the sliding section, and rollers on the bolts push up on the inside of the sliding section to hold the back part of it up. Front and back movement of the sliding front section is constrained by the slots in the sliding section. As the ball pushes up on the front of the sliding section, the section tries to move down in back, pivoting on the front rollers. Thus the rear rollers have to push up inside the sliding section to counteract the weight on the ball.

Since I had determined that my problem was that the sliding front section would not slide in and out properly, I took the whole assembly apart to see what might be wrong. I found a lack of grease in the front two roller assemblies. Here is a picture of the through bolts and rollers removed. You can see the galling on the top of one of the bolts. Notice the grease fitting on the end of the bolt. The bolts are drilled down through the center, then outward. Using the grease fitting, you can inject grease and it will come out of the bolt and into the area between the bolt and the roller. These two had no grease when I took them apart, they were as you see them here.

The next picture shows the hole drilled in the center of the bolt to lube the bolt and roller. There was no grease in sight.

Galling has also occurred on the inside of the roller. I called the dealer, told them what I found, and they got replacement parts on the way. In the mean time, I used some emery cloth to polish down the bolts as well as I could to remove the raised areas. I used a dowel and the cloth to clean up the inside of the roller. I put some grease on the inside of the roller, some on the bolt, and put this part back together. I turned the galled area of the bolt upwards, as the bolt takes the pressure of the roller on the bottom side of the bolt only, not the top. This would get me by for the front rollers until new parts arrived.

 

[Dave M.]

But the problem was not confined to the front bearings. Forward to the rear ones!

The next picture is a rear view of the sliding front section, removed from the housing and tuned upside down. I have put the rollers and bolts back into the front section to show what they look like.

This time there are three through bolts, and three sets of rollers. The ones in the bottom of the picture here (at top in service) are the ones that carry the weight. They have grease fittings. The single one at top in this photo does not normally carry any weight, just keeps things in place, and has no grease fittings.

When taken apart, the parts look like this (there is an extra sleeve in the photo). You can see that this time there are two sets of holes, so that grease is fed into the area under the larger rollers on each side.

I also found that there was no grease in these rear roller assemblies. I put in grease in those, and put the unit back together awaiting parts.

 

[Dave M.]

After putting it all back together again, I still had 'issues'; the brakes would still drag at times. So I took it apart again to see what else could be wrong. Here is a view of the rear of the sliding front section after removing it from the outer housing. You have to take out all the through bolts and rollers to do this. In the next picture, I have put the rollers and bolts back into the front piece to show what they look like. In this picture, the front section is laying upside down.

You can see that in addition to the roller sleeve that fits over the bolt, there are in addition two larger rollers on each shaft, separated by aspacer. These larger rollers are what should carry the weight, and roll against the inside casing of this front section. They should be free to roll front to back, and the bolt and sleeve should move freely in the slots in the side of the section. When assembled, the bolt is solidly bolted in the outer housing, and transfers weight to the sliding section via the large rollers against the inner section. It should not transfer weight by the bolt sleeve against the edge of the slot. But it did.

With the bolts and rollers removed from the housing, I looked at the parts. I did not find any indication of wear on the large rollers, or where the large rollers roll on the bolt sleeve. But I did spot some galling on the sleeve near the edge. This is where the sleeve is held in place in the slot in the housing. The sleeve should not be dragging on the slot in the housing, transferring weight from the bolt to the slot of the housing. There should not be in interference fit there.

Here is a closeup of one sleeve from the first post. I did not notice the first time the scuffing near the edge of the sleeve, nor understand that part should not touch the edge of the slot and bear weight.

When I realized the sleeve should free float in the slot, I looked closer at the clearance with the unit upside down. This positions the internal parts like they will be when carrying weight. It looked like this.

I could not be sure of the clearance, so removed all but one bearing set and used it to check the slot clearance. It looked like this on the outside.

I could tell it did not have clearance between the sleeve and the edge of the slot. Time for the grinder to make some space here! After doing a bit of work on the right side in the picture, I could put the parts loosely back in the slots, look in the end, and see daylight between the slot and the sleeve. You can see in the photo below that the side on the right is OK, the side on the left still needs work.

This problem seemed to be primarily caused by the added strenghening plates you can see welded inside the channel on the sides. It did not align perfectly with the channel. This is especially visible on the lower left slot, top side. You can see the inner piece is raised compared to the outside channel.

After doing both sides, I put it back together again. This time the problem was fixed for good. :thumbsup:

 

[slack250]

Thanks Dave, I too am having a bit of a dragging issue on my new trailer. I'll check for lube and fitting tolerances.

Great post!

 

[Dave M.]

slack250

Thanks for the feedback! I was beginning to wonder if the post had been worth doing or not, as no one had replied. But it was a real issue for me, and a learning experience. It took me a while to figure out just how the rear internal bearing system was supposed to work.

Then, after thinking about it some more, I am not sure the designers did it right. They put the small sleeved single bearing surfaces in the front, and the much larger diameter, sleeve plus rollers, two moving bearing surface things in the back. Looks like they think the back takes more force. (Edit: Now that I responded to Paul below, I remember why the rear is made like this. It has to have provision to mount the piston end of the internal shock absorbers. Only the rearmost shaft is just a spacer. The other two are shock absorber piston end rings.)

The front rollers are about equidistant between the ball and the rear bearing rollers. So common sense tells me that the rear rollers take the same weight as the ball, and the front rollers take twice that. Kind of like two 800 lb gorillas on a teeter-totter. If they are to have any fun, you better keep the pivot point well greased.

 

[slack250]

That I will do! My trailer is essentially the same, but a bit different. I'll have to take it apart and see what the insides look like ... didn't really have any direction to do so, but now I do. I wish more members would take the time to take photos and present the step by step as you have done. Congrats and thanks again!

 

[SearayPaul]

Dave:

This is a great article. I have the same setup as you. I have noticed that it sometimes takes a good pull from the truck to move the sliding coupler out. How much force I have to exert to have the coupler slide in and out? I can move the coupler but I really have to pull hard on it with the boat unhooked.

Thanks for your reply. I probably will have more questions.

Have a great day

Paul

 

[Dave M.]

Paul,

The front section would move freely except for one thing that I did not mention. In addition to the parts I talked about, there is also one or more shock absorbers inside the unit. And that probably explains why they designed the roller sleeves and bearing system the way they did; something I was grumbling about above.

So anyway, here is a side view of my unit. The shocks mount inside the unit between pins in the sliding front section and two of the rear bearing pins, like this.

So the front end of the shock is attached to the sliding section, and the rear end of the shock is attached to the outer housing. Here I have edited a picture from above, and you can see inside the housing is the shaft of the shock. It attaches to the center of the rear axle pins. In the photos from above, you see just a spacer in the center of the rear rollers. But there is only one like that. Two of these center spacers are actually the rear ends of the shock absorber shafts.

The shocks prevent the sliding section from bouncing in and out, applying brakes, while travelling down the road. When you are trying to pull the sliding front section in and out by hand, you have to overcome the resistance of these shocks in order to do so.

 

[SearayPaul]

Dave

Thank you. I did not see that shaft in your first picture, bad eye sight. I thought that was a groove that the acuator traveled in. I assume these shocks are just like car shocks and to reinstall them you just pull them out and line up the holes. Are the bolts torqued?

I understand this system a whole lot better now. My system is in need of adjustment I think. First stop the grease gun. What I find intersting is that I never noticed the zerc fittings on the hitch. It is amazing how you can look at something a million times and not see everything. Oh well.

Thanks for your time Dave.

I will let you know how things turn out.

Paul

 

[Dave M.]

Dave

Thank you. I did not see that shaft in your first picture, bad eye sight.

Don't feel bad. I took the thing apart and forgot about the shocks until you brought up the question. Think my old brain is suffering from CRS (can't remember stuff).

Are the bolts torqued?

Look at the three rear bolts in the photo immediately above. You can see the nuts are slotted for cotter keys. This is so they will stay on, but not be too tight. I think the front ones are the friction type nuts.

Basically, you don't want to compress the outer housing against the inner housing or the bearing sleeves. They need to be able to slide and spin, respectively.

You probably should look at your manual, if you have one, but I just get them nice and snug.

Dave

 

[Dave M.]

Dave

I understand this system a whole lot better now. My system is in need of adjustment I think. First stop the grease gun. What I find intersting is that I never noticed the zerc fittings on the hitch.
Paul

Paul, the front rollers, at least on mine, are very easy to take apart. You don't need to take the rest of the system apart to get to them. If you remove them, you can check their condition and make sure they did have grease and are OK. If they never had grease, then you probably have galling of the metal, and that needs to be cleaned up before you grease them.

 

[chuck1]

slack250

Thanks for the feedback! I was beginning to wonder if the post had been worth doing or not, as no one had replied. But it was a real issue for me, and a learning experience.

Hey Dave yes the post was worth doing. You've already got 90+ view on it. Its post like this that make the site so good. Keep up the good work :thumbsup:

 

[Dave M.]

Hey Dave yes the post was worth doing. You've already got 90+ view on it.

Thanks for the kind words Chuck. Now I have gone and done another one on the combined sea water pump/fuel pump that some of us have on our 7.4L engines.

 

[Dave M.]

Took the boat out today, ran a few miles to warm it up. But I got cold, the air temp was about 33, the water temp was 43.

When I got back I found this skid mark on the garage floor. Has to be from the right rear trailer tire. I think it was only one, as it would not have moved easily if all three were locked up, and I did not notice it when pulling out. Must be time for more grease, or a cleaning and grease job. The building is heated, so they would not have been frozen with ice. Don't know if the drum brake pads would stick from just sitting a month or not.



I threw a bale of hay in the back of the truck to give me some extra traction. So maybe I'll just pull the thing whether the wheels turn or not. :smt021

 

[jg300da]

Great post Dave. I don't have a trailer but I very much enjoyed reading your posts. Like yourself I have a need to dissassemble things to see how they work and maybe even improve them. I believe this makes us better and more able boaters, and increases our love and respect for boats and boating in general.

 

[never monday]

Dave,
Very nice write up. Did you see an increase in mileage with the trailer service?

 

[Dave M.]

Great post Dave. I don't have a trailer but I very much enjoyed reading your posts. Like yourself I have a need to dissassemble things to see how they work and maybe even improve them. I believe this makes us better and more able boaters, and increases our love and respect for boats and boating in general.

Thanks! My wife might say it is a disease I have, and wonders why the first thing that happens to something when I get it home is that it gets taken apart.

But I think you are right about the boating. If you have a problem on the water and need to fix it yourself, it would behoove you to have an idea of what it is you need to fix, and how it works.

Calling for :smt100 may not get you anything but a very long wait!

 

[SearayPaul]

Dave:

I got my boat back today from the dealer. It was in for gel coat cracks and winterization, that is another story. I looked at the hitch and it had very little grease in the bolts. Thanks for your article on how to fix couplers. I am going with the grease fix for now as the trailer is still under warrenty so I will let the dealer do the grinding or replace the coupler if needed. Our dealer is great to work with and will take care of any problem so I am not worried.

Have a great day

Paul

 

[Dave M.]

Dave,
Very nice write up. Did you see an increase in mileage with the trailer service?

Never Monday,

Sorry, I missed this question before. I would have to say the answer is probably no. I don't think I ever saw below 12 MPG pulling the boat. I did check the MPG one day over about 60 miles on flat land, and it was in the low 12's. It is possible that it should have been in the high 12's or above 13, but that is cutting it pretty close.

I would say that when I realized what was happening, I was able to feel it on the highway. When pulling away from a stop sign and accelerating in the 25-40 MPH range, I could sort of feel it. And I think if I put in the clutch, it would slow down more than normal. Normally my truck will coast forever on flat land, and quite well even with the boat.

But when it got real bad, I definitely could feel it, and sometimes it did not want to move. I would have to stop, lift the weight off the hitch with the trailer jack, pull out the slack with the truck, put the jack back up, and go. That gets old real quick. The other real giveaway is when you touch the hubs and they make you jerk your fingers away.

 

[Dave M.]

Dave:

I got my boat back today from the dealer. It was in for gel coat cracks and winterization, that is another story. I looked at the hitch and it had very little grease in the bolts. Thanks for your article on how to fix couplers. I am going with the grease fix for now as the trailer is still under warrenty so I will let the dealer do the grinding or replace the coupler if needed. Our dealer is great to work with and will take care of any problem so I am not worried.

Have a great day

Paul

Paul, I'm happy you found the information of value. I doubt that many will need grinding, I think that just happened on mine because when the inner support brace was welded in, it was not aligned properly first.

Dave