Crankshaft Balancing

[l0nestar]

I just got off the phone with the machine shop 'everyone' (local) suggested that I go with to balance my crank after having the collar put on. The guy said that you did not need to re-balance an inline 6 crank(already internally balanced). Possibly the rods and pistons, but not the crank. I said 'okay' and ended the call. I know the guy is used to building 1000+ HP domestics & diesels. He said that If I really wanted to, he would, but he would have to build 6 sets of counter weights and it would be cost prohibitive. I think he has a good idea of what he is doing, but not with JDM vehicles.

So, after having the collar put on, do you really need to re-balance the crank? I assume it should be an astounding 'YES!' but I wanted to make sure. Also, anybody know of any reputable shops near Indianapolis? (45-60min drive East for me, I live in Terre Haute) Thanks!

[Darius]

I didn't have my crank rebalanced because that is what my machinist told me as well. Basically an I6 crank balances itself with the opposing pistons (i.e. 1/6, 2/5, 3/4 balance each other out). I only had my RB26 rods balanced because my pistons were forged and within 0.2 grams of eachother

BTW this was my 1000th post

[l0nestar]

So you are telling me that I should not need to have my crank re-balanced? THEN WHY DOES EVERYONE SAY TO??? Sorry.. It just seems like you should at least _check_ it before putting it in, would you agree? I know your changing it a slight amount, but when it is spinning at 8k+ even a slight variation would / could throw the balance off... Darius, I respect your opinion, and not trying to start a flame war, but do you see where I am coming from? I was also told that the only thing to balance would be the rods / pistons. Oh yeah, what about micro-polishing my crank, needed or not? (motor will be mostly stock)

I need to MIC my bearing surfaces to check them, then possibly replace the bearings and slap it all back together and add an oil pump and I should have my motor finished!

*Edit* Congrats on 1000th p0zt!

[Sil240]

Yup he's right.

Most import motors are internally balance.So it doesn't matter what flywheel or crank pulley you put on the crank.As long as you dont mess with the counter wieghts or pistons, rods, pins etc...You'll be good.Now if you looking to be Super Duper Pro Comp Drag Dyno Queen to squeeze every tenth of a hp out of your motor.Then sure go for it, it'll help.

But you'll be straight.

[l0nestar]

Sil240,

Alright. Thanks!

[Stealth-Z]

A full balance job includes the crank, rods, pistons, main and rod bearings, front damper, and flywheel.

The machine shop building my motor contracts out the balancing work. All the guy does is balance motors. He has all the proper counter weights.

It gets expensive when they have to add weight to the crank. I noticed on my crank they removed a slight amount of material to get it all balanced out. BTW I also had the JUN collar installed.

[Sil240]

A full balance job includes the crank, rods, pistons, main and rod bearings, front damper, and flywheel.

The machine shop building my motor contracts out the balancing work. All the guy does is balance motors. He has all the proper counter weights.

It gets expensive when they have to add weight to the crank. I noticed on my crank they removed a slight amount of material to get it all balanced out. BTW I also had the JUN collar installed.

Yes, It's better to balance it.But...Its not a MUST to balance the crank when you put it on.So many guys change Crank pulleys and Flywheels without balancing the crank.

As long as the Part is balanced within itself you have no problems.

[StricNyne]

what if you use coller ?

[Sil240]

what if you use coller ?

Dunno if your asking me,But yeah, its the same thing.It's Right behind the crank pulley.

[StricNyne]

ahhh i got a r33 gtr crank ne way w00t i was just wondering