Severe Wheel Shake - High Speed Braking

[BadBrad]

So my 2001 RX300 AWD with 42k miles really seems to have perfect brakes until I've been jamming along at 70+ for a while on the freeway. If I have to brake (and especially when I REALLY have to brake) I get a very substantial steering wheel shake. Seems the front rotors might be warped. But, I don't get this at lower speeds and even if I take it out "cold" to 70+ and hammer the brakes I don't get this. This car has never had a brake job; pads looked great; never tow anything; it always gets the torque wrench on tire rotation; wife babies this car.

I mounted up my dial indicator (no household should be without one) this weekend and found maximum rotor runout of only about 0.0025 inches. This doesn't seem excessive; I wouldn't call it warped; but I don't know the max specs anyway. All I can think is the extra heat from a long drive is a contributing factor. I really don't want to do a brake job (even though I'd do it myself anyway) 'cuz we unload this baby within the year. :whistles:

Questions:

Anybody else have/had a similar situation?

What did you do about it?

Anybody know what the maximum runout spec might be?

Thanks for your input in advance.

[dal]

Anybody else have/had a similar situation?

What did you do about it?

Thanks for your input in advance. 

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If rotors check out OK, the vibration when braking at higher speeds can also be caused by cupped tires - uneven wear. I had this happen on a different vehicle - took some time to diagnose. Rotor issue is highest probability. Consider examining tires if rotors check out OK.

[BadBrad]

Thank you.

Tires are OK.

[SKperformance]

You rotors are warped 100%.

Do not machine them to make them true again as it will only warp faster.

[chimchim]

You rotors are warped 100%.

Do not machine them to make them true again as it will only warp faster.

←

Yeah but the alternative to machineing is new rotors, which is a lot more expensive than machining them.

And, don't forget that "uneven rotors" are not always due to actual rotor warpage. Rather, it is sometimes due to uneven bedding of the pad on the rotor. Always break in new pads properly and periodically re-break-in the pads to redeposit.

[lsrxlex]

Please show me how to:

-break-in new pads, and

-periodically re-break-in them

Thank you very much.

[wwest]

So my 2001 RX300 AWD with 42k miles really seems to have perfect brakes until I've been jamming along at 70+ for a while on the freeway. If I have to brake (and especially when I REALLY have to brake) I get a very substantial steering wheel shake. Seems the front rotors might be warped. But, I don't get this at lower speeds and even if I take it out "cold" to 70+ and hammer the brakes I don't get this. This car has never had a brake job; pads looked great; never tow anything; it always gets the torque wrench on tire rotation; wife babies this car.

I mounted up my dial indicator (no household should be without one) this weekend and found maximum rotor runout of only about 0.0025 inches. This doesn't seem excessive; I wouldn't call it warped; but I don't know the max specs anyway. All I can think is the extra heat from a long drive is a contributing factor. I really don't want to do a brake job (even though I'd do it myself anyway) 'cuz we unload this baby within the year. :whistles:

Questions:

Anybody else have/had a similar situation?

What did you do about it?

Anybody know what the maximum runout spec might be?

Thanks for your input in advance.

You may have an ABS wheel speed sensor that is slightly out of calibration/position. At higher speeds if a wheelspeed sensor signal "drops" out while you're on the brake...

Pull the ABS fuse and take a drive..

[mikey00]

So my 2001 RX300 AWD with 42k miles really seems to have perfect brakes until I've been jamming along at 70+ for a while on the freeway. If I have to brake (and especially when I REALLY have to brake) I get a very substantial steering wheel shake. Seems the front rotors might be warped. But, I don't get this at lower speeds and even if I take it out "cold" to 70+ and hammer the brakes I don't get this. This car has never had a brake job; pads looked great; never tow anything; it always gets the torque wrench on tire rotation; wife babies this car.

I mounted up my dial indicator (no household should be without one) this weekend and found maximum rotor runout of only about 0.0025 inches. This doesn't seem excessive; I wouldn't call it warped; but I don't know the max specs anyway. All I can think is the extra heat from a long drive is a contributing factor. I really don't want to do a brake job (even though I'd do it myself anyway) 'cuz we unload this baby within the year.:whistles:

Questions:

Anybody else have/had a similar situation?

What did you do about it?

Anybody know what the maximum runout spec might be?

Thanks for your input in advance.

You may have an ABS wheel speed sensor that is slightly out of calibration/position. At higher speeds if a wheelspeed sensor signal "drops" out while you're on the brake...

Pull the ABS fuse and take a drive..

Lets hope he got it fixed by now. You are replying to a post that is 2 years old.

[lsrxlex]

You rotors are warped 100%.

Do not machine them to make them true again as it will only warp faster.

I already bought front and rear brake pad sets. Then I called Lexus, and they wanted $199 for labor to turn rotors (front or rear set) and to install new pads (front or rear). So total cost to pay them is $199x2. ( When I brouht the car in for alignment earlier, they said my rear pads had about 2 mm left and they recommended the work).

But somehow, they didn't recommend replacing new rotors (?). Does Lexus now allow turning rotors instead of replacing them?

My 1999-RX300 has 121k miles, and this is the first time it needs brake pads replaced. (I cann't believe the original pads could last so long, 121k and 8 years).

So do you think I should buy 2 sets of shim kits and have them replace for me too?

And after the replacement, what should I do to break in the new pads and periodically maintain them?

Thanks