fireroasted

iTrader: (3)

We have talked about this a number of times, but I wanted to get some quick feedback on some minor shudder I have induced setting up my car for Laguna Seca his Saturday.

I have DBA4000s, and the front have been turned before. I DD the car and with mild pads its smooth as silk stopping. Recently, after two track days at Big Willow and CA Speedway I started to notice a tiny bit of shudder, and since the drive to Seca is a big investment in time and money I had the fronts turned again. All within thickness still and only tiny bit had to come off.

I have never done the rear.

When I got that rotors back I put them on with my track pads. Hawk HP Plus. These pads are relatively new, only the above track sessions.

I bed them in, but on mild DD brake pressure the car oscilates. Almost like I am pulsating the pedal, and not so much the wheel moving left to right, but very light pressure on the pedal will have me pulling up to a light stuttering. As if only part of the rotor touches the pad as it goes around.

Can anyone comment if this is expected, or is it the rears that need turning (which would be new for me, since they do so little comparatively, and on street pads the rears didn't shudder at all.

Just want to make sure I have everything dialed for the long ride to SEMA, and then to SECA.

SilverShadow03

iTrader: (19)

I know you only had a track session on the pads you installed but they may not be contacting the newly turned rotors evenly...even after bedding them in as you did. Track days can put more wear on the pads than you might be taking into consideration. Try out some new pads (if you can) and see if there is a difference.

I've never had my rears shudder or oscillate at any point during the life of them....so not sure if its your rears but you can have them checked out for piece of mind.

chrisw

iTrader: (2)

when you had the rotors turned, did you have them turned on or off the car? the service manual clearly states that rotors should be turned ON the car for proper results.

fireroasted

iTrader: (3)

? Yikes, I have never heard of the rotors being turned ON the car. I took them to a shop and they turned them, which is how I have always done it.

barneyb

I've had my front rotors turned off car too without problem. Still, from reading the manual it sounds like the brakes are sensitive to runout. Use a dial indicator to check the runout and keep pulling and turning the rotor until you have the least amount. You may have to have the rotors turned again on-car. Anyway, a dial indicator will tell you if that is the problem.

WRC-LVR

iTrader: (1)

yes this may help if the mounting surface or the rotor is slightly warped. if you do find a difference by clocking the rotor then you might consider swapping iit out. If clocking makes no difference try turning the rotor while it is on the car. make sure the rotor is solidly bolted in place while turning it on the car.

By any chance have you glanced off a curb recently? You may have damaged the hub causing a wobble .

fireroasted

iTrader: (3)

Just wanted to follow up here and thanks for the feedback. I tracked the car as it was. I felt the shudder pretty good at Laguna Seca but not enough to give me difficulty settling the front end, which was weird.

I expected the aggressive Hawk HP Plus pads to eat up and smooth out the shudder on track anyway, but it didn't really get better. That was weird.

when I got home I did the resolutions in stages so I could provide some info for anyone else. The shudder remained all the way home and the next day.

1- I switched back to street pads in front. Minor improvement but still shuddering.
2- I switched back to street pads in rear. Very minor improvement still shuddering.
Shuddering slightly even when not braking.
3- I had the rears turned for the first time. DBA 4000s. They were real bad. crap! Improvement but still shuddering a bit.
4- suspecting I have a stuck piston or something else I decide to get the fronts checked out again because I just had them turned. Damnit, they needed to be turned again. so that was one track day of 4 sessions. Also DBA 4000s.

After that final step 4. No shudder. Smooth as silk. I haven't had good luck with the DBA4000s since I bought them. I believe my stockers were better to resist warpage.

Can folks generalize why I am warping rotors so quickly? Pads too aggressive? I used to run DTC70s and backed off down to the HP Plus, but I am going through rotors like mad and the pads look new.

WRCLVR I never ever touch the curbs....check out my other new post.