Braking heat (hot wheel) after long downhills...caliper, lines, pads, rotors replaced...ideas? (1 Viewer)

[lasoundguy]

Did my lines, pads & rotors six months ago along with front knuckle service and new wheel bearings...all have been working great.

Went to the mountains three weeks ago, after a prolonged downhill I smelled a burning smell and noticed passenger front wheel was much warmer than the driver side...the hub wasn't too hot though. I figured it was a stuck caliper (drove fine the rest of the way home) so I replaced the front calipers with remanufactured ones from Rock Auto. I reused the old pads as they only had 4000 miles on them and seemed to be wearing evenly (no burnt spots I could see.)

All seems to be going fine, went back to the same spot last weekend, and when I got to the bottom of the long downhill I checked the wheel...still warmer than the driver side and there was a faint burning smell (not strong enough to make it into the cabin this time.)

No symptoms I can sense while driving--no drag, no pulling under braking, and goes along the road fine...just not sure what is causing the heat/burning smell. Suggestions on what to check or do next? Thanks!

 

[lasoundguy]

Just bumping this in the hopes someone can school me on the next logical thing to try...found some old threads were people say this happened to them periodically and they just ignored it, but I'd prefer to figure out root cause...and I'm a little stumped.

 

[ChiYota]

I'm not entirely sure, but IIRC, 80-series brakes aren't the best at dissipating heat. A burning smell, however, isn't something I've experienced on similar downgrades. Maybe search for LSPV (Load Sensing Proportioning Valve) issues. Maybe you're @ 100% front brakes on decline?

Hopefully that gives you a jumping off point...I can't think of anything else right now as I've only had 1 coffee today.

Edit: If you haven't already, make sure those calipers are moving correctly. Lubed moving parts and such.

 

[duncanrm]

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[SNLC]

Downshift you’re trans and don’t brake so much or so hard.

Tap your brakes not riding them.

Cheers

 

[lasoundguy]

Thanks for the advice, I'm less inclined to think this is my technique (aren't we all ) as I'm already using engine braking and aiming for a reasonably light duty cycle...and the driver side front wheel (and both rear wheels) seems totally fine after such descents...more just trying to figure out why the driver side is fine and the passenger side is hot.
@ChiYota thanks, I'll pull the wheels and reverify everything is moving nicely...if so I guess maybe I can try swapping pads side to side and seeing if the problem on the passenger side clears...or stay in flat ground for a while lol.

 

[CaptClose]

Do you have a lift? The LSPV valve may need to be adjusted. A lift changes the geometry slightly and it could be causing more load to be sent to the front brakes. A long decline could even be exacerbating the issue. Just grabbing straws, but if you’ve tried everything else, it’s worth a look.

 

[80t0ylc]

As a suggestion, a laser(infrared) thermometer is a valuable tool to have and they're reasonable in price at Harbor Freight. You can pinpoint the source of the heat and even compare sides to see how much difference there is. I like to use one on a trip to compare temps on all hubs and tranny, diffs and xfer case. It pays to keep informed.

 

[lasoundguy]

Thanks for the suggestions. @CaptClose and @ChiYota the PO installed a lift about five years ago but I don't think the shop that did it knew to adjust the LSPV...after another long downhill I noticed a slight burning smell on both front brakes, so I suspect you may be right...I just went under and gave LSPV adjustment a shot. Will test drive and see how it does.

@80t0ylc that's a good call...I should get a laser thermometer. It would be useful for this troubleshooting.

 

[Howard705]

Be sure the Rears ARE working enough. fronts will get hot doing ALL the work. lspv can be a problem not allowing enough rear braking. Turning motion into heat IS the brake's job. side to side temp difference is a problem tho. should both be fairly close temps. if not there is a problem. ck with thermometer.

 

[FirstToy]

Passenger side will always be warmer.

Not sure on burning smell if you eliminated burning pads and wheel bearings... anything on the exhaust?

 

[jpoole]

Passenger side will always be warmer.

Do you mean the wheel? Why is this, exhaust?

In terms of brake component temps they should be the same side to side in my experience. Front to rear is a different animal with the lspv system a big factor.

Some of the following may be flawed ideas due to specifics in the 80 series braking system and that pressure may be equalized side-to-side, etc. Many of these would also cause the truck to pull to the right during braking. In any case since they haven't been mentioned here are some ideas for you to consider looking into:

• brake bleed variance where the driver side lines still have a bit of air that's robbing braking power
• oil/grease contamination of driver side braking surfaces
• pad pin condition variance side to side where the driver side pads are sticking and that's holding them off of the rotor a bit more than passenger side
• a failing soft line/hose on the driver side that's ballooning and lowering brake pressure on that side a bit
• general condition/functionality variance of calipers or pads side to side, there's a lot that could could vary in terms of condition/performance here
• loose wheel bearings on driver side slowing pad engagement
• headgasket failure

I'd definitely work to get to the bottom of the side to side performance variance.

I'd also definitely work to use the drive train to save your brakes in situations like this. Sounds like you are doing this already though and the reality is that if your drivers front wheel is underperforming along with your lspv causing under-utilization of your rear brakes it would be very hard to avoid smoking your one fully-functional brake.

 

[Bambusiero]

The heat loading on one side, but with no pull to that side doesn't make sense - unless there is a low level constant drag on that side building heat without relief. How about traveling on some flat highway stretch at speed for a while, so there's no real braking action. Check temperature before and after, and also hands off wheel on the straight, for a sensitive side pull check? I second the suggestion to double check that the spindle bearings are properly seated and pre-loaded. A loose bearing could cause that wheel to be spinning at a bit of an angle relative to the calipers-causing constant drag? OR-over pre-loaded bearing would cause heat from the bearing, that would gradually heat everything up, without any braking involvement.

Note-the all wheel drive is amazingly stabilizing, making it pretty insensitive to one side drag. I drove along for quite a while one day, long ago, with one rear tire half flat. Felt nothing odd.

 

[SNLC]

You check that the caliper is not dragging?

It happened in my 100 once. Didn’t pull but caliper started dragging and could smell burning brakes. Pulled over and found RHS rear caliper dragging. Free’ed up caliper and tossed in some new pads and all good to go.

Cheers