I'm getting a slight wheel shake while braking, its only noticeable when applying breaks while moving more than 30+ mph. I notice that when the car is cold or just leaving the garage, I hardly feel vibration, but after 10-20 mins of driving the vibration is noticeable. Any idea on what this could be? is it the wheel or the rotors, I have to note that there is no pedal pulsation but a definite wheel vibration? thanks!.

 

To determine if the tires/wheels are the problem, inflate all your tires to exact OEM psi, then go for a drive on a flat stretch of freeway. If there is no wobble or pull at high speed, your tires and wheels are good.

If the problem only occurs upon braking, it is likely your rotors are starting to warp. I had the same symptoms when my front rotors starting warping. As the warping progressed, the warmup time was less and I could feel the wobble through the brake pedal and steering wheel. The wobble gradually became too noticeable in normal driving, so I had the dealership replace both front rotors.

To narrow down the cause of the problem, you could try checking your lug nuts for excessive torque. If an air tool was used to install your tires, they probably overtorqued the nuts, which can distort your rotors. Air tools are ok to remove wheels, but a torque wrench should be used to install.

Also check for sticking/dragging brake pistons. There are 4 pistons on each front brake, 2 on each rear. You could go for a drive and see if any wheel is much hotter than the others. You could also drive to a straight road and brake from varying speeds with your hands off the wheel to see if the car tracks straight. If you have some time, you can take the brake pads off and check the pistons by hand. A caliper rebuild kit would fix a sticking piston.

The cause of my problem was either rotor age + several years of winter road salt and/or the tire shop that used air tools to install the tires.

You can get the dealership or a tire or brake shop to measure your rotors for thickness variation and runout. Ask for the exact measurement numbers. This will confirm if the problem is your rotors. If you allow the rotors to warp too much, it will be impossible to resurface the rotors and you will need total replacement. Compare the costs of resurfacing vs replacement, keeping in mind resurfacing may not last very long. I figured the resurfacing costs at the dealer wasn't worth it, considering they don't even have an on-car lathe.

https://www.clublexus.com/forums/ls4...n-braking.html

https://www.clublexus.com/forums/ls4...placement.html

 

Thanks for the input, I'm trying to narrow down the problem, I'm thinking about swapping rear wheels to the front to see if the problem persists. Also this only started happening after I switched to 18" wheels, I'm thinking maybe the higher resistance caused more heat build up. It's definitely frustrating but I will try these steps to narrow down the problem, Thanks!.

 

Good idea to try and swap fronts to rears. These cars came with 18" tires as an option from the factory, so I wouldn't be concerned about heat build-up. Given that it started happening when you installed new rims & tires, it could very well be that they over-torqued the lug nuts. They should be 76 ft. lbs. by OEM spec, I do mine at 80 ft. lbs...

You don't feel any vibration through the wheel at 60~75 mph when not braking? If you do, I'd look towards a balance issue. Are the 18" rims OEM, or are they aftermarket rims with centering rings?

 

9 times out of 10,pedal pulsation is caused by disc runout. Get the discs checked and machined (or replaced) if necessary.

Wheels and tyres won't give you vibration in the pedal,only from the steering wheel.


Justin...

 

ditto, warped rotors. I tend to replace em once warped. While you can machine them (in some cases) it will only make then thinner and if they warped at old thinkness they're just that much more prone to warp once thinner. I buy non lexus rotors and they are reasonably priced.

 

Had the same problem and the rear rotors were to blame. If you have them done do all 4

 

Sounds like our discs are warped and need to me machined or replaced.

 

Don't bother having the rotors turned, as the thinner metal will means they won't be able to dissipate heat as effectively and will soon warp again. I'd recommend replacing them. They're only like $100/ea new if you don't buy from the dealer or buy mailorder. Also check and make sure the caliper bolts aren't loose. Brakes are one thing on a car that are extremely cheap if you DIY, but outrageously expensive if you have the dealer do them.

 

The thing is there is no brake pedal pulsation which is why I'm hesitant that it's the disks, and it's been too cold in Chicago this week for me to swap the wheels.

 

loose caliper?