What exactly does this do, beyond having the weights of the pistons and crank counterweights, etc, all in sync? What are the consequences of not doing this? I'm not sure if my machine shop did this during when I rebuilt my engine, I knew next to nothing then, so they may have, if it's standard procedure.

No, it's not generally standard procedure b/c they usually ask if you want it done b/c of the extra time and added expense.

Balancing an engine makes them smoother so that any out of balance conditions are corrected so don't work against themselves which costs engine longevity!!

My junk 301 was made of several different engine parts and was not balanced. It used ta throw it's damper off every so often which when driving down the road at 55 mph kinda gets exciting to say the least!!

It had several dynamic unbalance harmonics in it and after driving her as long as I did, I could pretty much tell my rpm!! It vibrated about three times going up to 7,000 and above which I ran it at many, many times up through the gears!!

Yes, spend the extra money and balance her, she will do you better, imho!!!

pdq67

Any time you change anything in the engine it should be balanced including flywheel and pressure plate. Just going from a cast piston to a forged somtimes is quite a differance in weight.

CNC BLOCKS, I'll be taking my assembly in for balancing soon, I asked the shop if I should bring the pressure plate and they said no. I was really hoping they could balance the assembly without the PPlate then bolt the PPlate on and balance that to nuetral. Do you think this would be the right approach. I was thinking that way if I needed to change PPlates in the future it would just need to be balanced nuetral. Make any sense? Bob

BOB
Your thinking is right,I highly recomend the flywheel and pressure plate be balanced.

We have a mandral we put the flywheel on we balance it neutral and then put on the pressure plate and balance that neutral and index pressure to flywheel so they go together in the same position as they were balanced.

On a external balance job. When finised balancing rotator we put the pressure plate on and neutral balance. We have seen pressure plates
of alot.

If you machine shop won't do that for you its time to find a shop that will.

Any time we turn a fywheel or change clutch and pressure plate we rebalance.

Bob,
I have to disagree with Carl a bit here. smile.gif

A clutch needs to be balanced in pieces. The plate part of the clutch assembly "floats" in the cover & it is almost impossible to center it in a static condition.
It hopefully tends to self center under running conditions if each part is balanced & assembled properly.
I know shops who "balance" the clutch but I do not agree with doing it unless you want to take it apart & balance the indivual parts separately.
Hopefully, just like a convertor it was balanced properly by the manufacturer.
I used to "balance" clutch's years ago until I spent some time at a clutch manufacturer & their balance guy showed me this.
They balanced each part separately & then assembled the clutch.
If you want to see this take your clutch in while your flywheel is being balanced, bolt it to the flywheel then spin it up & "balance" it. Stop the balancer & tap the plate lightly on any side & then respin it.

Thanks, I can see the problems witht trying to balance the clutch disk with the assembly since it is always in a different location relative to the crank when in use. I figured I'd have the pressure plate balanced and not worry about the disk.

Mike
I have a Stewart Warner balancer and a Hines balancer and have been doing this for 28 years now. A clutch disc weighs just a few pounds and is a lot smaller then the flywheel and pressure plate and we do balance in pieces. If you read my post. The clutch disk is never a problem its always the flywheel and clutch cover. So far I have had no one complain about anything we have balanced in fact some cutomers bring in flywheels and pressure plates to spin up because they had a vibration and after we balance it problem is solved.

Why would you smack a pressure plate with a hammer???? I never heard of that as bieng part of the balancing procedure, I will print this and pass it on to other shops to let them know they are doing it wrong.

And do you smack your crank when you get done balancing that???????????????????????

I'm stepping in here...

Sure I do with a "BFT" and a hard block of wood as I set the thrust bearing fore and aft as I spin the crank in the main saddles as I torque her down!!

Have a nice day and please don't let a pi--ing contest start... We can agree ta disagree can't we??

pdq67

Carl,
Don't get your panties in a bunch, :D
All I said was I disagree with you.
I did not say I beat on anything with a hammer.
I did read your post & I have balanced a few engines & flywheel assemblies over the years.
With all due respect to your 28 years I have about 35 years in this trade plus being around it since & was a kid but do not feel this is qualification enough to asume I have now learned all there is to know.
Hell, I'm still learnin & hope I can keep doing so.
What I posted was in fact what a well respected performance clutch manufacturer explained to me a number of years ago.
If you can expalin to me why this clutch manufacturer was wrong & you are right I will rethink my position on clutch balancing
He even took the time to show me & laughing explained that when I was trying to balance a complete pressure plate assembly I was pretty much "amusing myself"
I am in no way referring to the disc, rather the plate that "floats" in the cover.
I did not say anything about the disc.
As you know this piece (the Plate) weighs a few pounds & all you have to do is move this much weight a few thou & it will completly screw up the balance.
I have taken clutches apart & rebalanced covers seperatly & also the plate & will agree that I have found stuff that was "less than perfect".
What I am saying is if you bolt the complete pressure plate & cover assembly to the flywheel there is a very good chance the plate will not be centered in the cover.
I was not disrrespecting your qualifications, I simply have a difference of opinion with regard to the balancing of clutches.

Please do not take a difference of opinion as an attack & do not assume 28 years means it is time to stop gathering information.
As I said, I have been in this deal for a lot of years & I still find it a learning experience ;)

Originally posted by pdq67:
I'm stepping in here...

Sure I do with a "BFT" and a hard block of wood as I set the thrust bearing fore and aft as I spin the crank in the main saddles as I torque her down!!

Have a nice day and please don't let a pi--ing contest start... We can agree ta disagree can't we??
pdq67 PDQ,,
One would hope so smile.gif
I tend to listen to most opinions as it's how we learn. Or at least try to learn :D
Take all the info you can get, hell it's free, take it home, mix & stir & throw out what doesn't make sense to you then file the rest in that place where you put all the other information you were going to save.
Then all you gotta do is remember where you put it :D :D

MIKE
I have never heard of any body taking a clutch cover apart to balance it, The clutches I have seen you can't even get apart and they don't seem to be floating, I would imagine that balancing the cover as one unit is the way to go.

I have worked on a engine development project many years ago that Smokey Yunik and Jack Roush was a part of and Smokey mentioned that balancing was the most imperfect science there is as we can't duplicate what goes on in a engine meaning crank flex, oil in areas as pistons and rings and in the oil feed holes in the cranks, carbon on pistons etc.

check it out at www.edisonian.com (http://www.edisonian.com) click on power curve, I worked on that project for 10 years

Originally posted by CNC BLOCKS N/E:
MIKE
I have never heard of any body taking a clutch cover apart to balance it, The clutches I have seen you can't even get apart and they don't seem to be floating, I would imagine that balancing the cover as one unit is the way to go.

I have worked on a engine development project many years ago that Smokey Yunik and Jack Roush was a part of and Smokey mentioned that balancing was the most imperfect science there is as we can't duplicate what goes on in a engine meaning crank flex, oil in areas as pistons and rings and in the oil feed holes in the cranks, carbon on pistons etc.

check it out at www.edisonian.com (http://www.edisonian.com) click on power curve, I worked on that project for 10 years Hi Carl,
First, let me say thank you for the completly different tone in your response graemlins/beers.gif
Second, thanks for the link it was really interesting reading.

On to clutches smile.gif
To the best on my knolwdge taking them apart is how the manufacturers & rebuilders balance them.
I know what you are referring to about them not seeming to float but if you ever take one apart, at least the type that come apart like all Long style & Borg & Becks type & lot of the diaphrams with bolts & remove the springs you will find the pressure plate moves quite freely on it's pivots within the cover.
This is what I was referring to when I said they "float"
If you could devise a way to be sure the plate is centered in the cover then I agree balancing it as a unit is the way to go.
But as soon as the fingers or diaphram come back & hit the cover they will "lock the plate in whatever position the play in the pivots allow.
This in turn may or may not be a centered position.
When I referred to tapping the plate what I was trying to convey is how eaisly the plate will move off center or wherever it happens to be when you tap it. (or "beat it with a hammer" :D )
I have shown this to both customers & other machine shop folks as well as one of the balancer manufacturers at the PRI show one year while they were showing how to balance a flywheel/clutch by "balancing" a pressure plate with my trusty little hammer.
Just take the time to try a small experiment sometime.
Set up a clutch for balancing, find the heavy spot & then tap the plate on the outside edge to try & move it away from this point.
I think you will find you can achieve a "balanced conditon" without ever adding or subtracting weight ;)
If you really want to drive your balancer nuts, pull the springs out of a clutch, put it back together & spin it :D

I agree 100% about balancing being an imperfect science as we are doing a lot of guessing & assuming in regards to oil etc.
But in the end, we do the best job we can with our limited means & understanding of what is actually going on inside these simple devices we like to think we understand :rolleyes:

I can definately see that the balance operation is not a perfect science considering the weight of the oil etc. And I also relate to the fact that the pressure plate friction ring is floating within the plate asembly, but never realized the slight movement of the friction plate would make much of a difference, I bet if someone designed a coupler to seperate this stuff from the engine to reduce vibrations it would make the engine run alot smoother. The machine shop I talked to didn't want the pressure plate for balancing but I didn't discuss why. I'll be talking with him soon so I'll post any info gathered, this guy builds a lot of circle track engines for Wisconsin racers. I sure would like the pressure plate balanced or checked. I've had some engines in the past that spun up really nice and others that had a bad vibe at 2500-3000, I want this one to spin nice.

Bob,
I agree completly with you wanting it checked as I prefer to check everything.
If I could find a way to feel fairly confident the plate was in fact centered I would check every one that passed through my shop.
Unfortunatly I don't really know of a way to do this so the alternative is to trust that the manufacturer of the clutch has done his job,,
Just as we trust convertor manufacturers to do.
If it is a quality piece it is probably going to be well done. If it's a "bargain" one,,,,,who know's ;)

Mike
Thanks for the info. I should have mentioned that Smokey had an other good point that when we put our bob weights on in the center thats great but the rods have .020 side clearance move our bob weights .020 all one way, That will really give you a whole new out look on things. The term imperfect science fits good here. Agree??

Originally posted by CNC BLOCKS N/E:
Mike
Thanks for the info. I should have mentioned that Smokey had an other good point that when we put our bob weights on in the center thats great but the rods have .020 side clearance move our bob weights .020 all one way, That will really give you a whole new out look on things. The term imperfect science fits good here. Agree?? Carl,
Agree completly.
I have played with this years ago to see for myself when I was told about moving the bobweights forward or backward on the journals.
I believe it was Gary Hildrith (sp?) from G&H Balancing that was giving a demo at one of the shows.
He is the go to guy when you ever have a problem with your balancer or a queston.
He also keeps belts etc for most balancers in stock.
I am now very carful about centering them so at least I am doing it the same every time.
I have found rotating them a little doesn't effect the balance but moving them from center on the pin makes a huge difference :eek:
I guess you have to decide where you want to put your weights & do it the same every time. I feel centering them is the closest representation of how they run.

Mike, and Carl ...
Try snugging the bobweights down and sliding them all the way forward against the radius. Then try it with them all the way back. Then put them in the middle. I doubt that you will find a measurable difference in the three positions. This is something that Bob at Pro-Bal told me when I purchased my balancer. I have been sliding all the bob weights to the front and have not had any problems. I have tried all three positions. On some of the Chryslers and others that have an undercut fillet, I center them. Try it and let me know what you find.
As far as rotating them, IF you make both halves of the bobweight exactly the same, it should not matter because the center of gravity of the bobweight will always be at the center of the journal.

Hi Bill, smile.gif
Stayin busy back there?
I have never tried moving all of them one way or the other, I just found moving one or two different from the others really screwed up the works.
Now that you mention it, I believe Gary said something about that when he was giving the demo like put them all front, center or rear but do them all the same??
Crap,,,now I gotta try something else to see what it does :D

Mike,
More work than I can keep up with :( Yea, all of the bw's have to be the same way, either towards the front, towards the rear, or centered. I have found that by putting them all to the front I can put all four on the crank in about a minute. No more dial indicator, calipers etc, and I cannot see any difference in the three ways. You are correct in that if you have one moved from the others it will throw it all off. Try it, you'll like it smile.gif Let me know what you find.

Quick question to tag on.....

My engine will be being balanced soon, and i'm not sure what way they will be doing it. (internal or external)

What is the difference between something being balanced internally as opposed to externally? Also which is better?

Thanks in advance guys.

Originally posted by pegleg71:
Quick question to tag on.....

My engine will be being balanced soon, and i'm not sure what way they will be doing it. (internal or external)

What is the difference between something being balanced internally as opposed to externally? Also which is better?

Thanks in advance guys. It means exactly how it sounds smile.gif
External means there is added weight on the damper or some other part that is on the front of the crank & a flywheel that has weight added to it.
Internal means there is enough counterweight in the crankshaft so this is not necessary.
I prefer internal as the closer you put the weight to where it is needed the more effective it is. It lessens a condition called couple which is a whole new discussion but essentially a condition where when you add weight some distance from where it should be it causes a "rocking" or "flexing" motion in the crank
This is not the twisting motion that the damper helps control, rather more of a "rock" from end to end.
External will work fine & is much less expensive in almost all cases where you need to add more weight.
It gets very expensive to add Tungsten (heavy metal) to the crank to internal balance an engine & is really not necessary for the majority of cases

=====EDIT=====
High RPM & endurance type engines would be an example of where you would want to spend the money on internal balance as external balance is somewhat harder on the bearings that are closest to the unbalanced part of the crank

soccerguy, I live in Stillwater...whom will be doing your motor work..feel free to email me at tfocht@kicker.com

Tracy

Thanks for the explanation wolfplace. I just got back from talking with the machinist who's building my engine and I found out that it will be internally balanced. graemlins/thumbsup.gif It's going to cost $250 for the balancing...is that a decent price? While there he showed me the difference also, so now I know exactly how it works. Thanks a bunch.

I might add something that I didn't see in these posts...unless I missed it...when getting your rotating assembly balanced your machine shop should give you a balance sheet that tells you what it was and what it is now. If they don't give you a balance sheet...find another machine shop.

Erik,
Just curious but why would you want a sheet that tells you what it was or is as far as balance goes?
I can understand wanting all the individual weights of the parts & the total bobweight used, even possibly the factor used which we list on all our reciepts but what good does a number listing the before & after balance condition serve?
In 30+ years of balancing I have never been asked for a sheet giving "before & after" conditions but as I said I do list all weights & factor used along with total bobweight on the receipt for future reference.
We would be happy to give a customer one if asked but again kinda curious what the purpose would be?? ;)

I agree, the weights of the indivdual parts are all that should be needed if a replacment is necessary down the road.

Erik,
I have never had a customer even ask me for a bobweight card. I do mark every crank that I balance with a job number, and have balance cards on every one I have ever done. I will gladly give the info to anyone that wants it, but in this area, it is not really common practice to automatically give this information.
I think the "before and after" printouts that the newer "whiz bang" balancers print out are mainly marketing hype. When you get your tires balanced, do you ask for a readout of how bad they were out before the tire shop balanced them ? I doubt it, all that really matters is that they are balanced properly when finished.

What about an externally balanced 454, does the flywheel get bolted to the crank shaft while balancing? and if so, what do you do for balancing when replacing just the flywheel & clutch while in the car? (motor still in car just change out flywheel/clutch assembly) Dave

Originally posted by dsr:
What about an externally balanced 454, does the flywheel get bolted to the crank shaft while balancing? and if so, what do you do for balancing when replacing just the flywheel & clutch while in the car? (motor still in car just change out flywheel/clutch assembly) Dave =
Yes, the damper or front hub depending on what you are using for a damper & flywheel are bolted to the crank.
No reputable machine shop will change the weight of the damper or flywheel on an external balance deal, they will do all adjustments at the crank.
The reason is so you can replace the damper or flywheel with another one & be reasonably close to balance.
The best way to replace is to take your old one & new one to a shop & have them checked but not completly necessary if someone hasn't changed the "unbalance" of the part. They should all be fairly close to the same.
Now before someone gets all excited here, read the whole post first :D
What I am saying is you can interchange the damper or flywheel fairly confidently without rebalance if someone hasn't done a half assed balance job by removing weight from them because it is was easier than adding or removing weight at the crank.
I am not saying that it wouldn't be better to have them checked but sometimes you are in a situation where that's not possible. ;)

What do you guys think of the bolt on balance weights available for converting a neutral balanced flexplate/flywheel to external balance. Do they work? Also could something like this be used on a neutral balance engine to add weight for easier balancing? The piston and rod assemblies going in my son's 331 weigh about 100 grams heavier than stock so I'm sure the shop will be adding metal to the crank, I've got a 454 bolt on balance weight I was thinking of bringing in with the assembly if it will make the balance job easier.

They work very well & are a LOT less expensive than adding weight to the crank.
I like them for external balance as you no longer need to worry about anything but a neutral flywheel.
You will still have to use an external damper assembly or will have to have weight added to the front of the crank.
But,,,I do prefer to internal balance budget permitting, I feel it is a better balance.
That said, there are thousands of externally balanced engines running around with no problems so don't really feel it is a huge concern, just my preference ;)

Thanks, wow this site has been busy.