Need clutch help please

[Power Surge]

Ok, here's the deal... Drove the car around all day yesterday, performed flawless. As I was heading back to the shop to put the car away, I noticed all of a sudden that the pedal had some "play" in it, where there was no resistance for about the first 2 inches of travel. Once I got back to the shop, I couldn't put the trans in gear with the car running. Obviously, there was no longer enough throw to fully disengage it.

I checked the car this morning for leaks on the slave setup and found none. The clutch fork isn't loose either. Just seems as if all off a sudden I lost part of my slave cylinder throw.

Attached is a pic of the bar in the footbox. I didn't build the car, so I don't even know if it's setup right. But I do know it worked, and now something changed.

Any ideas on what it could be, or what I can check? Should I bleed the system out, and if so, what's the proper procedure for that?

[xlr8or]

If you just lost travel try bleeding the master and slave as you would your brakes.

[undy]

It sure sounds like and air bubble worked itself free..

[TRIG]

Same thing happend to me. I just bled the slave and it worked perfectly.

Trig2275

[Clois Harlan]

Bleed your master cylinder first (have someone pump the clutch a couple times and hold it down while you crack the bleed screw. Then do the same on the slave cylinder. I think you probably have air in your lines. Also, before you start check all your connections to make sure they are all tight and that none of your braided lines have been nicked by a rock or something from the road.

Good luck.


Clois

[Power Surge]

I don't think my master has a bleed screw, but I'll check. Worst case I can bleed by cracking the line to it. But I just vacuum bled all new fluid through the system and it seems the same. Still has the initial play before getting hard, and therefore doesn't have enough throw. What was interesting, is that the fluid that came out had the consistancy of dirty water.

[undy]

Seal, bore or internal M/C check valve failure??

[Power Surge]

Originally Posted by undy

Seal, bore or internal M/C check valve failure??

That's what I am thinking right now. The master moves a good 1.5-2 inches but the slave only moves like a half inch.

[Power Surge]

Ok, I'm pretty certain it's the master. I tried to bleed it out with no change. I think the first part of the bore is probably pitted up and bypassing fluid or something like that.

Does anyone know where to get one of these things? It's an AFCO part, and it's 3/4 bore. Other than that, that's all I know.

[Buzz]

Sal, what type of fluid did you run through the system? Some types (DOT 5, I think) are not compatible with the seals in some of our master and slave cylinders. The "dirty water" sounds like soot or black rubber residue from a chewed up seal. Some of the more learned guys might chime in with more accurate info.

[kris-kincaid]

I called Afco last week about master cylinders and they no longer make the kind like you have on your car. Wilwood makes one that'll work.

[Power Surge]

Originally Posted by kris-kincaid

I called Afco last week about master cylinders and they no longer make the kind like you have on your car. Wilwood makes one that'll work.

This the one Kris?....

http://www.wilwood.com/Products/006-...RRMC/index.asp

[lineslinger]

This probably isn't the answer you want to hear but unless you can see and feel the inside of both the slave and master cylinder it is going to be tough to tell which one, if not both, are causing the problem.
I had the same problem on an austin healy, after putting new seals in both the slave and master clylinder I still had a spongy clutch that kept getting worse.
I ended up sleeving both the slave and master cylinder after finding some very light scoring on the sleeve walls of both cylinders.
Never had a problem again after that.
My point is if I would have rebuilt both of them the first time I would have saved myself a lot of time and "creative language" in the long run.
Good luck

[Power Surge]

Well, the slave is definitely bad. Pulled the boot and fluid poured out. But I found a source for the AFCO masters, so I have one of each coming and will just change both. Cheap insurance.

[undy]

It sounds like Mr. Hygroscopic was not your friend Sal...

[Power Surge]

Looks like I'm not out of the water yet....

Pulled the slave apart yesterday, and sure enough, the seal was split in half. The bore was pretty corroded up too. Picked up a new one this morning and put it in. Bled the system out, and it's exactly the same, just with no leaks. So looks like the master is bad too. Might have got hyperextended or something when the slave seal split.

So yesterday when I thought the master was bad, I called Billy at HRE to see where to get a new one. He said I any speed shop will have one, I just need a 3/4 bore Afco torpedo. So I call Afco to see if I can get it direct, or get a close distributor. The guy there says "call Capitol Speed in MA, they stock them". Ok, great. I give them a call, and tell them I need a 3/4 bore Afco torpedo master. After the slave didn't solve the problem, I go get the box from Capitol speed which had just arrived from UPS. Open it up... it's a 7/8 bore standard style with built in resiviour. Wonderful. Call up the Capitol Speed and I'm told they never stocked or sold the 3/4 torpedo.

So now I am back to needing a master. At least I know the slave is new now, and the old slave WAS bad. But I still am not getting enough throw action to release the clutch. I adjusted the slave to fork rod to preload the fork a little to move me closer to the release point, but that's not healthy for the car, so it's just so I can still move it around.

Guess I'll have to get the Wilwood version? Also, could I go up to a 7/8 bore, or should I stick with the 3/4?

[undy]

The 7/8" piston M/C will give you a slightly longer stroke on your clutch actuating rod at the expense of a slight increase in required pedal effort. I run a 1" cylinder on my master cylinder. Personally I'd rather have a longer stroke and give up a little more pedal effort as a trade off. You'll be fine with the 7/8" M/C..

BTW... If you can hang with a 03/04 OEM Cobra clutch then nothing a hydraulic Cobra clutch can muster will slow ya down...

Dave

[ByronRACE]

Sal,

I used Tilton master cylinders on mine after talking to a bunch of racers that had problems with other brands. They are available in a bunch of bore sizes and reservoir options as well...and come with all of the reservoirs in the kit. I don't know if they'll fit for you, but I'm happy with mine...all 3 of them.

One of the guys I spoke with used a composite master cylinder and had the thing blow in half at the knit line on his brakes...hit the wall. After that story, I was rather turned off by the composites.

As far as bore size, I can't say for your car. In my case, a 3/4 is barely enough to disengage the clutch. I'm using an internal throwout bearing type slave...valving is probably different. I tried using a 5/8" bore to make the pedal effort real easy; it didn't move enough fluid. 7/8 would make the pedal effort even harder than the 3/4 and would cause the slave to throw further.

I'd also make sure you're not exceeding the travel limit on the master or the slave. In my case, I had to build a custom stop for the master to avoid throwing the slave too far...which can damage it. This might apply to you as well, I'm not sure.

[Mike Bartlett]

Sal,
I have gone through 2 master cylinders and one slave and it still isn't right. When I rebuilt my master the 2nd time, the 1st time I got a brand new master form SAI, I noticed the internl spring was bent about 45 deg. My theory now is that the rod going from the pedal to the master is too long and when I push in the pedal I am jamming the internal piston return spring so far down in the bore that it is bending it. Then the spring pushes the piston back up the bore at an angle and wears it out. Both times I have rebuilt mine the fluid had tiny aluminum particles in it and you could see one side of the internal piston had been rubbing the bore.

Another thing I noticed was that when I received my new master from SAI the rod, pedal to cylinder, was shorter then my original. At the time I couln't seem to get the shorter rod to disengage the clutch properly but now I am thinking maybe I should have tried harder. I may not have bled it entirely?

Mike

[Excaliber]

My slave went out, I bought a new one exact replacement, piece of cake right?

While bleeding the brand new slave I over tightened the air bleed screw and ruined the 'seat'. Fluid shot out all around the bleeder valve. Go gently on those tiny little bleeder valves, new or old!