Brake pulsing - hot spots or out of round rear drum?

This is all about my 2003 Tundra SR5 4WD access cab with 150K miles.

Two years and 29K miles ago I replaced the front rotors, calipers, and pads with new

$429 Power Stop KC2324-36 Z36 Truck & Tow Front Caliper Kit-Drilled/Slotted Brake Rotors, Carbon-Fiber Ceramic Brake Pads, Calipers

Power Stop KC2324-36 Z36 parts. I'm now getting a pulsating feeling when I brake.

I had read about our stock rotors being prone to warping, and since I had had warped rotors twice within the first two years of ownership, I figured I'd spend more to get good brake parts rather than pay for the hassle of resurfacing the rotors every 12 months.

These Power Stop brakes are slotted and drilled to dissipate heat and avoid problems. I read the instructions and, as best I can tell, went through the proper initial bedding procedure. The brakes were fine for 12-18 months.

I have a camper shell and some extra weight in the bed, but nothing crazy. I do not tow, I just drive off-road whenever I get a chance. I think I am gentle on brakes - I do not floor it and slam on the brakes between traffic lights, I anticipate slowdowns ahead and take my foot off the gas to slow down instead of braking, etc.

Obviously I have to slam on the brakes from time to time, especially in Phoenix traffic, but even then I try to lift my foot off the brake so the pad doesn't burn in.

Bottom line: in general I don't feel like I should be pushing the limits of these more expensive "Severe duty truck and tow" brake components.

Questions - are these statements accurate?

1. I've been told that hot spots are visible deposits of cementite on the surface. I've also read that they are not visible and go through the entire rotor. (So which is it?!)
2. I've been told that hot spots are not repairable. I can't resurface the rotors, I must replace them entirely.
3. I've also been told that drilled and slotted rotors aren't resurface-able in any case.
4. I've been told that if I replace the rotors I should replace the pads at the same time, even if they have life in them.
5. If all of the above is true: what's the point of spending 2x-3x more for Power Stop brakes instead of getting cheaper parts and just resigning myself to changing them annually?
6. I read in another thread about pulsing possibly being caused not by hot spots, but by problems with the rear drums. The suggestion in that thread was to drive and apply the emergency / parking brake to see if the problem occurred... but then others said the problem was actually a pulsing in the hydraulic fluid and that this testing method wouldn't work. So I'm not sure how to check that??
7. On that note, the rear brakes have been inspected recently, but not changed in the 50K miles I've owned it. I think the inspecting mechanic said they probably have 30% life left. I don't think they have ever been changed. Should I just replace those and see if the problem goes away, before spending more money on the front?
8. Could any of this be due to issues with other parts of the brake system, like the master cylinder?

Thanks, as always, for help with my lengthy questions.

 

The slotting and drilling don't help with cooling or warping. They are for off gassing pads and water removal (and slightly lighter rotors). All things not too worry about on most trucks.

I'd put new rotors and pads on if warped. You can use old pads on new rotors if you want to try. You'll want to scuff the pad surface so it's not grooved to fit the old rotors.


Hot spots are usually through the whole rotor material and why they usually can't be machined away. But if they can, then thats ok too.

A rotor that is drilled and slotted can snag when trying to machine them. Most won't touch them and you don't want to buy a new machine if something happens. Just get new rotors.

 

If I got the power stop I would have gotten the cryo-treated rotors for less susceptibility to warping.

Also, always use your emergency brake at least once a month to help keep it properly adjusted; it’s an important part of the braking system and the truck wasn’t designed to take all the braking force on the front rotors.

Right now just find out if the brakes are dragging against any of the rotors or drums to help narrow it down.

 

Wheel balance issues can be confused with rotor "warping" issues. This app is interesting because it can help you distinguish between the two.....suggest you give it a try. Run it multiple times on different road surfaces.
https://download.cnet.com/SmoothRide-Pro/3000-2094_4-77036353.html

If the vibration is indeed your brakes, rotor warping is usually not the issue - the issue is typically transfer of brake pad compound to high spots on the rotor. These high spots occur because of excessive rotor runout. Low quality rotors can have high runout due to manufacturing issues but the Powerstops I installed were very acceptable and I have had good results so far. I discuss the install techniques to make sure rotor runout is acceptable in the following thread. These techniques aren't anything fancy - just normal brake installation good practices.
https://www.tundras.com/threads/power-stop-z36-install.103380/#post-2759282

If I was having brake vibration issues, I would replace both the rotors and the pads.

Good luck

 

I bought my Tundra used and it always had a slight brake pedal pulsation. When I got around to doing my front brakes, I went with the same kit you did but the slight pulsation persisted. The rear brake shoes were in good shape so I took the drums to O'Reilly Auto Parts and had the drums resurfaced for what I think was about $30. Problem solved, the pulsation went away and hasn't come back.

 

Oh cool, I'll definitely check that out, thanks for the tip!

Yeah, now that I've heard of hot spots / cementite / etc, and thinking back to when I did have warped rotors, this is a different sensation. Pulsing now, vs vibrating and shaking the wheel back then.

But, after reading a few threads on here, and especially Lil Steve's post, I'm definitely going to look into the rear brakes as a first step at least.

Ah, now that you explained that, it all snaps into place, at least for now. I was all up in my head about making an appointment to have the rear drums inspected and turned, finding time, communicating the problem, etc... but since you mentioned just taking them to O'Reilly's is an option, voila!

I just called the local one. They quoted $25 and 45 minutes each. A bit more than your memory, but then it's 2022 too, where everything is more. (Like my rent, which goes up 25% next month...)

Should I assume I must replace the rear brake shoes when I get the drums resurfaced? I am not trying to save money, just trying to figure out timing for getting it all done. Is that a job I can handle in an apartment complex parking lot in Phoenix in July...? (i.e., how long approximately? I have done front disc brake pads myself, but nothing with the rear brakes.)

 

My shoes still had plenty of life left in them so I chose not to replace them. Me personally, I'd wait out the weather because who wants to stroke out doing anything outside during a Phoenix summer. At least you'll know if it addresses the problem and can always replace the shoes when it cools down.
Be sure to give the shoes a proper adjustment after the turned drums are back on.

 

Just something to keep in mind - always use a torque wrench to install your wheels. If you or your mechanic are pounding your lug nuts on with an impact gun, you will never solve this problem. Over-torquing or uneven torquing (which impact wrenches inherently do) can be the very cause of warped rotors. Also, someone said to use your parking brake at least once a month. No, use it daily. Your parking brake is what keeps your drums properly adjusted, which effects the entire braking effect of your system. Finally, pressure bleed your fluid using a dedicated pressure bleeder like the Motive Products kit. These are all little things, but they DO make a difference, especially considering the age of our trucks. You cannot fix a problem if the basics aren't up to factory standards, like properly torqued wheels, a properly bleed system with fresh fluid, and properly adjusted drums. And be sure to use dedicated, synthetic brake grease any time you work on your brakes. Non-synthetic grease can cause rubber to swell around the guide pins, which can prevent the calipers from moving freely, which can cause the pads to ride the rotors, which leads to - you guessed it - excessvie heat and warped rotors.

Good luck.

 

Hi everyone, reporting back with some notes. First off, THANK YOU everyone for the info. As I mentioned, this other thread got me thinking about the rear brakes being the problem, and some of you had similar experiences.

Short version: me too! It was the rear brakes causing my pulsation, not hot spots on the front rotors. Very cool to figure out, thanks for pointing me in the right direction!

Long version: hoooo boy.

A couple weeks ago I had the brakes inspected at a mechanic's shop. They quickly took the drums off and looked for wear and leaks in the cylinders. Everything looked nominal, about 30% life left in the shoes, but they didn't measure anything precisely, just a visual inspection.

After reading these threads I decided to just replace the shoes and hardware and resurface the drums, since it hasn't been done in 150K miles might as well, and might solve the pulsation at the same time. If it didn't then I'd revisit the front rotor hot spot idea.

Drums: Took the drums off and went to NAPA for resurfacing. The owner of the shop measured, and said they were already out of spec, he couldn't resurface them. But he said they were fine, not out of round, and as much as he'd like to sell me new ones, his suggestion was to just put these back on the truck.

Shoes: Since Power Stop front brakes had been recommended, I assumed Power Stop rear brake shoes would be good, too. VERY MUCH NO. I also got a Dorman hardware kit (springs and stuff). Also no on that.

I double- and cross-checked (multiple sites) that they were the correct parts. I followed a few different videos as well as the detailed instructions in my Haynes manual. I did one side at a time and compared parts and assembly.

I found that the adjuster screw Y ends didn't seat complete in the new shoes, so I banged with a hammer, pried with a screwdriver, and got them into place. If you know what I just did, you know where this is going.

I couldn't seem to get them to adjust properly. Didn't feel right by hand, and the e-brake didn't hold at all. I kept tightening them. Finally gave up. Drove 15 miles, in part at 75mph, to get back to my friend's place. By the time I got there the whole cul-de-sac smelled of hot brakes, and I actually thought things were about to catch on fire.

I managed to back them off and, miraculously, managed to get enough pity to get into a reputable mechanic up in Flagstaff on short notice. Drove slowly on back roads so I didn't overheat the front rotors, since the rear brakes were basically nonexistent now.

They charged me a $75 diagnostic fee. Diagnosis: I'm a dumb dumb. That adjuster screw has to slide back and forth freely. The fact that I banged on it hard to get it to seat was way bad. Also the spring in the Dorman kit for the adjuster lever was too short and hence too tight / strong. I had to borrow a car, drive back to my friend's, and dig through the garbage to find the old one.

Quote from the mechanic's invoice:

"Found brake shoes are mis-manufactured, adjuster arms do not seat correctly.
Has poor quality front brake pads.
Has poor quality rear brake shoes."





At least I was smart enough to admit I was over my head and get professional help. $75 diagnosis and $300 for actual Toyota shoes and installation, and I was good to go. I compared old parts to new, visually, but the main problem was that the metal frame of the new was a tiny bit - probably a fraction of a millimeter - too thick, and the receiving gap too narrow, and nobody mentioned that the adjuster screw Y thing has to slide freely.

Weird part: yeah, the pulsation is gone, even though I didn't resurface the drums. Nobody can really say for sure why, other than maybe one of the old springs was worn out, or something was gummed up and so the shoes weren't hitting the drum right, something like that.

Anyhow, aside from sending a box of shit parts back to Power Stop / Amazon, any recourse with Power Stop?

 

Always,Always,always compare OEM with aftermarket to see if there’s gonna be issues. I think you know that now though.