Rear Main Seal Crush

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Rear Main Seal Crush

Post  dbshelton on April 8th 2018, 8:50 am

I have read so much on this topic that my 60 year old brain is confused. Trying to get this straight since I can't find a diagram or picture. When setting crush to do I put seal half in the main cap flush on 1 end and cut seal to where it protrudes .010 on the other side? Do same, put seal flush in the block on 1 end and cut the seal end to .010 on the other side? Is this correct?
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Re: Rear Main Seal Crush

Post  cletus66 on April 8th 2018, 9:20 am

What kind of seal are you using? I have never cut one.
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Re: Rear Main Seal Crush

Post  pmrphil on April 8th 2018, 9:36 am

If you're using a normal 2 piece seal (NOT rope) install with one side protruding about 1/4" from the block and the other with the opposite side protruding from the cap, don't cut or trim anything, just LIGHTLY deburr the ends of the seal cavity where the protruding ends will have to go "in" so the backs of the seal ends don't get shaved. No silicone on the ENDS of the seal, just a touch on the cap-to-block flat area to prevent seepage.

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Re: Rear Main Seal Crush

Post  dbshelton on April 8th 2018, 10:41 am

I'm using a Felpro rubber 2 piece seal.
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Re: Rear Main Seal Crush

Post  69F100 on April 8th 2018, 12:02 pm

pmrphil wrote:If you're using a normal 2 piece seal (NOT rope) install with one side protruding about 1/4" from the block and the other with the opposite side protruding from the cap, don't cut or trim anything, just LIGHTLY deburr the ends of the seal cavity where the protruding ends will have to go "in" so the backs of the seal ends don't get shaved. No silicone on the ENDS of the seal, just a touch on the cap-to-block flat area to prevent seepage.

This the way I also do the 2 peace rear main seals never had a problem with one leaking so far.
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Re: Rear Main Seal Crush

Post  57ford custom on April 8th 2018, 3:09 pm

I've got the Kasse one piece and hope that it works ok I should know this week.
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Re: Rear Main Seal Crush

Post  rmcomprandy on April 8th 2018, 10:01 pm

Measuring "crush" on a two piece, steel core, rubber type seal requires a totally different installation than when actually building the engine with the seal ends offset...

Two much "crush" is just as bad for leakage as not enough.  One side of each half, I have protrude from .010" to .014" when doing the measurements for installation.
Some rear seals are OK as is but, not with a line bored/honed block.

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Re: Rear Main Seal Crush

Post  dbshelton on April 8th 2018, 10:09 pm

rmcomprandy wrote:Measuring "crush" on a two piece, steel core, rubber type seal requires a totally different installation than when actually building the engine with the seal ends offset...

Two much "crush" is just as bad for leakage as not enough.  One side of each half, I have protrude from .010" to .014" when doing the measurements for installation.
Some rear seals are OK as is but, not with a line bored/honed block.


Thanks Randy!! That's how I measured it. Only took a few thousands from each half to get it within those specs. Then I offset the ends and installed the crank.
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Re: Rear Main Seal Crush

Post  cletus66 on April 9th 2018, 11:24 am

rmcomprandy wrote:Measuring "crush" on a two piece, steel core, rubber type seal requires a totally different installation than when actually building the engine with the seal ends offset...

Two much "crush" is just as bad for leakage as not enough.  One side of each half, I have protrude from .010" to .014" when doing the measurements for installation.
Some rear seals are OK as is but, not with a line bored/honed block.


Good info. Thanks.
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