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Discussion Starter · #1 ·
Hey y’all, love this place, and could use your input.
My 06 sienna (fwd 150,000 miles) is starting to do what I thought I fixed, all over again.
The Problem: braking after getting warm is not smooth, but pulsating (not in the pedal) but the car/wheels seem to break uneven with rhythm. It feels like the driver is pushing hard and letting up, pushing and letting up. It break harder and then let’s up, breaks and let’s up in a pulsing manner leading to a stop. It’s faster when the wheels are faster and slower when slow moving. You can hear a noise, low pitch squeak (not high pitched and not too annoying) that matches the rhythm. It gets worse as the brakes warm up.

it’s just starting to do it again after replaced The rotors and pads two weeks ago.

What I think it could be: caliper is out of wack or square, or the bearings are going bad.

another symptom noticed yesterday as I let my uncle drive it: (may not be connected) when he applied torque (pushed the pedal) you could hear a little scraping raddle on both wheels.. more on the right than left. Like the rotor is scraping the breaks pads when accelerating pushing the gas up a hill or accelerating.

what has been done: new struts, new engine mounts (1 yr ago), new front a-arms, new tires and alignment (still drives great! Just this one problem).

doing my best to describe the situation, and my brother said it could be the front drive axles out of wack or unbalanced. It feels like my tires are not square or something.

Appreciate any advice or input.

nicky
 

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That really just sounds like either you didn't turn the rotors round or the pads are not contacting the rotor square and true. If you have rear drums, you probably need to adjust them too. If they're badly out of adjustment, your front brakes would be doing all the work.

Unfortunately, due to a combination of loose manufacturing tolerances and mediocre QA, brand new rotors need to be turned and, in some cases, pads need to be shimmed or ground down to contact fully.
 

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Brake pedal pulsation is usually caused by brake rotor run out. Brake rotor run out is a wobble of the rotor. The wobble is usually because the rotor does not sit squarely on the hub. Part of a thorough brake job is measuring rotor run out with a dial indicator.

Replacing the pads and rotors initially provide smooth braking until rotor run out causes pad material to build up unevenly on the brake rotor. This creates an uneven friction surface and leads to brake pedal pulsation.

Rotor run out should be .002 of an inch or less. If you measure more than.002, index the rotor on the hub (rotate it on the studs) and check again. If runout persists, wire brush the hub and try again.
 

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Discussion Starter · #4 ·
I appreciate all your info guys, thanks.... I have figured that the sound and braking issue may be coming from the rear brakes.. drum brakes... possibly outta round. My car is now jumping more to a stop than normal. This is a pain in the arse. I am going to check the run out on the front brake rotors. To double check
 

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I appreciate all your info guys, thanks.... I have figured that the sound and braking issue may be coming from the rear brakes.. drum brakes... possibly outta round. My car is now jumping more to a stop than normal. This is a pain in the arse. I am going to check the run out on the front brake rotors. To double check
My rear disk/drum brakes would emit a low pitched squeal. After pulling the rotors/drums, found the rear pads were almost down to the metal while the emergency brake shoes were fine. Replaced the rear pads, cleaned up the very dirty drum brake portion, adjusted the drum brakes, and the squeal went away. If you've got drums-only in the rear, it's entirely possible that the brake drums need turning or replacement.
 

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it's entirely possible that the brake drums need turning or replacement.
Turning the drums on my 06 fixed the high speed judder on my van. Replacing the front rotors and new semi metallic pads finally made the braking smooth again. There were times I would hear a weird intermittent sound from the rear brakes , like qrrk qrrk qrrk when slowing and applying brakes and I found that sanding the shoes helped in ridding it.
 

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When you replaced the front brakes, did you readjust the rear drums? I always had the procedure explained to me that you reverse moderately fast and hit the emergency brakes. Repeat 2-3 times and that should do it. Then, someone said you reverse and hard brake with the regular brakes. So, I don't know which one is correct, but one of them might help. Of course, if your rear brakes are toast, neither will help you.
 
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