Arcturus

Will warped rear rotors give pulsations through the steering wheel? I thought they would shake the car instead.

FatCat23

This has been a common problem for me. Most likely because I don't use stock brake pads. High performance pads don't do well with daily stop-and-go. They are meant to be used on the track and kept hot. A lot of guys want to run track pads on the street and you can as long as you understand there will be some compromises.

High performance pads "off-gas" when used hard and therefore high performance rotors are often cross-drilled to allow the gas to escape through the holes. If the hot gasses are trapped next to the rotor a residue will build up on the rotor. Because the residue is not distributed in a perfectly even pattern the pads will stick a little each time they scrape across the residue build up this causing the pulsing sensation in the pedal.

OEM pads don't do this but high friction (high-performance) pads do. OEM pads give up some ultimate grip in exchange for a smooth feel.

Expensive pads are baked at high temperature to bake out some of the gas to reduce this problem once installed. If you are having the pulsation as you describe you can "bed" your brakes. The bedding process will burn off the residue left on the rotor caused by the gasses that are given off during braking. So if I understand this process accurately, the problem is that the high performance brake pads don't get up to a sufficient temp in every day driving.
I read about bedding and re-bedding brakes on R1concepts.com. Now when my pedal gets that light pulsing I do 5 or 6" pedal to the floor" stops from 60-70mph and the pedal gets smooth again because it burns off the residue. Yes you will smell your brakes and yes it makes them hot. It won't hurt anything though.

I suppose you could take your rotors off the car and somehow de-glaze the surface as that would remove the residue build up too.

Arcturus

You know what after all of the above I'm still getting some vibration at highway speeds when I apply the brakes. It's not terrible, but I think I'm going to give the OEM pads a try and see if it resolves the issue. I'll let you and other know if it does. Should be able to get and install the pads in a week or two.

Robles84

Great write up. I'm having the same problem

5t341th

iTrader: (16)

i had a pulsing steering wheel when braking. I had the rotors resurfaced and now its gone.

gemineye

OP: The rear rotors aren't too difficult to remove.......pull them off and take them to O'Reillys (or equivalent) and have them machined/turned for $15 each. Put them back on and see if that fixes the prob.

I used to have the same symptoms you're having.......I pulled all 4 rotors, had them machined, then reinstalled. Problem solved......because I machined all 4 rotors at the same time, I have no clue if the problem was coming from the front or rear rotors, but I do know the problem is gone......and BOY is it nice to press the brake pedal and not have the steering wheel and car shimmy!

If you haven't pulled the rear rotors before (or it hasn't been done in a long time), you might have to thread in a metric bolt into the rear rotor to break the "rust weld." That's what happened to me......and I can't remember if it was a M8 or M10 bolt I used but it's one of them. You should be able to do a search (or read through my previous posts) and find out the correct bolt size needed to thread into the rear rotors if you're having probs getting the rotor to free itself from the hub......I made a post about it after I completed my brake job about 2 months ago.

Hope it all works out for you.

Regards,
Randy G.

gemineye

One more thing: I'm not sure how you're bolting the wheel back onto the lug studs, but make sure you're using a torque wrench and are fastening them to the hub using a star pattern.......I think the torque spec is 80-85 ft-lbs. I usually torque the lug nuts to 50 ft-lbs first in a star pattern, then go back and tighten them to 80 ft-lbs in a star pattern as well.

Arcturus

Thanks for your help, but all rotors were replaced with new ones as were the pads. If you read above you will see that they ran true and had lateral runout of 0.0007"-0.0008", well below the factory requirements of 0.002". I would find it difficult to believe that turning the rotors would improve on these numbers significantly, unless they were turned on the car.

I believe that the problems may result from aftermarket pads and rotors and that somehow the frictional properties or design of the pads may be the cause of them.

When I get time I will verify the runout again. If it is within spec I will replace the pads to isolate the root cause - if it's the pads or the rotors. I am hoping it's the pads as they're a lot cheaper.

zapola6

Just thinking out loud and would like to hear others thoughts. If you are getting a pulse through the steering wheel and peddle, it's coming from a rotating part or parts that are in contact with rotating parts...

So to me it's from the wheel bearing out, if it was a wheel bearing I would think that you would have the issue all of the time, are they tight, any roughness, any noise, any play?

About a year ago, I had a horrible pulsation on my 01 LS Base, turned the front rotors took care of 10% of the issue. Turned my back rotors and the problem was totally gone. I had never had rear rotors causing a pulse like I had. When I asked the tech how far the rear rotors were out, he responded with: not far at all. What that meant, I don’t know, however, the other 90% of my problem was gone.

If it were me, run out with dial indicator or not, I would start with a true known and turn all 4 rotors and move in from there. Ask to watch the rotor be turned so you can see for yourself….

Just another thought as I was getting to the end rather that working like I should be, are the rotors flat against the wheel hub, totally clean, but that would show in the run-out…. Don’t know if my rambles helped, please do keep us posted….. As much as it pains me to say: I'm running Autozone Duralast Gold rotors and pads

PersianOne

I too have been having this pulsing steering wheel when braking to a complete stop. I changed my brake pads and rotors all around and it fixed the problem for the most part. I still get the pulsing steering wheel quite often though (more of a vibration on the steering wheel). Weird thing is, when I turn on my A/C, the pulsing goes away completely. When I am braking at high speeds, the pulsing is non-existent. It's just coming to a complete stop, that's when it pulses. Not too bad, but definitely noticeable to me. Kind of like a cell phone vibration.

lsdude

I had the same issue until I replaced the LCA ball joints.

https://www.clublexus.com/forums/ls-...placement.html

PersianOne

Really? What weirds me out is that once I turn on the A/C, the vibration in the steering wheel goes away completely.. Like I said it's only when I am at a complete stop after braking, there will be slight vibration in the steering wheel. Sometimes its there, sometimes it isn't, and sometimes its more or less noticeable. But thanks for that thread link, I might go ahead and replace that as maintenance.

Arcturus

You know what this may be it. Reason being is when I brake the wheel shakes but not the pedal. Did you have this as well? I can feel more or less pulsation when the steering wheel is in certain positions. I would think I would get some pulsation in the pedal as well if the rotors were warped. I'll have a look at the lower ball joint to see if this is it. Thanks for the info.

Slvr surfr

iTrader: (1)

May wanna give your motor mounts a good looking over. Bad mounts can transmit vibration thru steering if it's bad enough. I had terrible vibration in my wheel when braking. Just had my LCA bushings replaced yesterday and most of that has been corrected. There's still a little bit due to tires being worn from misalignment.

lsdude

I don't recall the brake pedal shaking, just the wheel.