braking problem

CTS-V420 · #1 (**permalink**) 11-21-07, 02:48 AM

Ive been having some braking issues lately.... at highway speeds 65mph+ when i step on the brake the car shakes/vibrates slightly..it doesnt not feel safe. i took it to the dealer and they 'shaved' the rotors..but it still does it? any1 else with the same problem? any ideas what the problem could be? Its not the pads bc i got new ones a 2 or 3 months ago...
hmmmm
thanks in advance

CTSV_Rob · #2 (**permalink**) 11-21-07, 03:18 AM

When did the problem start?

Naf · #3 (**permalink**) 11-21-07, 03:58 AM

HAHAHA

I had this before on another vehicle, its a combination of little things...

One of your pads are cracked, look really hard and dump the brake cleaners on them all...
You may also want to take a look at your calipers, the shakin comes because the "floating" system is jammed. Typically your brakin cylinders swish side to side. If this is not possible then your car will shake. Its normal, 2 pistion calipers use a pin for sliding to float.
Lastly shimmin isnt always the best thing to do. I rarely shim, its not good for the coolin of the rotor. The thicker the less prone to brake fade, the thinner the more prone it is...
Best thing to do is feel the rotor, if it feels like there are ribs or is uneven yes you may have to shim, if not leave it alone. You are only wastin money. Uneven is 0.060+ inches or 1.5+mm grooves.

JMBCTSV · #4 (**permalink**) 11-21-07, 09:00 AM

Did they tighten the Caliper Mounting bolts enough?
Is the rattle clip in place properly?

nikon · #5 (**permalink**) 11-21-07, 10:25 AM

what shakes....the steering wheel or your ass??? at least that'll narrow it down a bit.

atdeneve · #6 (**permalink**) 11-21-07, 10:37 AM

I've had the same issue for over 15,000 miles.

Initially, I was beginning to think that it might have just been warped or grooved rotors. I do now have grooves that I can easily feel with my fingers. There's also visible dark spots along the fire path of the pads (hot spots?). Was gonna give my rotors to someone (forget who it was), but since I was thinking that they might be bad, I didn't want to hand off shoddy pieces. But there seems to be not one occurence of warped/cracked stock rotors (they seem to be a good piece). So, I began to wonder if my calipers were causing the vibration.

Now that you make mention of the calipers, it sorta confirms it. Could the problems with the calipers cause grooving of the rotors? Can it cause rotors to have hotspots? Are my rotors done or do they just need to be turned (basically, is it safe for me to send it to someone else)?

As for the calipers, Naf, what do you mean when you say the "floating" system is jammed? I thought the V calipers were fixed. How would you go about un-jamming the calipers?

What are you talking about when you say shimming? And when you talk about thickness and brake fade, are you referring to the thickness of the rotor or the shim?

Can you clarify some of the notes you made. Thanks.

CTS-V420 · #7 (**permalink**) 11-21-07, 01:40 PM

this has been happing for id say 2 weeks..but since i only drive on the highway maybe once a month, its not as noticable-
it is NOT just a steering wheel shake- my ass shakes, the car shakes- it does not feel safe
-what if gatherd from the above posts..it could be a slight crack in my pads, a not smooth rotor, and a floating thing?
-it was not my idea to shave the rotors..the dealer did it when i complaind about the shake- the shaving didnt help-
So my car is at Cadillac now getting an oil change..what shud i tell them to look at/tighten?
thanks again

ZEUSROTTY · #8 (**permalink**) 11-21-07, 01:46 PM

Who uses there brakes anyway?

nikon · #9 (**permalink**) 11-21-07, 02:12 PM

we don't have floating calipers....we've got pistons on each side of the rotor, so thats not it.....floating calipers are when the piston is only on one side of the caliper..........and eh, I too get this sometimes, really not sure what it is......

BBV · #10 (**permalink**) 11-21-07, 02:34 PM

Quote:

Originally Posted by nikon

we don't have floating calipers....we've got pistons on each side of the rotor, so thats not it.....floating calipers are when the piston is only on one side of the caliper..........and eh, I too get this sometimes, really not sure what it is......

^^Exactly what nikon said.

I too had this issue and as you and nikon noted it was intermittent.

Last week I turned all four rotors, installed new Hawk pads, and flushed and filled the brake fluid with ATE Super Blue. I have since done about 40-50 laps at the track and have not had any vibrations under braking at any brake pressure.

nikon · #11 (**permalink**) 11-21-07, 02:42 PM

^^ see what I don't get is I had this issue before I hit the track.....it would happen sometimes under light braking, sometimes under heavy breaking....but you usually had to be doing at least 65mph....now I only felt it on the track once/twice and attributed it too not letting the brakes cool long enough before I stopped the car and having some pad melt on there.....because after a couple hard stops it went away.....the only other thing I can think of is maybe the ABS/Stability system is doing something......and for me the problem was also only felt in the wheel (front brakes).....I flushed my fluid 2 weeks ago and haven't felt anything yet but at the same time I can't remember feeling anything for a couple weeks before that......I just chalk it up to a ghost in the machine, because I've got plenty of pad left, and if the rotors were warped you'd always feel a pulse due to the design of our brakes.....and she never pulls when you get on the brakes either.....so I just kinda forget about it.

ZEUSROTTY · #12 (**permalink**) 11-21-07, 04:35 PM

get new rotors and pads... easy to do in about 30 minutes. I did my rotors paads and brake lines this weekend in about 4 hours... Its is soooooo easy. After that make sure you bed them in properly, and enjoy... Problem solved.

nikon · #13 (**permalink**) 11-21-07, 05:45 PM

^^ the labor isn't the hard part....it's forkin over the dough for the pads and rotors.....

regardless I've never heard of an intermittent brake pulse...it makes no sense whatsoever.

ZEUSROTTY · #14 (**permalink**) 11-21-07, 05:59 PM

Then get your rotors turned again... And just get brake pads... If you turned your rotors, and put the same pads on it, you will still get an issue because your pads are garbage. If you have a high spot on any part of your pad you may see a change in feel as you noted. My family has owned brake shops for 20 years... So I do have some good experience with this...

nikon · #15 (**permalink**) 11-21-07, 06:12 PM

^^ I'm not the OP

I've never gotten my rotors turned and am on stock pads.......I do not get a vibration or pulse everytime I hit the brakes....in fact I can't remember the last time I got the vibration, however it has happened many time before...hence the reason I said it was an intermittent problem....if my rotors were warped I would feel the problem ALL the time. I don't.