Harmonic Balancer came off!!

[RVC]

Well I had a not so good weekend with the Nova. While driving down the road the crank bolt snapped and my balancer, v-belt pulley, and blower pulley came off at 30mph!:mad: Does anyone have any good Ideas on how to get the bolt out without damaging the crank? Also is the balancer safe to use until my new one comes and what kind of bolt should I use to replace the old one? Any input would help alot. Thanks.

[Nova_Power4]

l duno dude, but l usly drill out where the bolt broak then get new bolt and lock tight it. use preffbly grade 8 hardwear

[mrtimstik]

Just a thought....

Is there anything of the broken bolt sticking out? Tap it around a circle with a sharp center punch to remove.

If not...Remove everything in front of the work area to give you a clean shot straight at the broken bolt with a drill. Get a small drill and drill it through the center of a wooden dowel. Sandpaper the diameter down while spinning so it will just fit into the minor diameter of the bolt hole. Have a friend help look for alignment and drill a pilot into the bolt. Choose the correct Easy-Out and back the bolt out.

If nothing is sticking out and the bolt is flush with the crank snout I would Dremel a dot in the center with a carbide burr and drill out from there. Have a friend help with alignment when drilling. Best of luck.

[74sleeper]

Craftsman 52152 drill-out power extractor. For extracting 1/4 to 1/2 bolts. These work well and only cost about $40.00

[Real McCoy]

Why would the bolt break? That is not normal. If it broke the threaded part left in the crank should be easy to unscrew so maybe use a left hand drill bit. Since there is no load on the bolt to break it I'm thinking the bolt was damaged during installation so that may be a problem requiring a homemade fixture to alighn the hole and keep the drill bit square and level while you drill it. A sleeve that is snug on the crank OD with a neck the size of the drill to keep it square. RM

[RVC]

Why would the bolt break? That is not normal. If it broke the threaded part left in the crank should be easy to unscrew so maybe use a left hand drill bit. Since there is no load on the bolt to break it I'm thinking the bolt was damaged during installation so that may be a problem requiring a homemade fixture to alighn the hole and keep the drill bit square and level while you drill it. A sleeve that is snug on the crank OD with a neck the size of the drill to keep it square. RM

I'm not sure what would cause the bolt to break. Maybe the alignment keys weakened and sheared off causing the balancer to spin on the crank in turn snapping the bolt? I hope this $hit does not happen again!

Thanks to everyone that is helping me, I am probably going to have to try all the methods knowing my luck...nothing is easy!

[dreshersun]

That blower set-up put's alot of stress in the crank snout, probably worked it's way loose & finaly snapped. If you can successfully remove the bolt special order or have your a machine shop make you the hardest bolt they can. I have actually seen the crank snout's break off before the crank key breaks.

[Seattle_Mike]

l duno dude, but l usly drill out where the bolt broak then get new bolt and lock tight it. use preffbly grade 8 hardwear

Dang....wat langwidge ist dat? :confused:

[Real McCoy]

I totally read right past BLOWER PULLEY when I read the origional post. Blower will bust a bolt in a skinny minute. My bad but if you got to drill it out my suggestion will work if needed. We double key the crank for blowers and use Supertanium bolts that we properly torque. Cast cranks have broken off as already stated. RM

[RVC]

I totally read right past BLOWER PULLEY when I read the origional post. Blower will bust a bolt in a skinny minute. My bad but if you got to drill it out my suggestion will work if needed. We double key the crank for blowers and use Supertanium bolts that we properly torque. Cast cranks have broken off as already stated. RM

How does a blower snap a bolt so easy if it's keyed? My crank is double keyed and it's an Eagle 4340 forged unit. The crank looks good. Where can I get one of these Supertanium bolts? Thanks for the great info!

[stock z/28]

Just my view on this, but I hardly ever see an instance that a balancer comes off a crank like this that the crankshaft is not somewhat damaged.


If it were me, I would carefully check the crank snout for wear or damage. The balancer is a slight press fit and for it to come loose and break the bolt is not a good sign.

I would be afraid that if you just rethread the crank and install a new balancer it may fail prematurely if the snout is damaged, especially with the blower. As Joe said the blower adds a bunch of problems to the crank snout and balancer relationship anyway.



Good Luck

Jeff

[Dan_Lebherz]

Is it possible that the bolt used was too long and was bottoming out inside the end of the crank?

[RVC]

Is it possible that the bolt used was too long and was bottoming out inside the end of the crank?
Good idea, that may have been the problem. If it was I would be suprised cause there was a great deal of detail put into this engine, but wierder things have happned.:beat:

[RVC]

Just my view on this, but I hardly ever see an instance that a balancer comes off a crank like this that the crankshaft is not somewhat damaged.



If it were me, I would carefully check the crank snout for wear or damage. The balancer is a slight press fit and for it to come loose and break the bolt is not a good sign.

I would be afraid that if you just rethread the crank and install a new balancer it may fail prematurely if the snout is damaged, especially with the blower. As Joe said the blower adds a bunch of problems to the crank snout and balancer relationship anyway.


Good Luck

Jeff
I looked at the crank snout and everything looks good. Before I do any re-installing of any new parts I'll double and triple check it. Even the keyways look good, nice and straight. What exactly should I look for besides the obvious? Thanks for the help.

[stock z/28]

If it were me I would pull the timming cover and check it very close with a mic..

I hope it is fine, but I dont think I have ever encountered a crank that was not damaged when balancer came or broke.


My "guess" would be some harmonic? or vibration? possible side load? caused the balancer to move around and thats what sheared the bolt.

I try and fit these balancers (for a blower) at about .0015" to .0017" interference with a good strait crank snout. Any tighter and I am bit afraid of cracking the balancer in a key way.

A lot of serious guys use a crank with a big block snout with double keys and a 1/2" or sometime 9/16 bolt.


Im just guessing at this stuff, and I really hope you are in good shape, but if the crank is damaged I would think you would be better to fix it now and not gamble on it.

If its 4340 I have tig welded worn snouts (they sell carbon keys to keep from damaging the keyways) and reground the snout.


Like I said good luck!

Jeff

[Mike Goble]

Dang....wat langwidge ist dat? :confused:

Prolly sum nu werds u dono....