Vibration When Braking

[Marklouis]

okay all -Happy St. Patricks day by the way!

PLEASE READ DISCLAIMER-I know that the car-buff world is full of do it yourself shade tree Pad-slappers and the total brake system replacement all-outers with Certifications out the wazoo - I ask you all lay your differences aside and work together on this one - we have lost too many good men in Thread wars - God rest thier on-line souls. -_-

Here is my monday night fun:

New Front brakes, new rear brakes, Front rotors turned/lathed at Orielly's(man those front rotors are thick!!), new rear Rotors.

cleaned ALL parts with Brake Cleaner.

Checked emergency Drum Brakes parts - Very thin Pads there- Should I replace?

Backed Calipers back just a bit.

installed new Brakes into Calipers }lightly{ greased the contact points on the Brake sliders.

Torqued the Caliper Bolts to Spec.

Brake lines check good.

no Brake fluid Leaks.

Brake Fluid level good. (did not change out Brake Fluid)

Drove the Car Lastnight 5-10 miles braking lightly under 45 mph. all was well.

Driving to work this morning:

Light pressure braking from any speed - smooth

Medium pressure Braking from any speed - Vibration/Pulsation sets in. (maybe moisture in the brake lines???)

Heavy pressure braking from any speed - smooth

I'm hoping this will smooth out over the next two weeks, but im open to suggestions on what this might be. Thanks!

[Randy&Bonnie]

..

[TexasLexus94]

I've posted a lot about how the previous wealthy owners of my 94LS were robbed by the stealer every 20-30K miles for a new brake job. After 60K miles up to 90K, when I bought it. They paid at least $500 each time for pads and turned rotors.(I got the printout). So I looked at the rotors with 97K, and thought they looked worn out. The brakes were again starting to get that pulsation issue. So instead of turning the rotors, I installed economy new rotors and pads, and have never looked back. 120K, work smoothly. The cheap rotors were 60 bucks each. I figure that if you do it yourself, get new rotors, and forget about turning the old ones, you do OK, and the cost isn't that bad. Did the same thing with my 2005 Mazda MX-5 Turbo with larger brakes, and they're better than the originals-$120 including pads and rotors. I notice you got new rotors for the rear, but turned the front. Since the front rotors do most of the work, I'm wondering why?

Best of luck..

[Marklouis]

!

Hi Marklouis,

You didn't mention it, but I assume you bled the calipers well. I don't think if there was moisture in the brake lines this would cause what you describe? How old is the brake fluid?

In my experience, this type of vibration/pulsation would be abnormal after a brake job.

Does the steering wheel move when your experience the vibration/pulsation? If not, then if could be coming from the rear brakes. I'm wondering if is has anything to do with Anti-Lock system? I would think that if it were a physical rotor issue, you'd get pulsation at any brake pressure. If the rotors are the floating type, I always carefully tighten the lug nuts down on the wheel so that I gradually torque them back and forth across each other to make sure the rotor is torqued evenly on the wheel hub.

Did you rotate the tires while you have them off?

By the way, buying new rotors doesn't necessarily guarantee that they are machined properly.

That's all I can think of right now. Let us know what happens.

Thanks for the reply - not certain on the age of the brake fluid, never changed it when i bought the car. so im guessing it might be best to replace it totally - this is the first time after a brake job ive experienced this pulsation.

The Pulsation is definetly coming from the floorboard - so reaer brakes yes.

the rotors are the floating type - i had to replace 2 Wheel studs because Sears damaged them when they put on my new tires...that may be part of my issue, cause i couldnt get them to seat flush to the axle-plate. I will re-torque them tonight and see if that helps any.

im getting the tires rotated and balanced this weekend.

i've read posts of people having bought new rotors, and needing machining.

ill post my results..thanks Randy! :)

[Marklouis]

I've posted a lot about how the previous wealthy owners of my 94LS were robbed by the stealer every 20-30K miles for a new brake job. After 60K miles up to 90K, when I bought it. They paid at least $500 each time for pads and turned rotors.(I got the printout). So I looked at the rotors with 97K, and thought they looked worn out. The brakes were again starting to get that pulsation issue. So instead of turning the rotors, I installed economy new rotors and pads, and have never looked back. 120K, work smoothly. The cheap rotors were 60 bucks each. I figure that if you do it yourself, get new rotors, and forget about turning the old ones, you do OK, and the cost isn't that bad. Did the same thing with my 2005 Mazda MX-5 Turbo with larger brakes, and they're better than the originals-$120 including pads and rotors. I notice you got new rotors for the rear, but turned the front. Since the front rotors do most of the work, I'm wondering why?

Best of luck..

Hey Tex!

I actually had the rears replaced (economy-brake best) because they really were "uneven" - im like you, i would have had the Fronts replaced as well, but the cashflow for car maintanance is low - and the caliper mics showed uneveness on the fronts as well plus grooves, so i took a chance at getting them turned. so far they have done well after the bed-in process. $11 for turning each vs. $60-$80 for newer ones. once i get some cashflow back in the car maint. fund, i will replace them if any issues arrive with them..

this is a link i found on one of the posts:

http://www.stoptech.com/tech_info/tech_white_papers.shtml

very interesting, but i believe the best knowledge is obtained by hands on experience with just a little bit of guidance...there are just too many variables in life to worry about the molecular structure of things.

thanks Tex-lexy! ;)

[PureDrifter]

just wanted to point out that the $60-80/rotor you spent on some no-name brand that probably requires a turn when NEW because the tolerances are rather low could have gotten you some Brembo OEM replacement rotors which iirc run ~$60-65/each and are true to spec every time on ever car i've ever used them on.

[Marklouis]

just wanted to point out that the $60-80/rotor you spent on some no-name brand that probably requires a turn when NEW because the tolerances are rather low could have gotten you some Brembo OEM replacement rotors which iirc run ~$60-65/each and are true to spec every time on ever car i've ever used them on.

True i admit to buying $30 Brakebest rotors, but i checked them with my digital caliper mics (God i love those things) and they checked out wonderfully...the Brembo's did have a nice set of Vented Rotors...at $115 a piece. I drive my baby easy, so i didnt see any reason to go beyond Economy...

I have noticed today under heavy braking, there is no pulsating at all, just under medium braking.

I will post my findings.

[Mits Driver]

Did you check the runout on the front rotors after they were installed? If there was any rust on the hub where the old hole in the rotor was, or you didn't get a good turning job, not seated on the machine properly. Just something easy to check.