TypeRuz

after replacing my pads and rotors about 3000 miles ago, i soon after started noticing a shake in the steering wheel, almost identical to the shake i had in the previous set of rotors/pads. it only occurs at high speeds, say about 70-80. otherwise the brakes feel smooth. and it's only with moderate brake pedal pressure.
NOW, i went ahead and replaced my front rotors to some cryogenically treated rotors yesterday, and about after 100 miles i just moderately touched the brakes at 80....and again i have a shake!!!!
what's the heck is going on??

could there be something else either at the brake system or wheel hub, etc. area causing this shake??
the weird thing is i only feel it at high speeds. at low speeds it's super smooth.

BTW, i totally broke in everything correctly before i started to get rough with the brakes. and i'm still easy on the new rotors, but i already feel the same shake as the two previous sets.

thanks in advance!!

Bbasso

"Do you have mud in your wheels?"

From my cousin vinny...

Try getting the wheel balanced?

1GreyTeg

1st, does the vibration happen under braking at any speed only (in your case 80 or so MPH) or does it happen when the car is rolling without the brakes applied as well?

If it shakes without the brakes applied, the first thing to check would be wheel balance.

If it only shakes when the brakes are applied, then it sounds like either, the rotors weren't seasoned correctly and or the pads weren't bedded in properly, OR there is pad residue that stuck to the rotor surface making it uneven.

There are other possibilities, but the above are the more common.

Two relatively comprehensive listings on how to:

Season new rotors: http://www.baer.com/Support/Te...pID=4

And to Bed in new or used pads: http://www.baer.com/Support/Te...pID=5

And a good writeup about the myth of warped rotors (because it's just a matter of time before someone misdiagnoses your shake as "warped rotors"): http://stoptech.com/whitepaper...h.htm

TypeRuz

nope, only with applying the brakes.

and i definetly broke them in correctly.

1GreyTeg

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeRuz &raquo;</TD></TR><TR><TD CLASS="quote">nope, only with applying the brakes.

and i definetly broke them in correctly.</TD></TR></TABLE>

You seasoned the rotors?

And Bedded in the pads as listed above?

Not, that I don't beleive you it's just that many people say they do or think they do and they just don't and have these same issues.

As I said, it is quite possible that at one time when you came to a stop from a high speed, you got these new rotors and pads hot enough before they cooled and the pads left an uneven layer of pad residue on the rotor surface thus making them uneven and vibrate.

It usually works for me to just go and re-bed the pads and let them sit overnight and try driving on them again the next day.

Honestly, I've had the same issues, (amongst others brakewise not all of which are solved yet) and the vibration always went away after rebedding.

How does your ABS work?

What pads and rotors if I may ask?

jdmspoonitr

iTrader: (1)

Arghhh...where the hell are we supposed to go and do these tests? I highly doubt anyone can do all these 65-5 stops on the freeway and then get home without using the brakes. As if there are no stoplights or something.

1GreyTeg

I use back roads that are as straight and lonely as possible, and usually at night, late if possible, so there is no traffic. I have a state route that runs close to my house that is 55MPH with passing zones and is completely deserted at night. My area to do bedding and seasoning.

Just be forewarned that if you get the pads/rotors hot enough to bed properly, as soon as you come to a full stop without letting them cool significantly or fully, the pad will transfer that layer of residue as discussed.

I'm not saying that my explanation is the origional posters problem. I'm just saying that when I've had similar experiences, that what I posted was what they were and how I remedied them.


I'm sure someone like Andie or Rusty from Cobalt could explain or examine his situation on a professional level and more than likely come to a resolution for his problem. They have come through for me several times already and are very helpful and knowledgeable.

jdmspoonitr

iTrader: (1)

At the moment I'm trying to wear down my stock pads. I have Ultimates waiting when the stocks are done. But in my area I don't think there is any place I could go without using the brakes at least lightly.

I live at the top of a hill. If I install the pads at my house there would be nowhere I could go without using the brakes.

For me to get to a highway or freeway I would have to stop at at least three or four times.

There is a street that I could get up to 65 around my house, but it is a 25 zone and it is twisty. I'd probably get pulled over.

Another thing I was thinking about. Could I just change the front pads first? And use existing stock rear brakes to get me to a stop until I get to the freeway? And then after that bed the front?

Then go home change the rears and go out again?

Teepo

check the slides on the caliper. Make sure they move freely. Ford brake grease works good. Dont over-tighten them either.

Bbasso

Also if the whole break in procedure is done right and the wheels are ok and the rims are not filled with mud then you have one last item, Your brake rotor is not true and needs to be balanced/ cut/ shaved/ turned and that should only cost you 10 if you bring them to midas or minnakee (sp?)

TypeRuz

what part needs to be greased??

also, what part shouldn't be over-tighened? aren't there just two bolts holding the piston section of the caliper over the two pads?

TypeRuz

UPDATE:
(may or may not be helpful in my endevours to figure this whole thing out)

i went out to the car today and removed both front wheels to inspect for anything funny. to my surprise, the calipers DID NOT slide in/out at all!

i then removed the lower caliper pin bolt to inspect further and it was VERY difficult to move the middle piston section (not sure of official name) off the pads. once i got it off, i noticed the piston was sticking out about 2-3 mm obviously laying up against the inside pad which was why is was so difficult to move the middle section off the pads. i'm guessing this is also why the caliper wasn't sliding in/out before i removed the bottom bolt.

i specifically remember when the tech was installing the new rotors the other day that he "reset" the pistons all the way back in.....isn't that where they should sit??

i'm wondering if something may be wrong with the pistons, master cylinder, etc.
i don't know. i'm not knowledgable enough to make any conclusions. there are just my observations, and if anyone would like to assist me i would greatly appreciate it.

THANKS!!

Dr Pooface

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeRuz &raquo;</TD></TR><TR><TD CLASS="quote">UPDATE:

i went out to the car today and removed both front wheels to inspect for anything funny. to my surprise, the calipers DID NOT slide in/out at all!</TD></TR></TABLE>

Is this before you undid the bolts? You should not be able to move the calipers by hand when they are still bolted to the vehicle.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeRuz &raquo;</TD></TR><TR><TD CLASS="quote">
i specifically remember when the tech was installing the new rotors the other day that he "reset" the pistons all the way back in.....isn't that where they should sit??
</TD></TR></TABLE>

No. The piston will sit against the pad. When you release your foot off the brake the piston stops pushing, but there is nothing to pull it back so it just sits there.

TypeRuz

so let me get this clear....
the piston does not go all the way back into the housing after you let off the brake pedal?
it just settles right against the pads after the first time the pedal is engaged??

one more question:
when rotating the wheels with the car jacked up, should there be a *little drag of the pads on the rotors??

Pondus

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by TypeRuz &raquo;</TD></TR><TR><TD CLASS="quote">so let me get this clear....
the piston does not go all the way back into the housing after you let off the brake pedal?
it just settles right against the pads after the first time the pedal is engaged??

Yes

one more question:
when rotating the wheels with the car jacked up, should there be a *little drag of the pads on the rotors??

Yes </TD></TR></TABLE>