2-piece rear main seal

Jim Huseby

Jim Huseby

Senior Member
Has the 2-piece neoprene/cork rear main seal improved in quality and long-term effectiveness in the last couple years?
 
The two-piece cork/neoprene rear seal is fairly rigid and functions as a "pinch seal" much like the front seal albeit with a much greater oil flow. This requires just the right amount of pressure over the entire circumference and this can be a challenge given the possible variations in fitment within the upper and lower caps with respect to the centerline of the shaft. Too much pressure and wears fast and leaks and too little pressure at any given point and it will leak there. I have been told that the old design can be effective but only if one take extra time and effort to achieve a good fit. I don't know if there have been any improvements in design over the last couple years.
 
ursus said:
The two-piece cork/neoprene rear seal is fairly rigid and functions as a "pinch seal" much like the front seal albeit with a much greater oil flow. This requires just the right amount of pressure over the entire circumference and this can be a challenge given the possible variations in fitment within the upper and lower caps with respect to the centerline of the shaft. Too much pressure and wears fast and leaks and too little pressure at any given point and it will leak there. I have been told that the old design can be effective but only if one take extra time and effort to achieve a good fit. I don't know if there have been any improvements in design over the last couple years.
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Hey ursus,
The same words can be used to describe the proper installation of any rear main seal in an A/B engine, i.e.- install by one who knows how to achieve a GOOD fit ! I do not know of any recent improvement in the two piece cork/neoprene rear seal.
However, I second Jim B use (Terry Burtz) of the one piece real seal...properly fit. I have two such installs running in B engines at this time, with neither leaking at all.
 
The Burtz seal is a "lip seal" as are most modern oil control seals. The lip design allows for more axial movement without developing a leak. There is an even better design that I think is called a "clip seal" that wraps around the crankshaft and is secured with a latching clip. I have heard of its use in A and B engines but have never seen photos or instructions on how it is installed or the part numbers, etc. One guy told me that he simply filled the associated cavities in the upper and lower cap with anaerobic RTV and dropped in the crankshaft with the clip seal already mounted and bolted it up. Sounded almost too simple to me but he claimed it to be very effective.
 
ursus said:
The Burtz seal is a "lip seal" as are most modern oil control seals. The lip design allows for more axial movement without developing a leak. There is an even better design that I think is called a "clip seal" that wraps around the crankshaft and is secured with a latching clip. I have heard of its use in A and B engines but have never seen photos or instructions on how it is installed or the part numbers, etc. One guy told me that he simply filled the associated cavities in the upper and lower cap with anaerobic RTV and dropped in the crankshaft with the clip seal already mounted and bolted it up. Sounded almost too simple to me but he claimed it to be very effective.
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Interesting !
Google search turned up no info.
Wondering about source/maker name ?
 
Sorry, I didn't have the correct name. Google "clipper split seals" and you will find they are made by Johns Manville, Parker Hannefin, et al. They appear to be placed around the shaft and secured at the split by means of a "hook-and-eye" closure. Looks interesting.
 
ursus said:
Sorry, I didn't have the correct name. Google "clipper split seals" and you will find they are made by Johns Manville, Parker Hannefin, et al. They appear to be placed around the shaft and secured at the split by means of a "hook-and-eye" closure. Looks interesting.
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Thanks, I will study that information :) !
I'm now wondering if that type seal is what is used in some new vehicle engines ?
 
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