Crankshaft questions - Competition Diesel.Com

QMFB · 05-07-2017, 12:23 PM

Alright gentlemen, I'm in the middle of rebuilding my '04 and am trying to sort out all the modifications I want to make in the bottom end... So, Crankshaft.
What is the consensus on lightening, champering (knife edging), or even complete removal of the counterweights ?
I know this is all common practice in the performance gasser world, but are there benefits in a Cummins ? Drawbacks ?
Experience is great. But, as always, all opinions and discussions are valuable.

Mark Nixon · 05-07-2017, 12:32 PM

Having seen a few broken cranks on stock CR 5.9 engines, I'd be hesitant to do a whole lot to one to try to lighten it.

Mark.

QMFB · 05-07-2017, 12:37 PM

Wonder what caused them to break ? They are pretty stout pieces... I'm curious what the high HP trucks are doing ? 1000hp, 2000hp, 3000 ? I know not too many guys are dropping the coin on custom billet crankshafts like Winburg.

Mark Nixon · 05-07-2017, 12:44 PM

No clue, though one I know for sure, the crank cracking across a rod journal was the cause of the engine coming apart.

I have a 6.7 crank from a very low miles 2012 engine that broke on the crank arm between 5 and 6.
It's not the only one I have heard or seen do it, there have been others.

Mark.

QMFB · 05-07-2017, 12:53 PM

Wonder if lightening would reduce failures, or increase them ? A lighter crank would create less torsional load across the crank on the compression stroke, would it not ?

Mark Nixon · 05-07-2017, 01:03 PM

The biggest thing is making sure there are no stress risers.
These cranks are so hard on the surface that it's like cracking tempered glass, it can take a hard hit, but once it's fractured, it comes apart.

The hardening on these cranks is a lot of the reason many crank "rebuilders" will not weld and regrind a damaged B series crank.
Most won't even touch them if they show any sort of heat related discoloration on the journal or arm.

Mark.

QMFB · 05-07-2017, 01:07 PM

So possibly polishing the rough casting areas between the journals would help relieve cracking. Like is common practice on OEM forged rods.

Mark Nixon · 05-07-2017, 01:20 PM

Anything you can do to smooth it certainly is a possible gain.

Keep in mind, though, the rough part of the forging/casting is hardened along with the rest of it and the hardening only goes so deep, so if the forging/casting has any deep flaws in it, you can add insult to injury by correcting it.

You can smooth the appearance, but don't try to correct it. Make sense?

Shot blasting it after polishing/deflashing a part is common practice and alleviates minor stress risers from the tooling.

Mark.

QMFB · 05-07-2017, 01:28 PM

Thank you for the insight mark.

QMFB · 05-07-2017, 01:30 PM

That would still leave the counterweights free for lightening / champering since they are outside of the torsional stress line between main journal and rod journal ?

Mark Nixon · 05-07-2017, 02:30 PM

I see no harm in modifying them, but realize that re-balancing could be an issue.

Mark.

QMFB · 05-07-2017, 02:50 PM

Yeah, I might need to talk with my machinist about that, lol. Seems like if you removed equal amounts off of the counterweights on a pre balanced crank, then a final Ballance it could be done... But I'm no machinist.

Poulina · 05-07-2017, 03:37 PM

More hassle and headache than it would probably be worth...

QMFB · 05-07-2017, 03:46 PM

Well my crank is sitting on a pallet in my garage right now, so not much hassle... But cost to have it done, IDK ?

biggy238 · 05-07-2017, 06:21 PM

There is a thread on here about the Nordic machinist cutting the weights off his crank and he was driving it around in a suburban.

It's my opinion that the cranks that break between the last rod and main journals got rammed into something in manual trucks.
Just an unproven opinion.

Sent from my XT1575 using Tapatalk

QMFB · 05-07-2017, 06:24 PM

You got a link to that thread biggy ? I've searched and searched. Couldn't find much info on it one way or another.

95cummins5.9 · 05-07-2017, 06:38 PM

Crank lightening - Competition Diesel.Com - Bringing The BEST Together

QMFB · 05-07-2017, 06:43 PM

Thanks ! Wonder why that didn't show up in my search strings ....

YoungDiesel27 · 05-07-2017, 06:46 PM

Quote:

Originally Posted by biggy238

There is a thread on here about the Nordic machinist cutting the weights off his crank and he was driving it around in a suburban.

It's my opinion that the cranks that break between the last rod and main journals got rammed into something in manual trucks.
Just an unproven opinion.

Sent from my XT1575 using Tapatalk

I've seen quite a few broken cranks in mainly stock trucks. Probably near 10 in total and only two have been in automatics so I too believe operators are tearing them up.

jlibert · 05-07-2017, 07:26 PM

There are guys on this board that have ran with lightened crankshafts. I have one but have not used in in a build yet. Another one just like it is living in a higher hp truck.

05-07-2017, 12:23 PM	#1
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Crankshaft questions Alright gentlemen, I'm in the middle of rebuilding my '04 and am trying to sort out all the modifications I want to make in the bottom end... So, Crankshaft. What is the consensus on lightening, champering (knife edging), or even complete removal of the counterweights ? I know this is all common practice in the performance gasser world, but are there benefits in a Cummins ? Drawbacks ? Experience is great. But, as always, all opinions and discussions are valuable. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 12:32 PM	#2
Mark Nixon Name: Mark Nixon Title: No Savior among the flesh Status: Not Here Join Date: Feb 2009 Location: Brownville, Nebraska Member`s Gallery Posts: 8,676	Having seen a few broken cranks on stock CR 5.9 engines, I'd be hesitant to do a whole lot to one to try to lighten it. Mark. __________________ If you or I did business like the PEOPLE in government do business, we'd be put in jail. Government is coercive. Anarchy: The state of existence where there are no masters & no slaves. Therefore, Anarchy means the ABSENCE OF SLAVERY, or, in other words, FREEDOM.

05-07-2017, 12:37 PM	#3
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Wonder what caused them to break ? They are pretty stout pieces... I'm curious what the high HP trucks are doing ? 1000hp, 2000hp, 3000 ? I know not too many guys are dropping the coin on custom billet crankshafts like Winburg. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 12:44 PM	#4
Mark Nixon Name: Mark Nixon Title: No Savior among the flesh Status: Not Here Join Date: Feb 2009 Location: Brownville, Nebraska Member`s Gallery Posts: 8,676	No clue, though one I know for sure, the crank cracking across a rod journal was the cause of the engine coming apart. I have a 6.7 crank from a very low miles 2012 engine that broke on the crank arm between 5 and 6. It's not the only one I have heard or seen do it, there have been others. Mark. __________________ If you or I did business like the PEOPLE in government do business, we'd be put in jail. Government is coercive. Anarchy: The state of existence where there are no masters & no slaves. Therefore, Anarchy means the ABSENCE OF SLAVERY, or, in other words, FREEDOM.

05-07-2017, 12:53 PM	#5
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Wonder if lightening would reduce failures, or increase them ? A lighter crank would create less torsional load across the crank on the compression stroke, would it not ? __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 01:03 PM	#6
Mark Nixon Name: Mark Nixon Title: No Savior among the flesh Status: Not Here Join Date: Feb 2009 Location: Brownville, Nebraska Member`s Gallery Posts: 8,676	The biggest thing is making sure there are no stress risers. These cranks are so hard on the surface that it's like cracking tempered glass, it can take a hard hit, but once it's fractured, it comes apart. The hardening on these cranks is a lot of the reason many crank "rebuilders" will not weld and regrind a damaged B series crank. Most won't even touch them if they show any sort of heat related discoloration on the journal or arm. Mark. __________________ If you or I did business like the PEOPLE in government do business, we'd be put in jail. Government is coercive. Anarchy: The state of existence where there are no masters & no slaves. Therefore, Anarchy means the ABSENCE OF SLAVERY, or, in other words, FREEDOM.

05-07-2017, 01:07 PM	#7
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	So possibly polishing the rough casting areas between the journals would help relieve cracking. Like is common practice on OEM forged rods. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 01:20 PM	#8
Mark Nixon Name: Mark Nixon Title: No Savior among the flesh Status: Not Here Join Date: Feb 2009 Location: Brownville, Nebraska Member`s Gallery Posts: 8,676	Anything you can do to smooth it certainly is a possible gain. Keep in mind, though, the rough part of the forging/casting is hardened along with the rest of it and the hardening only goes so deep, so if the forging/casting has any deep flaws in it, you can add insult to injury by correcting it. You can smooth the appearance, but don't try to correct it. Make sense? Shot blasting it after polishing/deflashing a part is common practice and alleviates minor stress risers from the tooling. Mark. __________________ If you or I did business like the PEOPLE in government do business, we'd be put in jail. Government is coercive. Anarchy: The state of existence where there are no masters & no slaves. Therefore, Anarchy means the ABSENCE OF SLAVERY, or, in other words, FREEDOM.

05-07-2017, 01:28 PM	#9
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Thank you for the insight mark. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 01:30 PM	#10
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	That would still leave the counterweights free for lightening / champering since they are outside of the torsional stress line between main journal and rod journal ? __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 02:30 PM	#11
Mark Nixon Name: Mark Nixon Title: No Savior among the flesh Status: Not Here Join Date: Feb 2009 Location: Brownville, Nebraska Member`s Gallery Posts: 8,676	I see no harm in modifying them, but realize that re-balancing could be an issue. Mark. __________________ If you or I did business like the PEOPLE in government do business, we'd be put in jail. Government is coercive. Anarchy: The state of existence where there are no masters & no slaves. Therefore, Anarchy means the ABSENCE OF SLAVERY, or, in other words, FREEDOM.

05-07-2017, 02:50 PM	#12
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Yeah, I might need to talk with my machinist about that, lol. Seems like if you removed equal amounts off of the counterweights on a pre balanced crank, then a final Ballance it could be done... But I'm no machinist. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 03:37 PM	#13
Poulina Name: Poulina Title: Too Much Time Status: Not Here Join Date: Dec 2015 Location: Norcal Member`s Gallery Posts: 795	More hassle and headache than it would probably be worth... __________________ 2008 QCLB 6.8 48re Suncoast PCS, DDP supermentals, forcedinductions 467/87, Hamilton 188/220, Carrillos, studded mains w/stock girdle

05-07-2017, 03:46 PM	#14
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Well my crank is sitting on a pallet in my garage right now, so not much hassle... But cost to have it done, IDK ? __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 06:21 PM	#15
biggy238 Name: biggy238 Title: Too Much Time Status: Not Here Join Date: Aug 2008 Location: Just North of Wrong Member`s Gallery Posts: 10,868	There is a thread on here about the Nordic machinist cutting the weights off his crank and he was driving it around in a suburban. It's my opinion that the cranks that break between the last rod and main journals got rammed into something in manual trucks. Just an unproven opinion. Sent from my XT1575 using Tapatalk __________________ Check out @bdmaximusworx 05.5 Campanella White TDi Jetta 5spd 45.5MPG -Little Sexy '10 Silver F250 CCLB 4X4 6.4L cummins Swapped Insta @trash.panda250

05-07-2017, 06:24 PM	#16
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	You got a link to that thread biggy ? I've searched and searched. Couldn't find much info on it one way or another. __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 06:38 PM	#17
95cummins5.9 Name: 95cummins5.9 Title: Old man *** gossiper Status: Not Here Join Date: Jun 2012 Location: U.S.A Member`s Gallery Posts:** 4,720	Crank lightening - Competition Diesel.Com - Bringing The BEST Together

05-07-2017, 06:43 PM	#18
QMFB Name: QMFB Title: Fastest Welder in Texas Status: Not Here Join Date: Apr 2016 Location: Corpus Christi, TX. Member`s Gallery Posts: 1,061	Thanks ! Wonder why that didn't show up in my search strings .... __________________ 04 CCLB DRW - 6.4 Cummins, HPTuners, 80% S&S, 10mm S&S CP3, AD165, s464 /s475, full billet 48re, Arp's EVERYWHERE, mild head work, lots of time and money... And never done.

05-07-2017, 07:26 PM	#20
jlibert Name: jlibert Title: Too Much Time Status: Not Here Join Date: Jun 2007 Location: CA Member`s Gallery Posts: 3,454	There are guys on this board that have ran with lightened crankshafts. I have one but have not used in in a build yet. Another one just like it is living in a higher hp truck. __________________ J.P. Libert https://instagram.com/jplibert/