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washers
Is there any technical difference as to why Al crush washers would be used in place of Copper?
Porsche seem to use a lot of Al washers, where as I can often locally source a more readily available Cu substitute. Thanks Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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04-13-2024, 01:00 PM
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Join Date: Jan 2022
Posts: 172
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Hi
Suspect that the hard Al crush washers are used against magnesium parts in particular and also aluminum parts to reduce the risk of galvanic corrosion. Suggest you have a look at a Galvanic Table. Best regards |
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04-13-2024, 08:31 PM
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PCA Member since 1988
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Copper crush washers typically crush under much less pressure than the aluminum ones specified by Porsche. Those are not dead soft aluminum either, but an alloy that is fairly strong, so they deform some, but not much under the specified torques.
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1973.5 911T with RoW 1980 SC CIS stroked to 3.2, 10:1 Mahle Sport p/c's, TBC exhaust ports, M1 cams, SSI's. RSR bushings & adj spring plates, Koni Sports, 21/26mm T-bars, stock swaybars, 16x7 Fuchs w Michelin Pilot Sport A/S 3+, 205/55-16 at all 4 corners. Cars are for driving. If you want art, get something you can hang on the wall! |
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04-14-2024, 12:10 AM
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Yes the galvanic thing is an interesting idea, but I suspect not the reason. We are dealing with alloys and oxides of these. That is a completely different scenario regarding the electrolysis/electrochem series. For example, pure Mg dissolves in water, and Al is not far behind in reactivity. But the ngine blocks are far more inert. The physical parameters I suspect may be more important. But I am guessing there is a reason why Porsche have predominantly Al washers. Maybe the higher crush values are the answer.
Regards Alan
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83 SC, 82 930 (track) - Stock except for RarlyL8 race headers, RarlyL8 Zork, K27-7006, 22/28 T bars, 007 Fuel head, short 3&4 gears, NGK AFR, Greddy EBC (on the slippery slope), Wevo engine mounts, ERP rear camber adjust and mono balls, Tarret front monoball camber adjust, Elgin cams, 38mm ported heads, 964 IC. 380rwhp @ 0.8bar Apart from above, bone stock:-) |
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04-14-2024, 12:26 AM
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