LLY: Another broken crank this weekend

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schulte

New member
Jul 31, 2010
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Finally broke my crank this weekend. Fully built LLY, a couple dozen hooks on it, about 40-50,000mi on it daily driving (plenty of hammering on it), light towing/nothing over 8,000lbs.

This was with full billet main caps, studs, girdle, SoCal balancer and flywheel, and Fingers pistons (after I cracked my last pistons). With dual fueler and big twins, the best I had had dynoed was 982hp with a boost leak, and a bunch of other dyno pulls in that same range.

Driving around town not ripping on it, parked at my friends house and when I got in and started it up about 15 min later I noticed a loud knocking, it still drove but I pulled over and found balancer to be loose.

Will get it torn down and see what came apart but I know at least the crank is done...:D
 
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schulte

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Jul 31, 2010
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hondarider552 said:
Damn, tis the season.... :(:(


Your bottom end just proves further more a girdle doesn't do squat. :eek:
Click to expand...

I originally put the girdle on because I found some evidence of cap walk with just the billet caps, and I put this motor together planning on beating on it without giving a single ****.

I'm confident the girdle has helped keep everything together up until now, and may have saved the block. I was able to drive it about 15-20 miles or so even with the broken crank, we'll see how it looks when I pull it down.

But I agree, the bottom end itself obviously didn't save the crank from breaking, which seems to me like one more point for harmonics causing breakage not just raw power.
 
Burn Down

Burn Down

Hotrodder
Sep 14, 2008
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Boise Idaho
schulte said:
I originally put the girdle on because I found some evidence of cap walk with just the billet caps, and I put this motor together planning on beating on it without giving a single ****.

I'm confident the girdle has helped keep everything together up until now, and may have saved the block. I was able to drive it about 15-20 miles or so even with the broken crank, we'll see how it looks when I pull it down.

But I agree, the bottom end itself obviously didn't save the crank from breaking, which seems to me like one more point for harmonics causing breakage not just raw power.
Click to expand...

I'm convinced it's harmonics that are breaking cranks... Another 1200 hundred bucks (AF cam) into the endless black hole called built engines...

Sorry the crank went. Keep us updated on the piston condition, I'm betting Fingers has that end figured out for us though:thumb:
 
TROJAN366

TROJAN366

Gold Rush
Jan 13, 2012
2,474
1
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MASS
This is becoming way too common. I really hope the AF cams fix the problem for good and they don;t all break a year from now!
 
S

schulte

New member
Jul 31, 2010
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Here's some pics:

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ALLY Fox

ALLY Fox

Old Man Truck
Dec 14, 2010
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Oregon 7S5
I can't imagine being able to start and drive 15-20 miles with that going on! That's gotta be harsh on main webs!!
 
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schulte

New member
Jul 31, 2010
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ALLY Fox said:
I can't imagine being able to start and drive 15-20 miles with that going on! That's gotta be harsh on main webs!!
Click to expand...

I first noticed a vibration and didn't really think much of it; it just seemed like a bumper rubbing on something or a body panel vibrating, and this truck has Merchant mounts and plenty of miles so I'm no stranger to vibrations.

After 10 miles or so I figured I'd get out and check, the balancer seemed to be moving around but I couldn't tell if that was just because it has a counterweight on one side so it appeared to be moving, or if it was actually moving.

At that point I shut it down and pulled the belt, and was able to shake the crank. It was a Sunday night and I was only a few miles from home and I didn't really feel like waiting for a tow so I started it back up and drove it.
 
TheBac

TheBac

Why do I keep doing this?
Staff member
Apr 19, 2008
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schulte said:
I don't really mind the time and labor on my part, it's just the repeated thousands of $$$ that gets old fast.
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Thats what I meant. None of us have cubic dollars or a huge money tree.

At least, threads like these help everyone ID problems....and hopefully figure out solutions. Good luck to you.
 
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