Super Doody

Problem: On steep declines, applying slight to moderate pressure to brake pedal, there are some vibrations.

I already removed the calipers and had them turned at machine shop. The pads are in great conditions. The rotors has also have plenty of life in them. Only 58k on a 6 year old 4 runner.

I will bleeding the brake system once the bleeder arrives.

What is causing this warped rotors (as in not round)?



Thanks

BTW: Its a 1999 v6 2x4 4runner

celica

Common problem with these trucks. The rotor warp for a couple of reasons:

1) getting too hot from riding the brake
2) wheels are torqued too tight.

There are some rotors that are better than others to prevent the warping. I have OEM on my truck and they are OK but I have a standard and always downshift on long hills

Do a search in the general section and you will find tonnes of threads about this and everybody's opinion on which rotors to go with.

Matt

rimpainter.com

Don't bother bleeding the system and trying to figure out what is causing this. Trust us, the rotors are warped. Just replace them and make sure the ones you get have a warranty on them. Autozone has been pretty good to me. They even honored an expired warranty on some replacement rotors I bought from them, which was cool. They have some no-questions-asked-if-returned rotors with a 2-year warranty period. The rotors are easy to change out on your own, so do it yourself if you have the basic tools needed.

Super Doody

What brand of rotors were they from Autozone?

I know they are easy to replace as i already took them off to get them turned.

I'm bleeding the system for PM.

Super Doody

I suspect its 1. as my old man loves to ride coming down the mountain. Its his 4 runner
Its not 2 because I always tighten my lug nuts with torque wrench.

rimpainter.com

I can't remember the brand. You can get them off the Autozone website though. The price reflects the warranty. I think they were $80 for 2 or something.

Another thing to check is the rear brake adjustment. Make sure it is up to spec. I think the amount of e-brake travel is a good indication, but taking the drums off and checking the shoes is always a good idea. Heck, you might find a leaky axle seal or something, which would explain the "front-heavy" braking, creating a greater possibility for warped fronts.

Super Doody

Thanks for advice. You are right there tons of post on this issue. Should've search

Ironmike4x4

Thread hijack.... I'm in desperate need of replacing my rotors. They've been warped the past 2 months now and finally I have the money to replace them. I'm curious if anyone's used Autozone's Duralast rotors or even Bendix rotors. I searched both and one person does not recomment Bendix rotors at all. I'm still confused. Keep in mind these are the 2 brands I'm looking into and do not want to go with Brembos or any other really high dollar rotors. Then again I'm not going for the el-cheapos either. I've already resurfaced the current factory rotors twice and am quite sure the last time I checked I was already in the gray area as far as minimum thickness and do not want to resurface them again. Thanks in advance. Hijack off.

PO2SIMS

I had the same problem, so I got performance rotors and pads and still had the problem. I have non-abs, so I have a load sensor spring hooked onto my panhard bar. I simply took off the spring and now my truck brakes awsome!! To all w/ non-abs trucks, try removing spring or adjusting to slacked spring condition, before replacing rotors.

jumm

I had same problem with 8 inch wide reverse offset wheels. Put stock rims back on with advance auto parts rotors and problem stopped.

rimpainter.com

I am pretty sure that's what I have right now. I have had two sets from Autozone; the first warped and were replaced under warranty. The second are my current pair and carry the two year warranty instead of the one year. For some reason they threw that in on this pair.

The good news is that these are so easy to replace that changing them every couple years or so is no big deal. I guess...

so in summary: At first I got the one year warranty rotors. Upon replacement, they switched me over to the two-year ones.

arielb1

Been there, hopefully I resolved the problem. I finally replaced the rotor after resurfacing and warping. I purchased the Duralast rotors from Autozone along with new pads and calipers. Heck, I just did it all. Well, the problem stopped. I attribute it to adjusting the rear brakes. Apparently the rear brakes were not being used which put more pressure on the front brakes. I really think this was the problem. When I opened my rear drums, the pads were still new. After 110k miles, they should not be new. Search on ebrake and rear brake adjustment for the procedure. I adjusted the spindle on the back of the drum to spec.

If I could do anything different, dont buy autozone parts. I had to replace the rotors and brake pads, but not necessarily the calipers. The caliper change was because I wanted to learn and I thought they were not retracting. But the caliper was bigger than the pads. So now when I press on my brakes, I could see the pad slapping against the caliper making an anoying sound.

My advise, adjust and resolve the rear brakes. Then, replace the rotor and pads. If your ebrake clicks more than 5-7 times, then you need to adjust your rear brakes. Mine click 25 times before it stopped (applying the same torque while pulling). After adjusting my rear brake, I got it down to 5 clicks. Another way to tell if you need to adjust your rear brakes is when you push on your brake when driving. If your truck nose dives, well, your rears are not working.

Bleeding your brakes, in my opinion, is not the problem. After replacing your rotors, pads, maybe that would be a good time to bleed them and at the same time replace the fluids in the master cylinder.

Just my two cents.

Good luck.

CynicX

i wish i would have looked at this earlier. Yes a bad adjustment on the rear brakes will cause the front to warp really fast, since all the weight of the vehicle breaking will be on them. If they had enough life left you could have machine the fronts and adjusted the rears.

On my work van I thought I had warped rotors so I had them machined. Problem was still there so we adjusted the rear brakes and it stopped. What was happening is the weight of the van was to hard on the front and unless the road was absolutely perfect the van would start shaking uncontrollably since the back was pushing so hard on the front while braking. Once the rears were adjusted the problem went away. That was probably your problem to begin with, but at least you have new brakes.

I personally dont like Napa, Autozone, Pep Boys part, but as long as it gets the job done.

Ironmike4x4

I've already adjusted my rears and highly do NOT recommend adjusting the rears with the e-brakes after they were adjusted too much and caused my drums to over heat. I also adjusted my LSBPV and still having the problems. I may have to readjust the valve again.

ebelen1

Sorry Mike but how about this in basic English for me ( I don't know crap about cars). You don't recommend adjusting the rears or you don't recommend adjusting them with the e-brake? Is there a way to adjust the rears w/o adjusting the e-brake? I don't understand what this means.

I may have some issues w/ my rear drums and would to explain to my buddy what needs to be done. Thanks.

ebelen1

I checked my e-brake and it's definitely within the 5-7 clicks. I've also hit the brakes hard and I didn't feel a nosedive but more of a drift in the rear.

I'm assuming that means my rears are functioning. My mechanic is still scheduled to check these b/c I did the Tundra upgrade this weekend and he ran out of time to check the rears. Not to mention my drum cover has some rust on it and for "looks" purposes, I'd like to shoot them black.

Does this sound about right?