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Lastly what do you suppose the drill holes in the audi I5 damper/pulley are there for if not to offset the locking tool chunk of metal in the hub? I find it interesting that with these two examples that it's easy to see that the holes aren't even drilled into the same spots which makes one think balancing. I think they are zero balanced.

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And the one on the left has probably slipped on the rubber ring.
 

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Very possible even though it came off of a dead stock 7A. It would make as much sense that it slipped as that the hub balance was that far off of the locking tool lump.

On second thought, doesn't the crank turn clockwise looking at the pulley? If that is the case it seems that the slip would be the other way. ??
 

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I believe the Audi I5 is internally balanced. When I had all my components zero balanced, they didn't have to remove the crank locking tab on the pulley, and that was after I had the section for the AC and PS belts removed. Also, if the stock flywheel was also a balance agent, putting a zero balanced aluminum flywheel on would cause all kinds of vibration issues.
 

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RSCoupe said:
I believe the Audi I5 is internally balanced. When I had all my components zero balanced, they didn't have to remove the crank locking tab on the pulley, and that was after I had the section for the AC and PS belts removed. Also, if the stock flywheel was also a balance agent, putting a zero balanced aluminum flywheel on would cause all kinds of vibration issues.
Exactly, but instead we are revving to 8.5k. That wouldn't happen if balance had been messed up rather than a better balance.

Repaair said:
Take a look at the balancer, it has a large notch of metal next to where the bolt is.
It is anything but zero balanced. If someone has one post a picture, its easy to see.
One thing that your are right about is that it IS easy to see. My curiosity got the best of me so I went out and dug up an old mc flywheel. It has all of the zero balance drill holes in the back of the wheel. Very easy to see.

 

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Good example. See how far the drill holes are from the crank centerline, that is a lot of weight to remove from a flywheel that is supposed to already be zero balanced. I rarely use anything larger than a 5/16" bit for flywheel balance. If you don't remove the imbalance weight from the inside of the balancer you have to remove quite a bit from the outside of the balancer.

Audi, Mercedes and Volvo I5 engines are not massively enternally balanced. Thats why you can slap on a zero balanced flywheel and not notice it. Some engines are 50oz., some are 28oz.
Audis are much less. Some are internal at the front and external at the flywheel. I'll try to attach the AERA list of engine balance cheatsheet that all machinists have.
 

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That weight wasn't removed by me!!!! That is the original zero balance holes from Audi on the back of the flywheel and the same for the balancer. Neither one of those examples have been touched by me. They already are zero balanced!!
 

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To add something from the Subaru opposed 4 world. One of the reasons Subaru's have a hard time revving past 8K is that they haven't enough space for counterweights to fully balance the reciprocating assembly. Of course the opposed pistons are only slightly offset and apparently not enough that the factory worried about balancing them for a motor that was to go to 7k but it keeps a bunch of motors from going past 8.5k or so. I have a hard time thinking you could throw a balancer on the end of a rather long crank and get to 8.5k as easily as the I5 does
 

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Yes thats just the thing, with the Subaru it is the cams and springs and ports that hold it back but once you put a fully built head on then you run into problems stabilizing the crank in the mains. There seems to be different schools of thought where some think it is oiling issues but I tend to think it is more of a balance issue that some people overcome with loose tolerances and lots of oil. Strangely oiling isn't so much of a problem once the crank is balanced.
 

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Repaair said:
How can it be zero balanced with two big drill holes in it?
How can it be zero balanced with a big weight next to the bolt on the balancer?
I guess the AERA notes are wrong too.
What are you talking about when you say "it"? The balancer has four holes drilled into the hub (inside the rubber) that pretty much line up with that "big weight next to the bolt". My way of thinking tells me that those holes were drilled there for more than just looks and isn't coincidence that they are drilled on the same side as the "big weight".

Is it the flywheel that you are talking about that has the two big holes? The flywheel has eight holes drilled into the back of it of varying size and depth. Again, do you think that they are just for looks or are you saying that they drilled the holes into the flywheel and balancer to externally balance the rotating assembly? Post your AERA note...I'm interested.
 

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RSCoupe said:
All I know is that I had mine zero balanced without any significant material removed.
Mark, what are you talking about...the balancer right? No significant material sounds like zero balancing to me. I assume that you are running a lightweight zero balanced flywheel.
 

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Repaair said:
Check AERA balance list attachment on post at the top of the page.
Makes a guy want to go see how far off the flywheel and balancer is from zero. They can't be much and it sure seems like a lot of drilling front and rear to get the motor balanced. I guess I will just have to go back to Jim's statement about what works and ask questions at the machine shop on the next build. Thanks for the info.
 

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quattro87 said:
Repaair said:
Check AERA balance list attachment on post at the top of the page.
Makes a guy want to go see how far off the flywheel and balancer is from zero. They can't be much and it sure seems like a lot of drilling front and rear to get the motor balanced. I guess I will just have to go back to Jim's statement about what works and ask questions at the machine shop on the next build. Thanks for the info.
My guess would be 20-30 grams at the front and maybe 10g in the rear.
I'll spin some when I get a couple in the shop, but if you have anything zero balanced on a 5 cylinder your not balanced as well as stock.
 

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I don't think I believe that. My seat of my pants tells me I'm better balanced and the 8.5k reinforces that. I guess when you zero balance the internals and the aftermarket flywheel is zero balanced that only leaves the front balancer, which like Mark says was pretty close to zero. If that balancer is zero balanced also, I'd have to say you would be better than stock, but that's just me. If you spin some at work let us know , I would be interested.
 

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All 5 cylinders 50% the bob weight while your at it, interesting V8 engines use the same basic formula, and boxer engines, are just that boxer engines!!! 50oz 28oz externally, zero balance, my machinist rarely checks Honda cranks because they are in his words dead on, everything else is subject to inspection, especially once your talking about modifications! The larger the imbalance of rod, and piston rings piston pin weight vs the crank will determine the need for a externally balanced engine, for the most part smaller engines can be internally balance without in-balance modification necessary, if your talking about a big block Chevy you will need to get your external in-balanced parts book out. Great read for those of you inclined, I been over this several time with my machinist now, never really done it myself, but it makes sense to understand the physics of the reciprocating masses in relation to one another.

http://www.carcraft.com/howto/ccrp_0803 ... index.html

And yes there is nothing like the sound of a 5 cylinder Audi, or a nasty V8 engine...

http://www.youtube.com/watch?v=h05b2jLB ... 1&index=63

:eek:
 

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To get back to before, no im not kidding.. Thats why the fucking tool works. It doesnt take an engineer to figure this stuff out. Just BTDT. If you didnt engineer the damn thing its all speculation. Ive swapped pulleys(crank), FW's(resurfaced/balanced individually) and never had a problem. Everyones shit stinks on this forum, so take it down a notch, its a discussion.

How do you propose we stop the crank to tighten/remove the 27mm bolt without this "CHUNK". Also, about the pulley shifting on the rubber.. The stock 7a i guarantee will shift the pulley because I've seen it rotate almost 90 deg on said stock motor, BEWARE.
 
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