Trailer brakes won't lock-up?

[John]

Hey Gang,

Since owning my trailer, I have NEVER been able to get the trailer brakes to lock-up. They stop ok, but I don't trust them for a panic stop. Because of this, I always leave plenty of room to stop.

This situation has occured when using the Reese Brakeman and the Jordan Ultima. We just installed the Jordan yesterday and couldn't get the brakes to lock-up. I called Jordan and everything sounds right. I'm getting 13A, which means the controller is reading all 4 brakes. It does slow down great, no jerky feeling, but just won't lock-up. I'm returning it today so Jordan can bench test it.

Note: it's wired the off the battery using a 20A auto-reset CB. We even ran an additional ground wire. Adjusted the brakes until they stopped and then backed off until they were dragging slightly.

I replaced my brakes shoes earlier this yr. I used Red Line Trailer Parts- "trailer brake shoes/linings, fits Dexter, Fayette, Foreman 12"X2" electric brakes." The magnets looked great, wiring looked clean. I didn't turn the drums, as there was no scarring.

So if any of you have had this problem/experience or know a possible cure, Please share!!!! I'm needing help!!!

Many Thanks-John

p.s. I really don't want to get in to a discussion over brake controllers, as this is already being explored in another thread. I'm just looking for help in the no lock-up situation !

[RoadKingMoe]

When I started working in the RV business, I was taught that electric brakes on new trailers won't always lock the trailer tires on pavement, some will, some won't.

Unlike autos, trailers sit around and the inside of the drums rust just like the outside, especially in humid areas like Florida. This winds up putting a coating of iron oxide powder on the braking surface of the drum and reduces its friction until it burns out.

You don't say how much usage your new brakes have, but new trailer brakes are like new car brakes... it takes time for them to wear into each other and the new linings to be burnished. You may not have turned the drums, but did an earlier owner? If the drum diameter has been increased, there will be less contact area with the drum until the lining curvature has worn to fit it. In the old days, I had car linings arced to fit the drums after turning.

We adjusted brake controllers on a packed clay road, where it was easier to slide the tires, with two guys watching the truck and trailer wheels, and adjusted until the trailer tires just slid first. Then we did it again with a guy on each side to make sure both sides of the trailer were skidding at about the same time.

That's what's important as far as adjustment. I know a lot of folks want maximum braking and adjust the controller to be just short of lockup on pavement at full braking, but even with the Kelsey Hayes hydraulic controllers, this often lead to the trailer overbraking and pulling hard on the tow vehicle under normal situations.

Another problem with the trailer braking signifcantly more than the tow vehicle is that the drum brakes don't shed heat nearly as well as the discs on the tow vehicle, so it's important the trailer doesn't brake any more than necessary to keep slight tension on the truck, especially on long downhill grades.

13 amps sounds plenty for 4 brakes. That should tell you that you don't have brakes on one side accidentally wired in series (which would lower the current) rather than parallel, and that the controller and the wiring in both the truck and the trailer is doing its job. If the brakes really have some mileage on them and are past break-in, I'd probably take a meter to them just to check.

I wouldn't have worried about the controller since you were getting that much amperage. But Jordan's concientious enough to want to check it on another meter. BTW, if you ever change vehicles, send it back to him and he'll replace the cable at no charge.

Here's a link with some good info and troubleshooting.

Hope this helps,

[John]

Maurice,

I installed the trailer brake shoes prior to going to BC. I also wasn't able to lock-up the brakes on the dirt roads within the park.

I also heard that some brakes/axles don't lock-up, but I don't even get a very aggressive brake at full amps and Jordan didn't feel that this was a safe towing condition.

So before I go and replace the complete backing plates assembly, I'm hoping someone out here has experienced the same problem and knows an easy fit.

But if you think of anything else, I'm all ears.

John

[overlander64]

Greetings John!

I had the same problem with my '64 Overlander for the first two seasons of heavy use after I purchased the rig. The problems were multiple as it turned out.

The biggest problem was that the brake magnets were nearly worn out, but that wasn't the only problem. The springs and other attaching hardware was fatigued from years of use as well as two seasons of just sitting in storage. The biggest problem as it turned out was that the brakes had been rebuilt several times in the past by previous owners who DID NOT resurface the drums - - the drums were so uneven that the brake shoes could barely contact the drum due to ridges along the outer edges. The solution recommended to me by a trusted Brand X dealer was to install all new "fully loaded" backing paltes and have the drums resurfaced and shoes matched to the drums - - the machining ran a little more than the fully loaded backing plates - - but what a difference - - smooth, even braking with almost no clanking noises - - and the wheels uniformly locked up if the brake controller were adjusted to brake that severely.

The entire cost for the machining and four loaded backing plates installed by my nearby Brand X dealer was $750.00.

Good luck in finding a solution to your problem.

Kevin

[RoadKingMoe]

Originally posted by John
I installed the trailer brake shoes prior to going to BC. I also wasn't able to lock-up the brakes on the dirt roads within the park.

Now you've got me worried... you should be able to easily lock the trailer brakes on a dirt road with any controller, especially with the manual control.

I guess I'd be pulling the brakes apart again and checking the magnets, lever arm, shoes and drum faces.

I don't wanna sound condescending, but wanna cover all the bases.

Are you SURE the brakes are adjusted properly?

Did you clean everything well with Bra-Kleen before reassembly?

Were the magnets dead flat against the drum? Were both those surfaces in good condition? It isn't the magnet on the drum that stops the trailer, it's the drum pulling the magnet on the end of the lever that cams the linings out to the drum which stops the trailer. If the magnetism isn't strong enough, or if there isn't sufficient grip here, the drum can't pull the lever arm hard enough.

Are you sure the correct arms are installed correctly on each side of the trailer? (if not, it's easier to lock the wheels backing up than it is going forward).

With the high amperage, I'd be tempted to skip checking wiring, but wouldn't skip it. I'd check the voltage and amperage to each brake and really look over the trailer and truck wiring carefully.

Hope this helps,

[John]

Maurice,

My buddy's been a GM mechanic for 27 yrs now and he's one of the best. He did my brake job and inspected, cleaned and adjusted the brakes. Everything looked great and operated well. He measured the current at the wheels, looked at the magnets and drums. No signs of abnormal wear.

Kevin,

I think I'm going to go with what you did with your trailer. I have a couple of questions for you.

1. Backing plates-what all comes as an assembly? Do brakes shoes come with it?


Open question: Is turning the drums effective enough or is true machining needed?

Thanks for all of the responses and please keep them coming!

John

[overlander64]

Greetings John!

The fully loaded backing plates on my trailer included new shoes, all hold-down equipment, new magnets, and all wear items replaced such as adjuster mechanisms.

I really think the key to the process was the machining to match the drums and shoes - - especially since my drums had gone so long without any attention. There didn't appear to be any initial "wear-in" with this process - - the brakes performed flawlessly from the first stop throughout the past three plus years. At the time, the dealer who did my work suggested that he would have the process done in this manner if the coach were his, but that only about 50% of his customers were willing to foot the bill for the full matching procedure. I am convinced at this point as my brakes continue to meet my every expectation - - they are inspected annually at the beginning of each season as a part of my regular pre-season check-up and bearing repack.

Kevin

[Pick]

John, Backing plates come with everything, shoes, magnets, springs, etc. I paid $79 each for mine. Saw them for $71 at the AS store.

[RoadKingMoe]

I agree with Kevin, John. I never rebuilt my own drum brakes without having the linings arced to fit the drums. Perfect stopping from day one... no wear-in required.

[John]

Maurice,

Please explain having the linings arced to fit the drums? How is this done and who does this?

Tks-John


Pick,

I've called/emailed a couple of A/S dealers for pricing, but I did go to Dexter's web site and looked up their local dealers in FL.

RedNeck Trailers sells the complete brake assembly for $53 per wheel($10 S&H). I was floored at the price difference but their a large distributor of trailer parts, so their volume allows such a cost savings. I'm going to go this route since this is my home and I'll be in it for yrs to come!

Tks for the input-John


Kevin,

Thanks for this infor too! Who machined your drums? The Brand-X dealer?

Tks-John

[john hd]

john

simply put, arcing brake linings means sanding down the brake linings by hand to exactly match the curvature of the drum.

one takes sand paper cut to match the width of the drum and tape it rough side out to the inside of the drum. then you sand the brake shoe by sliding it back and forth on the paper until it matches the curve on the inside of the drum.

to finish the job, you cut a small bevel on the leading edge of the shoe so the shoe will not grab and self engage.

i have to do this to my harley's mechanical brakes every time i relace the linings in the drum brakes. they are small, and you need to get them 100% effective.

however, you must be very careful as many linings have asbestos.
i use a respirator and disposable coveralls when i do this. and keep the kids and pets away.

john

[John]

John,

I'm going to turn the drums, then I'll get my buddy to arced them.

Questions: after sanding the linings, if you can, describe how to bevel it.

Do I use a file? Make it bevel with a round edge?

Tks-John

[overlander64]

Greetings John!

The Brand X dealer who performed my brake work farms all of his machine shop work out to a local automotive machine shop that seems to do much of the machine shop work for many of our local automobile dealers. When I had the brakes overhauled on my '75 Cadillac, this same machine shop did all of the work on both its drums and rotors. If my memory serves correctly, the machine shop is Blakenship's Automotive Specialty Machine Shop. My receipts and information are all in my log book at my vacation home some 400 miles from my current location.

Kevin

[john hd]

Originally posted by John
John,

I'm going to turn the drums, then I'll get my buddy to arced them.

Questions: after sanding the linings, if you can, describe how to bevel it.

Do I use a file? Make it bevel with a round edge?

Tks-John

john

with a flat file. you are looking for a 45 degree bevel on the edge.


john

[John]

John,

if I wear disposable clothes, wearing a partial mask and sitting away from the trailer, would I be able to set the drum on my lap and turn the linings?

John

[Chuck]

Interesting thread, guys. I seem to have the opposite problem...which I guess from what you're saying, isn't a problem. My brakes seem to lock up easily on any gravel surface, but not on pavement. (of course, If I crank up the sensitivity on the controller, they'll lock on pavement, too...). anyway, what "feels" correct on hard pavement is very grabby on gravel, but I think I'm hearing that this is correct (?)

after noticing this effect on my first experience towing, I looked things over. I needed to re-pack the bearings for good measure, anyway, so while I had everything apart, I adjusted the brakes. everything looked ok...but I'm not an expert.

[John]

I emailed Airstream to see what the rating of my axles are and I found out that their 4000#'s each.

I've read other threads on axles and axle replacement and it seems like the were about 6000#'ders.

Does this seem a little lite for a trailer with a GVW of 8400#'s?

John


Also here's a good link on trailer brakes.

[Pahaska]

The axle ratings are in addition to the weight of wheels and tires. That gives some padding. Also, there is the hitch weight, a a large part of which is not on the axles, even with an equalizer hitch.

My trailer has 2 2500# axles. The original Airstream GVW was 5300# which fits very well once you subtract wheel, tire, and hitch weight. They apparently reduced the GVW to 5000# to be able to say that a large number of SUVs could tow it. I still consider it a 5300# GVW trailer, even though it may not be entirely legal.

Axles that are not rated overly high will provide a better ride for the trailer. The stiffer the axle is, the more impact that will be transmitted to the trailer.

[RoadKingMoe]

If a standalone axle rating includes the words, "to ground" it is the maximum weight you should see with that axle's tires on the scales. It includes an estimate of the weight of wheels and tires.

Vehicle GAWRs are provided for use with scales and are "to ground." That doesn't mean you can exceed them by the weight of the wheels and tires and still be within the rating.

From what I've seen, Airstream uses GAWR that don't add up to GVWR, but do add up to or exceed GVWR minus 10% tongue weight. As John said, for a softer ride.

[John]

Jordan called me and the controller works great on his bench test.

This leads me to believe that it's within my brakes. My trailer did sit for 1 1/2 yrs prior to myself buying it. So I'm sure the springs and such have been effected by our nice humid air down here.

I'm ordering the brake assemblies once I hear back from Dexter.

Thanks for all of your input and I'll let you know how everything works after the brakes are switched out.

John