Rolls Royce – 1975 Silver Shadow

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Having carefully prepared our 1975 Silver Shadow (SRD 22262) for the 1400-mile trip to the 2011 Lake Tahoe annual meet, we suffered an FTP before we even made it out of our hometown! The Low Brake Fluid light came on and smoke poured out from under the car. It was RR363 leaking out of the LH accumulator, specifically the front of the retaining plug (part UE 10294) that connects the bobbin and control piston to the accumulator case, and dripping onto the exhaust system. A perfect set-up for a ire and possible loss of a car.

When carrying out some previous work a couple of years ago on the brake and leveling system, I had the accumulators reworked by an approved Rolls-Royce shop. However, a while later I had a leak from this same location on the LH accumulator, but rather than having to pull off the accumulator, I obtained a replace- ment seal (UE 35101) from the local Rolls-Royce dealer. This seal stopped the leakage—for a while. After several inquiries with a couple of recognized repair facilities without much success, I called Walt Schonauer, the proprietor of Lone Wolf in Chino, CA, whom I had met some years ago when I was working on the leveling system. He was aware of the problem and had seen it on other Silver Shadows. After recognizing that replacement seals available from RR might work for a while until they flattened out and caused a leak, he did some research on the “0” ring cavity on the plug bobbin and on the cross-section of the seal. He found that the “0” ring oriice was marginally too large and the ring seal’s cross section was marginally too small. His ix was to use a seal with a larger cross-section. This is a Viton type of “0” ring identiied industrially as “Epylene Propylene” (2-113 EPR). It is used with a split Teflon back-up seal (8-113 TFE-S) to take up the “slack” in the oriice size. He had been successful with this ix on other Silver Shadows. (My experience with the leaking seal and on the previous seal that had leaked conirmed that the seal had lattened out; a scale across the top showed almost no inter- ference with the seal. At the 2,000+ psi pressure in the system, it was clear that this was the problem.)

I ordered three of these seals and the Telon back-ups and used one set for the repair, put another one in my spares box, and put the third set in my trunk (along with several cans of RR363 and a UNF cap screw to both remove and replace the plug) in case the RH accumulator should leak next.

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