Does the crankshaft have a keyway cut for the Harm. balancer?
02-21-2008, 07:15 PM
#1
Does the crankshaft have a keyway cut for the Harm. balancer?
I'm geting ready to order a new Powerbond balancer and have the old one replaced. The picture of the balancer shows a keyway cut in it.
Is the crankshaft also cut for a key? I'm thinking Not and that is why guys pin them.
Thanks
Is the crankshaft also cut for a key? I'm thinking Not and that is why guys pin them.
Thanks
02-21-2008, 07:28 PM
#6
Burning Brakes
02-21-2008, 07:35 PM
#7
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St. Jude Donor '03
Some aftermarket cranks will come with the keyway. The stock crank does not.
When you put on the Powerbond, it's the perfect time to pin it. But it's not a requirement either.
When you put on the Powerbond, it's the perfect time to pin it. But it's not a requirement either.
02-21-2008, 07:58 PM
#8
Team Owner
What's annoying is that, after a several-year hiatus from keying cranks, Chevy thought it better to release the LS-9 with a keyed crank. Many of the first C6's had the flying crank pulley syndrome that was all the rage.
Note the keyed crank, pulley and woodruff key in this exploded view of the LS-9.
Note the keyed crank, pulley and woodruff key in this exploded view of the LS-9.
02-21-2008, 08:20 PM
#10
Team Owner
Yes, that was a given for the LS-9. But, with the problems they had in the early LS-2, you'd think they would have moved there sooner. I have always used a keyed lock in my gear and pulley-based designs whenever possible. Press-fit designs have their place but not in high-powered, dynamic situations where inertial changes are violent, IMO.
02-21-2008, 08:44 PM
#11
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Yes, that was a given for the LS-9. But, with the problems they had in the early LS-2, you'd think they would have moved there sooner. I have always used a keyed lock in my gear and pulley-based designs whenever possible. Press-fit designs have their place but not in high-powered, dynamic situations where inertial changes are violent, IMO.
As for the LS2 issues, I forget, but what was the resolve for that? Was it deemed to be a balancer/crank fit issue, or a bolt/torque issue?
A loose balancer can be a chicken / egg scenario...did the bolt loosen first, allowing the balancer to spin/walk off, or did the balancer spin, and loosen the bolt with it when it spun?
Even a keyed balancer won't stay put if the bolt loosens and ejects itself.
02-21-2008, 09:04 PM
#12
Team Owner
The fix they used was to install a "friction washer" to prevent the bolt from backing out. There are a few reasons this could have occured, although the TSB described the problem as "The crankshaft balancer bolt may have become loose."
Who knows? If the press-fit was inadequate, the pulley could have begun to spin and walk forward creating a thrust force forward and the TTY bolt would have been overwhelmed by the forward pulley thrust, loosening it. If the bolt preload was inadequate, the pulley thrust would have created the same failure because it wasn't properly constrained.
C6 owners were reporting a washer with a frictional face was installed on their cranks along with a new pulley when the first one loosened on them. This sounds like a preventative measure to combat the pulley spinning/walking on the crank. In general it worked but a couple of members reported multiple failures before the issue was resolved. I remember that a few C6 owners requested that their crank pulleys be pinned to the crank using the method we use but the dealers refused and carried out the TSB fix.
Who knows? If the press-fit was inadequate, the pulley could have begun to spin and walk forward creating a thrust force forward and the TTY bolt would have been overwhelmed by the forward pulley thrust, loosening it. If the bolt preload was inadequate, the pulley thrust would have created the same failure because it wasn't properly constrained.
C6 owners were reporting a washer with a frictional face was installed on their cranks along with a new pulley when the first one loosened on them. This sounds like a preventative measure to combat the pulley spinning/walking on the crank. In general it worked but a couple of members reported multiple failures before the issue was resolved. I remember that a few C6 owners requested that their crank pulleys be pinned to the crank using the method we use but the dealers refused and carried out the TSB fix.
02-21-2008, 09:12 PM
#13
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St. Jude Donor '03
The fix they used was to install a "friction washer" to prevent the bolt from backing out. There are a few reasons this could have occured, although the TSB described the problem as "The crankshaft balancer bolt may have become loose."
Who knows? If the press-fit was inadequate, the pulley could have begun to spin and walk forward creating a thrust force forward and the TTY bolt would have been overwhelmed by the forward pulley thrust, loosening it. If the bolt preload was inadequate, the pulley thrust would have created the same failure because it wasn't properly constrained.
C6 owners were reporting a washer with a frictional face was installed on their cranks along with a new pulley when the first one loosened on them. This sounds like a preventative measure to combat the pulley spinning/walking on the crank. In general it worked but a couple of members reported multiple failures before the issue was resolved. I remember that a few C6 owners requested that their crank pulleys be pinned to the crank using the method we use but the dealers refused and carried out the TSB fix.
Who knows? If the press-fit was inadequate, the pulley could have begun to spin and walk forward creating a thrust force forward and the TTY bolt would have been overwhelmed by the forward pulley thrust, loosening it. If the bolt preload was inadequate, the pulley thrust would have created the same failure because it wasn't properly constrained.
C6 owners were reporting a washer with a frictional face was installed on their cranks along with a new pulley when the first one loosened on them. This sounds like a preventative measure to combat the pulley spinning/walking on the crank. In general it worked but a couple of members reported multiple failures before the issue was resolved. I remember that a few C6 owners requested that their crank pulleys be pinned to the crank using the method we use but the dealers refused and carried out the TSB fix.
I kinda thought they were just having dealers install and torque a new bolt. (which we both know wouldn't have worked once the pulley spun).
