Notices

Brake Shudder

 
Old 12-15-2004, 09:38 AM
  #1  
kdurg
Addict
Rennlist Member
Thread Starter
 
kdurg's Avatar
 
Join Date: May 2003
Location: Virginia
Posts: 1,695
Default Brake Shudder

Getting a strong vibration in steering wheel during braking at 70+mph and 40/50. Search of the archives provided some very good info. A link referenced by Graham:

http://www.stoptech.com/whitepapers/...otors_myth.htm

Suggested using GARNET PAPER on the rotors to remove any pad deposits materialized on the surface, which I suspicion is the cause. It said not to use regular sand paper.

A search on the web indicates Garnet Paper is used for woodworking finishes and is NOT to be used on metal surfaces......??? WTF ??

Has anyone used something other than what's mentioned to clean /scrub the surface of the rotor ????

Side note: After a good rotor scrub, I'll try the 60-5mph, 70-5mph, 80-5mph brake in to rebed the pads.

Thank You for any replies.
kdurg is offline  
Old 12-15-2004, 09:51 AM
  #2  
Mark in Baltimore
Moderator
Rennlist Member
 
Mark in Baltimore's Avatar
 
Join Date: May 2002
Location: Baltimore, MD
Posts: 21,176
Default

Keith,

Hawk Blues are great for cleaning off any deposited material. Try posting on the racing board to see if anyone has any really thin pads that they're on the verge of throwing out.
Mark in Baltimore is offline  
Old 12-15-2004, 10:06 AM
  #3  
Ray Calvo
Passed On
Rennlist Member

 
Ray Calvo's Avatar
 
Join Date: May 2001
Location: Pittsburgh, PA
Posts: 3,031
Default

My experience has been when I felt vibration, the rotors (fronts) are warped. Replacement cured the problem. Never found a rotor cleaning/sanding that did anything.
Ray Calvo is offline  
Old 12-15-2004, 10:24 AM
  #4  
Terry Adams
Addict
Rennlist Member
 
Terry Adams's Avatar
 
Join Date: May 2001
Location: Winter Garden, FL
Posts: 13,156
Default

Likely you have warped front rotors, in my recent experience. The shop turned them for me, and the vibration was gone. I don't know what method, or if they use any abrasion material.
Terry Adams is offline  
Old 12-15-2004, 11:15 AM
  #5  
clubrcr
Addict
Rennlist Member
 
clubrcr's Avatar
 
Join Date: Apr 2002
Location: Jacksonville, FL
Posts: 1,826
Default

Before you throw out your rotors or have them "turned", do this one simple thing. Take an air hose and blow out your cross drill holes and then take a small drill bit and and stick it through the hole to make sure it is cleaned out.

I had this same problem with a set of 993tt rotors. Everyone told me that they were warped. I asked someone at the track and was told to do what I have outlined. It cured the problem.

It's worth a shot.
clubrcr is offline  
Old 12-15-2004, 11:33 AM
  #6  
Greg Fishman
Addict
Lifetime Rennlist
Member
 
Greg Fishman's Avatar
 
Join Date: May 2001
Location: Austin TX
Posts: 7,166
Default

I have some HAwk Blues I could send you. That should take car of any uneven brake pad deposits.
Greg Fishman is offline  
Old 12-15-2004, 11:44 AM
  #7  
TrackJunke
Addict
Rennlist Member
 
TrackJunke's Avatar
 
Join Date: May 2002
Location: W-S, NC
Posts: 873
Default

I have found that sometimes just driving around for a few weeks will cure the problem if it is not really bad. However, I have also had rotors blanchard ground at a machine shop which also cured the problem.
TrackJunke is online now  
Old 12-15-2004, 12:06 PM
  #8  
djantlive
Super User
 
djantlive's Avatar
 
Join Date: Oct 2004
Posts: 2,409
Default

Get a caliper measurer, measure at different spots of the rotor to compare thickness of rotor. If they vary too much, your rotors are warped. If any measurement is lower than spec, your rotors should be tossed bc they aren't thick enough. If they are all higher than spec (stamped on rotor's center), you can have a shop turn them. They put it on a lathe and shave off excess metal to make it even in thickness.

Sanding to remove dust is fine but don't get too abrasive on the rotors bc you won't be sanding evenly and can make warping worse.
djantlive is offline  
Old 12-15-2004, 12:38 PM
  #9  
JPhillips-998
Cows-4-Rent
Rennlist Member
 
JPhillips-998's Avatar
 
Join Date: Jul 2001
Location: Colorado Springs, CO
Posts: 1,464
Default

The machine shop, even a pep boys can tell you if the rotors can be turned or if they are beyond hope. I'm not sure I have ever heard of a street car rotor warping but I'm sure it has happened.

Another cause could be a cracked rotor. You will have to pull them to get them turned, so do a good inspection to make sure they are not cracked.
JPhillips-998 is offline  
Old 12-15-2004, 01:14 PM
  #10  
Tom W
Addict
Rennlist Member

 
Tom W's Avatar
 
Join Date: Jul 2001
Location: Santa Rosa, CA
Posts: 4,482
Default

I had pretty bad shudder at a track event with my 964. Once I cleaned the rotors well (and got rid of any build-up in the holes) it went away. No sanding, no turning, no replacement was necessary. I cleaned with soap & water and used a "scrunge" type pad from the kitchen. I also poked every hole with a small srewdriver to ensure they were clean.
Tom W is offline  
Old 12-15-2004, 01:34 PM
  #11  
Mark in Baltimore
Moderator
Rennlist Member
 
Mark in Baltimore's Avatar
 
Join Date: May 2002
Location: Baltimore, MD
Posts: 21,176
Default

I use a pressure washer to blow out the crud in the holes. Safer on your lungs than compressed air and is quicker than a drill bit.
Mark in Baltimore is offline  
Old 12-15-2004, 06:23 PM
  #12  
Bill Verburg
Addict
Rennlist Member

 
Bill Verburg's Avatar
 
Join Date: May 2001
Posts: 10,943
Default

Regular cleaning w/ high pressure air and a garden hose goes a long way.

Regular kithcen scrubbies work will to clean pad deposition. Garnet paper does work well.

the big thing not to use is steel wool
Bill Verburg is online now  
Old 12-27-2004, 10:25 AM
  #13  
kdurg
Addict
Rennlist Member
Thread Starter
 
kdurg's Avatar
 
Join Date: May 2003
Location: Virginia
Posts: 1,695
Default update

My thanks for the tips and advice, particularly to Greg Fishman for offering up his Hawk Blues to help clean up the rotors.

I was able to eliminate the front end shudder in the brakes by doing the following:

-Power washed the front rotors followed by compressed air to dry them out.(took Clbrcr-Jim Newman's recommendation) and inserted a drill bit thru each hole in the rotor to ensure no buildup was left.

-"Dragged the Brakes" ...put the car in 2nd gear and drove it to 35mph while keeping one foot on the brake and the other on the gas maintaining a constant speed.

Followed the process in this link... http://www.pagidusa.com/bedding_in_procedure.htm

Shudder is GONE !! Although it worked for me, I won't go so far as to say it will for everyone. Just another option to try before going thru the expense of rotor replacements or turning them.

Additional thanks to AGRO1 for passing along the Pagid Link.
kdurg is offline  
Old 12-27-2004, 05:33 PM
  #14  
DamonsCarrera
Addict
Rennlist Member
 
DamonsCarrera's Avatar
 
Join Date: Feb 2003
Location: West Chicago IL
Posts: 114
Default

Anybody know of a good shop to blanchard grind rotors in the Long Beach CA area?

-Damon
'94 325i
'95 993
DamonsCarrera is offline  
 


Thread Tools
Search this Thread

Contact Us - About Us - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: