Read back.
It's been covered.
Nobody really knows for sure about any of this but I'm sure a girdle can't hurt.
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Cranks
- Thread starter Fingers
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It's been covered.
Nobody really knows for sure about any of this but I'm sure a girdle can't hurt.
Sent from my iPhone using Tapatalk - now Free
Its actually been suggested that a girdle may not help the situation at all...believe it or not, a lot of blown alcohol motors use aluminum caps even with an iron block to soak up the crank deflection and as long as the bearings and clearances are spec'd correctly, there haven't been any issues. I just learned that last week...cool info.
To put that more into perspective Tim the engines you talk about get turn down between passes regularly. That is not a fair comparison. Girdles will help cap walk certainly. People are trying to come up with why the cranks are failing and I can't get past the ones that fail are rarely and at different power levels really seem to point more to metal flaws.
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I know Randy would never say that since he makes a lot of money selling the gorilla girdle lol.
Not all of those motors get torn down that often. Most that do, aren't running iron blocks still....these motors I speak of are putting down 2500-5000 HP and are going rounds, and sometimes whole seasons or more. Not many people did this I'm sure, but there are those that have made it work very well for them.
Your post and Mikey's post refute 99% of what good contributors have already said in this thread, so whether randy says a girdle is necessary or not, cap walk isn't causing the majority of broken cranks if the machine work and assembly was done properly.
Caps
Tim they have been running aluminum main caps for a long time. I would guess I first seen it 20 plus years ago. It's not cap walk that is breaking the cranks. If a cap was walking that bad you would see it in the bearings. If it's walking that back somebody needs to check there tune/setup. I still run stock bolts and have not seen a problem with main caps turning 5500 rpm. External balance also. We ask a lot out of these engines at power levels only seen by all out race motors.
Tim they have been running aluminum main caps for a long time. I would guess I first seen it 20 plus years ago. It's not cap walk that is breaking the cranks. If a cap was walking that bad you would see it in the bearings. If it's walking that back somebody needs to check there tune/setup. I still run stock bolts and have not seen a problem with main caps turning 5500 rpm. External balance also. We ask a lot out of these engines at power levels only seen by all out race motors.
Tim if my post refutes what good contributors have said then do you have the answer as to why cranks break? Very few do break compared to the many running. A girdle will not stop one from breaking. It does serve a purpose like any other performance mod does. When I first put the girdle on my engine I had some tell me that my main bearings would wear unusual and just fall out when disassembled. I can say they were wrong. The most common failures occur at the same locations. There is a common link to why that occurs and since it happens rarely I have my beliefs as to why. That does not make me right and others wrong. None of us have the answer yet as to why and can prove their theory in a repeatable experiment. I applaud guys like Jon for his desire and hard work to advance the Dmax community.
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Shane, if I had the answers I wouldn't be in this thread telling everyone else what they were. I wasn't saying that you can't be wrong, I'm often wrong and it's how I learn new things. All I said was that it has been proven time and time again a girdle, filled block, billet main caps, internal balancing, billet cranks, all Dont prevent breakage...this discussion is past that point..stiffening up the bottom end isn't helping....let's move on.
I mentioned machine work and assembly because one of Max's Out's motors was found to have been align honed improperly, which led to some issues for them. That was documented over on Ricks site a couple years ago now.
I've got an idea, talk about something you know is factual and leave me to post facts about my stuff and equipment. This isn't the first time, so quit guessing and post about your own findings not crap you think you know or have read on the "net"
So, we still can't shake the material flaw train of thought.....
I will put forth that if it was a process or material issue, the failures locations would be more diverse.
I will put forth that if it was a process or material issue, the failures locations would be more diverse.
Try flying a jet built in 1960 and banking it way up in a hard break turn reacting to a threat at 480,000 lbs!
I know most of the damage happens before it gives out, but you hear so many of the trucks breaking while on cruise control towing a trailer or just cruising down the road at a constant speed (so RPM). Makes me think it is a minor/secondary/whatever you want to call it freq that they are hitting
That's how mine went eventually but tough to say if it was just a coincidence or the actual cause.
As I have said before I found other problems that may have been a long term issue that eventually caused the failure. I believe the one problem caused an imbalance or a vibration that over time fatigued the crank.
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Understandable Rob, no problem. Except that to find any "factual" information from you is like finding a needle in a haystack and we have to dig for it. You and Ken shared a lot of info back before Guy started building your motors....before you were making the big bucks And just another racer like the rest of us.
I could've used my own motor and broken crank ordeal in that same post, but my findings are already publicly documented on here.
Are there anymore pictures out there? so many breaks andno pictures readily?
From what fingers has been saying the more diverse the breaks could be, is this entailing that each break will have the same pattern due to a harmonic imbalance at each common break point because of the 'flow' of the harmonic frequency through the crankshaft?
From what fingers has been saying the more diverse the breaks could be, is this entailing that each break will have the same pattern due to a harmonic imbalance at each common break point because of the 'flow' of the harmonic frequency through the crankshaft?
If harmonics are a real issue, how come the LS & LQ engines don't have this problem? There are revised camshafts for these motors but they are not being utilized because the cranks aren't breaking like the duramaxes. If you look at the main cap design, the duramax is similar to the old sbc and the newer LS and LQ motors have better cap design. I just feel that a spread sheet of documentation should be started because there are way to many variables; factory specs have a wider range of acceptable clearances than a race engine would, some cranks have flaws from the factory, different tunes, different torque converters, and of course most of all assembled by different people.
I also noticed the that some of the crankshaft failures do have a spun bearing at the rear of the motor maybe indicating issues on that side.
I also noticed the that some of the crankshaft failures do have a spun bearing at the rear of the motor maybe indicating issues on that side.
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