I did a search and could not find anyone who has had this same problem. Looks like my crank pulley is splitting into two pieces. If I need a new pulley, how do you balance them? Does it matter that my old one is damaged? I also forgot to make reference marks for the alignment but I will before I take it off completely. There are a lot of balancing holes drilled in the damaged pulley, but no weights in them.

 

Just the info I needed thanks. So is the pulley balanced to zero itself or is it balanced to zero the engine? I ask because it seems aftermarket pulleys like the ATI Super Damper come balanced to zero, and some people install them out of the box with no issues. To install it the proper way, Should I have my new new pulley balanced to match the offset of old one? or is the old once just balanced to zero as well?

 

THIS APPLIES IF,,,,,,,,,,,,,,,, YOU HAVE A MN6/NMN12 STANDARD TRANS:

Yes,,,,,,,,, The crank pulley is HOT BALANCED to the engine after the engine is assembled and running.

IF,,,,,,,,,, you failed to mark the old pulley, its NOT as important as conducting the HOT BALANCE compensation to the Manual trans flywheel/pressure plate assy.

Order a new GM Replacement Dampener or install a new power bond dampener. I highly recommend spending the cash for a ARP Bolt!

If you have a A4 Trans,,, Its DOES NOT MATTER!

BC

 

just curious, why were you removing it in the first place?

 

That balancer isnt coming off if your pulling it as pictured, you need to set your puller on the inside of the balancer.

 

All you have removed is the outer rim. Now you have to get the jaws of the puller inside the HUB and yank it off.

SECRET: If you heat the hub until its approx. 200-250 deg, it comes off a LOT easier!


Bill

 

Great info thanks Bill. So if i understand correctly, the crank pulleys on vettes with MN6/MN12 are hot balanced but it just doesn't make too much of a difference. Where could i go to have the new damper balanced, are machine or performance shops able to do it? I will definitely make the investment in the ARP bolt; do you recommend the Power Bond over the ATI super pulley?

I am replacing the cam

You're correct, i thought that it didn't matter but unfortunately i realized that too late. Now i can't decide whether i should get a different puller and trying to salvage the pulley for balancing, or ripping off the outer hub then getting the inner hub of separately and trying to piece them together. I would get another puller i just can't find anything other than 3 arm pullers exactly like mine. I went to advanced auto parts and autozone and only found more standard 3 arms.

 

Bud,,,,, Your a little too late. The dampener is HOT balanced ON THE ENGINE as a WHOLE dampener.. That includes the outer ring, rubber elastomeric bonded seal and the HUB.

There is NO way you can balance the new damper to the old one as you have destroyed the old one.

When you balance the new dampener, you have to have a GOOD OLD OEM dampener that has been matched marked to the crank so it can go back on in the exact same orientation.

Just install a new one and don't worry about it.

 

When the time is right, bolt on the new Powerbond unit and torque the ARP bolt to spec. Done.

 

You will need a proper install tool also, DO NOT try and push the new one on with the crank bolt

 

True story...

 

ah ok

 

Agree with this. Your engine went through the hot balance and NO WEIGHTS needed to be added. So a zero balanced damper is what you need. All aftermarket and OEM dampers will be close to zero balance out of the box. Put on one of your choice and be done with it. No need to go to extra steps in this case.

 

Thanks for the tip, I missed this when i last replied but i read it before i finished removing the pulley. Used a heat gun + torch to get it really hot and it came right off.
Yeah i understood that it is balanced as a whole, i was just hoping i would find a way to press back together and salvage the old one. I did mark its orientation, and the orientation of the inner hub, elastomeric rubber, and outer hub has not changed. It would just need to be enough for the balancing, but as you said it is destroyed and probably beyond any repair. Regardless, if you guys say i can skip the balancing and don't have to worry i might have any problems at all, then that's what i'll do. I guess it is in my nature to second guess everything, i just cant help but think the offset holes are there for a reason and installing an unbalanced crank pulley in place of a balanced one would cause the engine to have some sort of loss in smoothness, but i could be dead wrong.

That's the plan Although i am leaning toward an ATI balancer.

Hah alright i'll take you all's word, thanks

This would be true if the only holes were the standard symmetrical holes they are manufactured with to accommodate the balancing weights. Mine has no weights but it has had its weight reduced on exclusively one side via a bunch of holes with varying depths. like you said they come zero balanced, so with all the holes i don't think mine is zero balanced. It seems that drilling holes instead of adding weights is just what they were doing at the factory when mine was built, my flywheel is the same way and also has a bunch of holes side by side, on one side, that vary in depth.

I know everyone has told me there's no need to take extra steps but my interest in learning how to hot balance a harmonic balancer is peaked.. I don't see why it would be a bad idea, but i'm sure it isn't easily done at home.

 

Unless you have access to GMs million dollar hot balance machine, HOT balancing isn't going to happen.

That said,,,, There are machines that can dynamically balance the engine and allow you to ADD or remove weight on the flywheel and or dampener with the engine in the car and running. Look in your Yellow Pages for machine balancing and inquire..

Bill

 

You have this backwards.
The Damper is delivered to GM by the manufacturer having been "zero balanced" to within a given balance tolerance. This is what the "non symmetrical patterned" blind holes, that do not go all the way through are for. They are drilled by the manufacturer to bring the damper to zero balance (within a given balance tolerance). The equally spaced through holes around the perimeter are there, by design, from the manufacturer to accept balance weights, if needed, that would be installed by GM during the hot balance procedure. During the hot balance, GM will ONLY ADD WEIGHTS as necessary to the damper and/or flywheel. They DO NOT do any additional drilling. So, the damper is zero balanced by the manufacturer by drilling blind holes (not the balance weight receptacle holes) before delivery to GM, and GM would install weights if needed after installation on to an engine and during the hot balance. If you do not see any weights in it, it did not need any added during the hot balance. And it is close to zero balance.

This is the exact same scenario with the flywheels. They are zero balanced (to within a given tolerance) by the manufacturer (LuK). This is done by drilling blind holes where needed. Then they also have 12 circumferential holes, equally spaced, to accept balance weights if needed during the hot balance. If there are no weights in them, they also did not need them added during the hot balance. HOWEVER, this is a different situation than the damper. The damper is but ONE component. The Flywheel AND Pressure Plate are both installed, as an assembly, during the hot balance. So any weights added to the flywheel are counting for the engine, flywheel, and pressure plate, all combined. Therefore it's a good idea to see what your balance/unbalance is of your stock FW/PP combo, regardless of the presence or absence of balance weights.

Of course it won't hurt to check the balance of your stock damper, but without weights, it is going to be very close to zero. And the small radius of the balance weight receptacle holes in the damper offer a much much smaller correction capability than do the holes of the flywheel. It's relatively cheap to try to have your new damper matched to the OEM, but unnecessary in this case.

If you ever change your clutch, pay attention to this and have the new clutch assembly matched to the original clutch assembly. Regardless of whether or not you see weights. The combined balance tolerances of the FW and PP as delivered are enough to potentially exceed the 0.5 oz∙in balance spec for the entire engine assembly.

Now wasn't that fun??

 

By the way,,,,, The "thbwlZ" is the FORUM EXPERT on engine balance!! BAR NONE!



I would consider his advice GOSPEL!

Bill

 

I know you were being sarcastic, but I'm ashamed to admit that actually was kinda fun.. God forbid i even grinned a couple times reading that. You're exactly right i had it backwards, I knew i had to be missing something. It makes so much more sense that the blind holes were drilled by the manufacturer to balance it to zero. I also enjoyed the comparisons to the flywheels hot balancing setup that i will put to use when i install my LS7 PP&FW. Thank you for taking the time, i very much appreciate your insight and attention to detail.


No kidding!
I am not worthy..

 

I can feel the love!

Here are a few links:
video of current LT4 and LS7 engine builds. Hot balance machine and weights are shown at approx 8:50
http://gmauthority.com/blog/2014/12/...engines-video/

article on LS3 dry sump build. Later photos show and discuss balance procedure.
http://www.superchevy.com/how-to/vem...-engine-build/

I just find this a very interesting topic.

 

You're the man
As do I That LT4 and LS7 build video is very cool. There's the hot balance machine in all its glory. It looks really expensive but it sure is neat. I'm assuming the balance at the front is at the pulley and rear at the flywheel, looks like the engine in the video did not require any correction, makes sense since the total unbalance of 0.382 oz-in doesn't exceed the 0.5 oz-in limit. Interesting stuff.
The LS3 build article's link doesn't work, looks like a ... got copied into the web address.
http://www.superchevy.com/how-to/vem...-engine-build/
I never fully understood the dry sump system.. i know i'll have to if i ever want to swap in a 427