For a while I am trying to track down a source of vibration during braking. The suspension can be ruled out because it is brand new and aligned. I was about to buy a new set of rotors and pads but decided to resurface the front left rotor (location of the vibration) after watching an Youtube video. I noticed some non-uniform wear and I used an orbital sander with 60 grid sandpaper. I was successful in removing edge groves and some imperfections which is great.

But then I noticed that the inner side of the rotor has more wear and pads seems to be different thickness. I removed the pads from the caliper and found that one of pistons is missing a portion of the boot.


My understanding is the piston causes the vibration and the caliper needs to replaced. Has anybody else had a similar issue? Please, let me know.

It seems that AWD and RWD non-sport share caliper part numbers, please, correct me if I am wrong.

I just fount out that there is a caliper repair seal set (04478-50040). It is around $50. If the piston is damaged, the set is just a waste of money.

 

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I found two of my front brake cylinder rubber boots broken during my annual brake maintenance not long ago (each fall, I take off my brake parts, clean and lubricate them as preventative maintenance). I happened to have spare cylinder boots around and replaced them without any issues. My brake has been functioning properly and normal before and after I replaced brake cylinder boots (the one shown in your photo). From your photo, it doesn't look that dirt and dust have entered your brake cylinder house and damaged that brake cylinder. So, your broken brake cylinder boot may not be the cause for your brake vibration. That aside, you don't need to replace the whole brake caliper. You could buy a single or set of brake cylinders, either OE or aftermarket, to just replace the bad brake cylinder(s). With my car getting to 13 years, I plan to replace all the brake cylinder seals and boots soon as preventative maintenance. Rockauto sells Centric brake caliper rebuild kits at nearly half of the cost of Lexus OE parts.
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I can get a low miles front caliper for $100. Oem set of a new cylinder and seals is around the same price.

I get it that something else can cause the vibration. But, the vibration happens only when breaking, there is more wear (rotor) on the side where the boot is damaged. And it seems the brake pad has more wear on the same side. I am going to take a better look at how to diagnose a sticky caliper.

 

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You are totally right that you won't know the condition of that brake cylinder or its housing until you remove the cylinder. If the cylinder housing is damaged, you'll have to replace the whole caliper. In that case, it doesn't make sense to buy a rebuild kit (and only to find that you can't use the rebuild kit to repair the caliper). On the other hand, I've seen brake calipers with far worse (dirty) conditions than yours but their brake cylinders were not damaged. After replacing brake cylinder seals and boots (rebuild), the brake calipers functioned as well as new. On the other hand, building brake caliber is a bit time consuming (about 45 minutes to 1 hour per caliper), unless you enjoy doing it, it's not worth the time compared with replacing the whole caliper. Also agree with you that purchasing a lightly used OE caliper is a better solution than buying an aftermarket caliper from less reputable venders. Just a friendly reminder - don't forget to use a new banjo brake hose seal when you install the replacement caliper. Re-using old banjo brake hose seals often lead to slow leaking of brake fluid.
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I rebuilt the front left caliper last night with parts provided from a RWD (supposed to be AWD) caliper. One of brake caliper cylinders on my car was dry and it was causing malfunction. I used boots and two cylinders from the donor part as they are in great condition. But I have a new set of seals and boots on its way just in case.

Vibration is definitely not as bad as it used to be especially during braking. I am going to install new front OEM rotors and pads once they come in. I did some reading and found out that drilled and slotted rotors (I purchased the vehicle with them) is more a gimmick these days.

 

I had drilled and slotted rotors on, now departed Infiniti, and currently have them on my wife 5.6 Q70AWD they’re absolutely amazing, no problems whatsoever.

 

My point was - drilled and slotted rotors are a marketing stunt and are needless these days. Drilling originally designed for gas release is not needed any more as it was resolved on materials level. Drilling weakens structural integrity of rotors and causes premature failure under heavy load conditions. Slotting is a little better but not by that much. In the same time, drilled and slotted rotors usually cost more than just solid type rotors.

 

You may be right however both my Mercedes CL 600 and SL 550 have these from the factory.....

 

Yes, you are right. Many makers put drilled/slotted rotors installed by original manufacturers. But the truth is they do it because it looks great and sells.

It is my personal opinion and is not intended to devalue anybodies drill, slotted rotors.

 

There are different qualities of drilled/slotted rotors. Most we see for sale are knockoffs, cheap and like you said...actually make the situation worse - by removing metal from the rotor it increases the chance of excessive lateral run out and or parallelism. However the ones that were actually manufactured correctly do serve their purpose and will keep aggressive drivers free and clear of those symptoms.

As for your brake pulsation. I’m not sure it’s your brake caliper. Although not ideal to have a torn boot like that, it shouldn’t really cause a pulsation so much as it will eventually cause the caliper piston to seize in the caliper bore (but you’d be able to diagnose this very easily when you push the piston back in). When enough corrosion forms above the square cut seal halfway down the caliper bore, the piston won’t be able to move. But I don’t think that piston would rock back and forth or cause some sort of brake pulsation - especially with a four piston fixed caliper design like this one.

And would not waste any time rebuilding a caliper today, unless the parts you’re rebuilding it with are OE, I find the aftermarket stuff just does not last. I’d buy a refurbished caliper - and yes I understand they probably aren’t using OE parts either, but at least they usually come with some sort of warranty...sometimes a lifetime warranty depending on where you buy it.

I almost always blame brake pulsations on the rotors. And sometimes suspension. I know you said the suspension is new, but is all of it? The lower ball joints? How’s the wheel bearings? Wheel bearings on these cars have been known to fail - they can sometimes become loose enough to cause a rotor to wobble a little bit. But if it were me I’d concentrate on the rotors. I’d also start thinking about the brake actuator at some point, when mine started failing it began to make a click noise, and then it started to sound/feel like when an axle is dried up.

 

I got new OEM front rotors and brakes, but I didn't receive it yet.

All front control arms, lower ball joints, inner and outer tie rods, sway bar links and bushing, front bearings were replaced with OEM parts.

Lexus dealership did brake fluid flush not so long ago. I don't hear any sounds from the actuator, only when the engine stops it comes on for 2-3 seconds and goes go off. I read that it is normal operation.