balance rotating assembly

[DNA666]

Iam using a .10 under crank in my 2.3L and it works fine.

 

[groundPork]

It will not take it out of spec, because each rod journal is 180 degrees off set from the others. Not to mention polishing a crank takes off an amount of meatal that isn't even worth mentioning. If it did you would have to have the crank ground to the corect size and tun .010 under barrings.

Precision... good to see someone with the ability to provide a service properly advise on it's relevance and value in an honest manner.

Guys... any balancer worth his salt will not charge you $120 friggen dollars to balance your inline four cylinder! the reason is exactly stated as Precision said earlier, the reciprocating forces will cancel eachother out... As long as you have near exact opposing weight the assembly will want to spin in place. Correct if I',m wrong Precision... I say for the effort and money for most motors, dont frieken bother!


If you had it so called knife edged (not, really, they just sliced a bunch of steel off the throw) then I could see even the bare crank balance being screwed up pretty bad.

 

[RedTalonTsi]

From this thread, posted by a wiseman,

From a technical point of view, every engine regardless of the application or its selling price can benefit from balancing. A smoother-running engine is also a more powerful engine. Less energy is wasted by the crank as it thrashes about in its bearings, which translates into a little more usable power at the flywheel. Reducing engine vibration also reduces stress on motor mounts and external accessories, and in big over-the-road trucks, the noise and vibration the driver has to endure mile after mile.

Though all engines are balanced from the factory (some to a better degree than others), the original balance is lost when the pistons, connecting rods or crankshaft are replaced or interchanged with those from other engines. The factory balance job is based on the reciprocating weight of the OE pistons and rods. If any replacements or substitutions are made, there’s no guarantee the new or reconditioned parts will match the weights of the original parts closely enough to retain the original balance. Most aftermarket replacement parts are "balanced" to the average weight of the OEM parts, which may or may not be close enough to maintain a reasonable degree of balance inside the engine. Aftermarket crank kits are even worse and can vary considerably because of variations within engine families.


Wiseman from another thread,

Suparata
DSM Wiseman-

"Inline engine balancing is done by individually balance each component that gets bolted to the crank and the crank itself. Rods and pistons are weight matched to the lightest one and just because aftermarket rods weigh overall is pretty close it doesn’t mean that their small and big ends weigh the same.
Your damper is balanced (sort of) from the factory and there are not too many places that can get it better so you will have to live with it."

Another wiseman,

Big Woo
DSM Wiseman

"When the crank is being balanced material should be removed or added to the crank to obtain a neutral balance. When the other parts are added (flywheel/ pulley, etc.) the material removed should come from the component being balanced. The end result being that all parts are individually neutral balanced. Thereby if a part needs to be changed out later, it to can be neutral balanced and added without effecting the existing engine balance.

This form of balancing should not be confused with balancing the entire assembly as one, as in this type of balancing the sum, and radii of the out of balances, can both counter act, and accentuate, dynamic, and kinetic balance at opposite ends of the assembly."


From another thread,

Mike1992
Proven Member

"How much is to much? $$$ wise I just dropped my crank, 1g big rods, 2g pistons and ARP rod bolts off to have everything done up. I asked how much balancing was and he said $135 is that to much?"

Another,

GVR4592
Proven Member

"My cousin just weighed his eagle rods and ross pistons. They varied almost 2 grams from cylinder to cylinder. That's a lot. It should cost under $150 to balance the engine, I would just do it."

From centuryperformance.com,

"I must first state that the cost of balancing will always be outweighed (oops, a PUN) by the benefits of the process. A typical machine shop is charging between $120.00 to $140.00."


I personally paid $110 to have my engine componants balanced individually.

From another thread,

Enraged78
Proven Member

"Balancing a rotating assembly isn't just to keep the assembly from shaking it self to death at 8K. It also helps tremendously in making the motor more enjoyable on the street. It's nice to be in a hard turn at 6K and not worry about the vibrations from your steering wheel throwing you into a ditch."



According to the above information, our motors are balanced (at least to some degree) from the factory, the proper way to balance an inline 4 is to balance each componant individually, and this should cost less than $150. $150 or less on top of whatever you are paying to rebuild your engine ($$$thousands$$$) is not very much and can only help your horspower, reliability, and overall drivability of you car.

Later,
Dana