Looking for some help. I keep warping rotors on my 2004 v8 4wd w/ about 325K. About 12 months ago I had a slow pulsing feeling while braking. Not a fast ABS feel or washboard, but slow. Replaced rotors and pads all the way around and inspected calipers. No obvious sticking in the calipers and problem went away for 3-4 months but then slowly returned. 6 months ago replaced all 4 calipers, bled brakes until fluid was new and did pads and rotors again.

6 months later problem is back. This is a pavement princess and no hard braking events I can recall. Any idea where to look? Stops fine (other than annoying pulse), and pedal is firm. Suspension all the way around could use a refresh as well TREs.

Could worn shocks / TREs cause this problem? Replace brake lines? Another brake flush?

Thoughts?

What pads are you using? Same ones again after replacement?

What were the rotors' condition coming off? Was there measurable runout to indicate they are physically warped, or can you see ghosting of the pad outline on the surface?

Highly recommend upgrading to the 2010-2015 4runner front calipers and rotors. Calipers are better than the 04s with slightly larger pistons. Still prone to seizing but not nearly as bad.

The big difference is in the rotors, which are both larger diameter and also thicker. The thickness will help eliminate the rotor warping problem you are experiencing.

5th gen front calipers and rotors are a direct bolt-on upgrade. The only thing that you need to do is trim the backing plates for the larger rotors if you reuse the 04 ones. Or replace the backing plates with the 5th gen ones.

Are you torqueing your lug nuts?

If the OP has 338mm (13.307") rotors now on his 2004 he won't need to do anything to the backing plate, if he has the smaller 319mm (12.559") rotors he will then have to do as you stated.

What pads? are they cheapies? Are you bedding in your pads when you change them? How worn down is the rotor (what thickness is it?)? If you are not having really hard braking events, and it's just regular driving, it probably isn't actual warping. Pads that aren't bedded in properly will deposit material unevenly onto the rotor surface and feels just like warpage. Maybe the slide pins are binding and the pads aren't engaging evenly and leading to some funny wear... Just some thoughts.

Is any kind of oil, grease, or petroleum/silicone based product getting on to your rotors?

After installation of new pads and rotors, are you spraying everything down with brake cleaner before bedding in the pads properly?

Absolute first step is to clean the hubs prior to rotor install and then measure lateral runout with the new rotors. I think the spec is 0.002" max on the front and maybe 0.008" max on the rear - maybe somebody can confirm. Index the rotors on the hub and remeasure the runout if you are having trouble meeting the spec - note that even if the hub is clean, rotors or hub may not be true. Cheap rotors can have more runout. Also, if you are replacing the rotors, you should replace the pads. I have installed coated Powerstop rotors and pads on my Tundra and '05 T4R (front and back). On the T4R, installed the Z17 pads and the solid rotors. On the Tundra, I have the Z36 pads with the drilled and slotted rotors.

Disc Thickness Variation and Lateral Runout Discussion - YouTube

Brake Job Tools: Hub Cleaning Tools - YouTube

Thanks for all the input. Unfortunately I don't have the old rotors and pads anymore. I do recall after the 1st change I noticed the inner pads on one of the wheels was worn way more than the outer and some of the calipers were harder to compress than others which is what prompted me to just do calipers all the way around as I knew sticking/frozen calipers were a known issue.

I've done many brake jobs in my life, I'm just a DIY guy, but did the usual change / clean old HW. Lube pins and pads, etc. Its possible I'm over lubing and causing grease to get on the rotors / pads. But I do hit everything w/ Brake clean when I take it out of package and as I assemble.

I'd have to look up which size rotors I have. I recall making sure I got the right size and matching up the code stamped on them when I did the change. Everything was the same size and bolted up, but not sure if its the bigger or smaller ones. Would have been nice to upgrade calipers had I known I was going to be throwing so many parts at it, but figured the stock worked for over almost a decade (with rotor / pad changes in between) and that more of the same would be good now.

Wheels are torqued (85 lbs I think). 1st go round was local chain store "gold" standard ceramic pads and rotors. Was my first time I had ceramic and thought maybe they didn't bed properly so I went with the Powerstop kit from Rock Auto for second go around. Calipers were reman from local store.

I've seen various threads on how to properly bed brakes, but honestly have never done much of it in the past. Always just drove / braked a little more cautiously the 1st few days after change.

If it is just a bedding / pad issue anything I can do? Will just changing pads work? Do shops even lathe rotors anymore? Or is it another replace job?

Here's a link to an Auto Zone How-To page on it
https://www.autozone.com/diy/brakes/bedding-brakes

I'm having the same issue with my brakes. I was wondering if I need to remove the rotors and use Brake Clean on them before doing the bedding again?

Anyone?

Bedding brakes isn't "one-size fits all". Different pad types/materials require different procedures.

The OEM ceramic pads (Akebono) require ~100miles of easy driving to bed them in. Which is the opposite of what most bedding procedures are; heat cycling them to max to cook off the adhesive. Good thing I read the manual before going out and ripping on them...

The manufacturer should provide a specification for bedding.

I've resolved this issue for a least a little while by removing the rotors and cleaning the braking surface with a flap disk that is not too coarse. Mainly just making it shine again so you can't see any of the pad ghosting. Then I go and do the bedding process. Funny, it seems to be the ladies in my life that get the pulsating brakes where as my 4runner brakes are buttery smooth after a couple years. I do the same process for all the cars in our stable but am in the habit of rarely letting my brake pads sit on one spot of the rotor when stopped, especially after a hard stop.

believe there is absolutely something to that (bolded above).

You get the brakes hot, don't let the pads just sit there clamped and cooking away against one spot on the rotor.