I'm having the famously flawed Harmonic Balancer replaced in my '05 (22.5K miles), my question is has anyone replaced theirs with another OEM GM unit? I called 2 local well respected shops and asked about the ATI unit, they both said to use the OEM unit as GM had fixed the separation problems and the replacement units work just fine. Cost (although not a factor) in considerably more for the ATI piece. Thanks, I'll also be asking this question in the General Discussion section.

 

Are you looking for more power? You could throw in a 10% or 25% underdrive and free up about 5-8whp.

ATI and Powerbond are 2 good choices.

I have not heard of any update to the balancer but if you trust your local shops that say there was a revision then I don't think it would hurt to do that.

 

Not really looking for more power, very happy just cruising with my 400 horses. I found it rather surprising that the local shops would recommend a GM unit, they could probably make more money from me by selling me the aftermarket unit so I have to believe the GM units must be O.K........unless there's other reasons like it might be easier to install, don't know. The Corvette mechanic at my local dealer also told me that GM fixed the separation problem, that's why 'm hoping someone has used the new unit and can give me some input. Thanks for your help....

 

When I swapped my cam I installed a PB even though the oem unit wasn't causing any issues. It has been trouble free for over two years now.

In spite of what others claim, I have zero faith in GM parts that have a known history of above avg failure rates. It's a lot of work to R&R the pulley so it makes sense to me to just go with what is known to work well.

Since your car is out of warranty, why would you go with the oem pulley? PB or ATI is a better quality unit and IIRC both are available in oem sizes if you don't want to drop down a size.

 

What's the downside of using an underdrive?

 

As long as GM stays with the current design, contrary to what some might believe on the new replacement - no good will come of it.

Fact is, elastomer has an finite shelf life just sitting there, adding Corvette's torque to the equation and promises of longevity just evaporates.

In the end, most just rationalize with their decision, including myself with my ATI.

 

GM indeed has fixed the problem. If your Vette is Stock, the GM replacement should be perfectly fine. If you want to upgrade, the ATI Product is indeed a set up from Stock, but we typically only go that direction if the Car is Modified (IE: Supercharged). As far as the Under Driven Balancers, we typically stay away from them as they will turn your Alternator and Waterpump a slower RPM. This changes the Load on the Alternator (mostly at Idle), and you can see some side effects such as dimming Headlights.

Hope this helps!!

Rich

 

Forgive my ignorance, since I have not seen the new GM Harmonic Damper.

Did GM use different material to join the inner and outer ring?

 

Not sure on the Specifics, but the Damper looks a little different, almost like they went to a different Supplier. But so far no failures.

 

Perhaps one of the Forum GM parts vendors can clue all of us in as to the difference in the "new" GM balancer that fixes the problem with the rubber bond failures.

 

My question is WHEN was the new balancer changed? Hope it was before Sep 15, 2011, when my '12 GS was born . Thx.

 

^^^If the method of connecting inner and outer ring is still involving elastomer, then, it will fail - just a matter of time.

Pliable elastomer has well defined shelf life. When twisting torque is factored in, durability will become an issue. It is physically impossible to have longevity when steel parts is joined with an elastomer, with inner part fixed and outer parts exposed to twisting torque.

fact is, GM could change stock # and supplier but the nature of the beast remains.

 

Do you have a part number for the "new" one?

 

I had to replace my 07 OEM unit with an ATI unit and never thought about it again. Also here is another thread about replacing the harmonic balancer - http://forums.corvetteforum.com/c6-t...austin-tx.html Good Luck!

 

Biggest downfall is the alternator turning more slowly at idle(~600rpms on manual trans vettes) so the computer will think the car isn't getting enough juice and throw a CEL. This is easily countered by a) turning off that code in the computer or b) upping the idle to around 850-900.

My car has a twin disk clutch and combined with the heavy lope of the cam at ~650rpms, the noise was too much. I upped my idle to 900 and it has been perfect ever since.

I have ~13.8 volts at idle and a solid 14.1-14.3 any other time.

 

True, but just like engine mounts, suspension bushings, and other similar parts, it should last a lot longer than some do IMO. But yes, time alone will always be a deteriorating factor (just like on tires, etc.), but heat cycles will accelerate it.

I assume those mentioned aftermarket units are not rubber-isolated, correct? Even if not a good design, GM spent extra on such a part for a reason, no? Otherwise they'd have fitted a solid unit themselves. The better question is what does a solid HB affects over time: main seals? Crank bearings? Hopefully the new design will last longer... and my car already has it .

 

I believe the new balancer came out in april 2012. I was one of the first to get one.

 

Just when the freaking car is going out of production; geez . Guess I missed it then. Looks like we all will have to replace it in 7 years or so then. Oh well. Thanks man.

 

Unlike this "engine mounts, suspension bushings, and other similar parts" mentioned. Harmonic damper is bonded to ferrous metal on both side to serve as cushion and absorb tremendous amount of torque from the V8. So beside time/heat being the factor, the elastomer faces multitude more and it is an unhill battle - causing it to deteriorate from day one.

It is also an impossibility in toolmaking, to ensure the precision mold/die, to provide the elastomer bond, between the inner/outer ring will ended up with an concentric runout. Now, contrary to some, thinking their OEM damper runs true, compounding with the poor fit, with erratic runout of the OEM belt tension damper and what we ended up is an nightmare in the making.

OEM engine mount often fail too and fail miserably. I personally have changed my shock bushings to Delrin and when the time comes, other suspension cushion will also be Delrin.

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ATI Damper is not solid, the unit is an assembly composed of many precision machined parts and it utilize "O" rings for cushion. It is rebuild-able and degree of damping can be control thru the use of different grade "O" rings. ATI is in a different league when compare with the more mundane after market varieties.

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When choose to stick with the OEM design, most because concern with warranty, then, it is like sitting on an time bomb. Serious damage could happen if damper breaks, then warranty repairs. It like an fender bender, then get repairs - but the car will never be the same again.

This is another case of to each his own.

Good Luck with your OEM Damper.

 

Tech Talk: The Ring’s The Thing – Inside Elastomer Engine Dampers

Here is a cool article I found