Eagle Forged Stroker Crank CRACKED
- Thread starter thomasfouraker
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Rat Bastid
Dunamis Metron
It may look fine but it may not be capable of damping the harmonics of your application.
And that’s the problem with that style of damper. It is what it is and you can’t tune it.
To me that thing is a door stop.
At least with the ATI damper you can check the bearings and mag the crank when doing maintenance and if you see something unhappy they can change the tune.
With what you have there is no tuning from what the manufacturer thought was acceptable.
thomasfouraker
Well-Known Member
I did notice there was a crack on the snout underneath the damper.
Likely a month before I pull the engine and tear it down but I am anxious to see what I find.
Better start shopping for dampers…..
Likely a month before I pull the engine and tear it down but I am anxious to see what I find.
Better start shopping for dampers…..
Dale Davies
Well-Known Member
I like the Fluidamper. Not suseptable to harmonics at different RPMs. Got familiar with them mainly on Detroit Diesel engines. On the V12, V16, V20 and V24 engines they used 2 dampers bolted to the hub. Long crankshafts in those engines. Some used 2 or three block bolted together and the crankshafts were bolted together. The 20V used three blocks, 2 6V and an 8V. Now these were not standard 6V or 8V blocks. They came out of the same castings but were machined differently. One 6V block was the front 20V block and the other was the rear 20V block. The 8V block was the center 20V block. These long crankshafts needed all the harmonic damping that could be supplied. These engines also run at 100% duty cycle for months at a time. In mine haul trucks they still have a ttough time with heavy loads and up and down the rev range. Most of these do drive a large generator to power large electric traction motors. The harmonic dampers get a workout.
justinp61
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Can you get a photo of the numbers on the front counterweight?
thomasfouraker
Well-Known Member
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justinp61
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Thanks, I can't read all the number but it looks like 36040006123ci. I'm wondering if the "ci" is for cast iron. The current forged umber is 436040006123 and the cast is 103604000.
Here
thomasfouraker
Well-Known Member
You know, I guess that would make sense. Especially since this rotating assembly had Eagle I beams and Hypereutectic pistons. Would kinda jive a little more to have a cast crank with those other components.
I will try to give Eagle a call tomorrow and inquire. I know the numbers are hard to see, especially the second set.
I will try to give Eagle a call tomorrow and inquire. I know the numbers are hard to see, especially the second set.
thomasfouraker
Well-Known Member
Seems like similar vintage crankshafts have 4340 stamped over the part number for forged components. With the second set of numbers likely being a time stamp.
mopardrew
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Welcome to the cast crank party! Had the same thing happen with cast eagle crank. Went molnar and no problems now. Gotta say that crank revved fast for the maybe 200 mi. Wouldn’t spend a dime on another cast eagle crank. Balancer won’t make a difference on them their junk! If someone wants to buy one put a great balancer on one go ahead! I’ll be the first one in line saying told u so lol.
I was so paranoid about cast cranks that I bought a 340 from a friend that had a nice stroker build but used an Eagle cast crank. He tore it apart and bought a cast Scat crank and had everything rebalanced. Scat rods, scat crank, Diamond pistons, nice solid lifter cam, etc. I ended up selling everything to an east coast guy because I knew I would be pushing my luck with that crank running 9’s.
Many years ago friend's S15 pickup with V6 broke the crank in half.
Another friend started it up, drove it on the trailer knocking to beat heck. (I was not there)
Anyhow reman .010/.010 crank new bearings, flipped the engine upside down on the engine stand completely assembled.
Swapped out the crank and bearings. In 24 hours he was back on the road again, ready for work Monday morning.
He drove it many years after that.
Had never seen that before, where the crank snaps in half, but in a manner that it still turned the front half of the crank.
Kind of what the OP has pictured above.
Glad you caught it early before it grenaded the whole engine.
☆☆☆☆☆
Another friend started it up, drove it on the trailer knocking to beat heck. (I was not there)
Anyhow reman .010/.010 crank new bearings, flipped the engine upside down on the engine stand completely assembled.
Swapped out the crank and bearings. In 24 hours he was back on the road again, ready for work Monday morning.
He drove it many years after that.
Had never seen that before, where the crank snaps in half, but in a manner that it still turned the front half of the crank.
Kind of what the OP has pictured above.
Glad you caught it early before it grenaded the whole engine.
☆☆☆☆☆
In the 1980’s I did the same thing on a 440 but I saw the oil pressure doing something funky on a 10 second pass so I loaded up the car and took it home. I had an open trailer with an open deck so I pulled the pan and started pulled main caps. I found the stock 440 crank broke in half so after work on Monday I unloaded the car, pulled the engine while my local speed shop did a crank for me. The hardest part was working a full time job in the mill and then replacing the crank but I had it rebuilt and made Friday nights point race. I did need to call on two friends to hold the rods back as I lowered the crank in. I wouldn’t do half the crazy stuff today that we used to do. But we sure had fun.
if it makes you feel good or smart you can blame it on the balancer but do some research and you will find that 99% of crank breakage are the shitty Eagle cranks . The balancer might be the cause but it seems the other cranks can live through it but the Eagle can't .
That reminds me of one long weekend racing. I was experimenting with a carb spacer that had a slot to insert a sheet metal divider. Long story short, the divider worked loose and metal went through the intake into a cylinder. There was no damage to the head or the cylinder, the piston just looked like it had been shot blasted clean. I pulled the heads and removed the metal bits, left the car at the track overnight, and went home and bought a gasket set. The next day I put everything back together and continued racing. Oh to be young and have that much energy again.
Rat Bastid
Dunamis Metron
When was the last time you saw a 3.58 stroke cast crank fail??
I can’t think of it either. So what is that telling us? Is it telling us Eagle makes junk ****? That the cast Eagle crank (that comes out of the exact same foundry as every other Chinese crank) is inferior in materiel?
That’s not what it’s telling me.
What I’m saying it says is when guys buy these cast cranks they are using the cheapest damper that can find (its not a ”balancer” and it has never been a “balancer”) and send it.
And IF that’s the case, in all likelihood that damper is tuned (at best) for a 3.58 stroke cast crank, not a 4 inch stroke crank. Also of note is the fact that I doubt the Chrysler production cranks used the same materiel as the Chinese cranks, and the topic of which used the better material is open for debate but I doubt the Chinese cranks are at least as good a material as the OE cranks.
So let’s say they are the same materiel. A .420 inch increase in stroke length most certainly changed the resonance frequency of the crank. And if the damper isn’t tuned for that, you’ll get a failure, just like we see in the pictures.
But, let’s say the Chinese cranks are a better materiel. Now you’ve added a bunch of stroke (changes the resonance frequency) AND the materiel is different and that changes the resonance frequency. And the damper was in no way tuned for that.
The OP also changes to a hypereutectic piston and THAT changes the RF of the assembly. I’m betting the damper wasn‘t tuned for all that.
What about the connecting rods? If those are a different materiel than the OE used, then that is another change in RF that the damper can’t deal with.
Even a change in gear ratio affect damper tuning because the elastomer damper (especially bonded type the OP used) has such a narrow range that a change in cruise RPM can put the crank assembly into a place where it is constantly excited and you start to get fractures and then failures.
I can’t count how many cranks I have wet mag’d but it’s enough to know what I’m looking at.
The biggest crank breakers ever was the Moroso solid aluminum hub. That piece of **** broke more cranks than all other shitty dampers combined. And Moroso sold the hell out of that junk and guys bought them because they were the lighted damper on the market.
What good is light if it kills the crank on a regular basis?
That crank failure IS a damper failure. The damper was totally incapable of controlling the harmonics off the crank for whatever reason. That’s the fact.
Can we say the Eagle crank is more prone to failure than other Chinese cranks because of where the lightning hole in the rod throw is in a different place or it’s too big or both? Certainly. But thats not why it failed.
Rat Bastid
Dunamis Metron
I did read it. My point was it would fail eventually anyway.
Unless guys are regularly maging their cranks on a regular basis they won’t see the signs of the crank being under serious distress. I‘m betting if he gets the crank mag’d now he will see a bunch of little fractures.
And, that’s an issue with cast cranks. Once a fracture starts it fails rather quickly where a forged crank will fracture and not fail for a much longer time.
Ive see damper failures so bad that when the crank finally failed it had fractured the block. The harmonics were so bad that they fractured the bulkheads at the outer main bolts.
And that was a KB billet crank and BBC Bow tie block. And the crank killing Moroso aluminum hub.
Bobzilla
Well-Known Member
Those marks are for identifying factory cranks. The aftermarket forged cranks I have seen do not have those on them. They probably started out like that, but they cleaned up and then maybe shot peened. See my next post.
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Dale Davies
Well-Known Member
That must have been the 2.8 V6 in the S15. My ex traded a fairly new at the time Mustang for the new Fiero GT with the 2.8 V6. That crank broke. The General's warranty repaired it and she went back to a Mustang. The early 2.8 V6 had a design flaw. The General fixed the problem and no more problem. They even came out with 3.1 and 3.4 variants. What was the cost of developing and emissions certifying those engines. They already had the Buick designed V6 that was pretty bullet proof
Bobzilla
Well-Known Member
Hopefully OP can get more pictures when he takes his apart and we can see more of it.
Here is an Eagle forged 4” crank with 360 mains. Not sure you can see it in my pictures, but the rod throw lightening hole is not drilled straight through. It looks like it goes from one side about half way and then the other side and meets up with the first hole/side. Problem is, the two paths are angled and there is a big *** ridge in the middle of the throw where they meet.
Editing to add: I don’t think any damper currently made is going to save this one. Time will tell.
Here is an Eagle forged 4” crank with 360 mains. Not sure you can see it in my pictures, but the rod throw lightening hole is not drilled straight through. It looks like it goes from one side about half way and then the other side and meets up with the first hole/side. Problem is, the two paths are angled and there is a big *** ridge in the middle of the throw where they meet.
Editing to add: I don’t think any damper currently made is going to save this one. Time will tell.
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jos51700
Green Bearing thread connoisseur
LOL at this thread. NONE of you have enough info to determine what caused the OP's breakage. NONE.
You don't know the alloy, you don't know the grain size, you don't know the damper condition, you don't know the material hardness, you don't know the material toughness. None of you can categorize the breakage as a fatigue fracture or an outright overload failure. You don't even know if the material is cast iron, cast steel, or Long Wang's House Of Secret Recipe's menu number 5. Any inclusions in the material? Don't know. Any corrosion? Don't know. Any casting flaws? Don't know. Any non-metallic alloying ingredients? Don't know. Post-production treatments? Don't know. Proper installation? Don't know. Proper handling during shipping? Don't know. Crank condition prior to install? Don't know.
You don't (in regards to the parts involved) know ****.
That is 100% NOT what 'those marks' are for. The forging is a piece of metal that's red hot, mashed into a crank shape by a massive hammer. The thick lines are flash (i.e. pieces of the original material that aren't going to be part of the crank. They are usually sawn off cold or cut off with a blade while still red hot. The forged crank is stronger because the material is 'worked' which strengthens it (for a variety of reasons). Think bending a paper clip or coat hanger; it's really hard to re-bend it in the same place, because the material has work-hardened in the bend. You don't usually see the flash lines on aftermarket cranks because they take great care to clean them up.
Maybe this will help:
The thin lines are where the two halves of the casting mold come together. It's thin because the two mold halves have to be a tight fit or the MOLTEN metal will just run out before it cools in the shape of a crank. The metal is not worked, which means it's strength as-cast is less than when it is forged. Please note that some processes can be used to change the properties of the material after it is cast, such as surface hardening, annealing, peening, etc.
A raw crankshaft casting. Note the thin parting lines, and that they are not all in-plane with one another.
That hole is CAST off center because Wang Dong didn't notice (or care) that the core was off when it was cast. It is impossible to 'manufacture in' a feature like this on a forging, so holes like this are machined after on forgings, but the surface conditions inside the hole and at the edge of the bore give it away; it is not machined and therefore the poorly-located feature was cast in place.
When you run a Chinese crankshaft, you don't know fuckall about what you just bought, other than that it's SUPPOSED to be what you wanted. I've see Chinese castings with gravel, bolts, broken end mills, and huge voids in them that you don't find until you machine them. There's ZERO accountability and ZERO U.S.-level Q.C until it gets here. After it gets here, VERY few people do material certs or anything else to verify it is what it's supposed to be. They take your money and they laugh all the way to the bank.
You don't know the alloy, you don't know the grain size, you don't know the damper condition, you don't know the material hardness, you don't know the material toughness. None of you can categorize the breakage as a fatigue fracture or an outright overload failure. You don't even know if the material is cast iron, cast steel, or Long Wang's House Of Secret Recipe's menu number 5. Any inclusions in the material? Don't know. Any corrosion? Don't know. Any casting flaws? Don't know. Any non-metallic alloying ingredients? Don't know. Post-production treatments? Don't know. Proper installation? Don't know. Proper handling during shipping? Don't know. Crank condition prior to install? Don't know.
You don't (in regards to the parts involved) know ****.
That is 100% NOT what 'those marks' are for. The forging is a piece of metal that's red hot, mashed into a crank shape by a massive hammer. The thick lines are flash (i.e. pieces of the original material that aren't going to be part of the crank. They are usually sawn off cold or cut off with a blade while still red hot. The forged crank is stronger because the material is 'worked' which strengthens it (for a variety of reasons). Think bending a paper clip or coat hanger; it's really hard to re-bend it in the same place, because the material has work-hardened in the bend. You don't usually see the flash lines on aftermarket cranks because they take great care to clean them up.
Maybe this will help:
The thin lines are where the two halves of the casting mold come together. It's thin because the two mold halves have to be a tight fit or the MOLTEN metal will just run out before it cools in the shape of a crank. The metal is not worked, which means it's strength as-cast is less than when it is forged. Please note that some processes can be used to change the properties of the material after it is cast, such as surface hardening, annealing, peening, etc.
A raw crankshaft casting. Note the thin parting lines, and that they are not all in-plane with one another.
That hole is CAST off center because Wang Dong didn't notice (or care) that the core was off when it was cast. It is impossible to 'manufacture in' a feature like this on a forging, so holes like this are machined after on forgings, but the surface conditions inside the hole and at the edge of the bore give it away; it is not machined and therefore the poorly-located feature was cast in place.
When you run a Chinese crankshaft, you don't know fuckall about what you just bought, other than that it's SUPPOSED to be what you wanted. I've see Chinese castings with gravel, bolts, broken end mills, and huge voids in them that you don't find until you machine them. There's ZERO accountability and ZERO U.S.-level Q.C until it gets here. After it gets here, VERY few people do material certs or anything else to verify it is what it's supposed to be. They take your money and they laugh all the way to the bank.
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Duane
Well-Known Member
If I can add a few pointers here without ruffling any feathers, I build my stroker small block a few years ago with a scat forged crank and eagle H beam rods.
Eagle offers more than one horsepower rating for the same rods.
I was hesitant to use Eagle as I had heard some stories about their quality.
My local machinist also said that years ago when Eagle started out there were quality issues with the bore sizes. He said that years later they had really improved the big end machining and that that is no longer an issue.
During my build I over torqued a couple of rod bolts and discarded them. I called arp to get a few new bolts and found out that eagle also uses there own proprietary arp rod bolts
As well. I am a toolmaker by trade and I know how to perform precision measurements. I can tell you that the rods measured right on the money all around.
I cannot speak to the quality of the material of the rods.
The higher horsepower eagle rods use the arp 2000 material to eagles own design and you can only get those bolts from eagle.
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