miamirice

i recently started running my k20 civic after driving an s2000 on track for the last year. I got use to really solid and planted braking. Now I am back in my civic and it doesn't feel very good. The car is race prepared and on r compound tires. Suspension is ground control/Koni 2812. 650f/950r. Under hard braking at speed of 80+ I get a pretty violent steering column juter/vibration. It's only with maximum braking. At 80% or less I don't feel it. It's not a side-to-side steering wheel kind of thing. It's not a brake caliper/rotor thing. It more I think a subframe type issue. Anybody felt with this and have suggestions.

Kaan

iTrader: (3)

have you rule out pad knock back? are your front control arm bushings okay?

miamirice

i have brand new LCA with hard rubber bushings. I don't really know what pad knock back is. I have Wiwood 4-pot DHPA brakes

Greyout

Pad knock back is when the pads get pushed black slightly under high lateral load. I don't think that's what happening here.

jdblock

I would try changing the axle nuts, and torquing them to spec. Lot of stress on those bearings with the grip and brake power.

rice_classic

Look at your brake rotor. The transfer layer should be perfectly smooth and uniform. If there's a "pattern" then you have an uneven transfer layer which produces the exact symptom you are describing. Bedding brake pads, it's a common topic because pads that are difficult to bed (aka, set down a smooth layer) are a bitch.

I'm 99.99% positive this is your issue.

After race sessions I flip my pads in the caliper to even out tapering and when I have an uneven transfer layer, sometimes this has corrected it and smoothed out the braking again. Good luck.

Josh R.

I 2nd rice_classic's diagnosis.

miamirice

I will say this is the exact feeling it has. Been there before with other cars. It would surprise me if it's that as these pads/rotors have been on the car for the last 10-12 sessions. I am actually at the end of the pad life so I am going back to ITR/11.1 rotors from these willwood/10.2" to see if I want the longevity over feel. I love the wilwood feel but in summer here in FL they will only go 15-20 minutes then I get a scary deep pedal that has to be pumped. Let you know if this is what it was. I am swapping them next week.

rice_classic

Look forward to the update. Keep in mind that rotor size, sessions etc, mean little. Everytime you go out on track the pads go through their cold state to hot state and layer to the rotor accordingly and sometimes if in the prior sessions the rotors got particularly hot the pattern will emerge on the rotor face where there's cool veins and where there's not. Then, the next time you go out the pads add to this unevenness as they heat up and the problem rapidly worsens.

One look at the rotor will tell you. But then again doing a good nut/bolt and chassis structural integrity check is also a good idea too.

miamirice

i will be swapping back on my ITR caliper/rotors (not because of this issue, just because it's summer and i want to compare). Hopefully I get the car out in July. I bought a spec Miata because it needed a good home and I want to drive that car the next couple events to see if I will keep it.

I will ill post up the brake results once I run the new set up.