brake wobble when it gets too hot
 

after a few hard braking the steering wheel starts to wobble under heavy braking, would getting them machine help or it is time to get new rotors. I cannot recreate the condition under street use, but at the track they start to show up after a few laps.

At first I would say, check that your lug nuts are tight. But I think it's more like pad build up on the rotor. Change your brand of brake pads.

I think so too...........cause i saw some pad build up. What is the best way to clear that build up, and would a ceramic pads be sufficient for HPDE where I only spend 20-30mins on the track at a time?

You can use sand paper to clean the face of the rotor.

There are numerous threads on pads. Start in this forum: Series I Wheels, Tires, Brakes & Suspension - RX8Club.com
You will have to change the dates to display, down near the bottom, to a year or more.

Are you on the stock suspension? What is your alignment? Have you changed your brake fluid?

My car is very nervous under braking with a balanced cornering setup and the stock suspension. I'd guess the rear RC is going way up with the front RC going way down in addition to the normal weight transfer.

Normal street ceramic pads are not suitable for track use. There are a few good threads covering track brakes in the racing section...do a search for pads in the thread title. I can recommend the DTC60s, but may try some carbotechs soon. Pad buildup and shudder is normal for me on light braking during/after a track day. It goes away in a day or two.

Could be brake pad deposits, which the sandpaper route can help

Could be improper lug nut torque

Could be warped rotors, which the only permanent fix is replacement



.

Is it more of a slow wobble or more of a jitter?

Are you feeling it in the wheel or is the whole car kind of squirming back and forth?

When i brake hard the steering wheel wobbles and it feels like I am driving over bumps, the car doesn't feel confident.

Are you sure you're not actually driving over bumps? Braking zones see the most wear on tracks. Also, this isn't the ABS you're feeling? (Had to check)

my experience with just OE pads is that they don't do this, so i'm going to make a couple suggestions.

sounds like the pad you have isn't working, i'd switch back to Mazda, or some different higher performance one.

i'd replace the rotors, although if you're frugal you could measure the thickness, and machine as needed.

the other possibility is that i've noticed nervous feeling = not enough rear toe in. i haven't done a lot of experimenting with the Rx8 specifically, but on other cars the rear toe makes a huge difference in the "plantedness" of the rear.

its also partly technique dependent, for example. a couple FC's ago, i just aligned it to zero toe all the way around, and when i could brake early, and get on the gas before i turned in, the car felt awesome (with the DTSS, it felt like it could square off a 25mph turn), the problem was that on the street you're not really able to BE on the gas before you turn in, and if you weren't on the gas, it felt really nervous.

a stock FC for comparison feels really planted all the time, even if you go into a corner hot and lift off the gas, (and spin) it still feels planted.

so rear toe can have a big influence on how the car feels on corner entry, that is DRIVER dependent. the solution for my street car was to add some toe back in.

I like that.

My angle was on a fast hard brake he was so slightly moving the wheel from gripping the wheel too tightly while bracing himself, which would make the backend wiggle and squirm around.

actually we've had that problem with one of our drivers, he complains the car is twitchy, but if you watch his in car, he's all elbows sawing at the wheel, so his twitchy = car responding to his steering input.

I guess I am going to pick up new rotors they are 30 a piece and some JIC front pads they are on clearance at my local shop.

Thanks for the help. The braking is pretty stable, I have front toe zeroed out and rear toe is set in.


I didn't have an issue at big willow or streets of willow since the flow on them is pretty good and don't have too many braking zone, but when I got to Buttonwillow, the pads probably had enough.

I have that problem when I death grip the wheel on fast braking (127-65.) I was telling my instructor about that while we were driving, so he suggested the next time I braked for the braking zone in question I let go of the wheel with hands at the ready to show it was me and not the car. I kept one finger on the wheel, like that would have mattered, :lol2: the car tracked perfectly straight. So now when I brake on that corner I relax and slightly open my fingers and palm the wheel. Does the trick for me. ;)

I was tracking a few weeks ago with a fellow 8 clubber and while we were talking about how our cars were running, he mentioned his car got a little sketchy in that same braking zone. I told him it was him and that he should relax his grip. After the session was over, I asked him how it went, and he said the problem went away :)

I am not sure what JIC pads you are looking at, but you're going to need real track pads (1000°+ F) to brake consistently if you're running fast. For reference, I haven't seen any for less than $300 a set but would love to know if someone has!

Interesting, I'm going to have to try this next time. Last time out at Thunderhill, braking for T14 I was struggling to keep the car straight, although it seemed fine everywhere else. At the time, I was thinking bumps, or the fact that there might be slightly different grip left to right.

It's the hardest braking zone on the track (over 100mph to below 50mph) and although it looks simple, I find it quite hard to line up everything as you go over a crest before the track opens slightly to the left and then head to a blind apex on the right... I've struggled there in the past and so am probably gripping the wheel harder than in other areas.

Another thought, I could be the shocks on the front are worn out. The least little ripple in the road could start the wheel bouncing.

Blu3, at the higher speeds under braking the littlest movement of the steering wheel will wiggle the car. Also a tight grip takes away from the information telegraphed through the steering wheel. I struggle to keep a light grip. I have to remind myself to relax several times a session :lol2:

Let me know if it works for you. Thunderhill looks like a lot of fun :)