Trailer Brake Adjustments

[michael_h]

If you were going to adjust your own trailer brakes is there a measurement of how close they should be to the drum when not engaged, do you adjust them till you hear them drag on the drum and then back off, or how do you know off truck when their adjusted correctly???

I read somewhere that to get a proper adjustment for towing, you need to drive about 30mph and apply the trailer brake only, you keep adjusting the gain on the controller till the trailer brakes lock up, then you back off till they don't .

Now I'm not sure the method above is true or not, but I know that if my built in ford controller is engaged with the gain set at 10 the brakes slow the tow vehicle but not to any extreme . . .

Dec of last year I paid the dealer to do a brake adjustment, but I'm now learning I may not have been adjusting my brake gain control to apply enough pressure hence it's now making me think that the dealer service department may not have preformed the work, or adjusted it properly

Thanks in advance for any advice

[buzzcop63]

I have a Promethious IQ brake controller that has three levels of adjustment, you select the level that describes your truck to trailer weight, the third level is for trucks that are towing trailers that weight more then the truck does so this level is more aggressive. That being said the instructions and DVD video that came with the unit say to bring the truck and trailer up to a speed of 25 MPH and then apply only the Brake Control to the point that the wheels lock on the trailer, then to back off a bit. By doing this I found that truck and trailer would brake well on the high way but in traffic stop and go the trailer would brake so hard that it would rock the front of the truck up and down. Consequently I have backed the brake setting off a little at a time until I found the brakes would pull the trailer down using just its brakes but in traffic would not set up a rocking motion of both truck and trailer. The manual also suggests that each time you head out towing that you approach the speed of 25MPH and then pull on the trailer brake only to make sure it is working. So far so good!

[rjsurfer]

I too had two different settings with my electric drum brakes, one for city and one for highway. After awhile it just became a normal part of driving.

That adjustment was OK for me but it was keeping me from letting my wife drive the trailer. I'm sure she didn't understand the concept and would find it bigger pain than I thought it was.

That's the one reason I went with disc brakes, no more worry.

Ron W.

[Seabee]

Depending on the weight of the trailer, the wheels may not lock up even with the gain turned all the way up. Easy way to test the trailer brakes is to pull the emergency break-away and see if your truck can move the trailer.

[michael_h]

well I think I answered my own question Friday. I finished my brakes on my truck and was taking my trailer to a campground near the house, I had to mash the brakes to avoid some traffic ahead, the brakes locked and the tires smoked the road . . . . I did a little tweaking of the EBC and feel more confident that the trailer is doing it's job to assist in stopping

[audio1der]

I also did some light emerg. stops on our maiden voyage home with our marshmallow. I have since gone down one notch as I view it in terms of service; if it's close to perfect (say 49/51% or 51/49%) do I want to service the brakes on the truck which I can do myself and there is a great selection of widely available parts, or the trailer which I have never done and only RV dealers would have the parts ($$)?

[shiggs68]

There two keys points to adjusting your trailer brakes properly.

First, the trailer brakes themselves should be adjusted mechanically to the point of dragging, them back off slightly. Just like adjusting vehicle brake shoes.

Second, is adjusting your controller gain to just below the point of lockup. This provides the maximum combined effect without total lockup. As in most instructions, pull the trailer at about 20mph, adjust the gain up to the point that brake pedal depression can lock the trailer. Then back off the gain slightly.

Someone above mentioned using the breakaway switch to check for lockup. This method should always work as the breakaway switch applies a full 12vdc signal from your trailer battery. A brake controller only applies 6 to 10vdc. If you can not lock them with the controller, the trailer itself needs adjustment. Has nothing to do with the breakaway.


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[slow]

Originally Posted by shiggs68

................First, the trailer brakes themselves should be adjusted mechanically to the point of dragging, them back off slightly. Just like adjusting vehicle brake shoes............

This is the adjustment I find the most difficult to know when it is done right. The procedure is simple enough, but what does "to the point of dragging" and "back off slightly" mean?

Why not define drag in terms of a torque value, and then the number of star nut notches to turn to back it off?

Further insights would be appreciated.

[SteveC7010]

Originally Posted by audio1der

I also did some light emerg. stops on our maiden voyage home with our marshmallow. I have since gone down one notch as I view it in terms of service; if it's close to perfect (say 49/51% or 51/49%) do I want to service the brakes on the truck which I can do myself and there is a great selection of widely available parts, or the trailer which I have never done and only RV dealers would have the parts ($$)?

Interesting thoughts, but not quite accurate. The drum brakes on a trailer are the same as drum brakes were on cars and light trucks for many years. They're virtually unchanged for at least the last 60+ years. The parts are readily available at some auto parts stores, and can be ordered by any of them. These axles and brakes are common to all kinds of trailers and not just RV's. That means that not only does your local auto parts store have easy access to them, but every utility trailer, horse trailer, any trailer dealer carries them.

Working on them is a breeze. If you can do car or light truck brakes, you can certainly do RV brakes; they are easier. All you need is a manual (readily available on the axle company's website and needed only if you've not done them before or need a parts cross reference) and basic hand tools. The most you might have to purchase is a drum brake adjuster which is an ancient tool, absolutely lowest of the low tech, and dirt cheap at any auto parts store including WalMart.

Final point, Keystone trailer axles (like so many other components) are not unique. Half the problem with folks getting service or parts is that they sometimes get too specific about what the part is for. Say the word RV (let alone Cougar or Passport) at an auto parts counter, they vapor lock. Don't walk into a Jayco dealer looking for Cougar parts, they instantly don't have them, even before you tell them what it is. Don't tell them it's for your OCP 6000SUX, tell 'em you've got a pair of Dexter 7,000 pound axles with 12" drums. If you're looking for parts for your Dometic 2652 fridge, don't get hung up on the fact it is in your Bullet. All the RV manufacturers get their stuff from a small group of manufacturers, no matter what the item is.

If your rig has drum brakes, they are no different than those found in autos and light trucks. See above for parts sources.

[SteveC7010]

Originally Posted by slow

This is the adjustment I find the most difficult to know when it is done right. The procedure is simple enough, but what does "to the point of dragging" and "back off slightly" mean?

Why not define drag in terms of a torque value, and then the number of star nut notches to turn to back it off?

Further insights would be appreciated.

You're way overthinking this. It's a simple process and does not require anywhere near the precision that you might think. With the tire just off the ground, you spin it slowly, and adjust the star wheel. When you tighten it, the shoes are pushed outward until they begin to contact the drums. At that point you will get a an unmistakable grating/sandpaper sound and you'll begin to feel resistance to spinning the wheel. At most another notch or two will get you to the point that you can barely move the wheel. That's too much. Back off until the wheel just spins freely and you're done. You only have to do the first wheel to become comfortable with this. The other three or five will come naturally.

There's no tools out there to evaluate drag torque. Well, they do exist, but are priced way beyond the financial means of even the most well equipped repair shop. They don't exist at an affordable price because they're not needed.

[X-Treme]

Originally Posted by SteveC7010

There's no tools out there to evaluate drag torque. Well, they do exist, but are priced way beyond the financial means of even the most well equipped repair shop. They don't exist at an affordable price because they're not needed.

While I agree with everything else you said in your post, THIS part, I do not. "Drag torque" is VERY easily measured. It can be measured the exact same way as rotating torque. Done with a plain meter torque wrench (a click type wouldn't work so well in this case). We measure rotating torque quite often in our repair shop with a $150 torque wrench.

[Desert185]

The difference between a car with hydraulic drum brakes and trailers with electric drum brakes is the magnet that drags all the time. This may throw off the "draggy feel" during adjustment. That's why it's probably a good idea to tighten the star adjustment until rotation is difficult, then loosen until the brake shoe drag is felt and heard.

A visual inspection along with a bearing relube and brake dust elimination (which contributes to the drag) is a good idea rather than just checking the adjustment on a newer trailer without pulling the drum.

I remember that we used to arc the shoes to the drum during a brake job when I was a "kid" working myself through school. I wonder if this is even considered these days with the proliferation of disc brakes?

Always replace return springs with new when replacing brake shoes, BTW.

[SteveC7010]

Originally Posted by X-Treme

While I agree with everything else you said in your post, THIS part, I do not. "Drag torque" is VERY easily measured. It can be measured the exact same way as rotating torque. Done with a plain meter torque wrench (a click type wouldn't work so well in this case). We measure rotating torque quite often in our repair shop with a $150 torque wrench.

You are right, and I forgot about that technique. But I would point out that the amount of drag that we look for in adjusting drum brakes is pretty minimal to the point that it might not even register on some torque wrenches.

[Whitewolf]

On a side note, I noticed the other day that there were no plugs for the adjuster holes. Back in the day, that was something we always made sure was installed. I went to the local NAPA store and the young guy looked at me like I was from another planet. I don't think he knew what a drum brake was. Went to AutoZone and the young guy knew exactly what I wanted. They didn't have any in stock but he ordered what I needed. I also ordered a set for my neighbor.

Also for anyone new to adjusting drums, that sandpapery grind noise you'll feel and hear, it may not be constant as you spin the wheel. Don't worry about getting each wheel perfectly the same as the others. Close. But not perfect. You'll drive yourself nuts trying to get them perfect.

[DirtyOil]

Here's a video how-to for adjusting electric trailer drum brakes..

http://www.bing.com/videos/search?q=...1693146CF3EAE3

[bobbecky]

Your best option would be to find out exactly what axles you have and what brakes are part of the axle assemblies. Most axles will have stickers on them telling who made them, and then there will also be stamped on the axle tubes a series of numbers. If the axle is, say Dexter, call them up and give them the numbers on the axle tube, and they will tell you anything you want to know about them as shipped to Keystone. Ours are 12" X 2" forward self adjusting Dexter brakes, which is great, because they do their own adjusting. I just have to pull the drums once a year, inspect the brakes and repack the bearings. This time, I will be replacing the entire backing plate/brake assembly, as the last time I pulled and inspected, I know from experience, they will need new shoes. Much cheaper and way less time spent just installing a new assembly than messing with all the springs and stuff.

[X-Treme]

Originally Posted by bobbecky

Your best option would be to find out exactly what axles you have and what brakes are part of the axle assemblies. Most axles will have stickers on them telling who made them, and then there will also be stamped on the axle tubes a series of numbers. If the axle is, say Dexter, call them up and give them the numbers on the axle tube, and they will tell you anything you want to know about them as shipped to Keystone. Ours are 12" X 2" forward self adjusting Dexter brakes, which is great, because they do their own adjusting. I just have to pull the drums once a year, inspect the brakes and repack the bearings. This time, I will be replacing the entire backing plate/brake assembly, as the last time I pulled and inspected, I know from experience, they will need new shoes. Much cheaper and way less time spent just installing a new assembly than messing with all the springs and stuff.

Wow! A 2012, and you already need new brakes? Put on a lot of miles, do ya?

[bobbecky]

Yes, we are full timers. We put a little over 13,000 miles last year on it, and this year will be less. We are almost 10,500 this year, which will probably be all we do. My wife is recovering from a knee replacement, which she just had done last Wednesday, but is already walking without a walker. Once she is fully functional, I hopefully will get a hip done. Before doing the hip, I'm going to do the brakes, so we can roll as soon as we are able.

[shiggs68]

Originally Posted by slow

This is the adjustment I find the most difficult to know when it is done right. The procedure is simple enough, but what does "to the point of dragging" and "back off slightly" mean?



Why not define drag in terms of a torque value, and then the number of star nut notches to turn to back it off?



Further insights would be appreciated.

Your questions are valid. However, as with auto, every drum, brake shoe size, and adjuster is different. Therefore no rule fits all cases. I would suggest researching your specific wheel/hub manufacture such as the Dexter web site which has numerous how-to videos.


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