I have tried to search about balancing flywheels and came across a few threads about reading the svc manual etc. So i went to the disk version of the manual that I have to read to see what it says. A bit of backround here...I bought my car used, it had a centerforce flywheel as well as a CF dual friction clutch. Along the years I have rebuilt my trans, and replaced the pilot bearing while I had this out, as well as the little metal cap inside the crank as it was leaking, that in itself is a different story. I have also replaced my crank pulley a few years back. I have always really had some vibrating from about 1800 on, but it has not really bothered me a ton. This year I figured I would tackle it so i started reading up on it.
My plan was to take my clutch out and flywheel and check to make sure everything was aligned correctly as I have heard horror stories about flywheels that were match balanced to the OE flywheel. Problem is i dont have that flywheel.
So in the manual under Balancing, i see about flywheel and crank pulley balancing. At this point im like oh shizzz. I threw my original crank pulley out years ago, and it was replaced with an OE again, not thinking at the time I had to orient it to a certain direction.

From the manual below....
• New balancer onto an existing engine:

Install the same size balance weights into the new balancer in the same location as the old component.

• New flywheel, clutch, and pressure plate assembly onto an existing engine:

Do not transfer or install balance weights.


According to this wording from the manual, technically would I be able to replace my crank pulley with one that does not have any balancing holes drilled in it, since my flywheel and clutch assy is a matched assy as well?



Hopefully I dont get flamed on too badly for thinking this...

 

Thoughts?

 

I'm curious about this since I'll be doing a pulley replacement in the next week or so.

 

Make certain you get a zero balanced flywheel/pressure plate kit and go with it.

 

What about the balancer?

 

Any balancer you buy for your LS engine will be 0 balanced.
Now as far as your engine vibration is concerned, there is portable equipment available to balance your engine in the car.
Back when I worked at GM proving grounds we used it just for that on prototype ZR1 cars.
It's a strobe light unit but you'll have to look around your area to see if anyone has this type of equipment.

 

100% correct!! Look on the internet and in the yellow pages.

BC

 

Excellent, thanks! This will be on my list of things for the summer yet. I remember it being alot worse last fall...it seems to be at 2000-2400 rpm at its worst

 

I had a zero balance clutch/flywheel installed on my '01z and it vibrated. It had a spot in the 2k range, then went away and came back in the 5k range.

In my searches to find out what was wrong. (at the time everybody said these cars were internally balanced so I was looking for anything from shop error to who knows what) -I spoke to a GM engineer who told me to go back to the shop, get my old flywheel and I'd see some weights in the form of metal dowel pins. Those were put in by the factory when the engine was assembled and fired.

He said that if I couldn't get the old flywheel there are 11 places in the U.S. that can actually do the strobe light rebalance with the car assembled... like on a chassis dyno type environment although the only place he knew of in person was located in Ohio somewhere. This gave me hope since at the time I didn't know if I could get my old flywheel back. Turns out the shop still had my old parts in the dumpster and we just resurfaced the old flywheel and put it back in with the new clutch. They didn't want to take the chance of messing with the new flywheel and transfering weights since they did the second R&R on warranty. Perfectly smooth with the old flywheel back in.

With that being said, I replaced my stock balancer recently when I did all the polishing work (with a stock size Powerbond pulley) and the engine is still glass smooth.

So, in my case, the aftermarket flywheel (without weights transfered) made the vibration, but the aftermarket balancer pulley didn't.

That's my $.02 - Good luck.

P.s. if you need to find out more about this, I spoke with a technician working for Luk clutches which is the maker of the oem LS6 (and many other oem) clutch(es).

 

Many "balanced" clutch/flywheel assemblies are notoriously out of balance as supplied. Possibly that is the source of your vibration? I would suspect that before either the dampener/rotating assembly being out of balance.

 

Joshua, excellent info. I went into my facebook to look at old pictures from when I had this stuff all out during rebuilding the trans. It looks as if my flywheel/clutch must have been a zero matched assembly. see picture.


I guess my next questions is, what if the torque tube bushings were going? would it do it at all RPM's, or would that be limited RPM's as well?

 

The reason I replaced my clutch was because the front torque tube bearing failed at 6500rpm as I shifted to 2nd gear... it killed the clutch hence the rebuild.... and my desire to get a lighter flywheel since the job was being done.

Before the TT failure, the car was glass smooth as always... no indication it was about to go except for the last week before I did hear a slight screetching sound for a split second as I engaged the clutch backing into my driveway... I wasn't sure what that was at the time.

So, the TT bearing on it's way out had no affect on vibration. Hope this helps a little more.

 

I should clarify that the TT bearing failed thereby putting a large amount of side-load stress on the clutch disk at the moment of failure.

And.... when the car was back together the 1st time and I was tracking down the vibration... and found out about the balancing options... I knew I would never do that.

Going from Atlanta to Ohio on a gamble wasn't the plan, I would've saved for an aftermarket 382 shortblock (or had mine rebuilt with the 382 aftermarket assembly) that was truly zero balanced and go from there.... but, I found the old flywheel so that's that.

 

Nver2loud, it would seem at this point that your only option would be to install proven zero-balanced FW/PP and balancer; since you have no way to determine if your engine was initially externally fine-balanced.
Balancers are probably pretty safe to install untested, but maybe checking the new FW/PP for balance would be prudent.

Then, if you have imbalance, you don't need to 2nd guess the components, you just need to find a shop with an EVA machine (strobe balancer) that can perform the external balance.
FYI: The EVA machine is explained in the vibration section of the 2000 shop manual.
Also, the 2000 manual definitely says to exchange the FW weights when installing a new FW/PP combo (which is supposed to be zero-balanced from the mfg). 2002-and-up manuals say not to replace the weights - so something changed at the factory, maybe tighter tolerances during build? So, that tells me quite a few of the early engines required the external balancing.

During my nitemare in 2000, the dealer messed around with the tiny balancer weights, but we couldn't feel any difference. The factory tech balanced the FW with the EVA, and left the balancer alone (no weights). Later, I installed an underdrive balancer and noticed no change, as expected.

DG

 

good info as well, thanks!

 

Hi . I don't suppose you would have any specific advise on how to find a shop with such a balancer would you ? I have been searching for it and have turned up nothing . I live in Atlanta and have a notable vibration after an clutch / flywheel replacement . Thanks .

 

Hi all, to make sure I understand, I am in the process of changing my harmonic balancer with a OEM (Delco) replacement on my 2001. I see that weights "as applicable" should be installed per the shop manual. However, I've seen many "they need to be" and "they do not need to be" threads on the forum. I actually spoke to a repair shop here in Houston that says they have installed many C5 balancers and they never put weights in them.

There is a lot of back and forth about this topic. I plan to put weights in my new balancer. My new balancer has 18 holes. My old one has 16. I can line the balancers up so that holes with weights in the old balancer match up to holes in the new balancer.

I'm trying to verify I should actually use the same size weights in the same holes on the new balancer even though the new one has additional holes. Also, do the additional holes in the new balancer have any impact on balancer performance? Seems it would since it's theoretically lighter.

 

The new balancers should be neutral balance as you receive them . The number of holes are not important , as that number varies . The extra holes are just what it took to get that one to balance out . Transferring any weights from your old balancer to your new one is good to do since they would have been installed there to bring that engine assembly into spec. balance while it was on the production line . I do not recall my balancer as having any weights though .

 

Thanks. Mine has them. The thing about it is that I'm sure the outer and inner hubs of my balancer slipped when the balancer split apart and the original balancer position relative to the crankshaft can't be determined.

 

it's unfortunate there is so much "back and forth" conflicting information on here and everywhere. There is only one actual situation. IF your vette has a manual transmission from the factory, it is a FACT that it went through a final post assembly "hot balance" procedure. Weights were added, AS REQUIRED (read: some engines had weights added, some did not) to either the front damper, the Flywheel, or both in order to bring the total engine assembly balance down to within 0.5 oz∙in at both the front and rear planes. That is an incontrovertible fact. It is YOUR CHOICE if you choose to maintain that factory balance when you replace your damper or clutch assembly. The engines are fine "as assembled" and the final hot balance procedure is done for NVH purposes to minimize unwanted vibrations.

and how many holes are you counting? holes to receive balance weights are through holes. Holes drilled into the face for balancing the damper BY ITSELF are blind holes. the through holes are a symmetrical pattern. The blind holes are wherever they were needed to bring the damper by itself into balance within the manufacturer's spec. You wouldn't put a balance weight into one of the blind holes, only a through hole. Most aftermarket dampers do not have the thru holes to accept balance weights.