My Camaro went home to Oshawa to die......

[Camarowguy]

When the engine failed, did it suddenly stop or die and still rotate a bit?

[mercedestech]

Just curious...was the cam bolt extremely loose when you took it off, or still pretty tight?

[2010 SS RS]

Originally Posted by PQ

Chain tensioner is still good too. So the chain did not slip or break a tooth. But the cam just turned.

I'm going with the hard loaded violent torque hit from the tranny failure did the deal.

But, you are right. We will never know now.

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

[S-eatin-grin]

Originally Posted by mercedestech

Just curious...was the cam bolt extremely loose when you took it off, or still pretty tight?

I was wondering the same thing....something had to be loose for that pin to see that much tension

[Camarowguy]

The pin breaking wasn't the cause. It was a result of what happened. My .02

[S-eatin-grin]

when the pin sheared wouldn't the cam go out of time (can see on the pics that the cam was turning against the surface where the pin was) and wouldn't that cause a lifter to stick or jam?? Ultimately it seems that whatever caused the pin to sheer is what caused the failure. We are all back yard garage theorist in here (most more experienced than me). Suprised there havn't been performance shops commenting in this thread?

[SUX2BU]

Originally Posted by Russell James

I'd bet the lifter, PR's, valves, pistons, rods, block.... all that stuff was victims after the cam gear turned. When a piston hits something solid at that RPM, especially with stronger than stock PR's, it can easily blast a lifter right through the block.

I think the question is why did the pin shear? Was the bolt shoulder bottomed out on the pin instead of gear. That bolt/gear/cam needs to be held in by 360 degrees of that bolt shoulder. If one side is cocked by the pin - the gear is going to be unstable. Pin could be too long, hole in cam not deep enough...

If no defect in the pin/bolt mounting, my next guess and I think most probable is harmonics beat up the dowel pin until it failed. The stock set up was engineered to run for days at 6600 rpm, full load, no bad harmonics. Now, change multiple things in the valve train, valve springs, PR's, cam lobe profile, balancer, raise the limiter.... will it still have no harmonics beating up the timing chain? That entire combo would have to be Spintron tested to know. Did Comp Cams Spintron that cam, those springs, PRs, balancer... and see no bad harmonics at 6800 RPM?

I'd call Comp Cams and see what they say.

That is why I never use hardened push rods. I use the weaker stock push rods as a safety device. Anything goes wrong i would rather bend a weak push rod than bend a valve.

Originally Posted by Camarowguy

When the engine failed, did it suddenly stop or die and still rotate a bit?

An engine never just stops when things are rotating at thousands of revolutions per minute.

Originally Posted by 2010 SS RS

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

I conquer.

Originally Posted by S-eatin-grin

when the pin sheared wouldn't the cam go out of time (can see on the pics that the cam was turning against the surface where the pin was) and wouldn't that cause a lifter to stick or jam?? Ultimately it seems that whatever caused the pin to sheer is what caused the failure. We are all back yard garage theorist in here (most more experienced than me). Suprised there havn't been performance shops commenting in this thread?

I'm thinking it all started with the cam bolt. I'm guessing the bolt might have not been torqued correctly, not used lock tight or something like that. Once it doesn't have the correct torque holding the cam and gear together it is only a matter of time.

[GEEo]

That sucks man!!

Hopefully you can get your baby up and running again soon.

[PQ]

Originally Posted by 2010 SS RS

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

So you're saying the flywheel and tranny interface with the engine dampens the release?

I just disagree with you on this. It would be MUCH more imediate and violent than even a side step off the clutch on a hard launch. All that pressure that's ALREADY built up on the system suddenly released in a milisecond. Maybe the tranny buffers the shock toward the cam. But for you to say it's not a much worse shock than a hard launch just seems wrong. I could see if the source of the power and torque was on the other side of the break. Then I suspect it would be violent for the axles and differential.

Myabe the transmission buffers the system. But I can't see it just being a simple rev. Not when it's already under extreme pressure.

[Camarowguy]

Maybe the bolt did come loose and make the pin break. So maybe the shop should eat it. Was the bolt loose? I never saw an answer back on that question.

[Huggerorange73]

Originally Posted by mercedestech

That pin isn't supposed to see any stress at all. It is merely there as a locating pin when installing the gear. The bolt is supposed to hold everything together. I know it seems like a crappy design, but even Mercedes uses it in their 6.3L AMG engines. Infact the Benz engine doesn't even have a pin, we have a special tool that lines everthing up (cam, cam sprocket, chain, etc) while we tighten everything down. Now mind you these are overhead cams with no pushrods etc, but still a very similar design as far as the holding the cam sprocket to the cam (the Benz cam has an adjuster for cam timing not just a sprocket, but very simialr). You guys probably don't care, but I just thought I would throw it out there that a very advanced high horsepower engine made by Mercedes uses a very similar techniquie to hold everything together....and I've never seen one fail. I'll apologize now for getting off the main topic, I just want to know why this keeps destroying LS3 engines. This thread bothered me so much I just sold my TSP cam. I'm going to hold off on a cam until we know why this is happening and I'm closer to being out of warranty......It would take me months to recover from a failure like this without resorting to charging up the plastic! I'm all about paying to play, but damn......this would suck no matter how much money you have in the bank!

Great info!!!!! You should keep the cam though!

Originally Posted by Russell James

I'd bet the lifter, PR's, valves, pistons, rods, block.... all that stuff was victims after the cam gear turned. When a piston hits something solid at that RPM, especially with stronger than stock PR's, it can easily blast a lifter right through the block.

I think the question is why did the pin shear? Was the bolt shoulder bottomed out on the pin instead of gear. That bolt/gear/cam needs to be held in by 360 degrees of that bolt shoulder. If one side is cocked by the pin - the gear is going to be unstable. Pin could be too long, hole in cam not deep enough...

If no defect in the pin/bolt mounting, my next guess and I think most probable is harmonics beat up the dowel pin until it failed. The stock set up was engineered to run for days at 6600 rpm, full load, no bad harmonics. Now, change multiple things in the valve train, valve springs, PR's, cam lobe profile, balancer, raise the limiter.... will it still have no harmonics beating up the timing chain? That entire combo would have to be Spintron tested to know. Did Comp Cams Spintron that cam, those springs, PRs, balancer... and see no bad harmonics at 6800 RPM?

I'd call Comp Cams and see what they say.

Let me know what you find out....I'll be calling Comp on Monday as well.

Originally Posted by Camarowguy

When the engine failed, did it suddenly stop or die and still rotate a bit?

It didn't just suddenly stop....something let loose and then it tore itself apart.

Originally Posted by mercedestech

Just curious...was the cam bolt extremely loose when you took it off, or still pretty tight?

It was tight....had to use a breaker bar to get it loose.

Originally Posted by 2010 SS RS

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

Makes sense!

Originally Posted by Camarowguy

Maybe the bolt did come loose and make the pin break. So maybe the shop should eat it. Was the bolt loose? I never saw an answer back on that question.

Sorry....I just got to a PC to answer the questions. The bolt is a torque to yield....a new bolt was used.

[Toasty]

I say we call in Mythbusters to test out our theories!!

Originally Posted by 2010 SS RS

Its not like it siezed up and locked. When an output shaft breaks it is clean like a broke glass rod. Then everything still works including the transmission but there is no power out of it to the driveshaft. A hard launch transfers much more shock back thru the system than when the output shaft breaks. I know you somehow want to pin this back on the shaft failure but it just holds no water or logic. Go bust your output shaft and tell me how violent of a shock it is to your engine... It just is not. just sayin.

I don't think he was saying it siezed up when the output shaft broke. Quite the opposite. The point that the output-shaft-snap-started-it camp is getting at is that the engine had some load on it when the ouput shaft snapped, thus causing a sudden spike in RPM without a load. - picture cutting a rubber band when stretched between your two fingers vs. cutting same rubber band when it is sitting in your hand. the stored energy in the streched rubber band has to go somewhere, just like the extra engery in the motor. Weather the rev limiter would have stopped the spike, that is unknown to me at this point... but i am assuming that the rev limiter was moved/removed along with the shift points.

[Russell James]

Looking at those pin pictures again, I think the evidence is in your first picture there of the front of the cam gear with the bolt removed. There is witness marks that the bolt shoulder was tightened against the pin, half the pin has wear marks from bolt shoulder.

Then looking at the cam gear wear marks from the bolt shoulder - how uneven they are - that bolt wasn't squarely against the cam gear. If that bolt had been tightened evenly 360 deg against the cam gear, and the gear slipped, it would have put even marks 360 degrees around it under the bolt shoulder. With uneven marks like it has, it was torqued against the pin.

The cam gear hole also looks oblonged, got beat up from vibrations/harmonics. With the cam gear not having even 360 deg pressure against it from the bolt shoulder, possibly that gear was not stable and beat the pin to death. Not to mention the other pin failures we've seen on here had that same look of the bolt bottomed out on the pin... and were Comp Cams....

I think they either have pin length issues, or were expecting the cam gear to be a little thicker.... But that bolt definately shouldn't be cranked into the pin like that. The gear will not be torqued flushly against the cam like that... and wobbling.

[mercedestech]

Originally Posted by Russell James

Looking at those pin pictures again, I think the evidence is in your first picture there of the front of the cam gear with the bolt removed. There is witness marks that the bolt shoulder was tightened against the pin, half the pin has wear marks from bolt shoulder.

Then looking at the cam gear wear marks from the bolt shoulder - how uneven they are - that bolt wasn't squarely against the cam gear. If that bolt had been tightened evenly 360 deg against the cam gear, and the gear slipped, it would have put even marks 360 degrees around it under the bolt shoulder. With uneven marks like it has, it was torqued against the pin.

I would have to agree. Has anyone measured the pin length of the comp cams versus the pin length of the stock cams before installation? A digital caliper with a depth gauge should be able to see if this is an issue. I have a tsp cam here (actually a comp cam), but my digital caliper is at work or I would check it. If anyone could post the measurements, you might be onto something. If the comp cam pins prove to be too long, I would be asking them for assistance with the replacement engine.