2G Balancing Eagle crank

[1995 AWD]

I have a stock 88mm Eagle crank, Eagle H-Beam rods, and Je pistons. Is it absolutely necessary to balance the crank? The reason I ask is because everything should be weight matched. Also getting a Fidanza flywheels and a act 2600 clutch. Any input would be great.

 

[RadDsm]

You should do it to be safe. It shouldn't cost much more than $100 to have it all balanced.

It's been known to get Eagle cranks that need to be balanced right out of the box.

 

[bryanwheat]

First off i'd call eagle and ask them if the crank has been balanced, and if so to what tolerances. You can have a machine shop spin it on the balance machine to verify whether or not it is in balance. As for the rods and pistons. They should be weight matched out of the box. I usually like to verify them on a scale though. With a inline engine you balance the crank separately from the rods and pistons. Basically the crank will be balanced to zero, than each rod balanced to which ever is the lightest, you do the overall weight, and the big end weight until they are within a gram or less from each other. Same with the pistons, weigh, find the lightest and remove material until the others are within a gram or less of each other.

 

[BogusSVO]

I would say have it all balanced.

I have seen rods and pistons out the box be off as much as 5g, not often but happens.

Also when you go in to have it balanced, Take the Crank, rods, pistons, rings, dampner, flywheel and pressure plate and the attaching bolts

this way the Flywheel/pressure plate can all be indexd to the crank.
It will run way smoother.

 

[1983gsp]

I would say have it all balanced.

I have seen rods and pistons out the box be off as much as 5g, not often but happens.

Also when you go in to have it balanced, Take the Crank, rods, pistons, rings, dampner, flywheel and pressure plate and the attaching bolts

this way the Flywheel/pressure plate can all be indexd to the crank.
It will run way smoother.

Spot on.

 

[1995 AWD]

I figured I would just bring in the crank since it's internally balanced motor. I'll weigh the pistons and rods they should match in weight.

 

[bryanwheat]

I would say have it all balanced.

I have seen rods and pistons out the box be off as much as 5g, not often but happens.

Also when you go in to have it balanced, Take the Crank, rods, pistons, rings, dampner, flywheel and pressure plate and the attaching bolts

this way the Flywheel/pressure plate can all be indexd to the crank.
It will run way smoother.

Everything balances out separately on an inline engine. It is a good idea to have the flywheel and balancer balanced, but they do not balance them with the crank. IT is all zero balanced as it should be from the factory.

 

[BogusSVO]

Everything balances out separately on an inline engine. It is a good idea to have the flywheel and balancer balanced, but they do not balance them with the crank. IT is all zero balanced as it should be from the factory.

Wrong They are close from the factory, but still sloppy
I have seen upwards if 10g out of balance on 4cyl cranks, but most fall with in 2g-5g range

Also I have seen 25g-30g out of balance when the flywheel/pressure plate combo, and most of this is corrected just by rotating the pressure plate on the flywheel and get down to 3g or so.

I have only balanced about 100 or set ups... So I may not know what I speak of.


Now op, unless you have a rod balancing fixture, and a scale that will mesure to the .1 of a gram, take it all to the machine shop

http://www.dsmtuners.com/forums/cylinder-head-short-block/342138-how-fix-balance-hang-pistons.html

On the connecting rods, the wrist pin end will all be balanced to the lightest one, then the overall weight will be briught in to the lighest one, the overall weight will have the material removed from the big end of the rod.

The 2 common ways to balance pistons is to drill under the crown of piston, I do not much care for this method. It can weaken and/or cause hot spots in the crown if drilled to deep.

The other is to buff/grind material away from cast flashing and other arears around the piston

 

[1995 AWD]

The reason I was just going to bring in just crank is because I have a fluidampr balancer. Weighed the pistons+rods 750g on 2 and 749g on the other 2. Scale might be off but still gives me an idea of weight difference. So with that said on to the clutch and flywheel. The flywheel I'm getting is a used ACT 2500 off a VR-4 and I want to do the Fidanza flywheel. That's just something I can bring in and have them measured separately I'm thinking.

 

[evil tsi]

The reason I was just going to bring in just crank is because I have a fluidampr balancer. Weighed the pistons+rods 750g on 2 and 749g on the other 2. Scale might be off but still gives me an idea of weight difference. So with that said on to the clutch and flywheel. The flywheel I'm getting is a used ACT 2500 off a VR-4 and I want to do the Fidanza flywheel. That's just something I can bring in and have them measured separately I'm thinking.

the fluidampr will not fix an unbalanced engine, it will only absorb the torsional vibration caused by the combustion process.

 

[NHerron]

Here's a link that answers some questions in this thread about eagle cranks.
Eagle Specialty Products, Inc.

Good stuff there

 

[Fotowntalon]

From everything I know, cranks do not come pre-balanced from the Factory, unless specified otherwise. As BogusSVO was saying, everything else SHOULD be weight matched, to within 1-2 grams normally for industry standards, but that doesn't necessarily mean that they are always 100% of the time. People make mistakes, so nothing wrong with double checking.