I'm getting ready to do a Z06 clutch, pressure plate, flywheel, master and slave cyl., and 410 gears, but you guys scare the heck out of me. I have seen a hundred posts on this subject but everyone seems to have different thoughts.
Here are my questions about the LS1, LS6.


1. Were all engines interally balanced?

2. Were all engines externally balanced?

3. Were some internally balanced and some externally balanced?

If the engines were externally balanced the flywheel would have had to follow the crank through the engine assembly process. This seems like it would be very cumbersome.

Why would any manuf. ever externally balance an engine??

I think I'm going to hold off on my instal till I feel very comfortable with this balance issue.

Thanks for your help. I hope to be :party: soon.

 

Call Chris at Speed Demon, a forum sponsor, and he'll clue you in to everything you need to know. :cheers:

 

only std shift engines have a final external balanced at the engine factory. the flywheel and clutch are balanced while they run the engine. they showed us the setup while touring the engine plant in canada. :chevy

 

:iagree: :thumbs:

 

So Clem, you are saying the engines on the six speed cars are run with the flywheel and pressure plate installed and if there is any additonal balancing needed they balance using weights or whatever on the flywheel ?
So I guess it would be luck of the draw. Some are proably fine and others need the flywheel balancing act.

If the rotating assembly is balanced before adding the balanced flywheel and PP they must just be doing one final check and correcting the 1 in 10,000
that is not quite right.

Does this sound right?

Or does it sound like :bs

:seeya :seeya

 

Where did this info come from? I would like to read it for myself. The manual says to zero balance the assembly.

 

i stood there and watched them do it and they explained what was going on. any other doubts?

 

every flywheel/clutch engine is given a extra balance after the clutch is added to make sure the clutch assy does not cause a out of balance condition. this is the last step in the line. if you would take the orignal flywheel and pressure plate assy and check the balance and duplicate that on the new setup you shoild be fine. :chevy


[Modified by clem zahrobsky, 2:20 PM 12/21/2003]

 

Clem, please bear with me. I'm not doubting anything you say or have seen or been told, nor am I trying to beat a dead horse to death. I'm just trying to get all the info I can before I start this clutch replace as you know afew members have had horror stories after a clutch replacement.

I must assume that the crank assy. is balanced before the flywheel is installed.

I also assume the flywheel is balanced with the PP as a unit. The PP will only install on the flywheel in one position.

Did you get the impression they were balancing all the 6speed engines or were they just double checking that everything was OK??

This balancing thing really bothers me so my clutch instal is on hold for now. Thanks for your help.

:auto: :auto: :auto:

 

after the engine assembly is balance including the flywheel the last step is the addition of the pressure plate and then the whole engine is checked for balance and balanced if necessary. if you take your orignal flywheel and pressure plate assy to a balance shop they should be able to duplicate the balance with your new pressure plate and flywheel


[Modified by clem zahrobsky, 2:42 PM 12/21/2003]

 

speedy, Check out this thread, and look for the post by bowtiebandit, basically, you need to zero balance all your new parts individually and not transfer any factory balance weights from the old flywheel to the new flywheel.
There is a lot of confusion on this because the factory manual says TO transfer the weights, which is now wrong info and is changed, but you can't go out and rewrite a million manuals.
http://forums.corvetteforum.com/zerothread?id=707377

 

any good balance shop can put your orignal FW and PP on a mandrel,check the balance. if neutral balance just have them do the same with your new setup. i have had external balanced BBC flywheel balance duplicated this way. they just mount the old and new flywheel offset weight 180 degrees apart on the mandral and balance the new setup to neutral balance. :chevy

 

Let's assume I take my old assembly in and say it's out of balance by 12 grams. Should I assume it was out by this much to compensate for an inbalance in the motor or was the motor balanced OK and this assembly was just not perfectly balanced? So should I get them to unbalance my new assy. by 12 grams?

How many grams out of balance would it take to feel a vibration?


I guess I'm making too much out of this. Just don't want to do it twice.

 

Let's assume I take my old assembly in and say it's out of balance by 12 grams. Should I assume it was out by this much to compensate for an inbalance in the motor or was the motor balanced OK and this assembly was just not perfectly balanced? So should I get them to unbalance my new assy. by 12 grams?

How many grams out of balance would it take to feel a vibration?


I guess I'm making too much out of this. Just don't want to do it twice.

:steering: :steering: :steering: :steering:

 

i do not think you will find the assy out of balance because they balance the flywheel to make up for the out of balance PP. make sure you get the PP back on the FW the way it came off. GM used to stamp a"X" on both parts but i do not know if they do it now. that is why you should never balance them as a unit because you run into this problem. if the engine is internal balance both the flywheel and the damper should be neutral. always balance the flywheel and then put on the pressure plate and do your balancing adjustments to the pressure plate. the factory does not do it this way so you must balance both the flywheel and the PP as a unit after that if you change the PP. since you are changing both i would check the balance the flywheel and then add the PP and if any balancing is needed do it to the PP. this way if you have to change a clutch all you need to check will be the clutch. i hope i am not making this more confuseing. :chevy

 

:crazy:

 

This topic is becoming confusing. I hope I do not add to it. Engine balancing involves pistons/rings, connecting rods/wrist pins, crankshaft, harmonic dampener, and flywheel/clutch assembly. When the engine is being built, the pistons (and technically rings also) are balanced by equalizing the weight of each unit (by removing material or carefully sorting a whole batch). The rods (and technically the pins) are also weighed and statically balanced (its a little more complicated since each end of the rod is separately weighed and balanced). Then "bobweights" are attached to each rod journal of the crankshaft to simulate the weight of the pistons and rods, and the crank is spun on a balancing machine (much like a tire/wheel balancer) and weight is added or removed as necessary to balance it. Internal balancing is now complete.
The harmonic balancer is spun by itself and balanced, and the flywheel and clutch are similarly balanced. Clem is correct that if you are installing a new assembly, each component, i.e. flywheel and pressure plate, should be balanced separately so that in the future you can change one without changing the other. I don't know if Chevrolet does this at the factory. If the flywheel and pressure plate are balanced bolted together as an assembly, they have to be replaced as an assembly, though the new components can be individually balanced before you install them if that was not by the manufacturer.
On my C5, my experience is limited to buying a complete Z06 flywheel/pressure plate assembly from GM and installing it just as I received it. I have no problems. Some on the Forum suggest you take the assembly to a good automotive machine shop and check the balance. That's good advice.

 

I would not 0 balance a new assembly and expect it to be right on a stock motor. Externally balanced means just that, engine is final balanced at end of line with clutch/PP/harmonic balancer to fine tune balance. A stock flywheel that has counterweights on it could be there for 1 and or 2 reasons: engine reciprocating assy out of balance and/or flywheel+clutch assy out of balance. So one could be in error to simply transfer the weights to new flywheel. They could also be in error is they 0 balance. Point is, you just dont know how much the engine or the stock flywheel was out of balance necessitating the external counterweights. So the proper thing to do is to do like Clem says, take your stock assy (entire clutch assy) to machine shop and request the new assembly is balanced to it. You will be good. Dont do it any other way. If you do, you could get lucky and not experience an out of balance vibration. but all the horror stories you've read about are about those that didnt get lucky. I've been down this road and have learned the hard way.
Robert Judd
Gen3 MS


[Modified by rwj383, 11:35 PM 12/21/2003]

 

rwj- what happened?

 

rwj-I don't understand your advice. You say that it could be a mistake to transfer the weights from the old flywheel to the new one if the weights were there to balance the old flywheel. Then you advise to go ahead and do it. I'm not so sure that's good advice.