Since it appears that I can close out my Clutch Master soap opera (Wilwood!), I am now being proactive to start researching clutch slave alternatives as I am on my second OE replacement part (first one leaked after 100+ miles).
Are there any alternatives to the Pantera vendor offering that will fit into the OE package (or with some minimal cobbling)?
Thanks!
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Rob, the only aftermarket slave cylinder I’m aware of is the “long throw” slave cylinder. It has a slightly smaller bore than OEM, to give a bit more travel (albeit with a heavier pedal). This was a Pantera East item but they are no longer in business, so I’m not aware of the current source. I’d try Dennis Quella or IPSCO (Mark Johnson).
The other aftermarket option is a hydraulic throwout bearing, such as the one McLeod makes, however, it is far from a bolt-in. To do it correctly requires some fabrication and non-trivial measurements and setup. TBS, once it’s installed and working properly, they can be very reliable and give lower pedal pressure with great clutch “feel”. Get it wrong though, and you’ll get lots of practice pulling your transaxle! Virtually all modern vehicles with manual transmissions use this style of slave cylinder/throwout bearing.
This might work for you.
Ditto on the non-stock choices but I'll add that sleeving a cast iron leaker with stainless steel also works- White Post Restorations in VA does this. If you find one used, long throw slave cylinders are either all stainless steel or aluminum for zero maintenance, and fit in the stock bracket.
I've run an adapted Tilton dirt track racing concentric-throwout for 25 years, and with that part the entire slave cylinder, all linkage and cross-shaft in the bell housing are eliminated (6 lbs lighter, anodized aluminum and far less complication) plus they are long-throw as well (ZF synchro benefits).
But concentric throwouts are EXTREMELY sensitive to internal clearances when setting up cold. The clutch in a Pantera changes clearances to the tight side when hot. You need to follow the directions EXACTLY to the thousandth which most guys do not. Get it too tight when smoking-hot and as was said, in 50 miles you will be pulling the ZF and rebuilding the $300 throwout. Plus, Tilton and others do not make a mounting nose for a ZF so you get to machine that part from scratch or adapt something. Good luck-
Thanks for these tips!! Hopefully I have a few more miles before pursuing these options. Agree that a hydraulic tb is best/modern but more work than I can stomach!
FWIW, I was talking to a guy that put a hyd tb on his ‘65 mustang and his was leaking. I understood his pain dealing with these parts!!
I installed a McLeod hydraulic T/O brg 25 years ago. On 2 separate occasions, when my ZF was removed, I replaced the unit with McLeod’s latest design. Trust me when I say there have been significant design changes since the first units were sold. That being said, I haven’t had a problem with any of them since my first installation. If someone wants to attempt the installation of one of these units you need to know two things: what McLeod calls a “kit” isn’t, and the freeplay measurements McLeod recommends are wrong for a Pantera installation.
FWIW, all known concentric throwouts seal by means of a single internal 'quad-ring'- a specialized type of o-ring. It seals both a piston traveling in and out its bore at considerable hydraulic pressure from the master cylinder, and also seals against the spinning clutch input shaft, but a single quad-ring simply cannot seal its piston rotationally as well.
So as was said, sufficient free play is vital to absolutely preventing the throwout bearing piston from bottoming and spinning with the clutch. Once that happens, the game is soon over for that quad-ring. I installed a ZF-lube temp gauge sender near the ring gear, and on a 'spirited' 500-mile desert road trip I saw only 190 F max. Racers have seen considerably more, hence the heat expansion problem. Leaving the stock ZF ventilation hole open reduces internal clutch heat.
When they work, they're an improvement over stock multipart hydro-mechanical linkage. When they don't, they're far more trouble to fix. With all concentric throwouts, the transmission/transaxle must come out or at least be slid back enough to change or repair any leaks. You need to run a flexible dash-3 hydraulic clutch line into the bellhousing and a second line out with a bleeder valve at its end. Empty ZF cross-shaft holes work- no drilling needed.
Incidentally on Tiltons, there's a large OD secondary o-ring that functions as a dust-ring in front of the throwout bearing itself, to help keep abrasive clutch particles out of the piston bore. I have had one of those fail, but it didn't result in a fluid leak. It was easily replaced when the ZF was pulled for other reasons.
