http://www.rpod-owners.com/ This is an XML content feed of; R-pod Owners Forum : I need HELP!!! : Brake magnet scoring drum Copyright (c) 2006-2009 Web Wiz Forums - All Rights Reserved. Thu, 21 May 2026 04:08:08 +0000 Sun, 12 Jun 2022 09:54:08 +0000 http://blogs.law.harvard.edu/tech/rss Web Wiz Forums 9.64 360 www.rpod-owners.com/RSS_post_feed.asp?TID=15306 http://www.rpod-owners.com/forum_images/web_wiz_forums.png http://www.rpod-owners.com/ http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148462#148462 Author: offgrid
Subject: 15306
Posted: 12 Jun 2022 at 9:54am

Lippert has it right. When you initially set up drum brakes (on any vehicle) that is how we adjusted them back in the day, just a sight drag.   You do need to engage them a couple of times while spinning the when when adjusting them to be sure the brake shoes are centered up on the drum. ]]> Sun, 12 Jun 2022 09:54:08 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148462#148462 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148460#148460 Author: Welchsoft
Subject: 15306
Posted: 12 Jun 2022 at 5:56am

At the moment, brake units, hubs and bearings are new.  Wheels turn about a complete revolution before stopping. Burnishing is not completed yet but drove about 20 miles with everything new and braking seems to be equal on both wheels.  On a side note, my part time mechanic worked on RV's ad a dealership for quite a few years and helped me with the problem.  He said that when you burnish new brakes, they need an initial adjustment that prevents the wheel from turning no more that one half turn.  When I called Lippert, they said the wheel should spin with just a slight resistance and you could hear a small amount of contact to start the burnishing process with.]]> Sun, 12 Jun 2022 05:56:54 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148460#148460 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148439#148439 Author: offgrid
Subject: 15306
Posted: 09 Jun 2022 at 4:45pm

I assumne these are pics of the the old brakes you replaced? There does seem to be quite a bit of wear on these. The wheel mounting studs should be recessed in the hub/drum but it looks like either they weren't recessed enough or the steel surface has been worn down till they are starting to get wear from the magnet.

Do the wheels turn freely now with the brake controller on but no braking activated? ]]> Thu, 09 Jun 2022 16:45:34 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148439#148439 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148430#148430 Author: Welchsoft
Subject: 15306
Posted: 09 Jun 2022 at 8:15am

]]> Thu, 09 Jun 2022 08:15:52 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148430#148430 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148429#148429 Author: Welchsoft
Subject: 15306
Posted: 09 Jun 2022 at 8:10am

]]> Thu, 09 Jun 2022 08:10:04 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148429#148429 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148428#148428 Author: offgrid
Subject: 15306
Posted: 09 Jun 2022 at 7:41am

Some scoring is normal, the magnets make contact with the drum surface when they are energized. It's the friction of that contact that activates the brake shoes.

But I'm not sure if what youre describing is normal or not. The contact shouldnt be producing metal shavings for example. Do you have any pics of the scoring?

A bad contact would make one magnet deenergize so that brake stopped making contact but it wouldn't cause scoring. Quite the opposite. I'd recommend getting rid of the insulation displacement connectors on the brake wiring and replacing them with butt splices or soldered connections and heat shrink tubing. The factory connectors are junk.   ]]> Thu, 09 Jun 2022 07:41:34 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148428#148428 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148427#148427 Author: Welchsoft
Subject: 15306
Posted: 09 Jun 2022 at 6:57am

I'll pick up an IR thermometer.  Just wish I could have had a definitive answer as to why the magnets are scoring the drums.  My thought is that a bad ground or loose connection might cause one magnet to be energized more than the other while the trailer is bouncing down the road.  Just don't know.]]> Thu, 09 Jun 2022 06:57:28 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148427#148427 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148416#148416 Author: offgrid
Subject: 15306
Posted: 08 Jun 2022 at 3:55pm

Glad you have it sorted out now. For sure the burnishing process gets the brakes pretty darn hot.

If you do the math it works out that the drums will heat up by about 300 degrees above starting temp if you use the trailer brakes alone to fully stop the rig from freeway speed.

Lippert has you do up to 50 gentler decelerations from 40 to 20 and wants you to get the drums up to around the same 350-400 degrees. Safer and more controllable that way.

I carry my ir thermometer in my tow vehicle arm rest and check bearing and tire temps while refueling, and brake temps once in awhile after making a full stop from freeway speeds or after a downhill grade. Great tool which can give you early warning of several potential problems. ]]> Wed, 08 Jun 2022 15:55:22 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148416#148416 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148414#148414 Author: Welchsoft
Subject: 15306
Posted: 08 Jun 2022 at 2:46pm

Both magnets are within specs on amps and ohms.  A friend checked it out and suggested that the brakes were not adjusted equally for brake-in and with the initial adjustment the wheel (jacked off the ground) should only do about a half of revolution, then you need to drive quite a bit applying the brakes until they settle in.  Replaced the hub what was slightly scored and the associated magnet.  Right not the brakes are pulling evenly and I had no idea just how hot the acceptable temperature was for the hubs during brake-in.  Time will tell.  Thanks for the help.]]> Wed, 08 Jun 2022 14:46:19 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148414#148414 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148355#148355 Author: Welchsoft
Subject: 15306
Posted: 04 Jun 2022 at 1:03pm

Thanks.  Amps with the car running.  L:.14, R:1.45.  While I see a big difference, still not sure about the measurement as I would expect the problem L site to be getting more not less than the R.  I'll test again with the battery.]]> Sat, 04 Jun 2022 13:03:20 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148355#148355 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148354#148354 Author: offgrid
Subject: 15306
Posted: 04 Jun 2022 at 12:17pm

If it's not getting pretty dang hot it's not working. The magnet runs on the drum when engaged so there will by design be some scoring.

If you have an IR thermometer measure the brake temps after a couple of stops using only the trailer brakes. A working drum will be several hundred degrees F and the drum paint will be out gassing if it's fresh. If one isn't working at all it will be nearly ambient temp.

Your strange current readings could be due to the pulse width modulation of your brake controller as it drops the TV battery voltage down. Try turning it all the way up and if that doesn't stabilize things then try a direct battery connection as you are suggesting. You can also look at the resistance of each magnet using the ohmmeter setting. Lippert has a spec for that in their manual.

At the end of the day you can do what I did, disconnect the hot brake temporarily, burnish the cold one, and see if it gets up to a similar temp once burned in and stops the rig ok. Then reconnect the two magnets in series, crank the controller all the way up, make a few stops. If you like the way that feels and both brakes are getting reasonably hot then go camping.

We all have to acknowledge that electric drum trailer brakes are 70 year old technology and will never work like we expect from our moderm sophisticated ABS hydraulic vehicle disk brakes.

]]> Sat, 04 Jun 2022 12:17:43 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148354#148354 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148353#148353 Author: Welchsoft
Subject: 15306
Posted: 04 Jun 2022 at 10:49am

I have a multi-meter that will measure up to 10A which I connected to one cut lead (on lead connected to each of the cut ends), and the second magnet wire still connected to the trailer wiring.  Got some strange results with the engine running.  I may need to disconnect all wires from the trailer and test with a battery.  What keeps coming back to me is the scoring which makes me think that the magnet is constantly sticking to the drum, even when my foot is not on the brake.  Is it possible that some short somewhere is sending power to the magnet when I'm not using the brakes?  As for the heat during burnishing.  It does appear that both brakes are working (from a visual inspection of the shoes) but only the left is getting quite hot and I'm attributing that back to the magnet since in a 2 mile trip to burnish, the drum is already scored and the magnet worn.

]]> Sat, 04 Jun 2022 10:49:05 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148353#148353 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148352#148352 Author: offgrid
Subject: 15306
Posted: 04 Jun 2022 at 10:25am

Since the magnets are in parallel they will always have close to the same voltage on them. You will need to measure current through them to see any difference.

Get a multimeter with a DC (not just AC which is more common) clamp on current meter and clamp it to one of the lines feeding the magnets. About $40 on Amazon.


Place it far from the magnets or the mag fields will screw up the readings. Then measure the current to each magnet and see if they are much different.

I did the same as you and got complete new brake assemblies. Still could never get the two brake magnets to balance so I ended up rewiring them in series. That way they are guaranteed to have the same current. You have to turn the brake controller up to double the voltage
though to get the same braking action. Better I think than having imbalanced trailer braking on a wet slippery mountain road someday.

Another point is that once one brake is getting hot and burnished while the other is not it will always do more work so you will have to disconnect the hot one and do your burnishing stops with just the unburnished one to get it to work properly.

While you have things disconnect us a good time to get rid of the crappy insulation displacemebt connectors FR uses and replace them with real sealed butt splices or soldered connections.

]]> Sat, 04 Jun 2022 10:25:07 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148352#148352 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148350#148350 Author: Welchsoft
Subject: 15306
Posted: 04 Jun 2022 at 7:50am

What I thought was a wheel rusting turned out to be the magnet scoring the drum surface and the iron filings sitting on the wheel and rusting.  Removed drums and found right chewed up by the magnet and left with grease on it so I assumed a bad seal on the left and the right was doing all the work.  Replace complete drum/bearing units and brake units.  Went to burnish the brakes and found that left drum very hot.  Removed the drum and found the magnet eating into the drum and the right not (although I could see that the right shoes were engaging).  I thought with no grease on the drum or magnets this must be an electrical problem.  With the brake controller manually operated by a helper and measuring voltage at each magnet: @2: L1.9, R.84, @4: L4.9, R4.41, @max: L9.4, R10.82.  So now I'm stumped.  Voltage seems to be close between L&R but my 'drum scored by the magnet' problem has moved from the right side to the left.  Any help troubleshooting would be appreciated.]]> Sat, 04 Jun 2022 07:50:25 +0000 http://www.rpod-owners.com/forum_posts.asp?TID=15306&PID=148350#148350