Longshot question, has anybody weighed an internally balanced LBZ+ crank and a LB7 stock crank? Also do you guys get you cranks re-nitrited? Where?

[Gentrysgarage]

I thought I would combine two short questions in one thread.
First question, has anybody weighed an internally balanced LBZ+ crank and an LB7 stock crank? Just wondering how much of a difference it is.
Second question, Do you guys renitrite your cranks after turning and where? (Preferably TX) Thanks

 

[Chevy1925]

IIRC a stock crank is 80lbs. internally balanced is close to or over 100lbs. my callies NRG crank was 93lbs and by time we drilled out the balancer and flexplate, there wasnt much left for external balance.

 

[Gentrysgarage]

IIRC a stock crank is 80lbs. internally balanced is close to or over 100lbs. my callies NRG crank was 93lbs and by time we drilled out the balancer and flexplate, there wasnt much left for external balance.

Hi James, is this the LBZ or LB7 crank? Pretty sure it’s LB7 by your signature, but want to verify. Thanks

 

[Chevy1925]

Hi James, is this the LBZ or LB7 crank? Pretty sure it’s LB7 by your signature, but want to verify. Thanks

they are relatively the same between all years (01-16). Gm didnt modify the crank counter weights when they changed the piston/rod weight on LBZ and up. Instead, they added it to the balancer and flexplate. hence why you can use a LML crank with LB7 rods and pistons if you wanted.

80lbs was the weight of my LB7 and the weight of the LML crank i put in a LBZ was 79.

 

[JoshH]

they are relatively the same between all years (01-16). Gm didnt modify the crank counter weights when they changed the piston/rod weight on LBZ and up. Instead, they added it to the balancer and flexplate. hence why you can use a LML crank with LB7 rods and pistons if you wanted.

80lbs was the weight of my LB7 and the weight of the LML crank i put in a LBZ was 79.

Not to be argumentative, but they did change the counterweights on the LBZ/LMM crank from the LB7/LLY. I'm not sure if they are less weight, but I know the OD is smaller. The reason for the smaller ID is because the bushing they started using in LBZ pistons required a larger pin boss on the piston, and the LB7/LLY counter weights would have interfered with the LBZ piston. I believe it is the smaller ID of the conterweights that require more weight on the balancer and flywheel.

 

[Chevy1925]

Not to be argumentative, but they did change the counterweights on the LBZ/LMM crank from the LB7/LLY. I'm not sure if they are less weight, but I know the OD is smaller. The reason for the smaller ID is because the bushing they started using in LBZ pistons required a larger pin boss on the piston, and the LB7/LLY counter weights would have interfered with the LBZ piston. I believe it is the smaller ID of the conterweights that require more weight on the balancer and flywheel.

maybe but the additional weight in the balancer/flexplate seemed to add up more to the additional bob weight LBZ and up take, that wouldnt justify a smaller counterweight but might be a small factor and the reason i saw a 1 lbs difference

 

[kidturbo]

When I saw internally balanced LBZ, was thinking Neutral Balanced Ultra Billets. Those are 83 or 86lbs. Would have to look back at my thread notes to be certain. With the no counterweight FD on front, and a custom monster 85lb flywheel on the back, my total rotating mass is somewhere around 240lbs. Seen no real difference in rev, but once spun up, has demonstrated a unique ability to twist off any attached hardware that's attempted to stop it from spinning..

To your second question, I once had a LLY welded, turned, and nitrited by a shop in NC. Was back in 2010, and don't recall the name right off. But they did fine work. Still installed today.

 

[Gentrysgarage]

Thanks for the replies, so only one person renitrited a crank? It doesn't need it after grinding? Thanks

 

[1FastBrick]

I haven't done any testing on the Duramax cranks to know how deep they are nitrated. If your only .010 it's likely fine. I have sent other cranks out and had them Re Nitrated with no Ill effect.

 

[kidturbo]

I'm probably only person known to spin a rod bearing out of one.. So normally they don't need a re-treat. However I spun two rod bearings into vaper, and the company I sent it off to was able to repair it. Just recall them saying they had to re-treat after the weld job.

 

[1FastBrick]

Yes, After welding, you would want to send it out and have the crank nitrated again.

The crank grinding process it self Generally does not effect the Nitrating. How ever in some cases you can grind through the treated surface.

The Nitrating usually only goes maybe .020 deep When done properly. It's hard to say for sure how deep it penetrated Thats why I typically send them out if the crank has to be ground more than .010.


Last crank I had nitrated was like $95 and that had a small mark up from the shop that sent it out for me. Frankley my time was worth more than the $20 or so mark up

 

[Gentrysgarage]

Thanks, I appreciate all the answers! hopefully we can stay under .010!