so it failed do to the vibration or it was failing and causing the vibration?
Broken Crankshaft Count?
- Thread starter EDP
- Start date
so it failed do to the vibration or it was failing and causing the vibration?
It failed due to the vibration/harmonics from the engine. If you hold it at the rpm the whole building shakes. In the truck it's not as noticeable becuase it sits on rubber and the converter absorbs some of it also. It is the reason ZF6 trucks came from the factory with a dual mass flywheel. With a regular southbend style clutch this vibration is very noticeable.
I worry abt breaking a crank every day, not sure is be able to build it a 3rd time.
Man that's a lot of vibration Mark... Did that engine have an alt fire cam in it?
I wonder if there was a vibration sensor you could mount in that water tank and test a std. cam & alt fire just to see what the difference is? Not Fingers scientific
but I think it would show enough to convince people of the af cams merits...
I wonder if there was a vibration sensor you could mount in that water tank and test a std. cam & alt fire just to see what the difference is? Not Fingers scientific
but I think it would show enough to convince people of the af cams merits...
After all this I still have yet to see me and maybe one other person break a crank towards the back, (4th main) or have any kind of explanation about them breaking in that area
Sent from a truck somewhere in the US
Sent from a truck somewhere in the US
I've noticed this in my truck. It's a zf6 solid flywheel and especially in 5gear just bringing it up, the gearshift really moves left to right from about 1700-2000 then stops like you flipped a switch.
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I've only seen one broken crank personally and I believe it was one of the first lml's, which had also broken at the back.
Mine broke at #4. And it was cruising down the highway at about 1650-1850 rpm. So it makes sense to me that harmonics killed it as that is where it always cruises at. Reading Fingers thread about cranks I strongly believe it's harmonics that break #4 and a combination of the load on the front and harmonics that break behind #1. FWIW my power level wasn't much above stock for the two years previous to this as my trans was mostly stock and wouldn't take much more than that anymore.
The billet crank that broke I heard of this rumor as well although nobody has ever owned up to it. Supposedly a crower. First I heard it had an AF cam though. That said it's not a real good example as being billet it's a different animal. Could have been a manufacturing flaw that caused it to fail.
So until someone stands up and says I BROKE A STOCK CRANK WITH AN AF CAM I'm going to call it all speculation and rumors. Not sure how many AF cams are out there but you would think someone would have had it happen and mentioned it by now. Maybe Guy and EDP are keeping quiet about too though. Who knows.....
The billet crank that broke I heard of this rumor as well although nobody has ever owned up to it. Supposedly a crower. First I heard it had an AF cam though. That said it's not a real good example as being billet it's a different animal. Could have been a manufacturing flaw that caused it to fail.
So until someone stands up and says I BROKE A STOCK CRANK WITH AN AF CAM I'm going to call it all speculation and rumors. Not sure how many AF cams are out there but you would think someone would have had it happen and mentioned it by now. Maybe Guy and EDP are keeping quiet about too though. Who knows.....
To all, What model D Max's are most prone to breakage? Seems most that I have been reading about are the LBZ motors with a couple LLY's.
Wow. Does Dale Banks run the AF cams in his motors?
It's kind of a crap shoot.
They all break and some stock some built. It seems LBZ/LMM seem to break more in stock form than the others though.
The converter will help, but the rubber mounts don't help the engine a lot (we care about the harmonics going on inside the engine not what you feel) wonder if different balancers will take some of that out. Combine that level of vibration with some front loading and I think you have your answer to what is breaking them
Crank
When mine broke it was in Ohio pulling 6 horses on level grond on the highway at 60mph. First the oil light came on pulled over checked oil it was good, with right at 4k on the oil change. Had it towed too dealer, they stated it had a bad injector, and put an injector in it, that didn't fix it so they said "well we guess it needs a motor." Looks like it had a hydro lock die too that bad injector. Which is a bunch of crap, because you don't have a hydrolock at 60mph! I bought the truck from the original owner for 18k with 118,000 and this bad motor. The crank snapped but not where most of you guys have yours break. Got a used motor with 30k on it and have been happy motoring since. BTW, this truck is bone stock and has never had any tunes or aftermarket parts. It by all accounts has led a good life with regular dealer services.
When mine broke it was in Ohio pulling 6 horses on level grond on the highway at 60mph. First the oil light came on pulled over checked oil it was good, with right at 4k on the oil change. Had it towed too dealer, they stated it had a bad injector, and put an injector in it, that didn't fix it so they said "well we guess it needs a motor." Looks like it had a hydro lock die too that bad injector. Which is a bunch of crap, because you don't have a hydrolock at 60mph! I bought the truck from the original owner for 18k with 118,000 and this bad motor. The crank snapped but not where most of you guys have yours break. Got a used motor with 30k on it and have been happy motoring since. BTW, this truck is bone stock and has never had any tunes or aftermarket parts. It by all accounts has led a good life with regular dealer services.
I was reading this thread right before i fell asleep and i had a dream that my crank broke. I hope its not an omen. Lol.
Lol, I know the rubber mounts don't help but they do isolate the vibration from the truck so you don't notice. Install Merchant's mounts and now you feel the vibration in the truck. The motor in the 1170hp video had a Fluidampner on it with internal balance and it shook more than motors with ATI/SoCal balancers seem to. I do notice that the lower the compression the smoother they run with a stock firing order. We are still at the early stages of figuring this mess out but breaking my dyno was probably a blessing in disguise as it pointed us at the problem and forced us to deal with it now.
Your telling me Chris! I have two stock motor trucks right now and I'm nervous about this. It's not like they all fail but knowing there could possibly be an issue at some time is a really bad feeling in the pit of your stomach that doesn't go away.
So a lower compression ratio (15.5:1) along with a AF cam would make a very smooth running motor correct mark?
Sent from a truck somewhere in the US
Sent from a truck somewhere in the US
In my experience the LBZ/LMM are more common but that might have something to do with the 6 speed transmission. A 5 speed truck cruising at 70-75 mph is past the 1650-1850 rpm range Mark mentioned. The 6 speed hangs out there all the time. But I'm still nervous my LB7's crank days are numbered
You and me are the only ones I know of so far to have an lbz break in the same spot and also under the same conditions, I was cruising at 40 down a back road, started to shake and rattle so I pulled over and she died
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Over the years there have been a few pics of broken ones at #4. Unfortunately, we aren't that special.......:dr: