Experience With 1-Piece Rear Main Seal?

[mbrunson427]

Our local engine builder turned us on to these 1-piece rear main seals.

You can find them here about 3/4 of the way down this page.
https://www.roushcompetitionengines.com/performance-parts/

We tried it Sunday, installed the crank in the block, torqued all the main caps. When we went to spin the crank it would hardly budge. We got out the torque gauge, it was taking right about 40 lb-ft to spin the crank. Sat there and scratched our heads, all of the main clearances looked perfect when measured. I started unbolting the caps, starting with the rear, and when got the rear cap bolts loose all of a sudden the crank freed right up. It was now taking less than 5 lb-ft to spin.

The crank is a Scat steel crank. The dimension of the crank at the seal matches every other crank we have in the shop, so I don't believe the crank is too big of diameter at that seal.

I asked an engine builder friend, he said yes he's used one (not on an FE engine), and it made the crank hard to turn so they threw it out and used a common rear main seal.

My question, has anybody on here used one and had luck doing so?? I'd like to run the seal because it seems like a better concept, but currently it's not working out so great.

[Phil Brown]

Torque the mains back up without the seal and see if the crank turns ok. If its fine then maybe try a two piece seal just to see, there cheap enough to try.

[blykins]

I used one, didn't really see any benefit to them, so I didn't use them anymore.  On an engine that can use a real 1-piece seal, it's kind of a no-brainer, but on an engine not designed for them, I see no pluses. 

[mbrunson427]

Torque the mains back up without the seal and see if the crank turns ok. If its fine then maybe try a two piece seal just to see, there cheap enough to try.

We're going to do an operation like this tomorrow night I'm thinking. My guess is we end up using a normal 2-piece seal.

[cjshaker]

By the looks of the instructions, you have to cut the seal to get it over the crank flange. Is that right? Seems that pretty much negates the benefits of a "one piece seal".

[Rory428]

By the looks of the instructions, you have to cut the seal to get it over the crank flange. Is that right? Seems that pretty much negates the benefits of a "one piece seal".

Exactly. The thought of cutting a 1 piece rear main seal, and twisting it to get it over the flywheel flange seems more likely to cause issues, than using the OE 2 piece rear seals. I normally find the side seals more problematic than the actual crank seals anyhow. Ironically, I just installed the crank and FelPro rear main seals in my 428 this afternoon, always a stressful PITA procedure.

[blykins]

By the looks of the instructions, you have to cut the seal to get it over the crank flange. Is that right? Seems that pretty much negates the benefits of a "one piece seal".

Exactly. The thought of cutting a 1 piece rear main seal, and twisting it to get it over the flywheel flange seems more likely to cause issues, than using the OE 2 piece rear seals. I normally find the side seals more problematic than the actual crank seals anyhow. Ironically, I just installed the crank and FelPro rear main seals in my 428 this afternoon, always a stressful PITA procedure.

I wish more guys would get into the habit of using silicone instead of side seals.  I've done this on every FE I've assembled in the past 7-8 years.  It takes all the fussiness out of fitting the side seals and cuts down the rear main seal/crank installation time as well. 

[My427stang]

By the looks of the instructions, you have to cut the seal to get it over the crank flange. Is that right? Seems that pretty much negates the benefits of a "one piece seal".

Exactly. The thought of cutting a 1 piece rear main seal, and twisting it to get it over the flywheel flange seems more likely to cause issues, than using the OE 2 piece rear seals. I normally find the side seals more problematic than the actual crank seals anyhow. Ironically, I just installed the crank and FelPro rear main seals in my 428 this afternoon, always a stressful PITA procedure.

I wish more guys would get into the habit of using silicone instead of side seals.  I've done this on every FE I've assembled in the past 7-8 years.  It takes all the fussiness out of fitting the side seals and cuts down the rear main seal/crank installation time as well.

Would never discount your success with silicone or even say it's not a viable solution, but the Felpro side seals and nails are the issue with side seals, not side seals themselves.

Old side seals used to be different.  Seals from Felpro have been too hard for about 10 years and the nails are sharp and thin, which seem to have got worse in the past 5 years, letting them cut into the side of the seal instead of pushing outwards.  A JV707P Clevite/Mahle seal with their soft side seals and blunt thick nails, installed after the cap is torqued, may take 5 minutes more than silicone, but work so much better than Felpro. 

Not saying AT ALL to convince you or anyone to use side seals, but the Felpro side seals are crap...they sit next to my Speedpro rod bearings as "just in case I am in a bind" pile

As far as 1 piece seal, as Brent said, I don't see a benefit, if done right they seal easy as a 2 piece, seems like a solution looking for a problem, and if they do have the drag Mike has seen, hard to believe they would last

[blykins]

By the looks of the instructions, you have to cut the seal to get it over the crank flange. Is that right? Seems that pretty much negates the benefits of a "one piece seal".

Exactly. The thought of cutting a 1 piece rear main seal, and twisting it to get it over the flywheel flange seems more likely to cause issues, than using the OE 2 piece rear seals. I normally find the side seals more problematic than the actual crank seals anyhow. Ironically, I just installed the crank and FelPro rear main seals in my 428 this afternoon, always a stressful PITA procedure.

I wish more guys would get into the habit of using silicone instead of side seals.  I've done this on every FE I've assembled in the past 7-8 years.  It takes all the fussiness out of fitting the side seals and cuts down the rear main seal/crank installation time as well.

Would never discount your success with silicone or even say it's not a viable solution, but the Felpro side seals and nails are the issue with side seals, not side seals themselves.

Old side seals used to be different.  Seals from Felpro have been too hard for about 10 years and the nails are sharp and thin, which seem to have got worse in the past 5 years, letting them cut into the side of the seal instead of pushing outwards.  A JV707P Clevite/Mahle seal with their soft side seals and blunt thick nails, installed after the cap is torqued, may take 5 minutes more than silicone, but work so much better than Felpro. 

Not saying AT ALL to convince you or anyone to use side seals, but the Felpro side seals are crap...they sit next to my Speedpro rod bearings as "just in case I am in a bind" pile

As far as 1 piece seal, as Brent said, I don't see a benefit, if done right they seal easy as a 2 piece, seems like a solution looking for a problem, and if they do have the drag Mike has seen, hard to believe they would last

The issue I always had was with the different sizes of cavities with different blocks.  The aftermarket block holes are different than factory (and even vary depending on the brand of block) and even the factory ones varied.  The side seals were loose on some blocks, too tight on others, which required shaving them down to get them to fit.   I was spending way more time than I should have been spending. 

[Katz427]

Well ,I must confess, the only time I have used a 1 pc seal, is a seal from Kaase installed in a 460.  I did work out ok.