Rob, the piston is 3cm for both Pantera and Alfa version. My old Pantera one on left side. @panterapatt agree that if it works then it works. Given some folks go with even longer throw slaves than stock I do wonder if going shorter than stock makes sense. Also if it was a straight swap for an Alfa slave then why has that not been done by anyone yet from what we can tell at this point. Thanks, Mike
It has been done before. Several guys in the San Diego club did this years ago. I would have MEASURED the stock slave before buying the alfa part and made sure it was the same size. There were numerous links I sent on the topic after a day of research pointing to multiple suppliers OTHER than our vendor's Chinese junk part. At this point, I am out on this topic.
FrogMike - Thanks for the piston dimensions!
Panterapatt - thanks for your help/research. Unfortunately, the folks answering the phone at Centerline simply sell parts without having, or willing to obtain, details on the parts. So - I took a $65 gamble. If I can get it bled (hopefully my newer Wilwood master hasn't failed causing the soft pedal) properly, I will verify proper clutch engagement.
@davidnunn posted:Isn't the throw determined by the bore and the volume of fluid the M/C pushes through it?
Yes. The smaller the diameter of the slave (i.e. reducing the slave's diameter), the longer the throw. This also increases pedal effort.
John
Maybe I am missing this, but the length difference appears to be at the top end of the cylinder at the bleed end which is NOT where the piston sits? The mounting bands machined into both cylinders look to be exactly the same. Can you not get 1.6" of piston movement within the "shorter" cylinder?
Guess modern things are built differently. I run a small Girling aluminum master cylinder that bolted on with 5 minutes of filing the 2 bolt holes to match the Pantera. One of my race friends gave it to me and its been in place without trouble since about 1985. I also run a Tilton concentric throwout so no slave, no ungreased linkage and all-Aeroquip stainess steel lines. That's been in place since 1995 but I did have to make my own ZF nose since Tilton's are designed for Dirt-track sprint cars.
For those who forgot, the Pantera clutch is marginal in throwout length to disconnect the engine and tranny when brand new. Wear always makes it less. Stick a feeler gauge down the bellhousing inspection hole to check the amount of disconnect between the clutch plate and flywheel. Have a friend absolutely mat the clutch pedal. You'll be lucky to get 0.020" and thats TOTAL clearance for both sides of the disc! Which means clutch drag when shifting since no one mats the pedal while driving- and when you get clutch drag, guess what takes up the slack?
Right- the ZF synchros! My Tilton's disconnect distance is around 0.080" or 4X stock, last time I checked. It also cost 4X the stock replacements. I'm guessing a synchro replacement could run up to $4000+ today since the synchro is steel running against a steel gear-cone. So when the synchro is worn out, so is the gear. Plus R&R-ing the ZF, shipping etc, etc. Thats why I ALWAYS advocate a longer throw slave than stock, in anodized aluminum or stainless steel to also resist steel pitting. Even if you need to fabricate a new slave bracket. FWIW-
The length difference is also within the cylinder where the piston sits. The Alfa version gives about 1.2 inches of piston travel vs. the 1.6 inches for the Pantera cylinder. I tried to show this in one of my earlier posts with the photos of each. Most of the length of the Pantera version is beyond the bleed end. Yes, the mounting bands line up the same between them.
Heck, it may work, and we'll see when Rob gets the bleeding figured out. I just feel there won't be enough travel if it's only got 1.2 inches to move in/out. Maybe there's an Alfa version with 1.6 inches of travel but I've not seen them yet (I have a 73 Spider).
I was an active San Diego member from 1988 until I moved to Seattle in 2006. Good folks there!
Hope you all have a great Thanksgiving : )
I think that you will find that the travel will be less than 1 inch. Not due to the length of the slave cylinder but due to the amount of fluid available from the master.
Rob and I spoke today regarding the shorter Alfa slave cylinder. In spite of it being shorter, it appears to be working for him once he gets his bleed issue resolved. That said, I did more research on the web and it turns out, best I can tell and confirmed by Rob's measurements of a leaking unit, that the Pantera used a longer slave cylinder than the normal Alfa 105/115 (which is readily available). This longer cylinder was fitted to the Alfa Montreal (70 - 74 with an original ATE part number of 03.2525-1901.3 with is no longer being made by ATE. The longer cylinder has the following dimensions:
Great additional details and research Rob and PanteraPatt! Glad to know I may be able to use the same clutch slave for both my 73 Alfa Spider and 74 Pantera. The Alfa Montreal slave from Classic Alfa is about 50% less than the Pantera version. Classic Alfa is a great aftermarket Alfa source which I've used multiple times. They regularly beat the price and quality of stateside Alfa vendors from my experience. Their shipping from the UK is crazy fast too. I've had Alfa parts come from them in mere days and faster than Alfa parts vendors only 2 states away from me. Thanks for the additional digging into this for the community!
In the spirit of adding more detail/background for this discussion, I was researching the Alfa Bulletin Board forum to learn more about Alfa Montreal owners using the shorter Alfa Spider/GTV clutch slave cylinders when the supply of longer versions dried up from ATE. I found some discussion and warning about using the shorter version and folks tended to refer to a site run by a Montreal enthusiast named Bruce Taylor. From his site, The Alfa Romeo Montreal Website (alfamontreal.info) in the clutch section deep down the page he cautions about some potential issues with the shorter slave cylinder for the Montreal. Not sure if the same issues would apply for the Pantera, but they may, based on Jack’s (Bosswrench) comments in this thread and his recommendation to get as much clutch throw as possible on the Pantera. I pasted the text from Bruce’s Alfa Montreal site where he covers the clutch slave cylinder in detail. Hope it's helpful. Thanks, Mike
“While the clutch slave cylinder (105.64.12.050.00, ATE 03.2525-1901.3) has the same 1-inch (25.4 mm) bore as that fitted to many other Alfa Romeo models, the Montreal version has a longer 76 mm pushrod and a longer cylinder that permits a stroke of 17-19 mm, compared with 11 mm for the version for 4-cylinder cars. The more readily available shorter slave cylinder can (only just) be used as a replacement if it is fitted with a pushrod of length about 70-72 mm. The margin for tolerances is quite small. With a shorter pushrod, the piston will be near to projecting from the cylinder when disengaging a new clutch. With a longer pushrod, the piston may bottom in the cylinder before a used clutch has reached the wear limit.
Replacement clutch slave cylinders with the same length as the original can be supplied by Giorgio Penatti. Classic Alfa can also supply a repro slave cylinder (MN014) of the correct dimensions that is made from aluminium alloy.
Alternatively, the original slave cylinder can be resleeved in brass by brake cylinder specialists such as Sierra Speciality (USD 50), White Post Restorations or J & L Spares. Stainless steel slave cylinders have been made in the Netherlands and are available for EUR 200 from Gert van Kooten. The ATE rebuild kit for the 4-cylinder car version of the slave cylinder is compatible with the longer version fitted to the Montreal.”
I don't know if this has already been mentioned but all of these slave cylinders are similar and it may be possible to transfer the rubber seals from one to another. Thus, if your Pantera slave cylinder is failing then donor seals from an Alfa cylinder could solve the problem. I have done this in the past with clutch master cylinders and simply transferred the entire piston from Alfa to Pantera.
A long time ago slave cylinder rebuild kits for Pantera were readily available and that ship has sailed.
