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Discussion Starter #1
Had this car about a year. Procharger has been on around 5 months. Then today this





The balancer is an sfi nodular iron one, and I would never thought making only 12 psi this would have happened. Was an expensive lesson. Radiator, electric fan, water pump and pulley, lower hose, both belts, and of course the balancer and lower procharger pulley. Plus I'll probably pull the engine and pull the pan and look at the block and main caps/bearings

I was at the drag races, made one time trial fine, second one the belt came off. I got the belt from the track crew and it was beat up so I threw the spare on and went up for first elimination. I was towards the end and car lost power then starting shaking like crazy, then a loud thud under the floor as I drove over the balancer and pulley at around 100 mph. It sucked and could have ended up worse had it punctured the oil pan and gotten the tires oily.

Anyway thought I'd share
 

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Wow... sorry to see that. What happened to the balancer bolt?
 

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damn sorry to see, you were sneaking up on it so good. you were kinda pushin it a little hard though. whats the plan now? did it damage the supercharger?
 

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Discussion Starter #4
Wow... sorry to see that. What happened to the balancer bolt?
damn sorry to see, you were sneaking up on it so good. you were kinda pushin it a little hard though. whats the plan now? did it damage the supercharger?
When the balancer broke it shook like crazy and snapped the bolt off. The procharger is fine tho. I'll be getting an ATI balancer this time.
 

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Is it possible the balancer bolt wasn't seated against the balancer (i.e. bottomed out in the crank)? Were you using a mechanical belt tensioner - was the belt super tight? I don't think I've ever seen a balancer break like that before.
 

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Seems plausible with that thin material cross section and the distance of the blower belt from the crank. It's creating a large moment arm that places this area in rotational bending, a very common failure mode in industrial gearboxes with high radial loading. If the blower belt was tight and the serpentine belt also tight, AND the forces on the crank from those two belts are acting in the same direction, AND he's spinning this thing at 6000RPM.... i'm not surprised.
 

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Discussion Starter #10
Seems plausible with that thin material cross section and the distance of the blower belt from the crank. It's creating a large moment arm that places this area in rotational bending, a very common failure mode in industrial gearboxes with high radial loading. If the blower belt was tight and the serpentine belt also tight, AND the forces on the crank from those two belts are acting in the same direction, AND he's spinning this thing at 6000RPM.... i'm not surprised.
I've probably made 60 passes on this thing with the blower on it, not to mention a few thousand miles of driving it. The belts aren't overly tight as they use a spring loaded tensioner. I know that the balancer failed from getting pulled on. I called procharger to ask them what they thought, the person I talked to said " never seen that". Which I wasn't really looking for answers so much as needing the part number for the pulley so I can buy another one. Mostly I was sharing with folks so they could see what can happen and to not skimp on the balancer. The extra 200$ an ATI would have cost would have saved me a couple grand by the time I pull the engine out and check the block, crank, etc.
 

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I've probably made 60 passes on this thing with the blower on it, not to mention a few thousand miles of driving it. The belts aren't overly tight as they use a spring loaded tensioner. I know that the balancer failed from getting pulled on. I called procharger to ask them what they thought, the person I talked to said " never seen that". Which I wasn't really looking for answers so much as needing the part number for the pulley so I can buy another one. Mostly I was sharing with folks so they could see what can happen and to not skimp on the balancer. The extra 200$ an ATI would have cost would have saved me a couple grand by the time I pull the engine out and check the block, crank, etc.
Understood, and I wasn't speaking negatively about any of your setup. Just saying IF all of those factors added up, this type of failure doesn't surprise me, as I see it regularly in heavy industry. It's too bad you can't have the belts directionally opposed to somewhat cancel each other out.
 

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Discussion Starter #13
How was this balancer installed?

was it easy to put on, did you use a hammer, or installer?
Used an installer, no wasn't easy to put on. Torqued accordingly. I'm not looking for reasons why it happened. I know why, just showing people what can happen and to spend more money in key areas like the balancer especially when driving a blower.
 

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Not to beat a dead horse, but looking at the pictures, it doesn't look like the balancer was seated against the end of the crank - looks to be about 1/2" shy. The only time I've ever seen a balancer bolt break is when they're loose, not installed all the way or some part is defective. This looks like a ####ty balancer design to me; but it makes me want to check my powerbond.

FWIW, when I was designing my pulley setup, I took pains to make sure the accessory belt and the blower belt pulled about as opposite as practical.

Here's a pic from way back in the day:


The current drive is similar.
 

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Discussion Starter #15
Not to beat a dead horse, but looking at the pictures, it doesn't look like the balancer was seated against the end of the crank - looks to be about 1/2" shy. The only time I've ever seen a balancer bolt break is when they're loose, not installed all the way or some part is defective. This looks like a ####ty balancer design to me; but it makes me want to check my powerbond.

FWIW, when I was designing my pulley setup, I took pains to make sure the accessory belt and the blower belt pulled about as opposite as practical.

Here's a pic from way back in the day:


The current drive is similar.
I can see why you would think it's not seated, but when I pulled the timing cover it is seated against the timing gear and the gear is against the crank. I kind of thought the same thing. Everything checks out and all points to the balancer just giving up. My blower is driver side mounted, so it pulls at about a 2 o'clock angle, accesory drive pulls to the passenger side at about a 10 o'clock angle.


In the end, no big deal. I wanted more motor anyway. Looking at building a 427 windsor, with the best balancer I can buy and toss the D1 on it and let her rip
 

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Discussion Starter #17
you can tell by looking at it the metal crystalized causing it to break. cheap junk metal. what brand was it ?
Hate to say, but professional products. I have 2 of them on 2 different engines that I've had for awhile. Until this happened no problems. But I will be replacing the other one as well.
 

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If you have the crank out of the engine during inspection, or if building a new combo, do yourself a favor and get the crank double keyed. ATI sells a damper hub that is larger in diameter and double keyed along with a matching timing cover crank seal to go with the larger crank hub. With the double key and larger OD crank hub you can eliminate any potential crank or damper hub failures. Putting a chineese damper on an engine is just pulling the pin on the grenade. It is not a matter of if, but when. I use a dual keyed ATI damper on a quality crank and have spun the engine to 8,400 rpm (7,800 typical) peak at over 20 psi with no issues. 2 years of drag racing at over 1K HP. Do it right the first time. Your wallet will thank you.
 
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