Shadetreemech

The evidence you have is the brakes were 'fading', the LF caliper was observed to be hot, when the brakes cooled the 'fade' was gone. This indicates the fluid reached its boiling point, became compressible then cooled and became incomprehensible again. The question is what generated the heat. The torque used for the bolts didn't. The most common culprit is a caliper piston is sticking in the caliper and constantly creating friction/heat. It can be a swollen flex line, it could even be trash in the hard lines. 50 years ago I was taught to open the bleeder valve completely before you push the piston back in the caliper. When you do this it takes a lot less force and pushes the dirty fluid out of the system. Be very careful how you push the piston back. I use a c-clamp on the back of the caliper and an old pad on the piston to compress it. This avoids any force that could egg the caliper casting. I've had many cars go to 200k miles with many pad replacements and never have replaced a caliper. You don't say how you compressed the piston. Maybe the caliper got egg shaped? Maybe trash was forced between the caliper and the piston? The fluid needs to be replaced any way. You might try flushing the fluid and exercising the piston while you are at it. But I suspect it is the caliper.

9KCanuck

Thanks for the info, Shadetreemech. Yes, you summarized the situation exactly right.

To compress the cylinder, I used a specific tool for this purpose kind of like the c clamp idea, and using an old pad against the cylinder. It compressed easily, for what it's worth, and I'm sure that I didn't damage the caliper doing this.

When I bleed the system, I'll do as you suggest -- with the bleeder valve open, compress the piston and hopefully flush out the fluid in the cylinder. I suppose that with a normal bleeding process, that old stuff won't necessarily come out.

Shadetreemech

Well......I wasn't much help. My bet would still be the caliper dragging for some reason though.

Car Analogy

First thing done wrong, pushing fluid backwards through system. ABS system doesn't like that. At all. You're supposed to loosen bleeders first, so compressing caliper all the fluid goes out bleeder.

But doubtful that is your issue.

My guess is you lubed the slide pins, and used too much lube, so its hydrolocking pin, caliper effectively frozen. Same as if bad, nasty rusted slide pin.

cosmomiller

All good advice, I will only point out that you need to be careful and thorough in cleaning up the spilled fluid in the engine bay. It does more than ruin paint. I will cause the failure of every hose it touches. Always clean that brake fluid immediately if it happens.

9KCanuck

Yes, sir! Thanks for the advice. I doused the area pretty well with some cups of soapy water from the track bathroom

engifineer

And I keep a big bottle of soapy water in my shop now partially for this reason (also good for finding leaks in my mower tires!). I had my Motive bleeder connected and pressurized to flush fluid recently. I have had that bleeder for I think about 12+ years now. Right as I sat on the stool to start bleeding one corner, I heard a pop and looked up to see the bleeder pissing fluid about 15 feet across the shop where the hose failed on it. Ran over, depressurized it and then used my bottle of soapy water to douse any areas on the car where fluid managed to land. What a mess lol. But good to have some nearby when messing with brake fluid. My shop is about 300 feet away from my house and down a large hill so saved me from rushing back up there to grab something.

9KCanuck

UPDATE


After that previous track day, I did the following:
- inspect all 4 brakes as best I could -- no obvious problems
- regrease slider pins on all 4 brakes
- ensure all bolts torqued properly
- push one litre of Motul RBF 600 through the system -- front left brake had lots of bubbles
- go for a drive and engage ABS a few times, then overnight with brakes slightly engaged to release air from ABS lines

With all that done, the brakes felt great. Although that's just street driving, and honestly they felt totally fine on the street previously as well.

Now *another* track day arrives and I'm about 50/50 that things will be any better. But I don't know any other way to be sure the brakes will be fine on the track without driving it on the track.

Sadly, after a couple hard laps, the same thing happens -- front left gets very hot and I can't brake well enough to keep up a decent pace (I would be holding up my group if I drove to what the brakes would currently allow). In the paddock, that one caliper is smoking again, as before. All other brakes OK though.

Some very smart and helpful Honda and S2000 friends gave me some things to try (and emotional support): check wheel bearing and check for binding (caliper locked up after another few laps?). So I did *another* session, this time with a slower group, and the brakes were totally fine. BUT, once the traffic allowed and I could push harder, the same thing happened... so back to the paddock I go. I got the wheel in the air right away and confirmed no play in the bearing, and the wheel itself spun freely. So can probably rule out the bearing or a locked-up caliper.

However, after this last session, all 4 calipers were smoking. Not a lot, but some from all of them. Those same Honda friends suggested that maybe it's the rotors that are the culprit, and not simply an issue with that left front brake -- that one just fails first for whatever reason. These are 4 year old rotors and have been on the car for maybe 15 track days and all my street driving since I don't have other rotors to swap in/out.

Hopefully it's as simple as that -- the rotors are no longer adequate for track duty. As I've said before, these rotors + these pads + RBF 600 have seen many many full sessions of me driving as fast as I can. Never once were the brakes an issue until that previous day and this last one.

Next year I'll get some inexpensive blanks and proper track pads and that setup will be strictly for the track. My old rotors are fine for the street, so probably just keep them on and use with my OEM pads.


** TL;DR ** -- almost certainly my issue is that the ROTORS are done, and my lack of knowledge meant that it took me 2 somewhat wasted track days to realize this.

B serious

When you say "can't brake well enough", what does that mean? Soft pedal? Or Wooden pedal?

engifineer

Another quick question.... do you happen to left foot brake on track?