Re-surface brake discs

[04_STi]

Does anyone know a shop that can turn warped rotors?

[Kolia]

Why do you think your rotors are warped ?

Many places can do it. It will not solve any problem long term.

[04_STi]

Why do you think your rotors are warped ?

Many places can do it. It will not solve any problem long term.

Vibration in the steering wheel when applying any pressure to the pedal at say 120km/h until about 80. It also noticeable when going slower than 80, but very much less intense.
When rolling to a stop I can feel the disc I'm guessing push the pedal up and down under my foot. This is from say 20km/h to a stop.

Here's the full story. About this time last year, I installed brembos on the legacy. Brand new DBA's and hawk hps all around. Did my proper bed in, guys at SwapShop showed me how and drove the car without issues for about 6 months. In March, or maybe April 2014, I start getting the same vibrations when braking above 100km/h and the same pedal feel when rolling to a stop. Butt dyno gets the feeling too, not just in the brake pedal. Anyways, went to Swapshop to have them take a look at it.
My brakes had an excessive amount of "grease" on the pads and disc face. Im assuming its the anti-seize compound they must have put to stop vibrations betwen the pad and the caliper pistons, for noise reduction Im guessing. Either way, it was everywhere. Andre at Swapshop was telling me that I was actually pretty lucky that they didnt catch on fire and that a surface covered in grease or oil is very much less likely to dissipate heat, which should have been the main cause of the warping...

Anyways, at that time, I was suggested to install new discs and new pads. Still on DBA 4000's and now using Ferrodo's instead of the Hawk pads, and I am now back to the same situation. Fronts discs are warped. Ideally I would like to try get a working solution with what Ive got. I've done maybe 10,000km on this set of discs and pads, and dont want to pay for more. This is quite frustrating at this point.

Either way, I am now thinking that something other than grease is the culprit. I will be taking that pads out this weekend to see what they look like.

Now, someone told me that "warped" rotors, dont actually have runout. I can understand how holding a hot pad against a disc could imprint the pad onto the disc, but what actually causes the pedal feedback, or the vibrations at high speed?

Now, on this set, I did get to drive some pretty fun and twisty roads, but in my mind, I didnt run the car hard to enough to merit "warping". And I didnt get to drive the car at all spiritedly with the set I warped in March or April.

What do you guys think is best course of action here? I really dont want to have to dish out more money for another set of discs. Hence the reason I would like to consider having them turned.
I still have the original set, so would like to turn them, re-install them and see how it works...
Then again, I do agree how removing mass from the disc wont help heat, but it may give me another few months without spending again for rotors....

[Kolia]

Damnit Tapatalk lost my ubber long post...

Warping is exceedingly rare. Very unlikely it is the problem. Do not turn your rotors you will only make things worst by reducing their heat resistance.

Pad imprint is the most common cause of pulsating brakes. It happens all the time.

You put Brembo calipers ? New or used ? If used, how old ? Did you replace the seals ? They might be dragging, causing extra heat to be generated.

Pad imprint happens when brake temperature is high and you come to a complete stop. Most of the time, it is user habits that are in cause as they tend to drag their brakes.

-Do not anticipate your braking with your foot on the brake pedal. Brake using a firm foot. Don't go crazy either, but be firm when braking.
-most important, make it ha habit of inching forward just as you stop. So that you do not leave your pads on the rotors at one place at the end of the brake event.

Be sure you use the correct pad for the correct application. Sport pads used lightly will not run well.

This is were the extra cost of OEM parts is justified. Their performance envelope is wider and are less sensitive to these things.

Have you tried to do a new bed in of the pads ? Did this help ?

Also, your car is manual or automatic ? Automatic means you'll be dragging your brake as a necessity...

[Yves B]

i have the problem with stop tech brakes .. shaking at around 80Km/h, as I may read here and on the stop-tech website, it's more a problem of uneven deposit of pad material on the disk brake .. It's really bad cause I think I'm one of the rare to use the bed in procedure . On this, you think if I try it again , 10 times from 100 to 30 at 80%of the breaking power .. ten times in a row, letting them cool down by driving a little while whitout braking and a second set of ten ... it may arrange them ? it's bad ..brakes at 4 months old.. and I'm really a "soft" driver .. and trying to bed them again .. can i make things worst ?

[Kolia]

I've "fixed" many sets of shaky brakes with a new bed in. Its worth a try.

Make sure the vibration isn't from a fractured rotor, bad bearing or fault suspension linkage before you go out.

[scooby_doo]

How about some stoptech rotors or centrics that are cryo treated? As for me I warp everything but then again I only do city driving so every 24 km I need to change them.


The Devil's Advocate plus my 2 cents from my iPhone using Tapatalk!

[04_STi]

I've "fixed" many sets of shaky brakes with a new bed in. Its worth a try.

Make sure the vibration isn't from a fractured rotor, bad bearing or fault suspension linkage before you go out.

Since I get the same pedal feedback when rolling to a stop, I would have to assume this is not caused
by something other than the brakes. I can understand how other damage would become amplified when braking but don't think this is the case with my current symptoms.

The front calipers where purchased used, and no, I didnt have them rebuilt. I had asked the shop who installed them to give them an inspection to see if a rebuild was necessary. I was told they were fine.
I dont know how many km on the calipers, they came from a JDM shop. However, visually they look almost new. No discoloration of the paint from overheating and again, asked the shop to inspect them
before installing.

After installing the brakes, I have had new suspension installed on the car. I had Bilsteins put on in August. New top mounts, swaybars, springs, tires and the shocks. However, after this, everything was fine, so issues or vibrations. It really seems like something in the braking system isnt functioning properly, and this worries me. I consider brakes to be more important than gasoline.

Damnit Tapatalk lost my ubber long post...

Warping is exceedingly rare. Very unlikely it is the problem. Do not turn your rotors you will only make things worst by reducing their heat resistance.

Pad imprint is the most common cause of pulsating brakes. It happens all the time.

Also, your car is manual or automatic ?

Car is manual...

If pad imprint is the most common cause of pulsating brakes, what is the best course of action to correct this? Another bed in process?
I'm just thinking, that if it is a surface condition, why not machine it off? I'm thinking I could have 0.02" removed, and should still have sufficient mass for heat dissipation. But honestly have no idea if 0.02" would be deep enough.
If the rotors aren't "warped", as in they don't have any runout, what actually causes the pulsation?
Im thinking the high spots on the rotors push back on the pad, which I feel in the pedal.

I've "fixed" many sets of shaky brakes with a new bed in. Its worth a try.

what is your bed procedure? maybe I am not doing that correctly.

[Yves B]

On StopTech website, there's a curing procedure, I will resume it .. sanding and doing another bed in ... but unfortunately in my case... but still shaking ... I'll have it replace by the garage ... not the manufacturer ... on this ... a big big thanks to Mécanique Étoile, maybe he made an exception don'T take that he'll do this for granted, and about machining your disk , it will probably resolve the problem, but you're removing material, and I personally don't think it will change anything with the heat exchange .. but I'm far to be an expert

[Kolia]

The pulsation comes from the variation of friction coefficient from the extra pads material deposit.

Turn the rotors is you want. It will "fix" it for a few weeks and then it will be back.

Look at your driving habits. Avoid dragging the brakes. Release the brakes just before you stop.

If you do drive "easy" and you have aggressive pads, it might be that you drive too easy for those pads.

[04_STi]

hmm, i really dont think its my driving since after warping the first set of rotors, I have really been paying attention to how I brake and slow down the car, especially when coming to a complete stop.

I am almost due for an oil change, currently at approx. 4300km since my last one and will ask the guys at Swapshop to give it a look over and see if re-bedding will help.

I will hit you guys back with an update after the run out to Blainville... thx again Kolia.

[BBQMAN]

Late to the thread, but you do not have warped discs. It is an uneven transfer layer that is causing the pulsation.

Either way, turning a disc makes no sense, but you can scuff the discs with emery paper to clear away the deposits and start the process from scratch.

[04_STi]

better late than never. i appreciate the input. i figured turning was the way to go, to simply machine off that layer of the disc face which has been causing the pulsating stops.

what is emery paper? scotchbrite? or sandpaper?
if so, what grit? and just the disc face? leave the pad as is?