Zetec and Caterham 6-speed hydraulic release bearing (slave cylinder)

[Pokey]

Long story short, hydraulic fluid dumped from the slave onto the bottom of the bell housing.  We replaced the slave, bled, and the same thing happened.  The original slave's manufacturer is unknown, but the replacement was a Perfection Clutch 360062.  The two look identical down to the first four digits of the number stenciled on the casting as shown in the picture below.  The release bearing touches the clutch's fingers but does not look to be depressing them.  When the clutch pedal is operated the release bearing does not move.

 

That's the facts, now comes the random thoughts:

 

• I took the clutch off to inspect, and while it seems unlikely I installed the clutch disc backwards, and unlikely that I could have cinched down the pressure plate had I done so, and it isn't clear how doing so would cause the fingers to become unmovable, if the fingers were stuck in position then what could have happened is the slave cylinder seals failed as the hydraulic fluid had to go somewhere.  Note that this thought does not explain why the original slave failed in seemingly the same manner.

 

• The clutch pedal does not have a stop, or more precisely the stop appears to be the bulkhead, which over the yeas has deformed outward by a centimeter or more.  Assuming the master cylinder can move more hydraulic fluid than the slave can accommodate, and that the pedal-induced bulkhead bulging allows more pedal movement and hence more fluid leaving the master, then, again, the slave cylinder's seals would suffer as a result.  This would also explain why the original slave failed, but it also requires that while bleeding the clutch I pressed down to where the pedal pushed on the bulkhead.  I can't say that I did or did not as I wasn't paying attention.

 

• Operating the pedal now using only half of the pedal stroke still results in hydraulic fluid transfer onto the floor of the bell housing, so that either means the clutch fingers are immovable or the slave's seals are so utterly destroyed that the resulting pressure isn't enough to move release bearing against the fingers.

 

Anyone every experience anything like this?  And those with a Zetec/6-speed setup, do you happen to know what slave you have installed?

 

 

[MV8]

There are several ways for this to have failed. I suggest correcting the pedal travel with a pedal travel stop, buy another HRB, and carefully follow maintenance practices.

The hydraulic release bearing assy (HRB) has a maximum travel stop. There is a coil spring inside the green boot/gaiter that keeps the assy fully extended until installed which compresses the assy.

The installed length of the HRB must be short enough that one full stroke of the pedal will not extend the HRB beyond the fully extended length. Some things that will cause the HRB to extend further than normal include turning the flywheel for a new wear face, extra pedal travel(master stroke), a larger bore master, or engine thrust bearing wear.

The HRB should be bled while still accessible. DO NOT use the clutch pedal to bleed the system when the trans and engine are not fully bolted together. Use the HRB as the pump by squeezing it to remove the air. If you use the pedal/master and the HRB is extended, it will likely fail immediately or at least leak. There are other ways to do it but this is safer.

[Pokey]

Thanks @MV8.  Sounds like you agree that the pedal stroke increasing could account for the failure then?

 

BTW, I bled using suction from the slave’s bleed screw after assembly.

[CarlB]

There are two different HRBs that are very similar. The difference is in the length. I have a LUK LSC-273 that is for a V-6 Ford Contour. My car has a Zetec with a T-9. Here is part of an old thread.  

 

Go to the thread because there are pictures. When I was trying to figure out what the parts were for my car, I was able to get in contact with someone at LUK and he identified my parts and gave me the part numbers. That worked for me. It was later that I saw this post.

 

[Pokey]

Thanks @CarlB, same here, I didn't use a LUK-273 but the equivalent.  I've installed a pedal stop and a new slave cylinder and all seems to be working as it should.

[MV8]

On 4/21/2024 at 8:49 PM, Pokey said:

Thanks @MV8.  Sounds like you agree that the pedal stroke increasing could account for the failure then?

 

BTW, I bled using suction from the slave’s bleed screw after assembly.

Sorry I missed your post. I agree that the stroke increase probably contributed. Sounds like you sorted it out. Interesting to hear about the two lengths though.

[Pokey]

For posterity, the combination Zetec with the Caterham 6-speed seems to work with these hydraulic release bearings (slave):

• Ford F5RZ7A508BA, F5RZ7A508BB, 94ZT7A564BA, 94ZT7A564BB
• Sachs SB60093
• Sachs 3182 654 208
• AMS Automotive N1767SA
• LuK 510 0067 770
• LuK LSC273
• Perfection Clutch 360062

I can personally vouch for the Sachs 3182 654 208 and the Perfection Clutch 360062.  The others should work but beware of one possible caveat in differences in the casting where the nipples are located.  I've seen some derivations that look to expect to have the top of the slave protrude out the opening in the bell housing which only works if the slave is aligned with the hole.