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Milodon Gear DRive
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White70JavelinSST View Drop Down
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Points: 4867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Feb/18/2019 at 8:10pm
Typhooner,

I have the instructions that 304_dude sent me on my work computer. I'll get them to you tomorrow.
70 Javelin SST, second owner, purchased 1972
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carlanga View Drop Down
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Lo he usado por años sin ningún problema si se graduan de manera correcta por las instrucciones de MILODON no se escuchan
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Originally posted by White70JavelinSST White70JavelinSST wrote:

Finally the voice of reason, thank you Ken_Parkman.

It just doesn't make sense that the gear drive system is more prone to causing failures versus a chain. There are harmonics troubles everywhere, Ken came up with the real trouble. if a bum damper gets in there and the crank or cam fails, blame it on the gear drive, make sense doesn't it. Look at some of the very exotic twelve cylinder engines and aircraft engines, no chains in a lot of them if not all. Especially from years ago when belts weren't available that could with stand the abuse. True they don't turn 10k rpm. Some of those exotic sports car engines turned in the vicinity of 10k. So what, gear drives work when set up properly with all the other components correct as well. BTW, My son owns a 94 Acura Integra, It has had two belt failures, one caused by snow getting up into the mechanism and one that a shop tried to fix that lasted maybe 3k to 5k miles then blew again. I fixed it the 2nd time myself and that belt is still going strong after umpteen thousands of miles, so don't say belts are better either. They fail too.



No one said gear drives break camshafts or cause failures (other than them failing). But they do provide a direct link to transmit crankshaft vibration to the camshaft- which doesn't seem like it could be beneficial. If the camshaft is being turned, the gears are under load and backlash is removed from the system providing a direct and rigid path.

No one said timing belts don't fail. Of course they do. I've driven vehicles with timing belts for ~400k miles with no issues. The only negative is they are a maintenance item and difficult to change- so they're unsuitable for most people which is why most manufacturers use chains. Otherwise belts are ideal as they give precise timing and will tend to dampen vibrations compared to other methods.

What does NASCAR use for cam timing?
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White70JavelinSST View Drop Down
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Points: 4867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Feb/19/2019 at 12:48pm
Originally posted by Steve_P    What does NASCAR use for cam timing?[/QUOTE Steve_P    What does NASCAR use for cam timing?[/QUOTE wrote:



What do sports cars use that endure up to 24


What do sports cars use that endure up to 24 hours of continuous punishment in endurance racing.


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74Bubblefender View Drop Down
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Points: 2589 		Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Feb/19/2019 at 1:51pm
Very good accurate timing, literally vibrate the oil away from wear surfaces in the heads.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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74Bubblefender View Drop Down
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Originally posted by Ken_Parkman Ken_Parkman wrote:

The big deal in all this is the damper.

Crankshaft "harmonics" are actually frequency modes than can be excited by the firing pulses, and if you operate the engine in a range where the exiting orders and the natural frequencies line up really bad things happen.

The SAE report on the Typhoon engine has a good graph - there are vibration peaks at 2500, 3900, and 4500 rpm where the graph stops. You can see the damper smooths it all out. Who knows what happens at higher rpm. This is the 290/343 engine graph.

The topic is incredibly complex, and those that know are not talking. It can explode your head trying to figure it out. Where I work we have some serious experts on shaft vibration, and I borrowed a text. My head almost exploded. Most of the aftermarket manufacturers do not even know what a damper does, let alone have any concept of the technology.

So transmitting the vibrations is a reality no matter what the cam drive, just some systems are better at it. The trick is to get rid of the vibrations out of the crank first with the right damper. But no one knows what that is.

BTW some might remember when NHRA banned stock dampers on race cars, and everyone went out and bought an aluminum hub. There was a rash of crank problems and timing chains pulled apart.


Yes, yes and in some cases a dampener isnt even used. So you eat up valve train parts faster. Fast forward a little while and those little anodized rings became lawn art.
We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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White70JavelinSST View Drop Down
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Points: 4867 		Post Options Post Options   Thanks (0) Thanks(0)   Quote White70JavelinSST Quote  Post ReplyReply Direct Link To This Post Posted: Feb/19/2019 at 2:15pm
74bubblefender,

Are your experiences with a Milodon drive or a Pete Jackson drive, or  both?

and

 from severe use of an engine thusly equipped, is that correct?
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Points: 2589 		Post Options Post Options   Thanks (0) Thanks(0)   Quote 74Bubblefender Quote  Post ReplyReply Direct Link To This Post Posted: Feb/19/2019 at 4:05pm
Milodon...well you dont put one it a street car thinking you did yourself a big favor. You also dont put one in a race engine of any kind and think you did yourself a favor. I would never touch a pete jackson gear drive or a milodon again in my forseeable future. They are conversation pieces and that is where they stand with me. Working on a new production front end soon here. Too early to discuss more but we are bringing in a young buck well known person who is in their senior year of engineering this spring to help on the project. Should be fun! If not exhausting.

We are just about to forge new AMC V8 crankshafts.. please check here
http://www.bulltear.com/forums/showthread.php?19564
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maximus7001 View Drop Down
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In general camshaft bearing clearance gets ignored. When someone just "throws" a new cam into an engine there is no regard to any clearances and the cam just flops around in the old bearings. This is going to cause problems with A: gear drives and B: distributor and cam gears. What happens to diff gears if the bearings are all floppy? Gears need to mesh without constantly changing clearances. There seems to be all sorts of mystery about both of these. I have never heard of anyone talk about these scenarios.


Edited by maximus7001 - Feb/19/2019 at 6:36pm
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Am I the only one that's read David Vizard's books on SBC engines? He talks about vibration dampers, gear drives, timing chains, etc.

Summary: In back to back dyno tests, a 350-400 HP engine equipped with a heavy factory vibration damper makes 5-10 more HP than the same one with a light aluminum hub. And a good aftermarket damper will make a little more power than the factory elastomer damper. How? Well, the damper does its job and dampens vibrations that would otherwise get transferred to the camshaft. Vibrating a camshaft is not good as it disturbs the intended motion profile that the designer spent so much time developing. Now add in a gear drive and you'll really get vibration transfer. This is not good.

direct quote: Tests indicate that on an all out race SBC there's the potential to lose 14 HP by allowing too much torsional crank vibration to be transmitted to the camshaft...

Gear drives present a solid coupling between the crank and the cam....and have a tendency to transmit greater vibration amplitudes than a chain or belt.


IMO, The only place a camshaft gear drive makes sense is in commercial vehicles where downtime is $.

Edited by Steve_P - Feb/20/2019 at 7:01am
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