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Join Date: Mar 2004
Location: Windsor, CT
Posts: 2,119
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Factory Case Through Bolt Seals were not O-rings?
Take a look at the image:
 It would appear the Porsche Factory installed pre-molded silicon rubber seals on the case through bolts. They are very flexible and stretchy, even after almost 33 years of searvice. These look nothing like the recommended o-rings, blue or green. Which are pretty stiff by comparison. Why can't we buy the factory molded shapes, instead of trying to squeeze an o-ring into a place where it doesn't really want to go? And using sealant/lube to help with the sealing of the o-ring? I took these off my 3.0l SC. The case is coming apart for the first time. These were installed in late 1981. (Feb 1982 build date) The double wedge makes sense since my case has a chamfer on the RHS case, where the head of the through bolt sits. Can't explain why the LHS case does not have the chamfer. What is the most notable is the precision of the flanged lip, that went into the hole itself, just inboard of the chamfer. That molded edge is perfect on all seals that were not torn during operation/disassembly. The consistency can not be explained by pure coincidence. In section view the length of the lip is the same for all. The factory seals look like the rubber wedge-seals used in plumbing, which rely in the conical clamping surfaces to compress the seal uniformly onto the pipe or pipe end. Curious, has anyone else seen this? Can we get them?
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Mike '82 911SC, SSI, 22/29 tbars, 22F/22R Adj swaybars, Bilstein Sport, Elephant polybronze & monoballs, Cambermeister bar, turbo tierods, Carrera oil cooler, front brake cooling ducts, Sparco Sprint 5 & Recaro SRD PAX seat, Teamtech harness, DAS Sport rollbar. |
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11-10-2014, 07:11 AM
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Join Date: Mar 2001
Location: Marysville Wa.
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mystery, but chamfer the LH side of the case before assembly.
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https://www.instagram.com/johnwalker8704 8009 103rd pl ne Marysville Wa 98270 206 637 4071 |
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11-10-2014, 07:59 AM
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Join Date: Mar 2004
Location: Windsor, CT
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Yes, I will be chamfering the left side. The seals were chewed up on that side, and near perfect on the RHS.
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11-10-2014, 08:00 AM
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Straight shooter
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Interesting. This does match the extrusion challenge we discussed in previous threads on the topic. When installing the bolts/nuts by hand, the bolt does have an opportunity to off-center slightly in the case hole which would produce an asymmetrical extrusion as the ring ages. Perhaps this perfect extrusion is the result of the factory assembly method; if they use a jig table to hold the case/through-bolts on one side then they may be able to achieve such a perfect alignment.
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“Of the value traps, the most widespread and pernicious is value rigidity. This is an inability to revalue what one sees because of commitment to previous values. In motorcycle maintenance, you MUST rediscover what you do as you go. Rigid values makes this impossible.” ― Robert M. Pirsig, Zen and the Art of Motorcycle Maintenance: An Inquiry Into Values |
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11-10-2014, 08:09 AM
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Join Date: Mar 2004
Location: Windsor, CT
Posts: 2,119
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It does seem like the bolt would be perfectly centered. If you saw the pieces in your hand, you would see they look like they were molded that way. Every one had the same formed lip. Exact same length of lip. IMHO too perfect to be the result of extrusion from installation.
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11-10-2014, 08:13 AM
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P911
