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914World.com _ 914World Garage _ Front brake problem?

Posted by: itsa914 Aug 27 2006, 11:04 AM

Question about front brakes. I ran our local AX on the 20th, on my 4th (of 6 runs) when I came in to grid it sounded like I had a rock stuck between the dust cover and rotor. I did the back up hit brake trick a few times and it still made that sound. It was coming from the passenger side front. I quickly jacked up the car and pulled the wheel. I didn't find any stones, I turned the rotor by hand and didn't here any noise. I put the tire back on and continued to race and all was good. On the way home I started to hear the "rubbing sound" sound again, but it would stop if a lightly tap the brakes.

I finally have time today to look at this. With the front wheel on or off it sounds like metal rubbing the rotor when I spin the wheel / rotor. It seems to me that pads are making contact with the rotor, but I need to check the venting clearance. I have never messed with brakes before, what should I be looking for?

I'm heading off to sears to get a fueller (sp) guage, dial caliper and micrometer. A man gotta have tools for the job.

Posted by: Brando Aug 27 2006, 11:08 AM

The venting clearance is only set on the rear brakes for the parking brake. Pull the front pads and inspect them asap.

Posted by: Eric_Shea Aug 27 2006, 11:18 AM

Same exact thing happened to me at Laguna Seca during the 98 Historics.

Wheel bearing.

Now... if it is a brake problem it might be a sticky "knockback" mechanism in that caliper. They are designed to knock the piston back toward the rotor offering a higher pedal feel in return. They have been known to be problematic, even loosing a few races because of front brakes overheating in battle.

If you decide to do a rebuild, either concentrate on cleaning those mechanisms thoroughly (they reside inside your pistons and ride on the pin inside the caliper) or... break them off.

Posted by: Brando Aug 27 2006, 01:29 PM

Another way a wheel bearing issue might present itself is when turning slightly left and/or right, you may hear a whine or grinding/metal-on-metal rubbing. Try going in a straight line and start with very small incremental turning of the wheel. I would try at varying speeds as well.

If you're going to pull the wheel for a bearing replacement, might as well check the pads. I believe headrage a year or so ago had a question about an intermittent grinding/rubbing noise, we found that the pad material separated from the backing. That was a fun afternoon in San Pedro

Posted by: Eric_Shea Aug 28 2006, 04:09 PM

What's the word turd?

Posted by: bd1308 Aug 28 2006, 04:14 PM

Garold, I just got done with a four corner rebuild of my brakes.

Lemme know if you need help, or even a looksy.

b