My crankshaft balancer has a noticeable wobble at idle speed, but it disappears above 1,500 rpm.

Is this low-rpm wobble normal for a stock '99 Corvette, or, is this a damaged balancer that should be replaced at the soonest opportunity?

It looks like the steering rack would need to be removed in order to gain access to the balancer, am I correct in assuming this? If I do need to replace the balancer, are there any special tips I should know before I get started?

Thanks,

Jason

 

It's not normal. You should replace it. You DO have to remove the steering rack to take it off. You also have to have a three jaw puller to get it off and M16 x 2 longer bolt or threaded rod, nut, and washers to put it back on. I'd probably put a slightly underdrive pully back on rather than just a stocker. You also need a new bolt from the dealer because they are a "torque to yield" bolt. Make sure you mark the relationship from the crank to the balancer as there is no key way. The factory fine tunes the balance by putting small round weights in the outer ring. You need to transfer those to the new pully if there are any in there.

Ray

 

Ray,

Thank you for the quick response! Removing the steering rack looks like a real chore, and messy, to say the least.

How do you remove the balance weights from the existing balancer? It doesn't appear that they can be driven out from the back side of the balancer. Also, the timing cover oil seal should probably be replaced; are there any surprises here?

Would you say that this is a weekend job?

Thanks again,

Jason

 

Nothing real surprising. You probably aren't going to get the weights out. GM supplies them with new flywheels and balancers. You can probably get them from the dealer. Yours may or may not have weights in them. LS1's are REAL sensitive to these little babies though. If your engine is modded you might not even notice the little shake you would get without transferring them. The rack has two bolts holding it in plus the two that attach to the hubs (tie rod ends). There are two lines at the bottom of the driver side of the motor that have to be removed as well as an electrical plug if for the magnasteer. You have to remove the four bolts that hold on the abs pump. You have to lift the rack straight up out of the brackets and slide it toward the passenger side. You don't have to take it all the way out, but if you want to you can pull it back into the engine bay after you slide it to the pass side and remove it to get better access to the balancer. You may have to remove the radiator and fans for better access. The seal is no big deal. Just pop it out with a screwdriver and use a large socket to seat the new one.

If you want a step by step, go to LS1Howto.com and look at the steps on how to do a head/cam swap. Just pay attention to the parts on how to get the rack out and pull the balancer.

By the way, if you wanted to do a cam swap, now is the time. You will have done around 80% of the work of doing a cam swap to change the balancer. All that would be left is to pull the valve covers and rockers and pick up some rods to hold the lifters up. (of course you would have to remove the timing cover and drop the timing chain down, but if you don't change the timing set you don't have to mess with the oil pump or anything.)

Ray

P.S. You should be able to do it in a weekend with no problem.....The balancer comes off kind of hard though. If you have impact tools it will greatly reduce your efforts.

 

Mine had a slight wobble with no other symptoms. Replaced with a new unit, still had a slight wobble.

I would just keep an eye on it.

 

Actually, the wieghts are installed to balance the pulley / balancer assembly and you do not transfer the old weights from the old pulley to the new unit. Just install the new balancer / pulley, insert the keeper pin onto the crankshaft and - this would be a good time to drill and pin the pulley so it does not work loose.

 

Thanks Jean; regarding the weights, I thought the same as you until I read Ray's post and looked at the service manual. The manual says: "Crankshaft balancer weights must be installed into the new balancer in the same location as the old balancer."

So, it sounds like the crankshaft and balancer were balanced as an assembly at the factory.

 

I never have had a car that didnt have a slight wobble at idle,and would stop at about 1200-1500-rpm. The thing to look for is rubber coming out of balancer, should be smooth all the way around if you have it protruding thats when id worry about changing it. If you dont do it then it will look like the one in Daves pic.......

 

The balancer is balanced by itself, and then the weights are used to balance the assembly. The same is true for the flywheel in a manual trans car. The GM service manual is very clear on this issue. I also have first hand experience with this.

Ray

 

Well, I purchased a new three-jaw puller and carefully reviewed the excellent "LS1HOWTO.COM" website so, I think I'm ready to tackle this job. I don't have a tie-rod-end puller that fits, but according to the website, the tie-rod-end comes off pretty easy, needing only a tap or two with a hammer after removing the nut.

My new three-jaw puller is fairly compact, so I'm hopeful that I won't have to remove the fans and associated shrouds.

One of my fears is needing some unexpected special tool that is only available via special order, but hopefully this won't be the case.

This time next weekend I hope to be done with this job and drinking an "Old Rasputin" in celebration; I'll report on the results.

Jason

 

Jason,

Good luck with the job! Don't worry about the tie rod ends, they pop out easily--especially because they are seated in aluminum-(they don't rust together).

Ray

 

Jean,

Please excuse me from this next rant because I'm sure you are just trying to express your opinion and are probably a nice guy.

I try to refrain from giving advice if I don't KNOW what I'm talking about. I very often see people expressing their OPINION, and representing it as fact. It is very easy to cause someone an extra amount of work or agony by leading them down the wrong road. I KNOW that it is GM's recommendation that the weights be properly documented and placed in the new balancer and the same goes with the flywheel on a manual car. He probably wouldn't have any major problems if he skipped that step except for a little more engine vibration than normal.

I just want to send a caution out to those that give advice here to clearly represent opinion and separate that from fact. I wait and listen for those wiser than I on matters that I do not, in-fact have enough knowledge to comment on. Just maybe I might learn something I didn't know. I do NOT assume something and state it as fact as in this earlier post. I certainly am not always right, but when giving advice to others I try to use caution in order to not get them into trouble.

Thanks for not getting upset with my rant!

Ray

 

One thing you will need is to make an installation tool. I can't emphasize enough that although there is a lot of good information on LS1howto.com, the method recommended for re-installation of the pulley has gotten more people into trouble that I can count. Don't use a bolt of any type to pull the new pulley into place. Make a tool similar to below to preserve the crank threads. Also, when you pull it, don't use the old bolt to bear against with the puller, use a large enough socket so you can push directly against the end of the crank not on the threads during removal.

 

vettenuts,

Did you get the 16mm stud from McMaster Carr? If so, what is their minimum order $$$? Also, what was the shipping time to your door?

Thanks,

Jason

 

ISEERED:

Take a look at the new OEM balancer and you will notice that it is already weighted. It is not the intention of GM to require the mechanic to punch out the weights in the new balancer and replace them with the punched out old balancer weights - the 2 balancers are different and have different weights / center of gravity. Reusing the old balancer weights would not properly weight the new balancer.

Each balancer must be weighted due to inherent out of tolerances when the rubber is installed. Each balancer is weighted and "balanced" by the manufacturer. It does not matter what orientation you set the balancer on the crank shaft. The idea is to avoid placing an unbalanced pulley (weight) at the end of the crankshaft where high RPM can cause a harmonic imbalance and damage the engine.

The Helms manual reference to weights is assuming you are rebuilding your old OEM unit, not replacing with a new one, and therefore you will need to balance the rebuild job. When I installed my H/C package I noticed the preinstalled weights and asked MTI (my tuner) about it for which I received the aforementioned explanation; which matched what another tuner shop mechanic told me - I do check my data.

At any rate, if he has doubts, let J Curtiss ask his local tuner or he can check the LS1 Forum and/or this forum - perhaps A&A would chime in here - about the balancer weights.

My H/C setup runs just fine at 6800rpm.

As for your rant, and veiled attempt at calling me ignorant - seems like you have issues dude. I have never told anyone bogus or inaccruate information on this Forum - if I don't know I don't respond - and can gladly say I have gotten more out of this Forum that I have contributed. You seem to prefer being the center of attention, so go for it - you are on center.

 

Again, the information is incorrect. The three volume service manual that is supplied to dealers from the manufacturer of the car is very explicit and DOES require you to install the weights in the pulley.

Since you continue to give mis-information and refuse to admit when you make assumptions I am attaching the related pages from the GM Service manual to help educate you on the matter.

I see that the Borg has impacted your ability to learn....

 

Just in case you're having trouble reading the pic it says:


Important: For manual transmission applications, note the position of the crankshaft balancer before removal. The balancer does not use a key or keyway for positioning. Mark or scribe the end of the crankshaft and the balancer before component removal. The crankshaft balancer must be reinstalled to the original position. If replacing the crankshaft balancer, note the location of any existing balance weights (if applicable). Install new balance weights into the new crankshaft balancer (if applicable). Crankshaft balancer weights must be installed into the new balancer in the same location as the old balancer. A properly installed balance weight will be either flush or below flush with the face of the balancer.

Do not reuse the crankshaft balancer bolt. Install a NEW crankshaft balancer bolt during final assembly.





As you can read above there is no rebuilding of the original balancer just replacement and insuring the assembly balance.

 

Yes I did. I don't believe they have a minimum dollar order, but the nuts come in a minimum number in a bag. It took a few days to get the parts. Some have had luck looking in local hardware stores for the threaded rod, but I personally can't find it as I am now looking for 8mm threaded rod to make some alignment rods for water pump installation.

 

IseeRed,
I read the service manual, and I see your point ,although it didn't leave me seeing red (pun intended). I guess the question really goes to those who have replaced the factory balancer with a factory balancer. It seems that many who do replace their balancer go with an aftermarket model (underdrive, etc). That being said, does the factory balancer come sans weights? If so, it would make sense to have to transfer the weights to the exact locations, and install the balancer in the exact position as well.

What has been your experience?

 

As said before, the factory balancer comes with the weights already installed. The crankshaft and pulley are not a match-machined pair. The Helms manual is telling you to install weights but does not address the fact that the pulley comes balanced from the factory with new weights.