Harmonic balancer pulley
Team Owner
Joined: Jul 2012
Posts: 34,479
Likes: 532
From: Central PA. - - My AR15 identifies as a muzzleloader
I believe in the Beer Fairy
Time, or more specifically environment and temperature definitely affects the rubber as well, no dispute there. But if you think 2 engines of 200hp and 600hp will kill a balancer at the same rate, you are mistaken. The crank is accelerating and decelerating on every power/compression stroke. The engine is basically one great big impact wrench, and the balancer is the thing that's supposed to take up that shock. The question I was responding to was the guy saying he's never seen this before in large numbers, and I'm simply pointing out he's probably not seen LS levels of performance in these numbers. There are no turbo 4cyl and V6 Corvettes at 250hp.
Team Owner
Joined: May 2001
Posts: 25,057
Likes: 1,265
From: Virginia
St. Jude Donor '11
Time, or more specifically environment and temperature definitely affects the rubber as well, no dispute there. But if you think 2 engines of 200hp and 600hp will kill a balancer at the same rate, you are mistaken. The crank is accelerating and decelerating on every power/compression stroke. The engine is basically one great big impact wrench, and the balancer is the thing that's supposed to take up that shock. The question I was responding to was the guy saying he's never seen this before in large numbers, and I'm simply pointing out he's probably not seen LS levels of performance in these numbers. There are no turbo 4cyl and V6 Corvettes at 250hp.
Instructor
Joined: Nov 2019
Posts: 226
Likes: 21
The cause really doesn’t matter. Bottom line is that they fail. Mark the pulley and keep an eye on it. The car was manufactured with saving costs in mind and a low sales price. It follows that the engineering won’t be top notch.
Racer
Joined: Dec 2014
Posts: 257
Likes: 7
From: Shady Shores Texas
Pro
Joined: Aug 2014
Posts: 717
Likes: 80
From: Michigan
This is from a thread found in another Corvette forum from 2011. The author, to my understanding, was extremely knowledgeable about the topic;
“Hi there,
First, the prevelance of this condition is there.
Second, there is NO SPECIFICATION for runout on the c5 or c6 harmonic balancer.
Third, rubber isolated harmonic balancers are known to rotate at times in some applications.
The AC belt is usually the first one to make noise as it has the weakest tensioner. Excessive runout in the balancer magnifies the noise when cold.
I have also installed BRAND NEW balancers that have had wobble.
The key, is accurate tension of the belts and alignment with the other pulleys.
My rule of thumb is 1/32 inch runout maximum.
Allthebest, c4c5”
“Hi there,
First, the prevelance of this condition is there.
Second, there is NO SPECIFICATION for runout on the c5 or c6 harmonic balancer.
Third, rubber isolated harmonic balancers are known to rotate at times in some applications.
The AC belt is usually the first one to make noise as it has the weakest tensioner. Excessive runout in the balancer magnifies the noise when cold.
I have also installed BRAND NEW balancers that have had wobble.
The key, is accurate tension of the belts and alignment with the other pulleys.
My rule of thumb is 1/32 inch runout maximum.
Allthebest, c4c5”
Team Owner
Joined: Jul 2012
Posts: 34,479
Likes: 532
From: Central PA. - - My AR15 identifies as a muzzleloader
I believe in the Beer Fairy
I'm going to go with fatigue and exposure as the most common causes of failure. If you want to go with age, we're going to have to agree to disagree.
Last edited by K-Spaz; Nov 16, 2019 at 08:25 PM.
Team Owner
Joined: May 2001
Posts: 25,057
Likes: 1,265
From: Virginia
St. Jude Donor '11
Look, it's Rubber and rubber will age differently depending upon the environment. Just like tire manufacturers will tell you that they keep tires in a climate-controlled environment so as long as they didn't sit on the Shelf at your retailer, you can install a tire that was 5 years old when they got it and it will still give you the same number of years as a new manufacture. Sunlight, temperature and environment dirt are probably 100 times more likely to cause a failure than simply time. Especially so if oil has gotten onto the rubber since oil is one of the components they use to make the rubber. In fact, if you take butyl Rubber and compress it for a long period of time you will see oil squeeze out of it. Point being if you have oil on the balancer or other petroleum based products, it is not good for the rubber and it will die in short order.
I'm going to go with fatigue and exposure as the most common causes of failure. If you want to go with age, we're going to have to agree to disagree.
I'm going to go with fatigue and exposure as the most common causes of failure. If you want to go with age, we're going to have to agree to disagree.
