Quote:
Originally Posted by KTL
I have a couple of questions about this location in the case halves.
1. I believe these main support surfaces are at the same depth/elevation as the case parting line? So wouldn't it make sense to provide sealant since the parting line is of course getting the sealant. In other words, you're keeping the surfaces same-same if you put sealant on both the parting line and the main supports.
2. I would beg to differ that there is some legitimate movement going on. Even on the later aluminum cases. I've seen both main support surfaces on my 3.0 case and my 3.2 case that have a roughened surface and others here have confirmed the same. I've been told it should be smooth like the parting line and thus that roughened condition is fretting from the two surfaces oh so slightly shuffling back and forth.
Is it catastrophic movement? I guess it doesn't appear so since the bearings don't show any problems. But why not arrest it if you can.
I have the through-bolt sleeves installed in my 3.0 case. cgarr did it for me. Unfortunately i've never run that case. Even if I did run it, I wouldn't be taking it apart any time soon so I could see the surfaces. I just figured it was a good thing to do since I noticed the fretting on the main support surfaces.
Here's how he does it on lowly factory cases. First make accurate plugs for the mains to hold it square bolted together and use a ½ inch reamer through the case through-bolt holes into the other case halve. This creates a ½ counter sunk bore to install the sleeve which is 1/2 inch OD 0.35 wall and 1 inch long. Then make sizing plugs for the case half that was reamed all the way through. This brings the through-bolt hole back to size. What this does is the case is used as a jig to line up everything. Works quite well. One thing people may not recognize is the 3 of the sleeves need to be notched out to allow oil passage for the piston squirters.
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YES, the mains are the same surface as the case parting line, but once the mains are clamped down together there is a degree of flex in the case parting line around the perimeter.
This is hinted at in the factory bolting order:
1. Bolt mains / case through bolts in star pattern
2. Bolt up case perimeter bolts.
Once you do #1 with zero gap, the case parting line is bolted together and with the sealant it will slightly flex open. Hard to believe, but the material does absolutely flex.
and good mention of not blocking the oil passages with the sleeves. We moved ours so that this isn't a factor.