I have long maintained that, because of the ram method of fluid displacement, the BTV did not require sleeving - at least not like other conventional master cylinder (single or tandem).
However, I see that I have to modify that position WRT to the fixed rubber cup seal.
The 55-56 shop manual clearly advises:
Quote:
Examine the hydraulic cylinder bore 1" from the open end. The surface must be free from scores, deep scratches, or corrosion, and be satisfactory for sealing with rubber hydraulic seal.
I can see where scores or porosity issues in this location would cause leakage into the vacuum shell and, thus, require sleeving. However, none of the units that I've personally rebuilt with my own tow hands have needed it.
Meanwhile, IIRC, the high-mounted BTV's in tri-five Chevies had, essentially, the same innards as the units on our Packards. Of course, the cover was redesigned to accommodate the horizontal, rather than angled, orientation.
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