Intermittent Braking Vibration?

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My 4Runner will stop smooth as silk most of the time. Then, out of the blue, it will vibrate when I apply the brakes. Reminds me of a warped rotor. Two stops later, smooth as silk when braking. It's not some terrible vibration as it only happens about 25% of the time when applying the brakes. What could this be? I only us Toyota OEM brakes. I lube the slide pins but maybe I got a caliper that is slightly sticking? What would you check first?
 
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Just had toyota OEM shocks replaced all around and it was doing the shaking before hand. The mechanic said the suspension components looked fine. I'll check the "steering stabilizer bar" and the front brakes again.
 
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If the 4Runner is anything like your LS4x0s, there's a strut bar bushing that can create a clunk when braking. Toyota uses anti-rattle springs on most of their cars. To me, it sounds like the friction film was removed and reapplied onto the rotors - NAO pads work via cohesive friction.
 
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My '01 Sequoia does this. Its subtle, but it is there, and only so often. Smooth braking all day long then out of the blue shake-shake-shake-shake while coming to a random stop. Then fine and smooth at the next stop sign or light. Makes no sense.
 
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Originally Posted by nthach
If the 4Runner is anything like your LS4x0s, there's a strut bar bushing that can create a clunk when braking. Toyota uses anti-rattle springs on most of their cars. To me, it sounds like the friction film was removed and reapplied onto the rotors - NAO pads work via cohesive friction.
These are OEM Toyota rotors that were replace about 10k miles ago. I don't think that is contributing to the problem. IDK?
 
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Originally Posted by quint
My '01 Sequoia does this. Its subtle, but it is there, and only so often. Smooth braking all day long then out of the blue shake-shake-shake-shake while coming to a random stop. Then fine and smooth at the next stop sign or light. Makes no sense.
Exactly!!!! It's not enough to make you wanna check it out. Just enough to irritate you. duh
 
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Originally Posted by Donald
Have you lubed the pad ears?
Donald, you may not remember but I'm that freak that only uses the 3 Toyota brake lubes. 1 for slides, 1 for shims and 1 for ears. LOL Looks like I'm gonna be taking a wheel off. Fiddlesticks 🤬 It would make sense if they just slightly hang up on one side every now and then.
 
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OP, check for signs of a rear axle seal leak. Gear oil can leak past the seal, and contaminate the brake shoes and drum, with consequent intermittent braking performance. If you do find an axle seal leak, that seal needs to be replaced, likely along with the wheel bearing on that side. If that is the case, you need to check the rear axle vent, to make sure it is in fact venting, and not causing pressure build up and a subsequent leak.
 
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Originally Posted by 02SE
OP, check for signs of a rear axle seal leak. Gear oil can leak past the seal, and contaminate the brake shoes and drum, with consequent intermittent braking performance. If you do find an axle seal leak, that seal needs to be replaced, likely along with the wheel bearing on that side. If that is the case, you need to check the rear axle vent, to make sure it is in fact venting, and not causing pressure build up and a subsequent leak.
Interesting. I have heard some faint roaring when under throttle going up grade that I thought was the muffler. Hmmmm.... Shoot, now I think I'll go chech the back first. cry
 
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I do remember reading rear axle and the drum itself being the source of vibrations when braking for some. Why I asked. Does make sense if that axle bearing is leaking. The drum is just like a rotor. It's going to get out of whack sooner or later.
 
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