Low pitched hum/vibration when braking, help? - Lexus IS Forum
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post #1 of 10 (permalink) Old 03-01-2017, 09:15 AM Thread Starter
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Low pitched hum/vibration when braking, help?

Hello All!

So Im in the process of putting new parts into my car.

2004 IS300 Sport Design 147k

- Installed new slotted & drilled rotors and ceramic pads
- Installed new Continental ExtremeContact DW tires
- Will be installing new lower control arms #2 (bushings are terrible right now)
- Will be installing ball joints

Heres my problem, before all of the new stuff, I was running basically all stock items and everything was off balanced and such.

After installing the new brakes and rotors, everything seemed fine. I followed instructions for new brakes. Braking was so much better! No problems. After installing the tires, almost seemed like didnt need alignment. Wheel was straight and no side drift while driving.

But now Im noticing that If I brake from high speed, I'm hearing a loud low-pitch hum/"whirl" sound until I come to a complete stop. If I use the manual shift and slowly shift down to 2nd gear, its not present.

Now, before any of the new installs, everything shook, everything sounded bad. After installs, nothing is really shaking (steering wheel or car), but that hum is pretty loud.

Any ideas of what it might be? Could it be the control arm that I still have to install?


***UPDATED INFO***

So I took the car out just now, its not a hum as much as it is a vibration that causes a loud hum.

If Im going fast, everything is smooth but as soon as I brake it seems like the rear vibrates and it slowly moves to the front. Felt it slightly in the brake pedal and then in the steering wheel. It starts in the back, moves forward then through pedal and finally through wheel.

Any help, thanks!

Last edited by noloc4545; 03-01-2017 at 09:39 AM. Reason: Update
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post #2 of 10 (permalink) Old 03-01-2017, 09:43 AM
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It sounds like the noise from the cross drilled and slotted rotors to me. I've driven on those type of rotors before and I couldn't stand the noise from them.

Also, the noise is only going to happen when you're pushing your foot on the brakes, it won't happen when the brakes aren't pushed.

02' Manual w/MKIII LSD and no sunroof.
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post #3 of 10 (permalink) Old 03-01-2017, 09:54 AM Thread Starter
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Originally Posted by Piggity View Post
It sounds like the noise from the cross drilled and slotted rotors to me. I've driven on those type of rotors before and I couldn't stand the noise from them.

Also, the noise is only going to happen when you're pushing your foot on the brakes, it won't happen when the brakes aren't pushed.

Yes, its only happening when I brake. What I meant that everything starts out smooth is that theres no vibration or noises or wheel alignment drifting or any sort.

Its when I brake, everything starts shaking.

I wish I had paid more attention when I started doing everything but I want to say that the day I had the new rotors/brakes installed, even with old/worn tires and bad alignment, that everything seemed to brake just fine. I dont recall hearing the loud rumbling and feeling the hard vibration. I want to say it just started happening. Also, and this is not even part of the problem but I started noticing that if I do a u-turn to the LEFT, on the right side I hear a constant tap/knocking (sort of like hearing rapid machine gun fire at a distance).


Again, my lower control arm bushing is destroyed but Amazon is slipping right now and what should have been a Tuesday fix is now a Thursday fix so I'm still waiting to rule that out.

Any other info/help is appreciated.

Thanks!
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post #4 of 10 (permalink) Old 03-01-2017, 11:01 AM
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I thought it was the noise that you were describing. If you have new brake rotors/pads and the shaking is still there, then it's the No.2 control arms that are causing the shaking. Mine does the same thing, even with new tires. I've yet to order my Figs replacement bushings.

When you're braking, you put a lot of stress on the No.2 bushing. If yours is as bad as you say, then this is definitely the cause of the shaking.

02' Manual w/MKIII LSD and no sunroof.
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post #5 of 10 (permalink) Old 03-01-2017, 11:25 AM Thread Starter
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Quote:
Originally Posted by Piggity View Post
I thought it was the noise that you were describing. If you have new brake rotors/pads and the shaking is still there, then it's the No.2 control arms that are causing the shaking. Mine does the same thing, even with new tires. I've yet to order my Figs replacement bushings.

When you're braking, you put a lot of stress on the No.2 bushing. If yours is as bad as you say, then this is definitely the cause of the shaking.
Well yes, at first I was because with the windows up, the noise created by the shaking is a LOUD low-pitch/low-roar type of rumbling. Thats why I noticed the sound first. After taking it out earlier, if I apply slight braking power, I dont hear it or feel it. I can be at 80mph and as long as I'm not slamming the brakes, the vibration isnt there. Its when I go from 80mph to 50mph and below in a split second that the vibration occurs.

I noticed that if Im at 80mph and hit the brakes, the vibration kinda seems to start at 60 through about 40mph and then goes down quickly. But this might be very bad and inconsistent info as I'm doing my best to reproduce problem while at the same time not crashing into anyone or catching the attention of a cop.

Tomorrow my LCA come in and Ill be replacing them and updating. For now, light braking or down shifting.
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post #6 of 10 (permalink) Old 03-01-2017, 06:53 PM
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If you replaced the brake hardware and lubed it good. The hum is the cross and sltted rotors. Now on top of that. If tey are cheaply made rotors. They may not be perfectly round or have a good flat braking surface.
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post #7 of 10 (permalink) Old 03-03-2017, 08:40 AM Thread Starter
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Originally Posted by 01 SolarYellow View Post
If you replaced the brake hardware and lubed it good. The hum is the cross and sltted rotors. Now on top of that. If tey are cheaply made rotors. They may not be perfectly round or have a good flat braking surface.
Hey, they are the Power Stop 1-Click Brake Kits K1079

Read good things about them....
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post #8 of 10 (permalink) Old 03-03-2017, 08:44 AM Thread Starter
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**update**

So last night I followed a thread here about replacing the bad Lower Control Arm #2 .

Thought this might fix my vibration/loud rumbling problem and it seems to have just slightly. Doesnt seem to have as bad now but its still there. What I have noticed is that I dont necessarily feel the vibration in my pedal or steering wheel anymore.

Now...I have done vigorous testing as I'm not a mechanic and I'm a little scared that my work is that great (loose bolts or something) so I've been a bit conservative with my driving since last night.

Any other thoughts?

- Upgraded rotors and pads: Yes, I bed them in as correctly as possible according to the instructions
- New tires: Will get them rebalanced today
- New LCA#2 : Will get alignment done today as well
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post #9 of 10 (permalink) Old 03-07-2017, 09:15 AM Thread Starter
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**update**

So I ordered tie rods (inner & outer) and lower ball joints.

This morning I took it to my local shop down the road (local...no name brand) and they lifted the car up and checked everything for me. They moved the tire left and right and other things aside from visual inspections.

They said everything looks good, sounds good, feels good.

That it must be warped rotors....

Im going to contact summit racing (where I got the rotor/brake sets) about a refund/replacement.

Any thoughts?
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post #10 of 10 (permalink) Old 03-19-2017, 07:00 AM
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Fact: Humming/ whirring is the new brake rotors. Performance parts introduce new sounds. I noticed this when i went with the slotted power stop rotors. More aggressive braking equals louder sounds.

Shaking in steering wheel while braking may mean your pads and rotors were not broken in properly? Or as another member suggested - maybe you just got a bad rotor.

Did you flush the brake fluid in your service?

Some other members have commented in other threads saying caliper seizure is common on these cars. Ive never experienced this on my is but worth some research.

Are your calipers painted? I know when i painted the calipers on my old toyota i introduced a world of problems from paint entering the piston area. I kid you not my brakes were flaming from the wet paint fumes. ? (Lazy DiY mod)

Do sounds change upon braking? Braking through turns? Etc. lots of moving parts here, some one should be able to help.

Also, the shop should warranty their labor.

Ps. I try not braking within one long stroke. For example: 60-40 brake, coast, 35-20 brake, coast. Not pumping the brakes per say, but brake hard when you need them as to limit brake fade and heat build-up. By all means, your brakes should have a ton of "bite" now
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