 Soft brakes / 1 hot rear, ??? autox tomorrow.. help! |
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| yarin |
 Mar 31 2007, 03:04 PM
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#1
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'14-X'in FOOL  Group: Members Posts: 988 Joined: 13-May 03 From: Guttenberg, NJ Member No.: 693 Region Association: North East States  |
HEy Guys,
I just took my car out for the first time since last november. So far so good, except the brake pedal feels VERY soft. I bled the system properly and tried my best to adjust the rear brakes. I think this is where my issue is. After short easy drive the right rear was pretty damn hot, it's dragging. But when spinning the wheel by hand it reaches a certain point and requires excess force to spin it. I noticed this when I first installed the brakes (Porterfield R4S and standard rotors). The I removed the rotor and sanded down the mating surface. The gap between the inner rotor and the hub looks consistent. Before I did the brakes I remember there was a slight vibration from the rear. Could the hub be the problem? I'm going to readjust the rear right caliper spacing and try again. Any ideas? So two issues: 1) very spongy brakes 2) dragging right rear Thanks |
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| Allan |
Mar 31 2007, 03:15 PM
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#2
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Teenerless Weenie Group: Members Posts: 8,373 Joined: 5-July 04 From: Western Mesopotamia Member No.: 2,304 Region Association: Southern California |
You might want to pull the disc and make sure there is absolutely nothing between it and the hub. I had the same thing happen once and found a very small clump of grease with some dirt in it. Cleaned the hub and inside of disc with some emery cloth and brake cleaner and all was well.
I hope yours is as easy to fix. |
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| john rogers |
Mar 31 2007, 03:17 PM
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#3
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Senior Member Group: Members Posts: 1,525 Joined: 4-March 03 From: Chula Vista CA Member No.: 391 |
For the soft pedal, you have air in the system. Try to find a pressure bleeder which will get it all out easily. If you have a prop valve it is probably too late to replace it with a tee but get rid of it as soon as possible as that is probably where the air is. A further possibility is that if your flex lines are original they are failing and need replacement as they can cause a spongy pedal. For the rear, the vent clearance should be 50% of what the book calls for. The stock setting is too large for good pedal feel. You can tell if the rear bearings are too worn just by shaking the wheel with the car jacked up, there should be no play. Try to find a dial indicator and check for warped rotor(s) since the wheel turns free and then hangs I would guess a warped rotor probably.
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| yarin |
Mar 31 2007, 03:21 PM
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#4
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'14-X'in FOOL Group: Members Posts: 988 Joined: 13-May 03 From: Guttenberg, NJ Member No.: 693 Region Association: North East States |
QUOTE(john rogers @ Mar 31 2007, 05:17 PM)  For the soft pedal, you have air in the system. Try to find a pressure bleeder which will get it all out easily. If you have a prop valve it is probably too late to replace it with a tee but get rid of it as soon as possible as that is probably where the air is. A further possibility is that if your flex lines are original they are failing and need replacement as they can cause a spongy pedal. For the rear, the vent clearance should be 50% of what the book calls for. The stock setting is too large for good pedal feel. You can tell if the rear bearings are too worn just by shaking the wheel with the car jacked up, there should be no play. Try to find a dial indicator and check for warped rotor(s) since the wheel turns free and then hangs I would guess a warped rotor probably. I can't imagine how i could have air in the system. I changed the brake hardware then bled the system with a speed bleeder. The pedal was rock solid before. SS lines all around. I'll pull the rotor off once it cools and check again. |
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| SirAndy |
Mar 31 2007, 04:29 PM
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#5
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Resident German Group: Admin Posts: 41,640 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(yarin @ Mar 31 2007, 01:04 PM) Any ideas? So two issues: 1) very spongy brakes 2) dragging right rear same issue. sticky caliper gets the brake really hot, brake fluid boils, you got bubbles in your braking system, makes for spongy pedal ... that, or you didn't bleed it right before the winter ... (IMG:style_emoticons/default/bye1.gif) Andy |
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| yarin |
Mar 31 2007, 07:27 PM
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#6
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'14-X'in FOOL Group: Members Posts: 988 Joined: 13-May 03 From: Guttenberg, NJ Member No.: 693 Region Association: North East States |
QUOTE(SirAndy @ Mar 31 2007, 06:29 PM) QUOTE(yarin @ Mar 31 2007, 01:04 PM) Any ideas? So two issues: 1) very spongy brakes 2) dragging right rear same issue. sticky caliper gets the brake really hot, brake fluid boils, you got bubbles in your braking system, makes for spongy pedal ... that, or you didn't bleed it right before the winter ... (IMG:style_emoticons/default/bye1.gif) Andy The brakes still seem a little spongy temperature doesnt change that, i haven't tried to lock them up yet. The rear right still gets hotter than the others... hmmm |
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| John |
Mar 31 2007, 07:30 PM
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#7
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member? what's a member? Group: Members Posts: 3,393 Joined: 30-January 04 From: Evansville, IN (SIRPCA) Member No.: 1,615 Region Association: None |
QUOTE(yarin @ Mar 31 2007, 05:27 PM) QUOTE(SirAndy @ Mar 31 2007, 06:29 PM) QUOTE(yarin @ Mar 31 2007, 01:04 PM) Any ideas? So two issues: 1) very spongy brakes 2) dragging right rear same issue. sticky caliper gets the brake really hot, brake fluid boils, you got bubbles in your braking system, makes for spongy pedal ... that, or you didn't bleed it right before the winter ... (IMG:style_emoticons/default/bye1.gif) Andy The brakes still seem a little spongy temperature doesnt change that, i haven't tried to lock them up yet. The rear right still gets hotter than the others... hmmm Time to rebuild the rears. |
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| SirAndy |
Mar 31 2007, 07:37 PM
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#8
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Resident German Group: Admin Posts: 41,640 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(yarin @ Mar 31 2007, 05:27 PM) The brakes still seem a little spongy temperature doesnt change that, i haven't tried to lock them up yet. The rear right still gets hotter than the others... once the fluid has boiled, the bubbles stay in the system, even after the system cools down again. i'd bleed again and see if that makes a difference ... (IMG:style_emoticons/default/bye1.gif) Andy |
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| Eric_Shea |
Apr 1 2007, 01:04 PM
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#9
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PMB Performance Group: Admin Posts: 19,275 Joined: 3-September 03 From: Salt Lake City, UT Member No.: 1,110 Region Association: Rocky Mountains  |
Yarin,
Do you have a gauge to check the runout? Check it on the rotor, then check the hub. My money would be on a bad rotor. Brakes... air in the system. Drive it hard then bleed again. My recommendation: Pre-Autocross - Reset your venting clearance on the high spot of the rotor. Post-Autocross - Get your rotor issue resolved. Rebleed the system. The autox should have enough braking to free up some air that may be trapped in the proportioning valve. |
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| yarin |
Apr 1 2007, 03:11 PM
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#10
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'14-X'in FOOL Group: Members Posts: 988 Joined: 13-May 03 From: Guttenberg, NJ Member No.: 693 Region Association: North East States |
QUOTE(Eric_Shea @ Apr 1 2007, 03:04 PM) Yarin, Do you have a gauge to check the runout? Check it on the rotor, then check the hub. My money would be on a bad rotor. Brakes... air in the system. Drive it hard then bleed again. My recommendation: Pre-Autocross - Reset your venting clearance on the high spot of the rotor. Post-Autocross - Get your rotor issue resolved. Rebleed the system. The autox should have enough braking to free up some air that may be trapped in the proportioning valve. I re-bled the rear right, saw a few bubbles come out. I reset the venting clearance on the high spot of the rotor. Took it for a drive and noticed the right rear didn't heat up as much. I decided not to autox today, temps are in the high 40s with a chance of rain. I tried getting a little aggressive with the brakes a few times and noticed the right rear would lockup really really early. In addition the car would pull badly to the right.. I'm going to take it out again with my brother and check it out. (IMG:style_emoticons/default/sad.gif) Ok, I took the car out again and really heated up the brakes... initially the right rear would lockup prematurely. After a few power stops the brakes started to smell a bit and lockup normally. The fronts lockup first, the car stops really well. I'm impressed! R4-S pads do the trick. No longer pulls to the right either. So after all of this, i'm going to say that my brakes are now functioning OK. The only issue is a slight uneven rotor rotation of the right rear. After breaking the pads in things seem to have settled. U guys think i'm OK? |
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