I did not want to hi-jack Mark's trailer thread with this discussion, but since the forum is slow, we can talk about it. I have taken apart many drum brake systems. I am so old that I have worked on automotive brakes that were pre-self adjusting. I have worked on mechanical brakes. In every case that I worked on with self adjusting brakes where the self adjusters were not working it was because the adjuster threads were frozen. I understand that the typical automotive self adjuster mechanism will not work on trailer brakes. Especially the ones with the single piston brake cylinders. This is no excuse for not having self adjusting brakes on the trailers. There is movement of the piston when the brakes are applied in trailer brakes. When the brakes get worn this movement is increased. The cable mechanism that operates the self adjusters could easily be made to work with the excess movement of the piston that happens when the brakes get out of adjustment. It is not rocket science. So, that is what inspired my comment that cars had self adjusting brakes 50 years ago and there is no excuse for trailer not having them. I would guess that most trailer owners are not aware that the brakes need to be adjusted unless they are ancient like me and remember when the cars were like that. It does not take that many miles for their trailers to get weak or non operative brakes. jim
Jim Actually, this is all relevant to the prior thread, and your timing with this issue is perfect. An internet sales person from trailerpartsdepot E-Mailed me and suggested that, if I'm going with a complete trailer brake rebuild, I should go with Disk brakes. Here's the situation. I have 7" inside diameter brake drums. The cost to replace the entire system with new hydraulic, free-backing drum brakes, from new backing plates, brake shoes, drums, brake lines, and actuator is about $340 before tax and shipping. Included with this is new pre-packed bearings, bearing covers, etc. To replace the system with disk brakes will be about $415 before tax and shipping. The sales person says that the disk brakes will last much longer, do not require adjusting, are easily inspected visually, and are less prone to moisure damage than drum brakes. So my question is... should I go this route? I sent an E-mail to the sales person asking if I need a reverse release solenoid if I go with disk brakes. Do you know the answer to this? I would assume that I would need it, because I don't think that the disk brakes can be purchased in a "free-backing" mechanical system like the drum systems. The downside of any system that requires a reverse release solenoid is that this requires an extra wire coming from the backup lights, and this makes it harder to switch the trailer between vehicles. What do you think?
As a side note, attached are diagrams of the typical trailer wire plugs - both 6 pin and 7 pin. Does anyone know if these harnesses have a connection to the back-up lighting circuit for use with reverse release solenoids? Or do you have to run an entirely separate wire to the back-up lights? You'd think the harness would already have this, but it doesn't look like it. The "electric brakes" wire is for an electric brake controller, I assume. I also assume that the "aux" has no wire attached to it, so perhaps this could be used. If I go with a system that requires a reverse solenoid, can I simply use a block of wood or something so that the brakes can be locked out when reversing with a tow vehicle that does not have the extra wire for reverse release solenoid? I know... a lot of questions. However, I'm sure others will have these issues as brakes become more common on boat trailers....
Mark, The disc brakes are just as effective in reverse as they are forward, so the solenoid is required. It is hooked to the back up light circuit. The hookups I have seen used the flat connector, but with five connections. I don't know the answer to the round connector, but I am sure it can be solved. This pretty much limits the trailer to your vehicle which is a good idea from a liability stand point also. Check with your insurance agent. The discs may be too effective on slippery roads. The drums might be also. It is possible to drill a hole in the hitch which would prevent hitch movement when a pin or bolt is installed. You might want this for slippery roads also. I think if I were going to change the whole system, and just use one vehicle, I would go with electric which can be modulated. This is getting complicated. jim
Which plug do you have? The 7 or 6 pin. It looks like you could use the aux in the 7 pin. You could use the electric brake circuit in the 6 pin and hook that circuit to the backup lights. I think it is normally hooked to the brake controller which you do not have. jim
Well, if I was trailering all the time, or if I was pulling a big enclosed trailer, which weighs more, I might consider electric brakes. I don't really want a controller in the car. The person that I would normally let use my trailer is my neighbor, as he sometimes needs to move aircraft parts or tools between his Poplar Grove and Naperville hangars (he used it to move some Skyhawk wings last weekend, in fact). He has a 2007 GM truck so his wiring will be the same as mine, anyway. At least with the hydraulic brakes, any vehicle with a hitch can use the trailer - and for backing up the brakes can be manually locked out. The electric controller kills the ability to ever let anyone use the trailer. I expect to lend the trailer from time to time to guys in the neighborhood like my neighbor, who is always helping me with stuff. I'm not really worried about the insurance aspect - I will have less than $2,500 in it. I think I'm going to pull the trigger on the disk brake system. My research and communications with the trailer parts guy convinces me that my tow vehicle wiring plug already has a wire that is tied to the back-up lights. I will verify that this evening. I would then need to replace the four pin plug on the trailer with a 5 pin plug, with the blue wire on the pig tail being for the solenoid on the brake actuator, and I'd need an adapter to go from the car, which has the GM round outlet, to the blade type plug on the trailer. I have a four-pin adapter now for the boat. I guess a wire tester will tell me whether the backup lights are outputting to the correct pin. Most of this stuff is standardized now, which helps. The thing I like about the disk brakes is that you can see everything, and inspect it, even with the wheels on. Drum brakes have a way of hiding what is going on inside the drum. The guy I bought the trailer from told me that "you can really feel when the brakes grab." Well, I've got news for him, the brakes on this trailer haven't grabbed for many years. He just didn't know it. If I can spend less than $100 more and have brakes that don't need to be adjusted, and which are less prone to rust and freezing up, then that seems like a better way to go. I will take some pics this weekend. The existing system is a real mess.
Jim I'm at the office now. I'm pretty sure I have the 7 pin connector. I did some research which suggests that the GM wire harness already has a wire that is hooked up to the reverse light circuit. The question is... which wire? Some diagrams I have seen show the "Aux" pin as being "Aux/Backup" so this wire may be hooked to the backup light circuit already. Wiring diagrams show the trailer-side wire for back up solenoids to be purple, and the vehicle side wire (in GM vehicles) to be light green. I just need to look at my manual, and use a tester, and figure this out. Typically, the "blue" wire is associated with the electric brake controller. However, the trailer parts guy told me to use the blue wire on the blade style 5 pin connector for the trailer to operate the actuator solenoid. It seems likely to me, however, that this blue wire will end up connecting to the blue wire in the vehicle that goes to the electric brake controller (which I do not have). Thus, the question is sort of open on which pin is (or could be) hooked to the backup lights. I will check the owners manual for the vehicle. Perhaps that will shed some light on this. It is still in the "mystery" stage here. I'm sure the answers are all sitting deep within some blog or forum somewhere. When I figure it out, I'll post it here.... :good:
You could install the pin I mentioned for when the trailer is borrowed. If there are only a couple of people that re going to borrow it, then just modify their cars too. I hope you are right about the standardization. A volt meter or test light will tell the answer. The real issue with the disc brake set up was with marine dealers trying to move boats around with a tractor or truck. The disc brakes require them to have all their stuff with the back up light circuit. The liability issue I mentioned would be you being the owner being liable for personal injury. You may not be covered in this instance when the trailer is hooked to a car that is not owned by you. The chances of this happening are slim. jim
Here is an interesting question. What about the option of just putting my old drums back on, sans brake shoes and hardware (the bearings are fine), and locking the actuator coupling, so that I have NO brakes. Or, to save on weight, I could go to standard bearing hubs and a non-actuating coupler, which would not cost much. Sound like a bad idea? I doubt this trailer weighs much more than my boat trailer. It is an aluminum trailer. Let's say the sleds are 500lbs each (which is high - my heaviest sled weighs 560 lbs but the other sleds are much less). That is 2,000 lbs. with four sleds. The trailer is 1,450 lbs empty weight - so we are talking about a total weight of 3,450 (max is 4,400lbs). I have always figured that my Eagle trailer and Hydrodyne are in the 3,500lb range, and I have no brakes on that trailer. I am pulling with a full size GM truck and have never had any problems. So, do I really need brakes or am I wasting time and money?
I know for a fact that the GM 7 pin connectors have a backup light pin (at least since 1999 anyway). My guess would be that it is the one labeled Aux. in your diagram, but I would confirm that with the owners manual, the electric brake wiring harness that was most likely in your glove box when you bought the vehicle, or a volt meter with the vehicle in reverse (and someone competent holding the brakes!!! and maybe some chocks too). I believe the one labeled 12V is constant 12 volt power (probably only when the ignition is on?) for lights inside the trailer. Some brake systems have a pin that you can put in the hitch to make sure it doens't actuate the brakes for backing up (I've seen it mostly on inboard trailers).
