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> Let's Talk Track Brakes
jdogg
post Aug 10 2007, 08:09 AM
Post #1


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Joined: 28-January 03
From: Youngsville, NC
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OK, so I've had my car for almost 6 years now, and it has been through a LOT of changes over those years...It started as a stock class 2.0 AXer, then to street prepared, the to SM2 with the addition of the -6. I had done a smattering of track events over those years, primarily focusing on AX, but last fall the track bug bit and bit hard!! I've done about 8 of 'em since October last year, and just can't get enough.
But this brings me to my question(s)/issues. As my driving is improving, I find I am being much harder on the car (a good thing), but some issues are coming to light, most notably the brakes.
I have the much hyped 914club billet hubs on my car, utilizing M calipers, SC vented (not cross drilled) rotors, Carbotech XP10 racing pads, brand new 19mm MC, etc. The brakes work very well...once the pads get some heat in them they will stick your eyeballs to the windshield with no fade issues. The issue I am having with this set up is the pedal softening and the travel growing after a couple sessions. At first I suspected the MC, so I replaced it...then after bleeding the system and leaving it under pressure with my power bleeder, I noticed some fluid seepage around the RF caliper. The calipers were rebuilt last fall and have about 8 track weekends on them, but I went and got a new rebuild kit and rebuilt it. I thought that maybe that was a potential source of air and a possible reason for the pedal travel issues.
I spent the past weekend at Carolina Motorsports Park (CMP) in lovely east bumfuck middle of nowhere no cell service one stoplight Kershaw, SC. A very challenging layout, tight and technical, and very hard on equipment with a lot of hard braking zones, so I figured it was the perfect venue to test out my brand new MC and freshly rebuilt caliper and see if I could keep a pedal all day long. After session 2 on Saturday the pedal travel had indeed moved again. So I bled the brakes (heel and toe with a low brake pedal is nearly impossible) and the pedal came right back where it needed to be. I resigned myself to the fact that I was just going to have to bleed 'em every two sessions. Well, it was successful, uneventful rest of the weekend with plenty of bleeding (although it was hot, really fucking hot...103 on Sunday with lots of humidity). Fast forward to Monday night when I go to unload the car from the trailer....no brakes!!! WTF?!?!
Seem I have blown the left front caliper out now too, and this one leaked fluid all over the damn place....

So does everyone need to bleed their brakes that often to keep a firm - high pedal? Is rebuilding calipers every 2 or 3 events whether they need it or not going to need to become a regular maintenance item? Is there a better way?
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jdogg   Let's Talk Track Brakes   Aug 10 2007, 08:09 AM
914forme   Not an issue I am aware of, you got other issues, ...   Aug 10 2007, 08:58 AM
drew365   I have a similar brake setup to yours. Yes a soft ...   Aug 10 2007, 09:09 AM
ptb   What brake fluid are you using and do you have any...   Aug 10 2007, 10:12 AM
Dave_Darling   I think you mean SRF? There is a recent discussio...   Aug 10 2007, 10:44 AM
jhadler   You mention a lot of the setup you have, but nothi...   Aug 10 2007, 11:03 AM
jdogg   Ok, the question of brake fluid has come up severa...   Aug 10 2007, 11:33 AM
jhadler   ATE is good, Motul is better, SRF is great. Brake...   Aug 10 2007, 11:45 AM
mudfoot76   +2 on switching to Motul and adding brake ducts. ...   Aug 10 2007, 12:01 PM
jdogg   Thanks for all the great input and suggestions...   Aug 10 2007, 01:13 PM
jhadler   CMP is VERY tough on brakes, any deficiencies you...   Aug 10 2007, 01:22 PM
914forme   SS Shims, and add some heat sync coumpund to them ...   Aug 10 2007, 01:50 PM
jhadler   SS Shims, and add some heat sync coumpund to them...   Aug 10 2007, 02:23 PM
914forme   Yes I did say that wrong. Unless he is the compit...   Aug 12 2007, 08:46 AM
Eric_Shea   Might want to look for the late model pistons (dis...   Aug 12 2007, 09:35 PM
jdogg   Might want to look for the late model pistons (di...   Aug 13 2007, 07:16 AM
Eric_Shea   Late model M-Caliper pistons (kinda harder to find...   Aug 13 2007, 09:24 AM
davep   Cryo'd rotors would be a good idea. The rotor ...   Aug 13 2007, 11:31 AM
alpha434   You can buy titanium sheet in 99% pure form and ma...   Aug 13 2007, 02:54 PM
alpha434   I've been doing the water cooled brakes for a ...   Aug 13 2007, 03:10 PM
jdogg   One thing I've noticed that hasn't been t...   Aug 13 2007, 07:49 PM
davep   I think 2mm would get you into the bores for the b...   Aug 13 2007, 08:02 PM
Eric_Shea   Maybe it's a Midwest thing. Maybe I'm t...   Aug 13 2007, 08:15 PM
jdogg   Thanks, guys! I have a plan!   Aug 14 2007, 07:18 AM
Eddie914   Are you overheating the front brakes or the rear b...   Sep 1 2007, 11:57 PM
davep   Using an IR gun is okay as long as you treat the v...   Sep 2 2007, 07:44 AM
Brando   I second the motion for more cooling - on all 4 wh...   Sep 2 2007, 12:55 PM
Eddie914   Here is a nice setup for rear brake cooling ducts....   Sep 2 2007, 02:01 PM
914forme   Nice setup for a 944, 911, VW beatle, Thing, or Gh...   Sep 3 2007, 08:19 AM
alpha434   BBS still sells wheel fans, I know of no other com...   Sep 5 2007, 10:15 PM
914forme   Yep, I have seen 80s vettes use Corvair fans in th...   Sep 7 2007, 08:26 AM
jdogg   OK...quick update..I had the rotors cut down at th...   Sep 9 2007, 07:58 PM
race914   You want to cool the rotors. Several vendors offe...   Sep 9 2007, 09:32 PM
Eric_Shea   Glad to help! ;) For your situation... go wit...   Sep 9 2007, 11:04 PM
jdogg   I am going to rig something up similar to that AJ ...   Sep 10 2007, 09:25 AM
Dan (Almaden Valley)   Ran 2 days at Laguna Seca this weekend and had abs...   Sep 10 2007, 10:39 AM
Joe Ricard   I had a lapping day with an LE air dam. no proble...   Sep 10 2007, 11:34 AM
Dan (Almaden Valley)   I had a lapping day with an LE air dam. no probl...   Sep 10 2007, 08:21 PM
jhadler   yes, on my 2.7L RS motored 914-6 I had a GT style...   Sep 10 2007, 10:53 PM
Dan (Almaden Valley)   yes, on my 2.7L RS motored 914-6 I had a GT styl...   Sep 10 2007, 11:07 PM
grantsfo   I use SC rotors with BMW 320 i calipers in front a...   Sep 11 2007, 12:48 AM
914forme   Th AJ pieces will work wonders up front, the rears...   Sep 11 2007, 10:27 AM
jdogg   Th AJ pieces will work wonders up front, the rear...   Sep 11 2007, 07:17 PM
914forme   I would NACA the rocker with a screen.   Sep 13 2007, 04:20 PM
jdogg   Update....I finished the brake ducting last night....   Sep 20 2007, 07:20 AM
jdogg   Going to VIR this weekend to test it all out.. Sat...   Sep 20 2007, 07:31 AM
Eric_Shea   Get screens on there... you will pickup marbles. ...   Sep 20 2007, 08:51 AM
jdogg   Get screens on there... you will pickup marbles. ...   Sep 20 2007, 09:27 AM
Joe Ricard   I've been thinking about this a lot. I am fai...   Sep 20 2007, 03:08 PM
jdogg   Joe- I looked at running it above the arm as well...   Sep 20 2007, 04:09 PM
Joe Ricard   I also was running into problems with my splitter/...   Sep 20 2007, 04:18 PM
race914   Some relevant pics from the 'turbo build' ...   Sep 20 2007, 05:31 PM
jdogg   OK...A successful weekend! No cooked calipers,...   Sep 25 2007, 07:17 AM
stownsen914   Is there any way to limit that knock back? Are...   Sep 25 2007, 09:02 AM
jdogg   Is there any way to limit that knock back? Ar...   Sep 25 2007, 11:07 AM
jdogg   Oh, and I met one of our members this weekend too,...   Sep 25 2007, 02:36 PM
davep   Well, the outer rear adjuster is locked, so it can...   Sep 29 2007, 09:53 PM
Eric_Shea   The knock back mechanism was designed to knock t...   Oct 13 2007, 03:43 PM


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