6G Celicas Forums

Hey everyone,

so in the past... I want to say year, I have gone through '4' master cylinders. the first one was the original(from 97), and I replaced it because it felt like it had a really short throw and was leaking. I replaced it with a cheapo one thinking I would wait till I could get a legit complete Toyota one. then that one started getting this black residue in the reservoir and then completely went within 6 months. so in the mean time I slapped the old one back in and it felt fine. now during this point I have had put in an E153 with a 3sgte ACT heavy duty Pressure plate and a single plate street clutch. so anyway the original one started to develop the same issue with black gunk show up, though this one being old only lasted a few months and I had to rush and get something quick and that was in town...on a Sunday. This one I don't even think lasted a month before I could feel it start to go and it ALSO started with the black crap in the reservoir. the cheap masters blew through their seals. they were just ripped and missing chunks. so I figured this one the gunk in the reservoir. the original one gracefully lost its seal and you can see the wear around it. at this point I had enough time to plan and order a Toyota rebuild for the original.

I could feel a complete difference from the others and the throw was nice. However, having dealt with all of these clutch problems, I sometimes start feeling things that might not even be there. so today I went and checked the master cylinder to see if there was crap in it. and sure enough there was gunk in it.

now I didn't really know how or if I should have cleaned out clutch lines, but I did try to push all of the old fluid out with a little air pressure and clean dot3.

so my questions are
what are the chances its just crap from the lines?
should I be worried?
am I using the right fluid? (Prestone high temp synthetic DOT3 brake fluid)
is the gunk going to cause problems for the seals in the master?
is my clutch causing me to go through masters?

Thanks I have a feeling that I am just so used to the peddle that I am not really able to feel the clutch catch point in the peddle and I am just making things up.

its crap like this that makes me lose interest in cars. I haven't been to a meet almost all year, and I was going to go wash my car today and wax it to go hang out tonight but seeing this just ruined the whole idea of going out.

again Thanks for the potential help,
Kevin

My friend, welcome to my life. Fortunately I've tracked down the causes for this. But first I'll answer your questions:

1. the black residue is tiny shreds of rubber coming from the seals in your master cyclinder. No chance its crap in the lines.

2. Yes you should worry. The master will fail and getting stranded sucks, it happened to me right before a midwest meet.

3. Prestone DOT 3 is indeed the correct fluid.

4. Doesn't matter.

5. Not directly.

So what causes this? A combination of heavy clutch and maxing out the pedal adjustment. A heavy aftermarket clutch will put more stress on the tiny seals inside of the master and slave cylinders just because there's more pressure in the lines than stock. However, this by itself wont kill the master. What will kill it is maxing out the adjustment on your pedal. If you are like me, then you had to adjust the pedal after you installed your new clutch. What's difficult to realize is that if you take it too far you will cause the internal seals to slide past the little hole that leads to the reservoir. So picture a tiny shred of rubber gets cut every time the seals is pushed past the hole. It's like a sharp edge for the seal to get caught on. Over time these cuts ruin the seal and the master fails. The black chunks of rubber in the reservoir are proof of this. If you dont believe me then take apart your master and compare the worn plunger to a new one. You'll see the seals are torn up.

So how do you fix this?

1. The crappy way to fix it is to buy an extended pushrod for the slave cylinder from speedsource.com. This will allow you to relax the pedal adjustment on you master while maintaining the friction point you want.
2. The right way to fix this is to call your clutch manufacturer and find out what step size they recommend for your particular clutch. Then have the flywheel machined with the correct step. A lot of people ignore the importance of step size and think that they will be okay as long as the flywheel gets resurfaced. I learned the hard way when my machine shop put on a step of 5 thou when clutchmasters insisted on a step of 20 thou. And thus I ended up where you are. Anyway once the step is corrected you'll see that the clutch pedal wont have to adjusted as far; and therefore you'll completely avoid having the seals slide past the reservoir hole.

hope this helps

This post has been edited by enderswift: Nov 30, 2013 - 7:21 PM

Oh yea, I should probably mention that I once had a crappy autozone slavecylinder that caused the fluid to turn grey. It turned out that the bore wasn't machined properly and the piston was actually sanding itself down leading to grey fluid. But that doesn't sound like what you have at the moment.

I also have the same issue, Autozone clutch master. I plan on flushing clean fluid through, and I believe the travel length is set appropriately. I read something on the forums here about priming the clutch master before installation, would that make a difference for seal longevity?