Clutch Slave Cylinder - Leaking Again

I received the Centerline clutch slave (fast response time, fast shipping, wow!) today. The only thing different that I noticed from the OEM type trash slave is that the length of the body is about 12mm shorter than the OEM. I could not find the stroke specs for this slave (made by Inter Brakes, Italy), hopefully it is adequate.

I won't have time to install it for a week or so, so stay tuned.

And.... hopefully the bleed screw doesn't need 100 ft lbs torque to seal like the OEM type slave!  And, hopefully, I can cancel my order for a 55 gallon drum of DOT3 fluid, and be done with 2 years of misery on replacing these parts every 5 months.

For $46 bucks you can't go wrong even if it fails to work.  I just bought some DOT 4 and that stuff is now $20 a quart.   I wish CNC were still in business as my slave they made is perfect.  Again, keep us posted on this project.

@Rob Fridenberg did you ever get the Alfa clutch slave cylinder installed?  My Pantera's clutch slave is starting to leak (it's original).  I planned on ordering one from Centerline Alfa as well.  I notice the Alfa version has a ball end vs. the Pantera version having an eyelet end for the pin which connects to the clutch lever arm.  I assume you just unscrewed the ball end rod and replace it with the Pantera's eyelet end rod?   I have an Alfa and have been happy with Centerline's parts.  Thanks, Mike

Hi Mike,

I finally installed it a week or so ago. I just used an old Pantera eyelet end rod - I didn't bother unscrewing the ball end.

I am having a major problem bleeding it though. This is the 3rd cylinder I have installed so I have plenty of experience with bleeding (and have bled multiple brake systems on many different cars over the years). I have tried many different methods and still can not get a hard pedal. If I pump the pedal rapidly a few times, it will build pressure, but temporarily. So somehow there must still be trapped air which compresses with the pumping. I will give it one more shot tomorrow.

If I still have the problem, I am inclined to send it back. I seemed to have picked up a Pantera clutch system curse along the way.

I'm open to any bleeding ideas!! (I do not have a pressure bleeder)

@Rob Fridenberg I just found my old OEM Alfa cylinder and answered my own question : )  Looks like they are simply different pushrods.  Pic attached of my OEM Alfa cylinder.  Still curious how install went for you.  Thanks, Mike

Whoops, crossed reply with you : )  For bleeding the clutch cylinder (and my brakes) I use speedbleeder screws along with a Motive pressure bleeder.   Initially I only used only the speedbleeders on my Pantera and had good results.  When I bought my Alfa 3 years ago I added the Motive pressure bleeder and was really happy with it.  Now the Pantera has speedbleeders and the Motive pressure bleeder for brake and clutch fluid changes.  I highly recommend both.  At a minimum you should get a speedbleeder screw for the clutch slave cylinder to ensure you get all the air out.  A Motive pressure bleeder is about $100 and well worth it for the results you get.  Mike

I use the MityVac vacuum system.  One man operation and pulls a hard vacuum thought the system.   Easy  to use.  

Somethings night right if it will not hold pressure.  One of the pistons is leaking, no?  If you have to pump it to build up pressure?

I also have a Mityvac. It worked great on the brakes (and I think the OEM style crap slaves), but for some reason it draws air around the bleeder threads and won't pull the fluid. The only variable that changed in my system was the slave. It doesn't leak fluid though! So confused right now....

Maybe try a different Mityvac cap.   or change the bleed screw?  sorry for this as this stuff really does suck (no pun intended)

LOL - the mitvac has a good seal to the bleeder end - using a clear vinyl tube. I do like the idea of swapping out the bleeder - I will try that!

I have tried:

-one-man bleeder bottle

-pumping fluid from the slave bleeder to the master - reverse bleeding

-Having my wife squeeze in the car and push the pedal for me while I work the bleeder. No change!

I was always told by some wise mechanics that if you had to pump your brakes, the master cylinder was leaking internally.  Am sure there are some on the forum that can opine on what pumping means.

Make sure that you rotate the slave cylinder so that the bleeder fitting is at the highest point.  

John

@Rob Fridenberg hope you figured out the bleeding issue.  Is the Alfa Romeo slave cylinder you installed working now?

I was looking closer at my extra Alfa Romeo clutch slave cylinder alongside my disassembled original Pantera slave cylinder, and I don't think the Alfa version (https://centerlinealfa.com/cat...ave-cylinder-115-119) mentioned in this thread and other related threads on this forum will work.  The Alfa slave is, as you mentioned earlier, about 12mm, shorter than the Pantera version.  I confirmed with my own measurements (see pics below).  I think the Alfa slave will have too short of a throw to properly operate the clutch.  I've not seen anyone in the past mention actually using the Alfa Slave cylinder in my search of this forum or the email list archives. It would be nice if it does work as they don't seem to have quality issues and are made in Italy vs who know where for the Pantera versions.

Has anyone successfully used the Alfa Romeo Slave with its shorter throw?  Maybe the Pantera slave piston doesn't need the full travel of the longer cylinder?

I just ordered a Pantera "original replacement" version from one of our vendors hoping I get lucky, and it doesn't leak on me shortly after installing. At the same time I may send my original slave cylinder to White Post for a rebuilt with non-iron insert installed.  They have a lifetime guarantee and I could move on to dealing with other parts of the Pantera : )

From the research I did, the Pantera used an Alfa slave cylinder.  It was not a special piece built for DeTomaso.  The specs on the original slave were An OEM Pantera Clutch Slave Cylinder bore measured 1.000 inches (25.4 mm) and had a max stroke 1.625 inches (41.27 mm).  I researched several Alfa part numbers including the Centerline piece but did not call them to investigate actual dimensions of bore and length.  ATE makes a unit that is supposedly correct dimensionally and the Centerline unit is made by someone in Italy.  Again, I never went the final mile to call them and get measurements as my CNC unit works fine.  Not sure the dimensions of what Rob actually got.

Isn't the throw determined by the bore and the volume of fluid the M/C pushes through it?

I still have the soft pedal problem. I will have my wife help me with the 2 person bleed one more time.

I did mention that the cylinder was shorter by about a 1/2 inch, the bore is identical.

I took some video of the clutch pressure plate moving while pumping the pedal (which gives me the hard pedal) and the plate movement seemed similar to older videos I have taken. So, I think it will work, when and if ever I get a hard pedal.

If I do not have success, I will try to return/exchange it. I feel like using a Pantera vendor part is a 5 month solution based on my sample size of 2.

I was speaking to Scott at SACC and he mentioned that his clutch slave is still dry after 18 years - I offered him $1000 for it.....

Hi all. I measured the throw of the Alfa cylinder with the piston installed and it's 1.287 inches (32.69mm) while the Pantera cylinder is about 1.625 inches (41.27) as @panterapatt mentions.  Both the Alfa and Pantera pistons are the same length. (pics below). So, the Alfa version will definitely have less stroke available than the Pantera version.  But, as @Rob Fridenberg mentioned, it still seemed to move the clutch the same amount.  Rob, let us know once you get the hard pedal and then how it works.

Seems to me if this was as simple as just using the shorter Alfa Romeo slave cylinder then the Pantera vendors would not have invested in the longer Pantera aftermarket versions to sell.  They could simply buy/repackage Italian made versions already being produced for Alfas.   

Thanks for this discussion as I'm looking for slave cylinder options going forward since CNC and stainless version seem no longer available.  I do appreciate and like supporting our vendors but sometimes I've found other options when the after-market parts aren't panning out.  Thanks, Mike

That is good info - but troubling. I'm a bit concerned now that I am going down another bad path. However, I also took videos of the arm travel and they do look the same???

Frogmike - can you provide the piston length comparison?

I guess not following the reason for alarm.  If it opens the clutch, then that is all it has to do.  The actual clutch movement is not inches.