mojorizing

Doesn't that plastic collar look like it once was a teflon back-up ring or anti- extrusion ring?



It prevents the oring from extruding out between the groove of the piston and the cylinder due to high fluid pressures. Those are available at a seal supplier. They're installed by soaking the in hot water and stretching over the piston.

garrett376

If it was a backup ring, shouldn't it be on the sides of the o-ring, not on the sealing surface? Our ring is actually on the sealing surface of the cylinder bore. The middle blue ring is odd because it even appears to have bumps in it along its surface.

Kenny - how did you figure your blue part of the middle seal was leaking? Was it broken also?

Yep - I have the other C4's but I don't feel like crawling under there - my back has been way too sore these past couple weeks!

kgorman

Yes, in my case that blue inner ring was mangled and obvious. I wish I took a picture of it.

garrett376

The lateral slave the same setup seal-wise; it just has a larger plunger that attaches to the piston and longer spring for more travel.

I've got two "sample" o-rings that I should receive sometime next week and I'll rebuild both of these and test them out. If they work, then we've found ourselves a fix!!!!

tgage

Garrett,
How did this work out for you... I see you moved on to "coils"...

I need to replace my slave cylinder... or start with the end of this thread...

Thanks,
tom

garrett376

I just called to check on the samples this guy told me he would put in the mail about 1.5 months ago and then again 3 weeks ago... well this other guy at this place says they don't send samples. Hmmm, I wonder what this guy was thinking? So now I am looking to find a different o-ring source. An 11mm x 1.8mm is the replacement size for the o-ring... and it needs to be made of EPDM...

DAVISRILEY

Garrett, any luck? I think my forward one is starting to leak and would love to rebuild instead of replace. Thanks.

kgorman

Boom! I blew another today at TH.

I think the MTTF for these units is about 10 track days for me. I am going to start budgeting it in. I have a spare I built up, so luckily I can just swap this one out and re-bleed, but for the next one I am going to need some seals!

Low speed corners tend to eat it alive I suspect. I am guessing it just overheats and the seal fails. Temperature is a factor, I am wondering how we spec a seal with the proper thermal requirements...

amr89c4

Not to make matters worse, but did you find the missing pieces of the seals?

amr89c4

In some of our high pressure hydraulic trim systems, there are seals that are built the way these seem to be "cut". Notice that both rings are cut at exactly the same place and the ends are cut with the same "angles".

The gaps are not as great on our trim units, but I wonder if these gaps have some interface with the center seal ring to cause a "shuttle valve" effect?

Makes me wonder, especially if you did not find the broken pieces. Just a thought , guys.

kgorman

I have not torn it down yet, but if it was like the last one, the two 'split' rings will be OK, it's the center ring that essentially melted.

Wachuko

+1

Do let us know please.

garrett376

Hi Guys - this project went on the back-burner since I had a spare and have been running it with no issues since. Plus the guys who were supposedly sending me samples never followed through, and part way through this process decided they will no longer send samples, and that I had to spend $100 minimum for $0.10 o-rings! But I now have some time and will re-investigate what will work since it is quite a simple system that should be completely repairable with the correct o-ring (with or without using the blue collar).

Kenny - take some pics of your dead slave if possible; I am interested as to what melts - the o-ring, or the blue seal.

kgorman

Will do. Planned for this weekend once I get back home.

kgorman

Ok, here are the pics below. Notice how there seemed to be an event where the thing blew apart. The washer is cupped the split ring is broken in half. The seals look like they just turned to mush. Perhaps the seals went, then this cause the rest to blow apart.

I have a rebuilt cylinder I am going to put back into the car, and see how it works. I will need new seals to fix this one up.