22 replies to this topic

[TimBail3y]

I have a 2010 WRX and have recently upgraded (or downgraded) to the 02 4 pots.

When I done the upgrade I took the Pistons out, cleaned them all up, brand new seal kits, shims and pads. Used the same T2 dba rotors I had (1 year old)

So a few months on now, I have a really bad steering wheel shake when I apply the brakes. Inspection shows everything as normal. I then bled the brakes again, and this seemed to have solved the problem. Few days later, it's back.

Any ideas? I'm thinking warped rotors, but 1 year old is a bit iffy, and bleeding the brakes helped, so I'm out of ideas!!

[duncanm]

I think warped rotors is considered a furphy -- they get hard spots due to metallurgical changes from deposition of pad material.. which then leads to friction and rotor thickness variability.

either way - it does sound like a disc issue. The bleeding of the brakes (air in the lines) may have changed the resonant freq, or maybe it only happens when they're hot.


Did you bed your new pads in properly ? A good couple of extended hard braking sessions to get them nice and hot, but making sure you didn't stop rolling completely? Stopping completely while you do this bed-in can lead to the deposition problem noted above.

See here for discussion: http://www.stoptech....and-other-myths

[CRUISN]

Did you machine the rotors?

Putting new pads on used rotors withought machining is a no no. Theyll be worn to suit the 2 pot pads.

Get the rotors machined.

[TimBail3y]

That was going to be my next bet, as thats what i originally thought the problem was.
But how would that explain that the shake went away when i bled the brakes?

 

And i feel machining isn't worth it. I got a quote before of roughly $150, but can get brand new for ~$200

If i can 100% pinpoint that is the reason, i think i will go with some T3's and better pads.

Edit: Sorry missed the first reply.
I did bed them in as you said, not stopping, hard braking etc. I know i did with the rotors when i originally got them, maybe i'm getting confused and didnt do so with the brakes :/

[TimBail3y]

I should also note, when i bled the brakes last weekend, a few good air bubbles did come out. 

I will try and bleed them again this weekend, but if there are more bubbles, the issue would be a leak and not the disc correct?

[CRUISN]

Bleeding properly or not has nothing to do with brake shudder.

[nickknack]

Last time i got rotors machined i think it was $20/corner....

[TimBail3y]

The only reason i say about bleeding, is that it did seem to help the problem. In theory if there is air coming through, one or more pistons may not be pushing enough, meaning the pad isn't flat. So if there is air in there again, there has to be another reason how its getting in anyway... Just trying to rule things out that arent costing a deal of money.

 

Not sure where abouts you are Nick, but the quote around here was $75/corner.

[LPM_B4]

Not sure where abouts you are Nick, but the quote around here was $75/corner.

Can get new RDA slotted and dimpled fronts for about $150 if that's the case 294mm rotor

[Ben_20EJT]

Dba t2 rotors are just a stock street series rotor with slots, no different to a stock dba rotor. Where as the dba t3 is a 4000 series and there a different metal compound and designed more for a performance brake pad and higher heats, good luck warping a 4000serise rotor.

[TimBail3y]

Thanks Ben! If it is a warping issue, I didn't really want to buy the same rotors again, to have it happen a second time.
My rears are T2's as well, but stock brakes, so I'd rather stick with DBA on all 4, so once I confirm it IS the rotors, T3 will be my choice!

[CRUISN]

I only mentioned machining as its only $60 a set of four locally here if you drop them in.

Your quoted price is ridiculous for machining.

[TimBail3y]

Would any problem with the Caliper be the culprit of the rotors going bad?
Reason I say this is I took the pads out of the calipers, pumped the brakes a few times and noticed the Pistons don't all come out at once, or one is a little more stubborn than the others.

Just don't want to buy new rotors to have the same thing happen.

[CRUISN]

Thats normal with the pistons. 

[TimBail3y]

Okay last query
Pulling the handbrake, slowly, whilst driving caused the same sort of shake. Would this just be the car abruptly stopping, or more so point to the rear?
New front rotors are on order regardless.

[RX25SE]

As above, machine or replace the rotors and Im sure it will solve your problem.

[TimBail3y]

Rotors should be here and on, on Thursday hopefully.
I just tend to over think things

[RXJezza]

Are the sliders (if thats what theyre called) moving freely? 

 

My rotors were warped so i replaced them and the pads and now my new rotors are warped cause the slider was jammed so only 1 piston was working properly.

[TimBail3y]

Was this with 4pots though?
Not sure what you mean by sliders.
I've greased the pins on the fronts, the slide pins on the rear seem fine, but I doubt if be getting this much shake through the rear brakes to the steering wheel.

[RXJezza]

nah 2pots but yeah the pins, if theyre fine then that shouldnt be your problem