I apologize for the length of this post, but it's enormously complicated & this is the best I can do to try to explain it in as few words as possible.
Unfortunately, the whole clutch assembly has to be an assemblage of mix-'n-match parts, because I'm using a Ford T-5 trans. The input shaft on a T5 trans is a 10-spline, whereas the Focus (Zetec) has a 23 spline, so I can't use a Focus friction plate.
I have a Ford Mustang II clutch assembly, a Fidanza aluminum flywheel with a hardened steel friction surface insert, and a 9" diameter 10-spline friction disc. While there's no "this side toward engine" legend anywhere on it, I'm fairly sure the protruding hub has to face outward, as it would contact the flywheel bolt heads, etc. if it was installed with this hub facing inward.
I've disassembled & reassembled it dozens of times, and the issue has to be a) the thickness of the friction disc (.3300" thick - Motorcraft XS41-7563-RB disc, made by Sachs, but labeled as Motorcraft), b) the thickness of the flywheel's friction surface, or c) the thickness of the driven plate's friction surface.
I can't realistically see the flywheel being the issue, as it's the appropriate flywheel specific to this engine, and at least according to Fidanza, it has precisely the same working dimensions as the OEM flywheel, including deck height, friction surface height, etc. Supposedly, it's a bolt-in identical unit, except it's 8 pounds vs. the Focus' 24 pound unit.
Here's what I've found - when the clutch bolts are just finger tight, and the friction plate is just touching both surfaces, there's about a .100" gap between the flywheel clutch mating surface & the clutch's mating surface.
Cinching the bolts down (and torquing them) the extra .100" causes the clutch fingers to move in about .800". This is about 2/3 of their total available travel (roughly 1.120" of travel before they contact the friction disc hub).
With NO friction disc installed, there's about .1275" gap between the two friction surfaces (as best I can measure).
When the (.3300"-thick) disc is installed & the clutch is torqued down (thereby compressing the clutch basket's spring an extra .2025", to accommodate the friction plate's extra thickness), the fingers move inward about .800".
So - according to my math, for each .100' the clutch spring compresses, the fingers move inward roughly .400".
Therefore, to retract the spring by .2025" (so the friction plate just contacts the surfaces), I'd need to compress the fingers .810".
I only have a little over 1/3 of that amount of finger travel left when everything's torqued down.
Clearly, I have a serious problem.
Possible solutions would seem to be:
1) Putting thin (say, .150" thick) spacers between the clutch basket & flywheel, increasing my finger travel by .600" 2) Finding a thinner friction disc (hard to do, as NONE of the manufacturers provide this dimension) 3) Machining the flywheel friction surface down, say, .150" Unfortunately, Fidanza says this isn't feasible, as it's extremely hard steel 4) Machining the flywheel's inner surface, where the steel friction plate is attached, by a similar amount (I suspect this might compromise the flywheel's strength, though) 5) Obtaining another clutch driven plate assembly, with a lower friction surface height (again, this is a dimension that manufacturers don't provide). 6) ???
I am WIDE open to any suggestions, and I REALLY appreciate your consideration!!
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