Brake drum temps mystery

[Steph and Dud B]

This is odd. I lost my little IR thermometer when we picked up our Ollie and recently replaced it. I'm in the habit of checking the brake drum temps when we reach our destinations.

On the last 2 trips my passenger side brake drums were registering 20-30 degrees higher than the driver's side drums (as measured through the wheel spoke openings). Here's the weird part. The driver's side and passenger side drums are different from each other, but consistent with their partner on the other axle on that side - within just a few degrees. For example, the driver's side drums might be 120 and 124 degrees, while the passenger side are 149 and 146.

The first time I thought it was because the passenger side was in the sun for most of the trip, but that wasn't the case last time.

TPMS reports all tires running about the same temp. We just had axle service due to a recall and I watched the tech do it. No inconsistencies there. The brakes are auto-adjusting Dexter. Steph has walked alongside the trailer while I'm moving it, listening for odd sounds, but nothing.

The only thing I can think of, and this is a real reach: the passenger side airflow might be affected by the step box and those drums cool slower????

On our last trailer there was one drum that always ran a bit hotter than the other 3. Figured that one brake adjusted itself a little tighter than the others, but I've never seen this happen in pairs on different axles before. Very strange.

[SeaDawg]

 I suppose that is possible.

Our curbside drums register a few degrees higher than steetside. I'm very confused by your big difference.  I think? that pur difference is normal, due to road crowning. Idk.

I'd open a service ticket, if I were you. 

[John E Davies]

Check each brake physically by spinning the tire with it in the air, to make sure that none are dragging. The auto adjusters are unreliable at best, especially as they age and get cruddy/ rusty. One can quit adjusting and that makes the other(s) do more of the work.

I replaced all mine with manual adjust, that makes one less thing to worry about…😳 I adjust them until they don’t rotate, then back out 8 clicks. 

John Davies

Spokane WA

[rideandfly]

First thing I would do is jack the wheels off the ground and see if they spin freely to see if brakes are dragging like JD said. If bearing (spindle) nuts are too tight, it could cause drag and heat, too. 

[BackofBeyond]

I used to experience similar differences, usually it was on the sunny side. I just stopped worrying about it unless it got really hot. As has been stated, I checked the free wheel spin once a year (tire rotation or grease) and no issues. Sometimes we worry about nothing. Verify then enjoy.

 

[topgun2]

Another thought although unless there is an extreme difference I doubt that it could explain the kind of difference you are seeing - have you checked the cargo loading of the trailer?  A fully loaded fridge plus loaded closet plus loaded kitchen drawers plus ....  could be placing too much weight on the curb side.

Bill

[Steph and Dud B]

25 minutes ago, topgun2 said:

have you checked the cargo loading of the trailer?

We were lightly loaded on the last trip.

[Steph and Dud B]

Just returned from another trip on a cloudy day. Drum temps when we got home were 125 on the driver's side, 180 on the passenger. Again, both wheels on each side consistent. Steph did not hear any brake dragging on either side but I will jack up and check as soon as possible.

From what I've read, those temps are acceptable for normal brake operations, just odd they're so different. BTW, where is the fresh water tank? We were traveling with that 1/2 full and the other tanks empty. Weight distribution???

[Frank C]

9 minutes ago, Steph and Dud B said:

Just returned from another trip on a cloudy day. Drum temps when we got home were 125 on the driver's side, 180 on the passenger. Again, both wheels on each side consistent. Steph did not hear any brake dragging on either side but I will jack up and check as soon as possible.

From what I've read, those temps are acceptable for normal brake operations, just odd they're so different. BTW, where is the fresh water tank? We were traveling with that 1/2 full and the other tanks empty. Weight distribution???

Does your tow vehicle have a single exhaust pipe pointing straight to the rear on the passenger side? 

[Steph and Dud B]

47 minutes ago, Frank C said:

Does your tow vehicle have a single exhaust pipe pointing straight to the rear on the passenger side? 

Yes it does. Almost exactly in line with those wheels, in fact. And I noticed today that those 2 tires run a few degrees hotter than the others. Still hard to believe the hot exhaust would reach that far back and have so much effect on brake temps...???

[topgun2]

I agree that your reported figures still seem high even if your exhaust were to flow straight back.  And, yes, the fresh water tank is more to the curb side and, yes, it could have something to do with the weight distribution.  But your cited temp differences still strike me as a bit much to be explained by either of these two things.

When was the last time you checked your bearings?

Bill

[Steph and Dud B]

Bearings were serviced last month by a mobile tech due to a recall on the bearing washers (NeverLube axles). I watched him do the entire job. He was competent and everything was done by the book. Nuts torqued correctly and the wheels spun freely when he was done. No issues noted with the brakes while he had the drums off.

[bhncb]

1 hour ago, Steph and Dud B said:

Weight distribution???

If it is a result of this, the tires on the right side should also be running proportionally warmer. When totally empty, my right side sits almost 1/4" lower than the left.

[Frank C]

Ok, this probably isn’t likely but just considering all possibilities that could cause the difference in readings.  There’s another possibility and it’s due to a feature (or lack of) on the inexpensive consumer infrared thermometers for setting an emissivity value.  Are the brake drums on your passenger side a noticeably different color or texture (surface rust) than the ones on the other side?  A surface will give a different apparent infrared temperature reading depending on how good of a radiator it is.    A shiny silver surface (a good reflector but a bad emitter) will give a different reading than a black surface (a bad reflector but a good emitter) even though both are at the same temperature.   It’s what is referred to as the emissivity value (flashback to Penn State Heat Transfer class).   The low cost consumer infrared thermometers typically have a fixed emissivity value programmed into their electronics to give a reading.  One IR thermometer example in the photo shows a fixed emissivity value 0.95.   I’ve seen others that have a selectable value of 0.5 or 1.0, but real world surfaces can vary widely in their value. 

Are the brake drums on your passenger side a noticeably different color or texture (surface rust) than the ones on the other side?  That’ll give a difference in readings.   An old trick we used at work when checking circuit board component temperatures was to paint the entire board with flat black spray paint to give a consistent emissivity value for all the components.   Here’s a basic explanation:

“Emissivity is defined as the ratio of the energy radiated from a material's surface to that radiated from a perfect emitter, known as a blackbody, at the same temperature and wavelength and under the same viewing conditions. It is a dimensionless number between 0 (for a perfect reflector) and 1 (for a perfect emitter).”   

 

[rideandfly]

This may have already been mentioned,  did you see higher temps on one side before bearing service?

[Steph and Dud B]

On 9/5/2022 at 9:54 PM, rideandfly said:

did you see higher temps on one side before bearing service?

They were serviced immediately after we got home from delivery. I didn't have my thermometer for that trip, so I don't know. I just did a short 1 hour tow and checked the temps immediately after stopping. There was a 60 degree difference! 130 on both lefts,190 on both rights, give or take a couple degrees. There was also an odd moment when I went to back up and the trailer brakes seemed to be on for a second. The trailer didn't budge, then suddenly it did. My wife heard a distinct click when the trailer started to move, like brakes releasing. I'm starting to really suspect this is a brake wiring problem, maybe an intermittent short on the wire feeding the left pair of brakes, causing the right brakes to work harder. Or vice versa, the right brakes coming on randomly. Service ticket created and I'm making an appointment with my local shop ASAP. Also going to see if I can inspect that wiring. Getting tired of chasing problems on this brand new Oliver...

[rideandfly]

In the 7 pin plug there is only one brake power pin making one power source to wiring for brakes. At first I thought it was bearings, but after the symptoms you're seeing and hearing, there may issues with drum brakes or magnets with both wheels on one side. It's possible to have a intermittent wiring problem (short) giving power to the brakes on one side from another power source.

Please let us know what the local shop finds.

[Steph and Dud B]

These are brand new NeverLube bearings. It seems highly unlikely I'd get 2 bad bearing cartridges, on different axles, on the same side if the trailer, out of the factory. I'm guessing brakes.

[John E Davies]

FYI, you haven’t mentioned how knowledgeable you are about the tech aspect.

https://olivertraveltrailers.com/forums/topic/2778-brakes-auto-adjust-vs-manual-adjust-what-are-the-differences/

In your shoes (brake pun intended) if there are problems with both right ones, which is what I suspect, I would install four new manual adjust assemblies. You must change them in pairs on each axle. Good luck, I loathe drum brakes on any kind of vehicle. Mine have been mostly trouble free since I trashed the auto adjust ones. They just don’t function well in normal towing conditions and they fade away completely on wet highways.

FYI Toyota Tacomas STILL come with rear drums. The fix is to install aftermarket disk brakes. That is what our Ollies need. Complain to Oliver! …. https://tacoma3g.com/threads/drum-brakes-worst-decision-toyota-made.11900/

John Davies

Spokane WA

[Steph and Dud B]

Yeah, I hate the Dexter "auto adjust" brakes. One assembly disintegrated on our last trailer. Not a fan.

[geokeg]

Sounds to me like a serious running clearance problem on the hot side brakes due to malfunctioning auto adjusters.  It also sounds like the brakes were  so hot they couldn't release on your one backing up event.  

My trailer had brake temp problems, dragging brakes, etc. thanks to auto adjustment 👎🏼.  I replaced with all new brakes and manual adjustment.  Problems solved.

[bhncb]

I wonder if Dexter built some axles with two left-hand brake assemblies. This type of self adjuster first gauges shoe/drum clearance when backing up, and subsequently  performs the adjustment on the next forward brake application. If this sequence was flipped, and with the front and rear brake shoes being reversed, both phenomena might be explained. I would expect to feel a more pronounced "tail wag" if the side-to side braking forces were too much out of balanced.

[Steph and Dud B]

The local shop just finished inspecting my running gear. "No problem found." He said, "I'd be concerned about 600 degrees, but not 60." I'm still concerned because I've never had trailer drums run that hot, or have such a discrepancy, before - even my last self adjusting ones. Not many choices now except continue to monitor. Can't even inspect the bearings directly, because they're NevRLube sealed units. If the wheels burst into flames, or fall off, I'll find the problem. 🙄

[Steph and Dud B]

For anyone following this, I just got a response from Dexter. If the drum temp goes over 200 degrees F in normal driving conditions it should be investigated. Something solid to hang your hat on.

[John E Davies]

1 hour ago, Steph and Dud B said:

For anyone following this, I just got a response from Dexter. If the drum temp goes over 200 degrees F in normal driving conditions it should be investigated. Something solid to hang your hat on.

Well, that is easy enough to test, just spit on the drum and if it sizzles and steams, it is too hot. I have intentionally overworked the brakes going half a mile down a 8% grade with the trailer brakes fully operating (manual mode) without letting up. I saw temps up near 200 on one drum only, and I could smell the brake linings. NOTE if you smell "hot brakes" never ever stick a finger on the drum or rotor. Ouch.

FYI: Some folks may not know, when going down long grades, use your lower GEARS and brake hard to slow down then let up and coast a while to allow them to cool. Do not ride them all the way down....

So what is your next step with your brakes? You sound pretty unhappy to me. ;(

John Davies

Spokane WA