Crankshaft issues

[SteveFord]

I'd say it's just one of those things. The stock crank in my opinion has done very well but as the advancement of the Duramax has taken place like said above nothing has really been done as far as a better crank to have with stock lenght rods. Aren't most of these trucks that broke cranks daily drivers/sled pullers/drag racing trucks? I would think if your going to use it daily with big hp the faster the metal would fatigue. There's always going to be a part that fails in lower hp applications but making upwards and beyond 1000 rwhp on a stock crank GM gave us, I'd say we are doing pretty good.
As far as load on the front I can see that being an issue. Also when the converter locks up and brings the rpms down has to be an enormus load also.

 

[fishsmith]

Mine wasn't a daily driver. I did drag race it some but not like some of the others have. Maybe 15 passes in a year. I probably had a total of 5000 mi on my build and a total of 125,000 on the truck.

 

[paint94979]

Mine wasn't a daily driver. I did drag race it some but not like some of the others have. Maybe 15 passes in a year. I probably had a total of 5000 mi on my build and a total of 125,000 on the truck.

thats scary 5,000 miles and 15 passes.

 

[LBZ]

My shortblock had some signs of crank walking as well when I tore it down. I think it is a combination of time and that undersized front main bearing that's causing the breaking. I know my crank is getting inspected before it goes in and gets the keyway cut and balanced. Hopefully it's good.

 

[JoshH]

My shortblock had some signs of crank walking as well when I tore it down. I think it is a combination of time and that undersized front main bearing that's causing the breaking. I know my crank is getting inspected before it goes in and gets the keyway cut and balanced. Hopefully it's good.

Undersized as in not wide enough, not big enough diameter or both?

 

[LBZ]

Really narrow. Close to half that of the rest of the main bearings in width.

 

[RENODMAX]

Most of these failures are after builds correct? Anyone ever take the difference in rod weight into account? Meaning from stock to aftermarket

 

[McRat]

The same thingy about crank failures is the same thingy that bugs me about LBZ pistons failures:

The first busted crank I saw with my own eyes was in 2005, it was a LLY with ~50k mi, and running a Predator handheld. It snapped clean, like it was over-hardened. MAny other "mild" trucks have since done the same.

I've run far more HP yet have not seen this yet. So I'm confused about it.

I'm currently not worried about it for us. I have lots of stuff I want to beef up, but cranks aren't a problem yet.

 

[Bluemax]

Most of these failures are after builds correct? Anyone ever take the difference in rod weight into account? Meaning from stock to aftermarket

Mine broke when the engine was all stock with a tune.

 

[RENODMAX]

Mine broke when the engine was all stock with a tune.

Of course there are always exceptions and QC may not be that good but it seems like alot of the ones which are taken apart fail

 

[Trippin]

Now if someone would only exert the time and expense of building a billet crankshaft.

3 years ago I set out to build a billet crank in response to these same types of failures. I didn't set out to build a stroker crank, but it occurred to me along the way that the cost of the crank would be the same whether or not it was a stock stroke or increased stroke. It turns out that +.250 in stroke would fit in the block with out any surgery. So we built 20 stroker cranks and 6 stock stroke cranks. We sold out of the strokers and still had 3 stockers left so I built 20 more strokers. By the time the 40th stroker left we finally sold the last stock stroke.

I won't keep any of the stock stroke on the shelf as it is just too slow of a mover. However if anyone wants one I can slip it in with the next run of strokers. Usually takes about 10 -12 weeks.

Guy

 

[RPM Motorsports]

In all honesty, to put the rumors aside, How many Billet cranks have broke Guy?

 

[Osubeaver]

What kind of inspection are people doing to their stock crank before putting it back in a high HP built engine?

 

[eds04max]

Wet mag................maybe chemo-theropy and radi-ology.

 

[S Phinney]

Mine broke on a stock truck with a 135hp Quad tune on it. I think it is just a flaw in some cranks.

 

[duramaximizer]

here ya' go........

My dad's looked the same. It broke while crossing the railroad tracks at an idle. That alone tells me it has to be a harmonics issue or a crank quality issue. As this truck was a stock engine and stock trans. It ran a quad 135 tune some, but was mostly a 90hp tune on DSP5. So over powering the stock crank was not the issue, or shouldn't have been the issue IMO.

Heck, the last I knew Banks was running a stock crank.

 

[fishsmith]

Here are some pics of mine.

 

[IdahoRob]

We put 78 passes on the truck in the 10's this year. Started out with one engine that we decided to do testing for turbos/tuning/and general beating on.

If my notes are right, put about 35-40 passes on it before pulling it because of loose converter bolts and coolant out of the over flow. The other engine that went in is partially filled, neither one has had a failure except the push rods in #2 and a couple water pumps.

I don't know the history of the cranks to say one way or the other.

The water pumps are pushing the impeller forward and grinding the rotors against the housings. I'm thinking of either grinding down the impeller or just redoing the whole deal with an electric pump. Gear driving that water pump at those RPM's has to be hurting HP. Track only truck now, so I'm not worried about keeping it cool.

 

[TheBac]

Where did I see that post that explained the 5-digit crankshaft rating stamp? It would be interesting to compare the quality of the broken cranks by comparing those numbers.

 

[68skylark455]

Now if someone would only exert the time and expense of building a billet crankshaft.
Guy

And a damn fine you built to-except the damn thing is very heavy
we need one out of carbon/carbon so we can spin em to 6 grand!!!!