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View Full Version : 91 sc Harmonic Balancer possibly Broke



hmeric7
09-28-2010, 11:44 PM
hey guys. new to this forum but an old member of tccoa. i just got a 91 sc from a my friend that he had bought off someone and hasent had time to look at it. he beilives that the harmonic balncer broke or that the crnak has broke right at the fornt of the block. he never really got into tearign it down to see what the problem was so im not sur eyet eithe rbut befor ei get the car to my place i was wondering wehat you guys thoguth was the likely problem

oppie
09-29-2010, 12:08 AM
What problems is he having to think that

Surgin
09-29-2010, 08:42 AM
Look inside the balancer and see if the bolt head is there.

Justin

90turbo1
09-29-2010, 12:42 PM
Sorry to jack this thread


but does arp make a better bolt and washer for this application. i have seen mustangs running a arp bolt on the balancer.

does the balancer break or does the bolt break then the balancer.

anlo
09-29-2010, 02:31 PM
a thought came to me last night -- the key on the crankshaft does not protrude to the end of the crankshaft it stops with about an inch or so to the end which is right where the shear occurs.. with all the weight at the pully and balancer end theres no key to aid the support of the balancer itself and with the aluminum used inside causes a twisting to the heaviest part hence a clean shear leaving snout / sleeve intact due to the keyway in place. as im in the middle of a second balancer job with the same break right where key ends. i feel if key went the length of crank shaft this wouldnt be such a popular issue.. the key way is cut the entire length of i.d. on balancer.
just a thought to ponder would any one else like to agree with this senario ?

Blackened300A
09-29-2010, 05:18 PM
a thought came to me last night -- the key on the crankshaft does not protrude to the end of the crankshaft it stops with about an inch or so to the end which is right where the shear occurs.. with all the weight at the pully and balancer end theres no key to aid the support of the balancer itself and with the aluminum used inside causes a twisting to the heaviest part hence a clean shear leaving snout / sleeve intact due to the keyway in place. as im in the middle of a second balancer job with the same break right where key ends. i feel if key went the length of crank shaft this wouldnt be such a popular issue.. the key way is cut the entire length of i.d. on balancer.
just a thought to ponder would any one else like to agree with this senario ?


I agree. The added pressure from the S/C and all the accessories would make it likely that it would be the weak spot of the dampener. Its also possible that its over-tightened and instead of the bolt having a little room to stretch, its just breaking the head off. Do you guys use a TTY bolt or its a hardened re-usable crank bolt?