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Discussion Starter #1
I was towing a car on a steel trailer (total about 5000 pounds) and the truck was doing great thru the mountains except for "the hill" - which is a 6 mile hill to get out of NC on I40 west or in I40 east - up going west, down going east. Had no problems going up...

Problem was coming home and down that same 6 mile hill, the brakes progressively got worse and worse. They started out very smooth but by the time I was to the bottom they were pulsating almost violently when I pressed the brake pedal. Of course I didn't ride them all the way down, and lower-geared the engine for engine braking. And I've towed a lot more with our shops F360 Turbo Diesel (43' trailer with 2 cars totalling about 17,000 pounds) with no similar issues.

Cusious... Is this normal for the Tundra brakes? I know Toyota strongly promoted the braking of the Tundra, but that was REALLY bad by the time I got to the bottom of the hill. And the really odd thing is.... Within about an hour or so (less probably, was just open highway afte rthe downhill) the brakes were back to smooth as butter..... I mean, I race my car on the open track and have never had brakes do anything like that. It wasn't brke fade, it was like the rotors were severely warped, but then smoothed back out. I've just never encountered or even heard of that.

Thoughts/input?

EricB
 

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First question is did your trailer have brakes and were they working? If the trailer does not have brakes or if they weren't working the brakes in your truck would have fade problems trying to slow the whole rig down over that distance. When they cooled down they would come back to normal.
 

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obviously your trailer brakes were either not hooked up or not working... yes that was brake fade...
 

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I agree - sounds like your trailer brakes weren't working.
 

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Doesn't sound like fade to me.

Fade is when the pedal progressively gets softer and softer.

Sounds like warped rotors except for the fact they smoothed out after the fact.


At the risk of being inter-whipped, I do not have a brake controller on my truck and have towed 6K many times and up to and maybe over 9K (recent thread) with 0 braking problems.

The 6K towing trips are up and down some major grades.......
 

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Doesn't sound like fade to me.

Fade is when the pedal progressively gets softer and softer.

Sounds like warped rotors except for the fact they smoothed out after the fact.


At the risk of being inter-whipped, I do not have a brake controller on my truck and have towed 6K many times and up to and maybe over 9K (recent thread) with 0 braking problems.

The 6K towing trips are up and down some major grades.......
That't my understanding of brake fade too. Was it ABS you were feeling maybe? Warped rotor doesnt seem right as it went away.....
 

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its back to the whole warped rotor feel but its not...its deposits on the rotor surface that have embedded them selves in the surface..even resurfacing them wont make it go away, its like particles bond themselves to the surface, and even turning them just shaves the top layer off and leaves them deposited in teh low spots....so its the brake pads "slipping" or having different friction over those areas causing that pulsation...feels like warped rotors but its not...just irregular surfaces now...and when the pads get hot it affects them more so they grip on differing surfaces differently. alot of the deposits are from driving through puddles when hot etc...its been discussed in brake warping threads before..mine does it too...after spirited driving mine will do it...then after cooled off they are fine...need to replace the rotors....just too lazy...but its not just the tundra that does it, i have read it on other forums as well lately, seems like whatever they are building crap out of nowadays is just more prone to picking up irregularities and deposits on teh surface...
 

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That't my understanding of brake fade too. Was it ABS you were feeling maybe? Warped rotor doesnt seem right as it went away.....

I was thinking that too..........then the post above from Andy's deputy shed some light on it.

I went through my OEM pads rather quickly, then screwed up by installing Vato Zone lifetime ceramic pads which promptly tore up my rotors.

Re-surfaced and went with a cheaper pad and all seems well again.
 

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theres a couple of articles online about "deposits" etc causing these hot spots and uneven braking surfaces....

this one discusses the deposit of brake pad material after a hard stop and clamping down on the brakes..
Power Stop

this one basically the same under item 8
10 of Your Top Brake Pulsation Questions

and one from ebaymotors...
eBay Guides - What causes rotor warping

but basically all these discuss the brake pad material being deposited unevenly but the same can be said for crap roadborne that gets on a hot rotor and dries instantly...

hope that helps some
 

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Your Tundra, plus that 5000lbs, going down a LONG hill without trailer brakes.. Is what caused it. I wouldn't expect any vehicle to go down that hill with that much (unassisted) weight, and not have brake pulsation.

Vehicles are heavier than ever these days, and without trailer brakes, it's just TOO much for the rotors. The surface of the rotors and brake pads become glazed.. and its all down hill from there..

I wouldn't be too concerned about what happened.. I imagine it felt pretty dangerous! I've seen many drivers warp their rotors without a single extra pound in the vehicle, much less towing another.
 

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its back to the whole warped rotor feel but its not...its deposits on the rotor surface that have embedded them selves in the surface..even resurfacing them wont make it go away, its like particles bond themselves to the surface, and even turning them just shaves the top layer off and leaves them deposited in teh low spots....so its the brake pads "slipping" or having different friction over those areas causing that pulsation...feels like warped rotors but its not...just irregular surfaces now...and when the pads get hot it affects them more so they grip on differing surfaces differently. alot of the deposits are from driving through puddles when hot etc...its been discussed in brake warping threads before..mine does it too...after spirited driving mine will do it...then after cooled off they are fine...need to replace the rotors....just too lazy...but its not just the tundra that does it, i have read it on other forums as well lately, seems like whatever they are building crap out of nowadays is just more prone to picking up irregularities and deposits on teh surface...
i agree.. it happens on flywheels from clutches overheating also,, cant usually be cut out,,
 

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Discussion Starter #12
Thanks for the feedback. Trailer didn't have brakes. I was just curious if anyone else had come across this before. I'm well aware of braking issues - I manage a performance shop and road course and autocross my car. It was just odd thgat it fot worse and worse as I got further down the hill (ok, expected) but then alleviated itself shortly thereafter (that was the odd part). Everything's been fine ever since, normal smooth braking whether soft or stomped on. Which is good I guess :) Don't have to replace brakes yet...

EricB
 

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you will have to or wind up in the hospital or morgue if you keep towing that heavy w/o trailer brakes...also probally get a ticket as well since most, if not all, state's laws say trailers over 3000 lbs are required to have brakes...plus its just a horrible idea not to...you are trying to stop almost twice your truck's weight with just the trucks brakes....

just googled, NC gives u an extra thousand before brakes...so anything over 4000lbs needs brakes. so u need brakes. someone that is "experienced" in brakes with the performance shop etc should already have known all that though and not tried it...
 

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Thanks for the feedback. Trailer didn't have brakes. I was just curious if anyone else had come across this before. I'm well aware of braking issues - I manage a performance shop and road course and autocross my car. It was just odd thgat it fot worse and worse as I got further down the hill (ok, expected) but then alleviated itself shortly thereafter (that was the odd part). Everything's been fine ever since, normal smooth braking whether soft or stomped on. Which is good I guess :) Don't have to replace brakes yet...

EricB
The build-up of heat from those poor brakes handling that all by themselves probably caused a combination of uneven pad material transfer and temporary misshaping of the rotors. To a certain degree if the brakes get a chance to cool gradually after something like this the symptom is alleviated.
 

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I've had my brakes heat up and start pulsing just coming down a mountain pass empty and I don't even ride my brakes. Seems like when the rotors get heated above normal use they tend to warp slightly. Mine also smooth back out when they cool down.

I pull a 3000 lb pontoon/trailer that is not equipped with brakes. You have to be extra careful when slowing down. Even though 3000 lbs is nothing for the Tundra to pull, it's a ton (and a half) of weight to try to slow down with just the truck brakes - especially with a bed full of coolers.
 

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I have a 2007 5.7 Tundra 4WD. On my way out of Yosemite three weeks ago, my brakes started pulsating violently during a long downhill section, and I was not towing anything, and I had nothing in the back of the truck. I was only braking lightly the whole way down in order to comply with a 45 mph speed limit. Once the brakes cooled down, things returned to normal. My truck has 40K miles.
 

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Yep, me too. Long downhills always cause my brakes to pulsate. I am ditching my factory rotors and getting some cross drilled/slotted rotors like I put in my old GMC. They make all the difference when it comes to keeping the rotors cool.
 

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I have had the same issue with long downhills. I think its a heat issue, warping the rotors, when it cools down, smooth as butter.

Ceramic brake pads do not dissipate heat as well. My next set of rotors will be cross drilled.
 

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You just need to downshift 1 or 2 gears in "S" mode, on a long downhill...that alone will help the brakes run cooler and might prevent hot spots from forming and/or get some trailer brakes...
 
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