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To begin, I am/was in the process of rebuilding the engine in a 1997 Camaro Z28. I just started the car today, however I had to run it without any accessories due to an issue I am currently having. In short, the machine shop "lost" my harmonic balancer when having the rotating assembly balanced, so I opted to purchase a new harmonic balancer from the local AutoZone. It is a Dorman 594-017. I installed the hub onto the crankshaft when the engine was on the stand (properly with a threaded rod), and then planned to install the harmonic balancer when the engine was placed in the car. I attempted to install this new harmonic balancer in the car today, however the inner diameter is too small to fit onto crank hub (in the realm of 20-30 thousands difference). Pictured below is the new Dorman harmonic balancer I received. Is it possible that the hub I installed onto the engine (not original to this specific LT1) is different in one form or another? Is one of the pieces not machined properly? To top all of this off, I have a second hub and harmonic balancer I wanted to compared each against. The new harmonic balancer from AutoZone DOES fit onto this hub (not the hub installed on the motor), yet none of the bolt holes align properly in any of the three possible orientations. The old harmonic balancer that was with this old hub is certainly an interference fit, but the bolt holes do align properly. In short, what gives? Am I dealing with poorly made parts, or perhaps physical differences between model years? Any insight would be greatly appreciated.
New harmonic balancer Old crankshaft hub (not the one installed on the vehicle currently) New harmonic balancer fits onto the old hub, yet none of the bolt holes align properly Old harmonic balancer, fits onto old hub and the bolt holes align properly
There are differences in the hub. 93-95 are longer, 96/97 are shorter to allow for the thickness of the crank position reluctor. I believe the hubs for the Corvette and B-Body applications can be different lengths as well. Diameter of the mount for the damper are all the same as far as I know, This is the first time I've seen a problem like yours.
There are differences in the hub. 93-95 are longer, 96/97 are shorter to allow for the thickness of the crank position reluctor. I believe the hubs for the Corvette and B-Body applications can be different lengths as well. Diameter of the mount for the damper are all the same as far as I know, This is the first time I've seen a problem like yours.
Could you explain how to identify the differences between the 93-95 and 96-97 hubs? Even with the different year lengths, would the bolt hole alignment problem with the new harmonic dampener indicate it is made incorrectly or for a different application? In other words, there is no good reason as to why it should have bolt alignment issues?
I don't know the actual measured length. Just that the F-Body 96/97 hub is "shorter" by the thickness of the crank position reluctor. The long hub or the shorter+reluctor is supposed to bottom out on the crank. If you aren't using the crank reluctor on a 96/97 use the 93-95 F-Body hub. The aftermarket units like the ATI for example are all made "short" and come with a shim/spacer if are using the hub on a 93-95, or using it on a 96/97 without the using the reluctor. Also have heard that the B-Body and Corvette hubs are 1/2" longer than the F-Body, but I have never measured any of them.
I only mentioned the variation in length because you indicated you have two different hubs. It is my understanding that the inside diameter and the bolt hole diameter of all the LT1 hubs are the same.
The Dorman listing shows the part you posted fits all the LT1 applications. Is it possible you have an incorrect hub (or hubs)? Other than that I can't explain it. And in the 21+ years I've been on this site, and others like it, I have never seen this problem before.
Just to keep things clear, the part is a damper, not a balancer.
I don't know the actual measured length. Just that the F-Body 96/97 hub is "shorter" by the thickness of the crank position reluctor. The long hub or the shorter+reluctor is supposed to bottom out on the crank. If you aren't using the crank reluctor on a 96/97 use the 93-95 F-Body hub. The aftermarket units like the ATI for example are all made "short" and come with a shim/spacer if are using the hub on a 93-95, or using it on a 96/97 without the using the reluctor. Also have heard that the B-Body and Corvette hubs are 1/2" longer than the F-Body, but I have never measured any of them.
I only mentioned the variation in length because you indicated you have two different hubs. It is my understanding that the inside diameter and the bolt hole diameter of all the LT1 hubs are the same.
The Dorman listing shows the part you posted fits all the LT1 applications. Is it possible you have an incorrect hub (or hubs)? Other than that I can't explain it. And in the 21+ years I've been on this site, and others like it, I have never seen this problem before.
Just to keep things clear, the part is a damper, not a balancer.
Thank you for correcting my error, it is a damper. I am beginning to wonder if I somehow have an improper hub. I will remove the hub on the vehicle and compare it to the second hub I have. Perhaps that will give us some insight.
Is the interference problem with the hub that is already on the engine possibly a problem of rust buildup? When my Formula was only a couple years old I unbolted the damper and it literally fell off. When I've helped with older high mile cars the hub is rusted to the extent you sometimes have to use a puller to get the damper off the hub.
Is the interference problem with the hub that is already on the engine possibly a problem of rust buildup? When my Formula was only a couple years old I unbolted the damper and it literally fell off. When I've helped with older high mile cars the hub is rusted to the extent you sometimes have to use a puller to get the damper off the hub.
That was my initial thought as well, however there is almost zero rust on this hub at all. In addition to this, the previous harmonic damper that was lost by the machine shop fit on without any issues. My 97 TA damper falls right off when the three bolts are removed. I am removing the hub as we speak, will post an update soon.
I removed the hub and began comparing the one that was installed on the car to the old extra I have. There are certainly some differences between the two, enough to make me question whether one is from a different application. Comparing the removed hub to the old hub, it can be noted that removed hub is approximately 0.1" taller than the extra hub I have on hand. The older hub has what I believe to be one balancing hole drilled, the removed hub has two present. I will say the the removed hub does not have a consistent outer diameter, it appears to perhaps be ballooned (damaged). If roughly 10-15 thousands of material were to be removed from either the new harmonic damper or the removed hub, I believe it would fit over. The bolt holes align properly between the removed hub and the new harmonic damper as well, further leading me to believe the "old" hub and damper I have laying around are from a different application. It appears that the fix for me would likely be to purchase a new hub for a 96-97' LT1 that is not damaged. Online prices are steep however.
Removing the hub Removed hub on the left, previously referenced "old" hub on the right Another view of the hubs Height difference more apparent
Your 97 would require the short hub to properly align the belt. The short hub is needed because of the crank sensor reluctor that was added in 1996. That does not address the bolt hole issue, which I believe is improper machining of the damper you bought.
Thank you for the replies, it appears we have narrowed down what each hub belongs to respectively. After picking up the pieces off my desk again this morning, I must have made an error in my exhaustion after work. The bolt holes DO align with the new harmonic damper and the hub with the thin edge of the harmonic damper placed closer to the timing cover respectively, they cannot align with the thinner edge placed away from the timing cover. Pictures are included below, I am sorry for the stupidity on my part. I have one small addition to this, looking at the first photo, should the rubber (believe to be) ring already show a separation? To my previous knowledge, separations in the ring were often the cause for needed to replace a damper in the first place.
Bolt holes will align Bolt holes will not align
Last edited by WhiteWS6; Aug 24, 2022 at 10:15 AM.
Reason: Addition
