ARP Harmonic Balancer Bolt Size
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
Likes: 0
ARP Harmonic Balancer Bolt Size
Hi Folks,
Long story short, Does anyone know the socket size of the ARP Harmonic Balancer bolt for the ls3 motor?
(long version)
i THINK someone installed an underdrive HB on my 08 C6 and i KNOW they used an ARP bolt (can see the stamping on its face)
Chasing squeaks, removed all belts, replaced all pulleys, was fiddling around with HB and noticed that it was 'loose' on the crankshaft (about 1mm of play)
I know there are many (some very bad) reasons this could happen but want to start with the simplest explanation, a loose HB bolt. Dont seem to have the right sized socket to try and snug it up a little. Anyone who has done this know the right size? Cant yet find it on the interwebs.
I plan on taking the car in to have the HB replaced with a new one along with a new HB ARP bolt but want to fiddle with it first before driving it in.
thanks!
Brad in Atlanta
Long story short, Does anyone know the socket size of the ARP Harmonic Balancer bolt for the ls3 motor?
(long version)
i THINK someone installed an underdrive HB on my 08 C6 and i KNOW they used an ARP bolt (can see the stamping on its face)
Chasing squeaks, removed all belts, replaced all pulleys, was fiddling around with HB and noticed that it was 'loose' on the crankshaft (about 1mm of play)
I know there are many (some very bad) reasons this could happen but want to start with the simplest explanation, a loose HB bolt. Dont seem to have the right sized socket to try and snug it up a little. Anyone who has done this know the right size? Cant yet find it on the interwebs.
I plan on taking the car in to have the HB replaced with a new one along with a new HB ARP bolt but want to fiddle with it first before driving it in.
thanks!
Brad in Atlanta
Last edited by lowerlattitudes; May 19, 2017 at 03:20 PM. Reason: misspelling
Burning Brakes
Joined: Jan 2017
Posts: 1,122
Likes: 199
From: TX
I do not know the size of the bolt but a warning.
Be VERY careful with messing with that bolt. It could have not been installed correctly which when you try to tighten it or loosen it you could be dealing with cross threading or who knows what else. It could end up costing a lot of money if the crank threads are messed up bad enough.
Be VERY careful with messing with that bolt. It could have not been installed correctly which when you try to tighten it or loosen it you could be dealing with cross threading or who knows what else. It could end up costing a lot of money if the crank threads are messed up bad enough.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
Likes: 0
I do not know the size of the bolt but a warning.
Be VERY careful with messing with that bolt. It could have not been installed correctly which when you try to tighten it or loosen it you could be dealing with cross threading or who knows what else. It could end up costing a lot of money if the crank threads are messed up bad enough.
Be VERY careful with messing with that bolt. It could have not been installed correctly which when you try to tighten it or loosen it you could be dealing with cross threading or who knows what else. It could end up costing a lot of money if the crank threads are messed up bad enough.
Burning Brakes
Joined: Jan 2017
Posts: 1,122
Likes: 199
From: TX
Also, just found...
According to this guide the OEM bolt is 24mm; http://ls1howto.com/index.php?article=1
I would imagine it is the same but you never know.
According to this guide the OEM bolt is 24mm; http://ls1howto.com/index.php?article=1
I would imagine it is the same but you never know.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
Likes: 0
Also, just found...
According to this guide the OEM bolt is 24mm; http://ls1howto.com/index.php?article=1
I would imagine it is the same but you never know.
According to this guide the OEM bolt is 24mm; http://ls1howto.com/index.php?article=1
I would imagine it is the same but you never know.
Drifting
Joined: May 2015
Posts: 1,525
Likes: 391
From: Martinez CA
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
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Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
Hi Folks,
Long story short, Does anyone know the socket size of the ARP Harmonic Balancer bolt for the ls3 motor?
(long version)
i THINK someone installed an underdrive HB on my 08 C6 and i KNOW they used an ARP bolt (can see the stamping on its face)
Chasing squeaks, removed all belts, replaced all pulleys, was fiddling around with HB and noticed that it was 'loose' on the crankshaft (about 1mm of play)
I know there are many (some very bad) reasons this could happen but want to start with the simplest explanation, a loose HB bolt. Dont seem to have the right sized socket to try and snug it up a little. Anyone who has done this know the right size? Cant yet find it on the interwebs.
I plan on taking the car in to have the HB replaced with a new one along with a new HB ARP bolt but want to fiddle with it first before driving it in.
thanks!
Brad in Atlanta
Long story short, Does anyone know the socket size of the ARP Harmonic Balancer bolt for the ls3 motor?
(long version)
i THINK someone installed an underdrive HB on my 08 C6 and i KNOW they used an ARP bolt (can see the stamping on its face)
Chasing squeaks, removed all belts, replaced all pulleys, was fiddling around with HB and noticed that it was 'loose' on the crankshaft (about 1mm of play)
I know there are many (some very bad) reasons this could happen but want to start with the simplest explanation, a loose HB bolt. Dont seem to have the right sized socket to try and snug it up a little. Anyone who has done this know the right size? Cant yet find it on the interwebs.
I plan on taking the car in to have the HB replaced with a new one along with a new HB ARP bolt but want to fiddle with it first before driving it in.
thanks!
Brad in Atlanta
BTW, I have seen one of those ARP bolts fly out the bottom of an LS1 Camaro before. I don't like using them unless you have an aftermarket balancer that's pinned or keyed, and even then I would use a shitload of Red Locktite on the threads. The stock bolt is not reusable, but is very cheap, so prefer to use one of those with the stock balancer, although I'm currently running the IW bolt that came with my IW balancer.
I'm hoping that is only the bolt that's loose and not the actual balancer.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
Likes: 0
If the harmonic balancer (as opposed to the bolt) is loose (even just 1mm of play) on the crank snout, then you have much bigger problems, and tightening the bolt won't help now. If that is the case, you need to pull the steering rack and get the balancer off to see if the crank snout is damaged. The balancer is installed with an interference fit on the crank, and the bolt is there to keep the balancer from vibrating loose.
BTW, I have seen one of those ARP bolts fly out the bottom of an LS1 Camaro before. I don't like using them unless you have an aftermarket balancer that's pinned or keyed, and even then I would use a shitload of Red Locktite on the threads. The stock bolt is not reusable, but is very cheap, so prefer to use one of those with the stock balancer, although I'm currently running the IW bolt that came with my IW balancer.
I'm hoping that is only the bolt that's loose and not the actual balancer.
BTW, I have seen one of those ARP bolts fly out the bottom of an LS1 Camaro before. I don't like using them unless you have an aftermarket balancer that's pinned or keyed, and even then I would use a shitload of Red Locktite on the threads. The stock bolt is not reusable, but is very cheap, so prefer to use one of those with the stock balancer, although I'm currently running the IW bolt that came with my IW balancer.
I'm hoping that is only the bolt that's loose and not the actual balancer.
Yah, as mentioned, regardless of current conditions, I AM swapping the current balancer out. I just want to see if the bolt is loose before i take it to American Corvette to get the work done. Trying to mitigate any additional damage if I can.
I guess I will find out in about two weeks, when Jim can get to it, what is really going on, for now, it will stay parked in the garage.
As for the original question, the ARP bolt is most definitely 1 1/16 12 point.
Thanks for all the input folks, I will give you guys a post findings update on what he finds.
Cheers,
Brad
Le Mans Master
Joined: Apr 2013
Posts: 5,376
Likes: 1,118
Okay, no worries. I had no idea what size the ARP bolt is, but a quick google search revealed that it is in fact 1 1/6" 12-point:
http://arp-bolts.com/kits/Make.php?_...&_EngModelID=*
But the simple point I was trying to make is that if your balancer can shake, move, wobble or turn, at all, on the crank now, then you shouldn't even start the motor again to drive the car anywhere. Tightening the bolt won't help, if the balancer isn't keyed the crank snout, it will spin on the crank snout. I'm not trying to be a dick, just trying to help you avoid any further damage.
http://arp-bolts.com/kits/Make.php?_...&_EngModelID=*
But the simple point I was trying to make is that if your balancer can shake, move, wobble or turn, at all, on the crank now, then you shouldn't even start the motor again to drive the car anywhere. Tightening the bolt won't help, if the balancer isn't keyed the crank snout, it will spin on the crank snout. I'm not trying to be a dick, just trying to help you avoid any further damage.
Melting Slicks
Joined: Aug 2004
Posts: 2,906
Likes: 228
From: Oakbank Manitoba
It's a metric fastener so the socket size is 27mm. A 1 1/16" just happens to be almost identical in fact it fits a little bit better. I just installed a ARP bolt on my LS9 ATI damer.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
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Okay, no worries. I had no idea what size the ARP bolt is, but a quick google search revealed that it is in fact 1 1/6" 12-point:
http://arp-bolts.com/kits/Make.php?_...&_EngModelID=*
But the simple point I was trying to make is that if your balancer can shake, move, wobble or turn, at all, on the crank now, then you shouldn't even start the motor again to drive the car anywhere. Tightening the bolt won't help, if the balancer isn't keyed the crank snout, it will spin on the crank snout. I'm not trying to be a dick, just trying to help you avoid any further damage.
http://arp-bolts.com/kits/Make.php?_...&_EngModelID=*
But the simple point I was trying to make is that if your balancer can shake, move, wobble or turn, at all, on the crank now, then you shouldn't even start the motor again to drive the car anywhere. Tightening the bolt won't help, if the balancer isn't keyed the crank snout, it will spin on the crank snout. I'm not trying to be a dick, just trying to help you avoid any further damage.
not at all! I appreciate the feedback. Matter of Fact may just have trailered to a local mech instead of risking a spin out of the HB.
Definitely off the road until I get it fixed. And only 33K
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
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Pro
Joined: Apr 2017
Posts: 681
Likes: 99
From: Cincinnati
I just installed mine yesterday with an 1-1/16. Hopefully they didnt run the crank on with the ARP bolt or the old stocker and messed up the threads in the crank. I got the install tool for the crank to avoid any issues like this, hopefully it all works out for you.
Last edited by EviLS7; Jun 6, 2017 at 12:49 PM.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
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Update on Bolts and what not
Hey Folks,
Just a quick update on my loose HB thread. The good guys at AC in powder springs confirmed the existing balancer was bad. Almost complete rubber separation between the two sections. I do not know the brand (yet) but it is an under-drive pulley.
They also confirmed that previous work has been done on the car's bottom end. Believe the crankshaft was replaced at some point.
The ARP bolt I purchased does NOT work, it is to short to catch the threads of the crankshaft so no idea of what brand of crank is in there now. Next steps will be to get a proper grade bolt that fits properly and see how it runs...
Stay tuned.
Thanks for all the feedback!
Just a quick update on my loose HB thread. The good guys at AC in powder springs confirmed the existing balancer was bad. Almost complete rubber separation between the two sections. I do not know the brand (yet) but it is an under-drive pulley.
They also confirmed that previous work has been done on the car's bottom end. Believe the crankshaft was replaced at some point.
The ARP bolt I purchased does NOT work, it is to short to catch the threads of the crankshaft so no idea of what brand of crank is in there now. Next steps will be to get a proper grade bolt that fits properly and see how it runs...
Stay tuned.
Thanks for all the feedback!
Last edited by lowerlattitudes; Jun 5, 2017 at 11:34 AM.
Thread Starter
Cruising
Joined: Apr 2015
Posts: 12
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