[Stan65]

All,

I have a new Eagle crank for my 455 and am planning on using a 1 or 2 piece rear main seal. I keep seeing to make sure the serrations are not too aggressive. This is a very objective statement. What defines aggressive? The Eagle crank doesn’t seem as aggressive as the original crank. Has anyone had a crank shop weld up the area and grind smooth?

Any thoughts would be appreciated.

Stan.

[Formulajones]

I simply ask the machine shop to polish that spot so as to just remove the sharp edges and provide a smooth surface for the seal to ride on that won't chew it up.

Done that on the last few Pontiac builds and those seals have worked perfectly for me.

[Gach]

The Eagle Cranks are noted for having very rough serrations, and its a problem for any type of seal. I would definitely get the serrations area polished.

[Stan65]

I have read in the archives that they are rough. Crazy, the eagle is less pronounced and smoother than the original? That’s why I’m curious what aggressive is.

[dataway]

Sharp is probably more of problem than aggressive. If it feels like a nail file, too sharp. Feels "pebbly" but not too tall, probably ok. Basically a lip seal probably does best on a completely smooth surface, but taking it down that far might make it a bit loose?

[Verdoro 68]

When I was dealing with rear main seals I sent a pic of my Eagle crank to Wade at BOP and he said they looked aggressive. Compared to my factory crank they're definitely more pronounced and frequent so I guess that's what folks mean when they say "aggressive".

After burning up two rope seals, I decided to try the one piece seal but I had the serrations polished before installation. So far so good.

[mysticmissle]

did you try the ""best Rope seal" ? ^^^^^
i have used on factory cranks and like. BOP 2 piece on my scat cranks on IA2 blocks have a one piece will try on IA2A

[Formulajones]

I can't help but imagine that when looking at factory cranks they are already somewhat polished after running 150,000 miles on a rope which might make them appear "less aggressive"

Just a thought.

I've never had an NOS Pontiac crank in my hands to really compare.

[Verdoro 68]

My factory crank is in storage and I don't have any pics handy, but my recollection is that it was quite a bit smoother with less serrations at a different angle than the Eagle.

Originally Posted by mysticmissle

did you try the ""best Rope seal" ? ^^^^^
i have used on factory cranks and like. BOP 2 piece on my scat cranks on IA2 blocks have a one piece will try on IA2A

Yes. I started with those and destroyed two. The first time it rotated in the channel, the second time it melted. I wrote off the failures to installation errors on my part (issues with the way they were packed seemed to be a common assessment) but never really had a definitive answer on why they failed.

[Gach]

My factory crank is in storage and I don't have any pics handy, but my recollection is that it was quite a bit smoother with less serrations at a different angle than the Eagle.

.

Thats my experience comparing stock crank with Eagle crank. I can see why there’s been many issues with Eagle. Don’t have a picture of stock crank handy. looking at your Eagle crank, my opinion that was good part of the issues you were having. Now that it polish definitely seems to have helped.

[Half-Inch Stud]

Sooooo, the angled serrations are there for some sort of micro-vane pump effect or what.

[Dragncar]

With all the issues with Eagle and their serrations that makes the choice simple, buy Scat-Molnar and run the one piece.

[jhein]

Originally Posted by Half-Inch Stud

Sooooo, the angled serrations are there for some sort of micro-vane pump effect or what.

That's what I've been wondering.

[jhein]

Is it this? The crank serrations are "oil return threads" to scoop up any oil that gets past the seal and return it to the engine? Huh. So does that mean that the engineers knew the seals would never really seal and they just had to find a way to make it less noticable?

Scroll down to the diagram of the crankshaft and see that these are referred to as "oil return threads".

https://www.theengineerspost.com/cra...-and-function/

[jhein]

Is it this? The crank serrations are "oil return threads" to scoop up any oil that gets past the seal and return it to the engine? Huh. So does that mean that the engineers knew the seals would never really seal and they just had to find a way to make it less noticable?

Scroll down to the diagram of the crankshaft and see that these are referred to as "oil return threads".

https://www.theengineerspost.com/cra...-and-function/

[Dragncar]

If you are buying a aftermarket crankshaft, there is no reason to use 100 year old rear main sealing tech. Buy smooth.

[lust4speed]

Really what you don't want to see or feel is a cheese grater. Usually a roll of sand paper or emery cloth will smooth things right down. The sanded down serrations left on the first crank didn't hurt anything, and the serrations on the second crank pictured actually didn't touch the area where the seal rode. The Best Teflon/Graphite seal discolored the crank where it rode.

[Formulajones]

The serrations were likely there for a couple reasons. One may be as you mentioned to scoop oil, and another likely reason is to hold oil and keep that rope lubricated.

[Stan65]

I finally got to mess with the cranks a little today.

The original 73 455 crank is “cheese grater like” when I run my fingernail across it (the dirty crank picture)

The new eagle crank feels smoother for sure. (New crank picture)

So what grit emery cloth should I use to polish it? Do you just fold it over and run it around or do you back it up with something ridged?

I have a lathe I can put the crank in to spin it.

Thanks all!

[Dragncar]

I have a old Indian Adventures Eagle cast crank that was not straight and had tapper on the jornals.
I had to have it ground .010-.010 and those serrations are almost gone. But they started out kinds deep.