Shudder when breaking at high speeds / pulsating breaking


jessb45
02-20-2004, 01:43 AM
I have had this problem for a while, but it is really starting to get annoying. Whenever I am driving on the freeway over 60MPH and I have to hit my breaks hard, the steering wheel shudders ... you can feel it through the whole car. It is definately in the front wheels.

Also, I think it is related, but when I slow down very easy, the breaking feels uneven. It does not pull to one side ... it sort of pulsates. Very strange ...

I have purchased all new tires, had the car realigned, installed new pads and calipers, and I obviously had to bleed the system. Nothing seems to fix it.

I thought that it seemed better after I got it realigned, but it is back to normal (if it was ever really any better) it still has a problem. The car was in bad need of realignment however and there was a great inprovement when I had that done but I still have the breaking trouble.

Also, I still hear a faint pulsating squeek from the front left wheel at low speeds. I thought the new calipers would fix this but they did not.

Any ideas would be greatly appreciated.

BKVic
02-20-2004, 09:35 AM
From what your saying I would almost bet it is the rotors. When I purchased my 97 Aurora it also did just what yours is doing and it was the rotors. This is a very easy do it your self fix if your so inclined. All you have to do is remove the the front brake pads and calipers and the caliper mounting brakets and the rotor will come right off. A good set of front rotors will run you about $90-$120 each depending on where you go or you could spend $30 for the elecheepo at Advance Auto or Auto Zone.


BKVic

jessb45
02-20-2004, 09:38 AM
It makes logical sense, I have just never heard of rotors bending or doing anything that could cause that. Is that what happenes to them (bending) what causes it? Also, my rotors are a smooth as glass right now.

BKVic
02-20-2004, 12:33 PM
It makes logical sense, I have just never heard of rotors bending or doing anything that could cause that. Is that what happenes to them (bending) what causes it? Also, my rotors are a smooth as glass right now.

There are two things that make rotors wear out faster these days then thet used to.


#1 To save weight in order to meet federal fuel mileage levels the car makers have been making rotors and such thinner. Being thinner not only makes the rotors wear out faster but by not having as much mass they dont handle the heat generated by the process of breaking as well and will warp. I have read where several foreign makers consider the rotors a throw away part. Meaning that they do not make them with enough thickness that they can be machined true if they do warp.

#2 People have been complaining about the squeel that happens sometimes when the brakes are applied using modern semi-matallic brake pads. To over come this problem the manufactors have been switching to a softer materal to make the rotors out of to eliminate that noise.This does a great job of making the breaks quieter but makes the rotors wear out much faster.

When I purchased my 97 Aurora it only had 55,000 miles on it but when I took the pads in to be turned I was told they were already to thin to be safely done. My wifes 98 Pontiac Montana's front rotors had to be changed out at 75,000 miles ,if I remember correctly, for the same reason.


BKVic

jjdewd
02-20-2004, 02:30 PM
Definately sounds like rotors! My "96" was doing the same thing. I replaced brakes and rotors all the way around. That solved the problem!
Did the work myself. Mine took the smaller rotors from the "95" model year. (I think GM upgraded to a lager rotor sometime in 96). I got them at advance auto for like $20 a peice ...the brakes were cheap to. The more expensive pads they offer are less apt to squeek
The Aurora is heavy and tends to go thru rotors at least once a year.
You could however buy more expensive proformance brake parts and they will last a bit longer. I'm happy with stock for now.

KillerKeller_jr
02-20-2004, 04:58 PM
The shuddering could also be coming from the ABS itself. The Aurora has a little bit more safisticated braking sytem than normal cars and tend to feel like they are shuddering at times but not because the ABS is kicking in but for other reasons in the way it applies pressure to the brakes. My local dealer said that this is normal and he has owned 3 different years of Auroras. In all it is still a good recomendation to take the rotors off and have someone measure them for wear and tear and to see if they need replacing. Your local parts store that can resurface them should be able to check that for you. Hope that helps.

Indy8
02-21-2004, 02:58 AM
Over-tightening of wheel lug nuts is the most common cause of warped rotors. Second, is improper resurfacing by cheap machines used in chain auto parts stores. Third, is cooking them through abuse or mountain driving. Buy an inexpensive set of dial calipers and check the thickness yourself, the minimum is usually cast into the hub area of the rotor. If you choose to have them turned, pay a few bucks more and go to a real auto machine shop. When you get them back they should have a cross hatch pattern on both sides, not smooth. Ask about this before you allow them to do the work. Got cash? Get Domestic's slotted new rotors with Bendix ceramic pads. This combination will put you through the windshield!

jessb45
02-21-2004, 01:34 PM
I think that it just needs new rotors ... someone before I bought the car probably put some cheap set on.

I know how the ABS feels and this is way before ABS should have to kick it. Like I said, the pulsating is noticeable even under very very light breaking.

Also, I have been really careful with my torques, but it is possible that some idiot could have messed it up before me.

Indy, where did you get those rotors/pads?

Thanks for all of the help everyone.

jjdewd
02-23-2004, 12:50 PM
SLOTTED ROTORS @

http://www.domesticperformance.com/default.php?cPath=26_313_314&osCsid=cdff3888e48b142c9e4b78e97b940f46

tjm
03-03-2004, 04:05 PM
a tip on installing new rotors - Be sure to TOTALLY scrape off the hubs of all scaling rust and debris; I mean PERFECT (I had the same prob). If the new rotors don't seat completely flat against the hubs then all your time and $$ is for not. Properly torque the lugs. - recheck the torque after a week or so. = smoooooth _________

dafrazi
03-07-2004, 01:07 PM
If you can feel the ABS pulsating at low speeds you may have a problem with the ABS system. If you have kept the brake lines clean by bleeding out all the the old brake fluid every 18 months to 2 years you should be alright. Otherwise, the moisture that the brake fluid absorbs from the air can reek havoc on the ABS system.

jessb45
03-08-2004, 12:07 AM
New rotors fixed the problem 100% ... thanks to all you contributed.

rustyhub
07-14-2004, 11:29 AM
New rotors fixed the problem 100% ... thanks to all you contributed.

I have the same problem. I also replaced the front rotors/pads (both Bendix OEM) and it did not fix the shudders at high or low (worse right at 32MPH decelerating through)--in fact it's worse if anything. Could new rotors be warpped? That was going to be my next step is to take the new ones and have them checked for warpping. Aslo, I have not touched the rear ones. Could that be the problem. The pulsating seems to come from the front as I can feel it in th brake pedal and the steering wheel. Help I'm frustrated and can't enjoy driving the car.

ghutchin
07-14-2004, 12:00 PM
There is a reason that there are 4 brakes on your car. You car uses all of them. The vibration could very well be due to problems with the rear brakes. People don't think the rear brakes due a lot but they do and if they aren't functioning properly the front brakes have to work harder then they are supposed to which leads to warping of the front rotors due to excessive heat. Get those rear brakes checked.

cmdrgala
07-14-2004, 12:26 PM
Hello:

I had your problem, it turned out to be a bent break rotor.
My problem came with bad roads, California the land of 3rd world roads and high price gas, and the Terminatior for Governor.

You can get a good deal on brake rotors on Ebay look under
"Oldsmobile Aurora" or Olds Aurora.

Get the slotted ones they take heat better and last longer.

apostolakisl
07-14-2004, 01:19 PM
One more quick note on how to take care of rotors.

If you have been driving hard and the rotors are hot. Don't stop and hold the break, especially not with much force. If you keep rolling just barely it helps even out heat disipation and keeps pressure off of one spot. The break pads only apply pressure to a short section of the rotor. If the rotor is very hot and therefore soft, then heavy pressure on the break pad can cause the rotor to get thinner in that area.

rustyhub
07-14-2004, 01:41 PM
There is a reason that there are 4 brakes on your car. You car uses all of them. The vibration could very well be due to problems with the rear brakes. People don't think the rear brakes due a lot but they do and if they aren't functioning properly the front brakes have to work harder then they are supposed to which leads to warping of the front rotors due to excessive heat. Get those rear brakes checked.
Glutchin,
Thanks for the reply and confirmation of what I've been told, that it could be my rear brakes. I just didn't want to believe that as my senses keep telling me "it feels like it's coming from the front."

I was going down a step interstate grade about 75 MPH and had to hit the breaks hard and I thought my front end was going to shake off. I had to back off and pump it down slowly. That's the only time I've experienced it at high spleed. Mostly it's around town coming to a stop from 45 MPH and as I go through 35-30 MPH is worse. I'll get the back breaks checked. Thanks again.

rustyhub
09-28-2004, 10:01 AM
Glutchin,
Thanks for the reply and confirmation of what I've been told, that it could be my rear brakes. I just didn't want to believe that as my senses keep telling me "it feels like it's coming from the front."

I was going down a step interstate grade about 75 MPH and had to hit the breaks hard and I thought my front end was going to shake off. I had to back off and pump it down slowly. That's the only time I've experienced it at high spleed. Mostly it's around town coming to a stop from 45 MPH and as I go through 35-30 MPH is worse. I'll get the back breaks checked. Thanks again.

9/28/04

Yep, got the rear brakes checked and that was the problem! Unbelieveable. Had those babies turned and now smooth as a baby's "hinny." Thanks.

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