BigVette427

My Dad has an '03 Z06 with <10k miles and as he is finding out first hand, apparently C5 and C6's (LS2 at least) are prone to the harmonic balancers going bad. Apparently, the OE GM HB's suck @$$?

Since the process to r/r this part is labor intensive, I was wondering if it was a good idea when I will otherwise be taking everything off to swap heads and cam on my LS7 to replace this with a better designed HB, say a PowerBond PB1503N or PB1503SS? I've only got 6.5k miles on my Z06 LS7, but it is over five years old now.

I'm not looking for a high(er) performance variant and have no interest in swapping belts, just wondering if the LS7 HB is as bad as the LS1/6 and maybe LS2 HB's? Does anybody know how these direct replacement Power Bond units compare to OE quality?

redbird555

They're not as bad but yes they still fail...I would upgrade it but it wouldn't be with a powerbond. Quality isn't bad but it's not the greatest either.

Go with an ATI or IW they're actually real harmonic balancer that are better than oem. I'm not sure why you wouldn't want an UD pulley, it's a free 7whp or so and with the cam you'll have to raise you idle speed anyway. There's virtually no downside with one

AzDave47

A few of the ATI C6Z06 harmonic balancers have had manufacturing problems and failed. Mine failed at 600 miles on a road course after HCI install. CPR did my HCI work and did required repairs at no charge to me. ATI indicated a problem with heat treating on some of their HBs. At 46K miles and ~17 road course days I had not had any problems with the OEM HB before the HCI work was done with a lot of 4-7K rpm time. The replacement ATI HB has been in service now for about 6000 miles and run a number of times to 7300 RPM with no recurring problems.

[Cerberus]

I didn't replace my balencer while I was doing the cam work, and I should have because the next spring I was taking it out and replacing it with the ATI unit. While you are there I would just replace it with whichever brand you would like to.

BigVette427

I'm looking for OE appearance with superior durability/reliability; not really interested in chasing down all the small gains. My 'Vette was a May 2012 build and only has about 6,400 miles on it now. Not sure if it's age or miles that wears these things out. (My Dad's '03 Z06 has <10k miles it and it's HB has just begun to start chirping.) Can you get a good idea if you need to replace it when you take it off?

Does anybody know what happened to the original GM LS7 harmonic balancer, p/n 12599862? It appears to have been replaced by GM p/n 12675716? Anybody know who makes this part or has anybody ever had their eyes on both and been able to discern what the differences were? Any idea as to when this new p/n came out?

I can get the new superseded GM part number for LS7 HB, GM # 12675716 for $212 shipped.

Power Bond OE replacement, PB1503N for $221 shipped.
http://www.daycoproducts.com/part?ca...mber%3DPB1503N
Power Bond Race Performance Balancer, PB1503SS for $310 shipped.
http://www.daycoproducts.com/part?ca...ber%3DPB1503SS

Would these PB HB's line up with everything else and retain the OE belts? The overall OD of the SS looks a little larger, has timing marks, and has 8 grooves in pulley 2 vs. 6.

Unreal

Yes they fail just like any other GM/LS motor.

BigVette427

I ended up going with the Power Bond Race Series balancer, PB1503SS. Given that Dayco bought Power Bond back in 2013, PB balancers can actually be ordered through local retailers like AutoZone and O'Reilly's. With AZ's emphasis on ship-to-home now, they essentially drop ship from the manufacturer when you order it, and gave me 20% off the part, even if I did have to pay local sales tax. Couldn't beat $272 shipped. Another interesting thing is that AZ says the balancer has a limited lifetime warranty, too.

I liked what I read on the PB Race Series balancers:



As for ATI, I just found too many recent examples of ATI balancer failures (links below) that coupled with their additional cost just didn't meet my goals. The main reason for swapping the balancer while I have it off to do the heads/cam is for peace of mind over the OE balancer, and I don't think an ATI balancer at this point in time would give me that. I trust they will right their ship, but I'm just not certain as of now.

I even found a new OE balancer under the newer GM LS7 p/n (12675716) that was taken off a crate motor for half the price of a new one, but that means the problem that apparently plagues all GM balancers would still remain. Not exactly what I'm aiming for in my build.
https://ohiospeedshops.com/swap-meet...f-ls7-balancer

I have also read numerous threads talking about their ARP crank bolts backing out, so I'm not 100% what to do there. ARP says don't use Loctite and instead just use their own lube that comes with it, and when you tq. it to 235 ft. lbs. it will have close to 29,000 psi clamp force to keep it in place. Not sure if the majority of these issues can be attributed to inaccurate torque wrenches or what, but ARP's reply does make sense to me.

If you look up the ATI install instructions for LS balancers, they specifically say that if you're going to use an ARP crank bolt, then just use high-temp RTV on the washer and then use 262 Red Loctite and tighten to 230 ft/lbs. Not sure how you ever get a crank bolt off that had red Loctite on it without heating it up to the point of doing damage.



https://www.corvetteforum.com/forums...ls7-crank.html

https://www.corvetteforum.com/forums...-question.html

https://www.corvetteforum.com/forums...ailures-3.html

redbird555

No offense to the op but why do people start threads like this if they're going to just but what they initially said anyway?

Stock gm and powerbond both have issues being of the same design. Not to mention other powerbond products aren't even real dampers like the ati or IW....

ati has had some failures but then again they are they are the sole balancer of NASCAR race teams and cook racig programs.


i guess I just don't get what the op was trying to accomplish here at all. He basically just bought a new stock balancer?

BigVette427

Big difference between the stock balancer and Power Bond Race Series. Trying to learn more about it all, and share what I learned.

Maybe ATI is focusing on their NASCAR customers and neglected the LS7 918620 balancers, but I don't have the time/budget to R&D ATI's balancers. And I'm not taking it off every 5 to 10 years to send back to ATI to have it rebuilt. There are almost as many occurrences in this forum of LS7 ATI balancer failures in the last 2 or 3 years as there are dropped valves. I'm sure ATI makes a great product most of the time, but I decided I wasn't interested in 2x the price for "most of the time."

redbird555

If you torque the arp bolt correctly and follow their instructions there's no issues with them backing out. I personally have never seen one come out so once again failure rate if any is very low. Also ARP says nothing about using red loctite for the crank bolt. Just to lube the threads with their moly lube so I'm not sure where that's coming from

also gm bolts come with red loctite under the bolt head to help stop the bolt from backing out and they release just fine

redbird555

I'm not here to argue with you but if you think 3-4 failures o this website constituates a bad product I can't help you....there are literally thousands out there going just fine for years. The balancer they use on copo cars and NASCAR are of the same design as the street car ones.

Also any balancer thats 5-10 years old idc who made it is going to need a rebuild or replace. Yes even a stock gm balancer that hasn't failed at 7 years old probably could use the rubber redone as it does break down with age

also with what you posted, aside from some holes drilled and paint I don't see what the powerbond differs from the stock piece in....

BigVette427

There are numerous threads on ARP crank bolts backing out both on this forum and others, look into it if you're interested. Maybe some of those are from uncalibrated tq. wrenches and or tight spaces with high torque values, I dunno. Yes, ARP says no to Loctite and suggests to only use a generous amount of their supplied ARP lube over the threads and under the head of the bolt. ATI contradicts this in their balancer instructions and says to use high temp RTV all around the washer and then use 262 Red Loctite (I'm assuming on the threads?,) and then tq. it to 230 ft/lbs. Big difference between red Loctite on the back of the head bolt and on the threads.

I'm not talking about any other ATI balancer other than the 918620 series for the LS7 (and dry-sump LS3's,) as that is the only balancer that fits my motor. All I'm saying is that I went in a different direction based in part from some first-hand accounts of specific failures on 918620 balancers. There are far less of those out there than wet sump LS3 and LS2 balancers.

BigVette427

Power Bond is a neat little company in Australia who has been solely making harmonic balancers for over 40 years. They were acquired by Dayco in 2013. The PB Race Series HB's meet SFI spec 18.1, come with a unique serial number, have laser etched 360 timing marks, and go through a three step coating process (no corrosion like on the OE GM balancer.)

They are CNC machined, 1045 forged steel hub and ring. They offer up to 10x push part strength compared to that of a OEM HB, capable of up to 10-ton vertical pressure (the OEM HB is lucky to take 1 ton,) and utilize a high strength bonding process (as opposed to simply pressing the rubber into the assembly) using a high-pressure, low-cure process. It's a superior design, manufacturing process, and overall even their OEM HB are superior to the OE GM HB's, let alone the Race Series.

Michael_D

And also in response to your PM.....

I do not have personal experience with Powerbond dampers, so I can't/won't suggest them. They are the same 'type' of damper as the OE damper. They are a bit different though. Possibly higher QC and improved bonding. Also, they are neutral balanced. The OE damper has weights/plugs that are positioned to polish up on balance. So does the OE flywheel. It's important to reinstall the OE damper in the same position as removed.

I have been using ATI and FluidDamper for decades, so I have confidence in them. The ATI damper for this engine has had some failures reported on this board, and maybe others (I don't surf internet boards). The ATI failures have been reported to be a result of fastener failure. I am about half convinced they failed from installation error..... There are A LOT of people, included "professionals", on this forum who blatantly disregard torque specs.

I think the same rationale applies to the ARP bolt. Installation error. I would not ever use red Loctite on damper bolt threads.

I'm also an advocate for pinning the damper to the crank.

AzDave47

ATI reported to Cordes Performance Racing that my LS7 ATI HB failed due to improper heat treatment in their manufacturing process. Mine failed 600 miles after HCI build on a road course event at ~6K RPM (engine run 4-7K+ for 4 15-20 minute sessions at 100*F+. The fasteners did fail but that was not the cause of the failure but the result. The replacement ATI balancer has been run many times to 7K+ RPM and thru ~5400 miles and seems to be holding up well.

Michael_D

Improper heat treatment of what? Bolts are hardened through heat treatment....

AzDave47

I didn't see the failed HB, but I believe part of the hub fractured and as a result of that the bolts sheared, not bolts sheared causing the fractured hub.

Michael_D

Thanks for the clarification.

Somebody else recently posted a few pics of a failed ATI. The hub did not look damaged, but the bolts were sheared.

Kinda hard to come to a conclusion what's going on with some of these ATIs without knowing exactly what their findings were. Tll then, it's a chicken or egg thing....

Cman01

On the subject of whether to follow ATI's damper bolt instructions or ARP's whatever bolt you are using to tighten down your damper (ARP or stock bolt)..............FOLLOW THOSE INSTRUCTIONS!!!!

I'm using a new stock damper bolt when I did my HCI install last year and I followed the GM shop manual procedure to tighten that bolt to my ATI UD damper.

BTW, I bought my damper Dec. 2015 from Summit I wonder if it has the possible issues that some ATI's have had. I check it off and on and so far so good (been over a year now since install). I followed ATI's instructions when installing those 9 little bolts with locktite and torqued properly.

Tony

Cman01

BTW, I took a look at Dayco's parts catalog listing these dampers, are they mistaken or do they ACTUALLY sell 10% OVERDRIVE LS7 dampers??

http://www.daycoproducts.com/parts?c...cription=10759

In my books, the integrity of any company selling a product is whether they know what they are listing and not have errors in describing said products.