I think the issue is that you are stuck on balance shafts doing "something" to take some type of load off internal engine parts. They do not. Once you get past that, I think you will be good to go.

 

Heres the actual BS patent that discusses all the facts

 

You guys could be correct.This was my thinking:

BS and crankshaft ride in a thin film of oil within the clearance between bearings and the journals. BS force from weights are transferred to block journals which transfers the load to block. Since the 2 BS are rotating in opposite directions with weights in positions where side loads are in opposite positions, lateral loads balances out. The vertical loads double up to move block slightly upward or downward. I was thinking that this slight movement helps brace the crank journals. I can buy that it is insignificant enough to call it zero load.

At some point when RPM is high enough, the oil film is squeezed out and the 2 metal makes contact. At 16,000 RPM (or 8,000 crank RPM), I was thinking contact is being made on BS at the points where the weight is as it spins around. That force is transferred to the block to help brace the crank as it starts squeezing out the oil film. Maybe it is insignificant and can be considered zero too, but I do see main bearing contact in engines without BS. Look at the 9:00 mark and see the slight wear.

 

Nope.

You know how when something vibrates and makes noise, you can put material on it to dampen it? That way the noise stops? Like Dynamat on door panels.
That's kinda how a balance shaft works. The door panel isn't being damaged, it's just vibrating.

Everyone has tried to explain it, so it is what it is at this point.

 

I see no signifficant wear in this video.... you should see the upper main nr1 on stock engines after some miles..

BS doesnt brace anything... it puts some load into the block to counter the resultant forces of the two sets of pistons not accelerating at the same rate.. that is it.. .the whole point is that pistons do not travel the same distance on the top half of the crank rotation as they to on the bottom half. As a result of that the pair of pistons going up is not canceled completely by the pistons going down... the resultant difference in force is your secondary harmonic..

bearing damage is the result of oil pressure loss, potential wrong clearences, crank flex, etc etc... but nothing to do with BS..

Another good example of BS delete is another rally car.. Lancia delta integrale... Stock car had them for two reasons... The block with BS was a later design (fiat lancia had almost identical block but without BS) and was stronger.. so it was used for homologation purposes.. In competition the BS were kept in block, without their drive belt (it used separate belt that ran both shafts) and were blocked so they wouldnt turn..

 

actually a great analogy is noise canceling headphones... they emit the same noise as that is incoming, just in the opposite direction.. So if you think about it.. the tottal ammount of vibration in the engine with BS is DOUBLE that of the engine without them..

 

Twice the vibration. truth

 

What you guys are reffering to is known as destructive interference or wave interference. When two identical waves meet at opposite(180°) phases the net amplitude of the waves is reduced, not doubled. That's how active noise cancelling works, you're not really experiencing double the amplitude in those sound waves.

 

Oh man...constructive and destructive interference. I forgot about those days in school!

 

Yes, but that kinda kills the joke. The other way is much more funny.

 

Fair enough

 

Hence the smiley at the end

 

you still have multiple sources of vibrations inside the engine, its just the net result of them from the outside is no vibration. For another crappy analogy, imagine that the vibration is a truck pulling, and the engine block is a chain. When you tie the chain to the end of the truck and the truck pulls the chain moves. Now lets add another truck (vibration) to the other side of the chain. Now they both pull at the same time. Now the chain doesn't move when the trucks pull. If you where sitting on the chain you might perceive that the chain isn't moving anymore so it seems no more force is being applied to it. If you are one of those trucks though you still very much feel and are putting force on that chain, and if your the chain you are now getting the same force but from both ends.

 

It’s very interesting to read all this info, but I opted to not run bs when I had my engine built , though they could come in use for a nice paper weight for a desk.

 

*and the engine is not being damaged.