Tap front of crank after broken bolt?
Tap front of crank after broken bolt? Long story short, my dumbass broke my harmonic balancer bolt off in my crank try to install my Powerbond underdrive pulley. (Another victim of LS1HowTo.com) I've went through numerous cobalt drill bits trying to drill it out and I'm sick of spending money of those. I've seen where some on here have tapped the unthreaded front part of the crank with success. I'm thinking of doing this. I just want some more feedback before I do, good or bad idea?
Also, I'm thinking of punning it for more insurance. Is that possible not using the stock pulley bolt size?
Also, I'm thinking of punning it for more insurance. Is that possible not using the stock pulley bolt size?
It has been done, the key to ensure the bolt preload remains the same. I would use the torque value of the ARP bolt to calculate the tension (preload) in the bolt and then use that value to find a new torque for the thread size you plan to use for the new larger bolt. This is key, if not I would pin the damper. It is the preload that keeps it from spinning on the crank.
It's where they say to use the crank bolt to pull the harmonic dampener onto the crank.
This is bad advice. NEVER use the crank bolt for this.
There's a bunch of inexpensive tools available: http://www.coloradospeed.com/tools-e...3-p-10976.html
This is bad advice. NEVER use the crank bolt for this.
There's a bunch of inexpensive tools available: http://www.coloradospeed.com/tools-e...3-p-10976.html
OK perfect I have an install tool so that makes me feel better.. want to make sure I wasn't missing anything that would cause this.. hopefully you get that bolt out of there.. are you using left handed bits by chance? If not try them, take the drill in slowly to build heat and intermittently apply pressure..
Trending Topics
Make a sleeve/bushing that will slip into the crank bore. That will align the drill w/ the center of the broken bolt. [Softest part of the fastener.]
A carbide drill, even a left hand one, if available, should do the trik.
A carbide drill, even a left hand one, if available, should do the trik.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Don't use the old bolt to push on during removal either. You need something solid that you can put on the face of the crank snout to push on. I use a short piece of solid steel round bar for this.
But I'd say these bolts are heat treated all the way through, the center is as hard as the shank.
Staying centered is important, once the bit wanders into the threads, it's impossible to get it centered again.
Well I won't have to worry about tapping the front of the crank because I kept messing with the broken bolt and got it out!
I started by slipping a 12mm socket in the end of the crank and used it as a guide to start drilling my hole. I ran my 5/16" drill bit through the socket and drilled my first hole. Then stepped up to a 3/8", then a 7/16", followed by 1/2". At that point I took a 5/8" chisel and basically made a cross in the remains of the broken bolt. After that I finished drilling with my 35/64" bit. Once that punched through the bolt started coming out in chunks. I finished by by running my tap in and out quite a few times and threaded my new balancer bolt all the way in. To get this done I used solid cobalt steel bits, plenty of Tapfree cutting fluid, WD40, Kroil, and compressed air in a can.
I started by slipping a 12mm socket in the end of the crank and used it as a guide to start drilling my hole. I ran my 5/16" drill bit through the socket and drilled my first hole. Then stepped up to a 3/8", then a 7/16", followed by 1/2". At that point I took a 5/8" chisel and basically made a cross in the remains of the broken bolt. After that I finished drilling with my 35/64" bit. Once that punched through the bolt started coming out in chunks. I finished by by running my tap in and out quite a few times and threaded my new balancer bolt all the way in. To get this done I used solid cobalt steel bits, plenty of Tapfree cutting fluid, WD40, Kroil, and compressed air in a can.
