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Had my harmonic balancer replaced several months ago and i took my car out today because it was a beautiful day in south jersey and my balancer pully came off anyone know why it may have happen,, c5 VETTE thanx craig
Last edited by BLACKBELT2; Nov 3, 2017 at 04:29 PM.
Reason: more description
Without physically seeing the car, it's a little hard to diagnose, but my first reaction is along the lines of twokbolt. It's possible they reused your old bolt. If so, it is almost a certainty it will come off, the question is when. The original bolts were "torque to yield". These bolts will typically do a good job holding whatever pieces together but they are a one time use only bolt; as part of the torque to yield process the bolt stretches.
It's also possible someone installed a new OEM bolt and did not torque it down properly. As twokbolt mentioned, it is to be torqued down to 240 lb/ft (or 247 as twokbolt stated - I would have to double check the torque to be sure, but am certain it is at least 240 lb/ft).
Possibly whoever installed the HB used an ARP bolt and didn't tighten it enough.
Also, the HB has to fit snugly and if not placed properly a bolt, even tightened, would probably not secure it for long.
As I mentioned earlier, it's hard to tell without looking at it, but I would first follow up with the shop that did the work and ask them how they installed the HB.
Good luck. Please let us know what you discover. We all learn that way.
Last edited by Route99; Nov 3, 2017 at 06:47 PM.
Reason: typo
Had my harmonic balancer replaced several months ago and i took my car out today because it was a beautiful day in south jersey and my balancer pully came off anyone know why it may have happen,, c5 VETTE thanx craig
And I thought I had problems
Take it back to the repair shop and tell them to fix it...they did give you a year warranty I hope...Good Luck...
If you didn't do the install, then it's not likely you'll be doing the repair. But, if you do - the new OEM bolt is torqued to 37 lbs ft and then turned another 140 degrees with a long crossover wrench to properly stretch the bolt. That's directly from the factory service manual.
Without physically seeing the car, it's a little hard to diagnose, but my first reaction is along the lines of twokbolt. It's possible they reused your old bolt. If so, it is almost a certainty it will come off, the question is when. The original bolts were "torque to yield". These bolts will typically do a good job holding whatever pieces together but they are a one time use only bolt; as part of the torque to yield process the bolt stretches.
It's also possible someone installed a new OEM bolt and did not torque it down properly. As twokbolt mentioned, it is to be torqued down to 240 lb/ft (or 247 as twokbolt stated - I would have to double check the torque to be sure, but am certain it is at least 240 lb/ft).
Possibly whoever installed the HB used an ARP bolt and didn't tighten it enough.
Also, the HB has to fit snugly and if not placed properly a bolt, even tightened, would probably not secure it for long.
As I mentioned earlier, it's hard to tell without looking at it, but I would first follow up with the shop that did the work and ask them how they installed the HB.
Good luck. Please let us know what you discover. We all learn that way.
Thank you for this reply ,the car will be picked up on Monday morning to be brought to the repair shop , and this shop does all my work on all my vehicles that I cant do , they do have a very good rating from the BBB and my friend owns it ,in fact they let me in the shop area when working on my vehicles when I stay with the car , on this repair since it was going to take many hours to fix , I didn't stay during the repair. As soon as it is repaired I certainly will let you all know what and why it happened.. One question , can a repair shop get this bolt easily like in hours cause I got the car back the same day.......... Thanks Craig,,,
Take it back to the repair shop and tell them to fix it...they did give you a year warranty I hope...Good Luck...
the car will be towed to their shop Monday morning, and yes they better make good on there mistake , I have all these posts to prove if it was done correct ,this should have NEVER happened....
For a stock GM bolt, the tightening specifications provided above are not correct. Here is the GM procedure for tightening the stock bolt.
I have seen dealers re-use the same stock bolt, which should not be done as mentioned in the above posts. Using a torque value of 240 lb-ft is not correct, it must be rotated 140 degrees after tightening with a torque wrench to 37 lb-ft.
Last edited by vettenuts; Nov 4, 2017 at 08:22 AM.
For a stock GM bolt, the tightening specifications provided above are not correct. Here is the GM procedure for tightening the stock bolt.
I have seen dealers re-use the same stock bolt, which should not be done as mentioned in the above posts. Using a torque value of 240 lb-ft is not correct, it must be rotated 140 degrees after tightening with a torque wrench to 37 lb-ft.
Thanks, vettenuts.
I should have taken time to go out and pull the service manual. I think tbrowne and I were getting a part of the info to the OP, but you put it all together. As you point out from the manual, the old bolt is used to torque the HB on using 240 lb ft, and then removed. Then the new bolt is installed and torqued to 37 lb ft and then tightened another 140 degrees on the second pass.
Your taking time to copy and paste the applicable pages of the service manual should give BLACKBELT2 all the information he needs to ensure the shop properly installs (or re-installs) his HB.
BLACKBELT2 - I apologize for any confusion I caused.
feeder82 - good point, too, that OP's shop could check.
A lot of people jumped to the conclusion that it was a bolt problem. (and it could be)
But when you say "my balancer pully came off" it is unclear what came loose.
Was it only the pulley and the center balancer section remained? If so, your new replacement balancer failed by separating the pulley from the balancer hub. If it was a stock GM balancer, they fail frequently although usually not in just a couple months. Mine failed at 30k miles.
Was it the whole balancer assembly which is the hub and the pulley? If so, the bolt is probably the cause. Either using the one time use bolt again or improper torque.
Not a "while you wait" type of repair. The shop has to partially remove the steering rack, and radiator, so it's a big job. I would recommend any aftermarket balancer, but you don't have to spend big $$$. A Powerbond will be much better than stock at about $180. It would be a good idea to use an ARP bolt as said, but I'd also pin the crank while you're there.
Thank everyone who gave their help and advise with my problem with c5 balancer, my mechanic did back up his warranty on the work they did on my harmonic balancer , although never gave a reason for the failure , also towed the car in at no expensive to me. Jon Miller Car Care in Tuckerton New Jersey family owned and operated , and a good friend ....
This is the instruction for installing the ARP bolt , which I will be using when I replace my balancer these days
Dont use the ARP lube, mine backed back out using the lube and 240lbs. I ended up using red locktite 262 and keying the balancer (ATI) then put witness marks on the bolt and balancer. It hasn't moved since
If you are going to the trouble of putting on a new Harmonic Balancer then you should take the extra step of pinning the crank. While the stock balancer may still have the problem of separating you will not have any problem if the crank bolt will work its way loose. For those of us who autocross in the stock class, we have to use the factory HB and bolt, when installing a new OEM bolt you end up with more than 240 ft-lb of torque. My brother-in-law is a truck mechanic and we were using all of his 360 ft-lb torque wrench to get those last 5-6 degrees.
Harmonic balancer
