Braking from 115 MPH. Brake shudder?
 

So I was doing 115 MPH (open, barren road, as safe as possible) and when I hit the brakes I felt a shudder, kind of rumble sound.

Does that mean my rotors are worn? Under normal driving circumstances, I don't notice much and my brakes feel excellent. Just askin'. Thanks!

Abs

Yep! Let up just a touch and you will actually stop faster.

:SHOCKED:

Well, he was right, your brakes shouldn't squeek after that. What are you complaining about?

ROFL !!!!

why are we saying that it was the abs? I have to seriously jump on my brakes to engage ABS. My old 280ZX would shudder when stopping from high speed but not make a very noticeable pulse in the peddle at lower speed. That turned out to be warped rotors. Not saying this was the case, just wondering if I missed some memo, like, RE: ABS ENGAGES UNDER ANY BRAKEING OVER 100MPH.

u guys are pretty dang funny. so back to my issue:

i thought it might have been warped rotors, but I figured i may have felt that at lower speeds, too. I know it's not ABS because that's a totally different feeling (and it's in the pedal). This felt like the whole car was rumbling. I'll go elsewhere for some advice I guess. Peace :)

I think if your rotors were shot, you would feel it during normal speeds liek around 40--60mph braking. I know because i've driven a few family members cars and had to tell them to get their brakes checked, turned out to be warp rotors. I think if you're doing any type of high speed and then suddenly brake, i think its expected to have some brake shudder....cause it is a lot of load on the brakes to slow that car down.

Thats great. But really, I've been wondering how to tell if your rotors are too hot to begin washing the 'ol 8. I try to drive easy and allow a couple of minutes for them to cool if I've been driving around much.

Is there any good way to judge this, thermometer? Hopefully there is a rule of thumb out there so I don't have to haul one of these around.

However, today I washed her, and eventhough it was pretty cool today, I let them sit for a couple of minutes before I started hosing down the wheels, and despite this there was some steam that came off of my right front rotor :Eyecrazy: So far dont notice any warpage.

Dude, stupid questions get stupid answers. This type of thing cannot be described in a forum very well and there are so many factors (road conditions, road texture, wind, etc) that there is no way to answer your question.

Word. I'll try that out.

hey, 9k: there are no stupid questions.

and who knows, maybe there was a general consensus that RX-8s do indeed brake-shudder at high speeds and i thought you guys might know. thanks :)

and the specific road conditions were a normal highway in dry weather. about 65 degrees.

I have never heard of the consensus. Does your car exhibit any radial pull when cruising at high speed?

If one side is a lot hotter than the other, you may have a caliper that is dragging...or siezed.

You can check with your hand...if your careful..or use a IR pyrometer.

Could be a wheel bearing as well...but it should do it all the time....

Great way to warp your brakes. Wash them when they're smoking hot.

How many miles on the car? How hard are you braking on a regular basis? Have you had a brake job before? If so did they turn the rotors? Were they the front and rear or one or the other?
Personally if you were slamming on the brakes (But were the tires locking up?) coming to as fast a stop as possible then I would attribute it to ABS.
If you were just trying to slow your speed at a rapid rate without locking up the wheels, then I might have to say a warped rotor.
ABS will not work unless the wheel is skiding (stops rotating). Then it releases brake pressure and then reapplies it at a somewhat rapid rate. But not to be a rapid consistant shuddering feeling. I've seen maybe 3-4 pulses on the full brake lock up from 60 mph. The wheel will lock up and release and lock up and release three to four times.
Rapid vibration/pulse is more than likely a case of warped brake rotor.

Your rotors are warped, nothing more nothing less. Get them recut, if there to thin then you will have to buy new ones. And don't listen to these yahoo's about spraying water on hot rotors.

Even if they are joking there not very funny..... i swear all the unpaid comedians on this board. :rolleyes:

Or you could just have a tire problem on the front. Hard braking will load the front wheels, increasing their responsiveness... oversteer. Any play in your steering rack will also become more apparent under hard braking.

Your rotors are slightly warped. If you don't feel it at normal speed, shouldn't be a big deal. If it was severe at speed, get them replaced. I noticed a similar thing on mine braking HARD from 125 (of course I was smart enough to do it on a track, but we won't go there!) It wasn't enough to make me go "oh shit!", but I knew it was there.

My IS300 would vibrate a bit under moderate-heavy braking after I tracked it pretty hard a couple of times. Grinding the rotors fixed it perfectly

last summer i was pushing around 115, and had to brake suddenly, and HARD......some dumb ass was braking infront way front .....i ended up stoping 4 feet away from the car. the car handled amazingly.....so im assuming u have brake issues, cuz my car from the same speed did what it was suppose too and was very smooth. which was bad, cuz after that inccodent, i realised how even better the car is, so that just made me wanna push it harder...lol

Thnx for the input, guys. And I know the guys are trying to be funny with the garden hose on the hot rotors. Good ones! (is there a sarcasm font?)

Anyway, I will have the brakes looked at. I am certain it's not the ABS. I just decided to go to you guys first because I really don't have another dealership/rental car trip in me. I judt got the car a few weeks ago and have already been to the dealership a number of times.

Good thing it's an 04 with 28k miles on it and full warranty until Feb. 2008.

So far:
Stereo died. Had replaced.
Steering died. Soldered the connector.
Driver's side door light fell into the door. Still haven't had that taken care of.
Had new started and beefier battery installed.
(yes, all recalls were done on the car before I bought it)

My next dealer visit:
Rotor check.
Fix door rattle.
Fix door light that dropped in.

*Good thing I love this car or I'd be pissed.*