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Rear Main Seal from Best Gasket 1953-59


48ply1stcar

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How many have purchased and used this gasket? From where did you buy it and what was the cost.

I attempted to replace this seal 25-years-ago in my 53 flathead.  The upper seal was flush and I was not able to remove it. It's time to replace the seal on my 56.  I watched a video attached, that shows installing the seal NOT flush which makes sense to me.  I'm ready to try again with 25 years more experience.

 

Rear main seal.PNG

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The main seal on my Dodge 230 cu. in. was bolted to the rear of the block, and the bottom half was bolted to the rear bearing cap.  It would not slide out.  Is this "new and improved" seal meant to replace the bolted in seal?

 

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9 hours ago, busycoupe said:

The main seal on my Dodge 230 cu. in. was bolted to the rear of the block, and the bottom half was bolted to the rear bearing cap.  It would not slide out.  Is this "new and improved" seal meant to replace the bolted in seal?

 

No, I believe that the seals are either or.  I had a 53 218 with the above.  I attempted to replace it 25 years ago, but I only was able to replace the bottom half.  I believe the 218 had the bolt-in in the 52 and before.  

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I used that seal on my 56 block, but it has yet to be installed.  The block seal area was changed sometime in the 50s, 56 or slightly earlier to use this type.  I don't think it will fit earlier blocks.

 

Even in a block machined for this type, I don't think changing the upper half would be possible.  Maybe, if the mains were all loosened , the transmission pulled back enough to let the crank drop somewhat, there may be enough room to roll it out.  There is a lot of contact area, rubber seal to cast iron and it would be hard to push or roll out.

 

The one in your video is much smaller in cross section and only contacts the block on two narrow sides and has a steel core to push/pull on.

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I would strongly suggest checking exactly what type of seal is actually present before assuming that a particular type or style is there.........my stock 1941 Plymouth with its stock 201 was supposed to have the old style rope seal and even tho' I had a Best gasket set for the 230 engine I was building with the 2 types of neoprene seal and 2 types of side seals I assumed I needed a rope seal so went ahead and purchased a rope seal..............only when I'd drained and dropped the sump and unbolted the rear main did I discover that this 201 had a neoprene seal of one of the 2 types in the Best gasket set BUT more importantly the rear main cap had NO side or what I call "ear" seals, nothing, zip, so whilst I could have replaced the lower neoprene seal I thought that as it didn't look too bad the installation of the side seals was a better bet which I duly did and a new sump gasket as well...........the moral of this story is........ do NOT assume your engine has what it should have..............it maybe leaking because a previous owner was too lazy or didn't do it right.........installing these side seals and a new sump gasket virtually eliminated the rear main leak, at least enough so that it wasn't an embarrassment as before..............my Oz 2 cents worth ..........andyd  

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I have had nothing but trouble with the Best seal shown in the photo. My engine when rebuilt had an NOS 251 crankshaft that was sent to the crankshaft shop to be checked and had the thing polished. I have tried three times to get the rear seal to do its thing and it leaks. More than my c.1962 Automotive Engineering quick rebuilt motor.

 

I have asked Best on a couple of occasions what is the crankshaft minimum ID and Maximum OD, as well as the surface finish in Ra, for this seal. That way one can check to make sure that a crankshaft is not too big, to small or too rough/smooth for the seal.

 

They never have responded.

 

James.

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