c5 vibration towards rear

[cntrhub]

Crazy,
The harmonic balancer is a very busy part. It is attached to the front of the crankshaft. There is a rubber cushion that deadens the vibration characteristics of spinning mass, and acts as a mini-flywheel. It is designed to attach a main pulley, to turn the other components off the engine by using a single belt or multi belts.... for example, the balancer pulley might turn the components such as the A/C, Alt. P/Steering, etc. It's other function is to help set the ignition timing (if applicable).
It also goes by other names as, Torsional Damper. Basically, they add mass or inertia to the end of the crankshaft oposite the flywheel and in order to minimize the twisting of the crankshaft.

 

[mick_s3]

I dont have any solutions to B.O.B.'s problem but for those of us (me) who dont know what a harmonic balancer is, could you please explain that? also where is it located?

sorry to barge in but I like to expand my knowledge, for future ownership.

I am sure others will elaborate/expand on this but, basically a harmonic balancer is there to dampen the vibration created by the rotation of the crank, which is never perfect balanced.

RPM is the measurement of how many times per minute your crank rotates 360 degrees (or one full power/exhaust cycle). If you are turning 5000RPM that means the crank is rotating 5000 times a minute. The balancer is there to keep any variations in the "spin" of the crank from bothering the bearings and to keep the motor from slinging itself apart.

The harmonic balancer is mounted to the end of the crankshaft, behind the main pulley for the serpentine belt.

Someone here who has a firmer grasp on the physics involved will probably make that explanation sound silly, but there yea go. Pretty sure I got the "where" part right. :eyerole

Or read this:
http://www.mycarwizard.com/autoshop/eng1.html

Mick

 

[97_B.O.B._6]

Thanks for the input, I will check the harmonic balancer tonight. I must admit, I do know a good bit about cars, but every once in a while some help is always appreciated. I own 6 myself, my girlfriend owns 2 , her mom's car is here waiting for a transmission, and I'm rebuilding 1 for a friend. an '81 Monte.

 

[97_B.O.B._6]

Oops, i mis counted
Make that 7

 

[97_B.O.B._6]

Hey! i can post Again!!!!

I tried the suggestions the other day and found out that with the belts off, the vibration is still there. the odd thing is, the harmonic balancer wobbles from left to right. at first i thought that the rubber in between the inner and outer shells was messed up, but then i checked the inner shell its shaking too. at best, i can hope for a bad balancer at worst, bottom end rebuild.

Ted

 

[cntrhub]

There are millions of balancers moving from left to right. If your belts haven't spit off a number of times by now, I wouldn't worry about the pulley. I am concerned thought about the movement you have on the crank. When you replace it, make sure you change the seal, and use a new key.
Do this first........ Have you tried to tighten the crank bolt? But before you do, find out the high spot of the pulley. Try to tap the high spot to get the wobble out. Then tighten the bolt. Better yet, install the balancer R&R special tool to send the balancer home instead of the crank bolt. Start the car without the belts on it again. Did the "VIB" go away? You may have found it!
Let's say it didn't help.
Here we go again. You have a friend with the same year Vette? One of my off the wall thoughts makes me think that the "Fuel Map" inside the ECM, might be losing a signal at the 2K RPM range? Sounds like a lot of fuel (rich running) is dumping inside to cause that vibration to happen? If it was a lean condition, you'd have a nice flat spot, like it's running out of gas. Hey, I told you this would be a little Waldon's Pondish....(hear's the sound of a different drummer).
Now I looked at your laundry list of parts installed. You have the stock MAF? Swap that first before you bug a friend for his ECM.

 

[c4c5specialist]

HI there,
If there is wobble, you should be replacing the balancer. There should be none in Corvette engines.
Just remember, placement of this is critical as there is no key.
Also, there may be balancing pins in the balancer. These need to be changed over to the new balancer.
If there are none, then the only thing you need to concern yourself with, is correct positioning of the new balancer.
Allthebest, c4c5

 

[97_B.O.B._6]

Ok, First off, to whomever fixed my problem with my account, I thank you.

Unfortunately, I don't have a stock MAF, nor do i have a friend with the same year vette, let alone a vette at all! I bought the car with all the mods done already. I'm expecting a GM service manual in the next couple of days, so i'll be working on the balancer next weekend. from my looking around friday and yesterday, It seems that im going to be removing or just moving the steering rack in order to work on the balancer. I have a balancer installation tool that i bought from Eastwood Co. that has a bunch of adapters, do you think that will work for seating the balancer? also, how in the world do you remove the balancer, there are no threaded holes that i can see to put a removal tool on. Im asking all of this because of my lack of knowledge with the LS1. Give me any older Chevy, Ford, Mopar, import or other engine, and i'll fix it no problem. My knowledge extends up to about the LT1 years and then stops. Something about working like a dog for my current employer.

anybody need a network admin in florida?? LOL

Again, Thanks for all the help.


Ted

 

[cntrhub]

Ted,
You might have to wait for c4c5 to help you on that damper. I've been out of the loop with the latest Vettes for awhile. I'm like you with the old style designs.
Like I mentioned a few posts back?.....you may have found the vibration. I wouldn't jump on the MAF dianostic yet. Do one thing at a time.
Right now, you have a problem with the damper. I'd concentrate on this first. Repair it and get it out of the way. I'm sure the shop manual might chapter the procedure to install this "keyless?" dampener onto the crank? If not, c4 or someone else with more experience than I, might take you through the steps.
Wait on the Eastwood tool insallation for the damper. Check the shop manual and see if there is some mark on the damper and a set position on the crankshaft where both should line up before cranking down the damper now with the Eastwood tool. The damper might be "out of phase" with the crank!
If you say the the inner damper was lose, .... " but then i checked the inner shell its shaking too".... I am thinking you might have a worn crank caused by the spinning damper? You lost the tolerance fit and thus the lose damper on the crank. Don't jump to conclusions just yet. I am taking a guess according to your quote stated above. Wait for the shop manual.

 

[c4c5specialist]

HI there,
Well, it is very tough.
You have to remove the rack and pinion, and with that, have to drop the subframe slightly to remove the rack.
Now, it isnt easy to mark the crankshaft balancer, and remove it without turning the crankshaft.
There is a special tool that we use to lock the crankshaft in place.
You must also use a new bolt for the balancer.
It will take me about 4 hours to correctly install a new balancer.
Allthebest, c4c5

 

[97_B.O.B._6]

well, after getting the service manual and looking over the procedures, i'm thinking that i need to find a good shop in the central florida area. I just really dont want to mess anything up. anybody know of a reputable shop in the Ocala / Orlando / Tampa triangle?


Ted