Crankshaft balance question.

[turbovanman²]

I had my engine balanced before it let go, I am reusing the crank but running different pistons and lighter rods, so do I need to get the crank rebalanced? I fell out with my machine shop so I can't ask him, lol!

[GLHS0658]

Yes reuse it. Your crank retains its own balance. It is not balanced with the rods and pistons. It is an opposing crank, 2 throws up and 2 throws down.

Mike

[turbovanman²]

Thanks, I was sure that was the case but needed someone to back me up, lol!

[XR Tuner]

Yes reuse it. Your crank retains its own balance. It is not balanced with the rods and pistons. It is an opposing crank, 2 throws up and 2 throws down.

Mike

Wrong.

Why do you think they weigh the rods,pistons,pins,clips and rings when they balance a crank. They then use a bob weight to these specs when they spin the crank on the machine.

[Directconnection]

Wrong.

Why do you think they weigh the rods,pistons,pins,clips and rings when they balance a crank. They then use a bob weight to these specs when they spin the crank on the machine.

Nope, you're wrong! hehe

Bobweights are used for V-engines. Not inline-4 engines.

Depends on what kind of V-engine it is, depends on what % factor to use in the bobweight as well. I balanced a Ford 3 cylinder diesel crank a few weeks ago. I had to cut down the counterweights and then the balance was all frigged up. The original engine building shop frigged it all up with the wrong crank and rod pistons block combo. It shook so bad, the 100+lb flywheel sheared the bolts of the flange. Only 3 rod journals 120 degrees apart, but rotating weight was factored only once instead of 2 times for a V-8. For a V-8... you weigh the big end, then the small end, then the piston and pin, then the rings, then the rod bearings, then the clips and then an oil allownace for the oil's assumed weight in the journal and bearing clearance. For a V-8, you double the roatating weight, so rod big end and rod bearing is factored in twise. reciprocating is just once. Add them all up and that is your bobweight.

On an inline 4, there is no bobweight.

[John B]

The only balancing we can do on our in-line fours is to match weight the rods and pistons. If a shop says they can dynamicly balance it, they are full of horse-pucky and will try to sell you an electric supercharger to go with the balance job.

[turbovanman²]

So, does my crank need to be rebalanced??????

[Directconnection]

man... you can't read?

Yes, it must be balanced my a professional with the special variac inbalance flux capacitor setup. Our shop is the only one in the country that can do thise. Ship it to me and paypal me $800 and you'll be all set.

NO!!!!

[turbovanman²]

man... you can't read?

Yes, it must be balanced my a professional with the special variac inbalance flux capacitor setup. Our shop is the only one in the country that can do thise. Ship it to me and paypal me $800 and you'll be all set.

NO!!!!

Read, whats that,

[Directconnection]

anyways...you are all set.

[GLHS0658]

The $800 Steve charges includes the latest greatest electric supercharger...shipped (even to Canada)

[turbovanman²]

The $800 Steve charges includes the latest greatest electric supercharger...shipped (even to Canada)

I'll take 2,

[GLHS0658]

me?

[turbovanman²]

me?

Sure, 2 birds with one stone,