I know I’m F’d, but how bad I don’t know yet. While installing an ATI harmonic balancer I broke the ARP damper bolt in the end of the crankshaft while trying to seat the balancer. The interference fit on these things is ridiculous (.009”) and I kept thinking it needed to be deeper and then the bolt exploded. Any suggestions short of pulling the motor?, that is already being discussed. Has anyone seen or heard of anything like this? To add insult to injury, I dented the top of the left fender with the breaker bar on my way down to sitting my *** on the floor.

 

Sorry, that sucks.

Without clamping load behind the bolt head, wouldn't the threads be relaxed and easy to spin out?

 

I don’t know yet. I was so frustrated and angry with myself that I just packed up and went inside. I am hoping that will be the case, but it is 4 inches inside face of the damper.

 

Man that sucks. Even if you remove the balancer, the piece in the crank will be difficult to remove. Since the top of the broken piece is jagged, you will not be able to drill it for an easy-out. The drill bit would just keep slipping off-center. Assuming you could find a drill bit long enough.

Good luck,

Fred

 

Thanks Fred. To exasperate the situation, the engine is in the car and the anti-sway bar is in front of the center of the balancer. I have to jack the engine up 6 inches to gain access to the center of the damper, but can’t get my head in there to evaluate the damage. I’ll need all of the luck I can get.

 

Why were you using that bolt to seat the damper?? That's what an installer tool is for.
I am surprised that a ARP bolt broke though...

 

I did use an installation tool to draw the damper on to the point that I could turn the draw nut with a wrench. Unfortunately I felt it needed more and broke out the 3 foot breaker bar and used the bolt to draw it in more. I should have just torqued it to 235 ft/lb and been done with it. I also thought that there would be no way for me to break an ARP bolt this size. We now know that it can be done, I just didn’t want to be the guy to prove it.

 

Well, you do have something that mates up perfectly to the broken piece in the crank....

Maybe grind off the threads from the broken piece and put a small dab of epoxy or JB weld on the end. Slip it into the crank and mate up the ends and let it set. Then turn it out.

I don't know if it will work but trying is free. Just don't JB Weld it to the crank

 

Look how far those threads have stretched! Wowza
had to have been some serious tq on the bolt to do that.
could make a sleeve/bushing to fit down the balancer to center a reverse drill bit

 

^^^ That's a better idea. The more I think about it the two bolt halves won't make contact because they have shrunk.

 

Best idea I have been given so far. A friend suggested the reverse drill bit, but the centering bushing is brilliant. Thanks.

 

X2

 

Centering bushing is great idea.

Fred

 

Hopefully this will get it done

I was able to look inside at the end of the bolt and it appears to have a thread exposed, so it didn’t snap off inside the threaded hole. This is encouraging so I found a 1/4 LH drill bit and extension and made a wooden drill guide that fits in the end of the balancer. It would be great if the drill bit is successful in backing the broken bolt out, but I have an extractor on hand just in case. I will find out tomorrow and report back here with the results. On a side note: the damaged area on top of the fender is a chip in the clear coat. No dent and the paint was untouched. That should be an easy repair. Wish me luck.

 

We're all crossing our fingers...

 

SUCCESS!!!
I can’t believe I got this out without having to remove the balancer. It took over 3 hours turning it by hand with a pair of needle nose pliers and a magnetic pickup tool. The LH drill bit and wooden guide would have worked perfectly if not for the shaft spinning in the chuck of the 90 degree drill. The important thing is that it came out. That bolt has more stretch than a cheese pizza, it’s amazing that I got it out. I want to thank everyone here for talking me off the ledge. I was so stressed out over this. I will install the new bolt when it arrives and move on.

 

That is great news. Enjoy your success.

Fred

 

Excellent. I love a story with a happy ending...

 

Congratulations on getting that broken bolt out of the crankshaft!

 

Dodged the bullet on this one. Good job.

 

Doesn't look like you used any ARP lube anywhere on that bolt. Supposed to use it on the threads and both sides of that washer. I've taken mine out a bunch and crank it down to 240 ft/lbs every time without issue.

 

Why in the world would it need to be 240 ft.-lbs.???...

 

Because that's what ARP calls for. Well 235 ft/lbs

For an LS engine with an ARP crank bolt, the correct torque is 235 ft-lbs,

 

HOLY SMOKES! I am just seeing this thread now. It was quite a roller coaster ride to read about all of that, and I want you to know I came so super close to being in this same scenario last year. I put a new ATI super-damper on the 406 this past winter and could NOT get it to seat. I had full body force on it and was ready for a catastrophe.
I used the installer tool and everything. Failed multiple days in a row. One day I took the plunge and read about heating up the damper to a certain degree in the oven, and freezing the crank snout, so I took my freakin nitrous bottle and shot it at the crank snout for a while. then used the tool and some lube and finally finally got it to seat in there. I also deburred the key and keyway a slight chamfer too. what a wild experience you had; real glad you got it removed. Next... whats your plan for getting things back together?


the saga of my damper situation begins at post #563 on Dec 24th 2024 at this link:
https://www.thirdgen.org/forums/tech...nstall-12.html

 

They usually need a light hone job before installing so they just slip on without issue. The machine shop did it all for me when they assembled my 370 short block. Just baked the hub for 20 minutes on 350* and it went on smooth as butter

 

Here’s a follow up. I ordered a new ARP bolt and torqued it to 235 ft/lb. It turns out that the balancer was fully seated. If you look inside the balancer without the bolt installed the end of the crankshaft is supposed to be an 1/8 inch recessed in the hub ( the original balancer was like that). The instructions from ATI specifically stated “Do Not resize or defeat the interference fit of the hub”. I also did not want to heat the balancer and risk damaging the elastomer ring. The belts line up and I am waiting for the steering rack and pump to come back from Turn One before I can put it back together. The chip in the paint turned out to be just the clear coat and I was able to fill and color sand it. I got really lucky and I don’t want to ever go through this again.

 

Are you using a stock crank with no key?? I have an LSA crank that's keyed and a quick hone job makes life much easier. I don't see how a guy could damage to elastomer rings when all you need to do is heat the hub up separately from the damper, install the hub then bolt the damper on

 

That's a change since I last bought an ATI damper about 8 years ago. Back then the hubs were shipped a little tight and they expected you to hone the ID of the hub to proper interference fit to the measured OD of your crank.

My LS7 crank was on the high side of the OD spec which required that I hone the ATI hub or it would have been waaaaay too tight

 

Glad you got it taken care of.
That could have been a real nightmare..

 

I have an Eagle 4” stroker crank with a key. The interference fit on the hub was .007, within the recommended .006-.009 range, so it didn’t require honing. The A/C pulley is mounted on the back of the hub and uses the three bolts through the face of the damper to attach it, basically sandwiching the hub so I couldn’t install the hub to the crank before assembling the balancer. The fact that I was doing all of this in a rented space with basic hand tools and no air with the engine in the car also complicated things.

My tolerance range was .006-.009. I can’t imagine trying to press this on at the high end of that range.

 

Are we sure that decimal is not supposed to be one more place to the left as in .0006-.0009 inch interference fit? I have an ATI damper destined for my forever in the corner of the garage project and that range is what I remember.

M

 

This is a very good question. There is a big difference between .0006-.0009" and .006-.009" interference!