Never before has so little power been made from so much displacement! (Page 39 of 57)

sure, PM me an address. i'll send the shaft too if you can tell me just how far off i was on the ability for that shaft to carry the load.

I vaguely recall this being a topic of discussion at gingerman at dinner.

Seems there was an early radial rotary in which the motor did spin. Guess that would solve the flywheel problem huh?

FJ40Jim kindly illustrated in way too much detail that the large spinning mass acted as a gyroscope of sorts and made it sort of hard to turn the plane which was bad if someone was shooting at you.

What does this have to do with this thread? Nothing... I just figured as it came up and the topic slowed down the consumption of steaks and mixed drinks that everyone should have to pay the price with those of us who were there.

You mean like the little Megola motorcycle?

figured i'd give you guys an update. someone generously offered to use their facilities to analyze my sprocket wear and shaft failure.

I won't name him because i'm not sure if he wants me to, but it was an amazingly generous offer and i'll post the results when i get them back.

meanwhile, it looks like we'll be racing autobahn at the end of the summer. it would be nice if the new drive system is done by then but i make no promises, i'm not rushing this again.

Somehow I think this is a suboptimal solution, let alone a needlessly complex one.

You're going to be running power through 8 different assemblies, of which almost all will need to be custom-adapted, 3 of them will be changing drive ratio (first up, then down), and finally there are 3-4 points where you'd have to get major components aligned pretty damn well.

A keg against this particular design working and not blowing up in some spectacular fashion for the entire race.

Do you have a schematic of your engine bay that identifies basic dimensions and location of the engine, wheel hubs (when on the ground), and any points of interference? I really want to be more constructive and not just sit there and shoot down ideas, but I don't know the dimensions of what you're working with...

sure. our first child was born healthy last tuesday

so no, i don't really have an update at this point. but i still have a decent plan i think.

Congrats on the baby Marc! Hope you are all well and happy!

congrats Marc....
Now you really have a complex piece of machinery to take care of.
Good luck.

thanks guys, here is the little guy and his mom.

well guys, I've got some very interesting results back from the guys that analysed my broken materials. (I don't want to name them in case they do not want to be named, but if they want to post who they are I'd be happy to let them plug their awesome services in my thread)

First thing is they did a chemical analysis on the shaft and the sprocket:

The shaft was as expected for a tough but not hardened shaft:
Cr    0.46
Ni    0.54
Mo    0.20
Cu    0.26
W    0.00
V    0.02
Mn    0.87
Fe    96.72
Ti    0.00

The gear on the other hand was very disappointing:
Cr    0.19
Ni    0.40
Mo    0.03
Cu    0.56
W    2.72
V    0.02
Mn    0.42
Fe    97.01
Ti    0.00

there are a few interesting points there. first thing is the manufacturer refers to this a ti-moly alloy. the titanium contents is undetectable if any at all. the moly contents is also very small. but in all fairness, from what i understand a little moly goes a very long way in an alloy.

the stuff machines like leaded chromoly alloy. I found this out because the piece wasn't entirely to size when i received it and i had to correct the bolt pattern.

but all that is sure with the above information is that the component i bought was mis-marketed. it was a motorcycle part that i was abusing. it may be fantastic for the original intended application.

here's the very interesting part, the fracture analysis indicated that the failure was mostly torsional rather than in bending.

the only torque on that part of the shaft is the drag from the end bearing. i haven't opened the angry hamster box yet, but I suspect the end bearing is completely failed/bound up. this is entirely not the failure that i expected, but the reason is probably the same. simply too much side load on the shaft destroyed the bearing which applied torque to the shaft.

the sum of all this means that the chain approach might be able to work, but at a minimum I'd need to place the chain in an oil bath with both ends mounted in double shear.

moving to an oil bath means i can use bigger industrial chains that require an oil bath and i can easily get a double sprocket and run two chains.

if i do this and support the whole lot on the transmission i can then use a short driveshaft between the engine and the top sprocket with rubber isolators or even a dual mass flywheel on the motor.

i could then put a lightweight flywheel in the Subaru box to reduce the back and forth pounding. the current is 27lbs and there are 9lb options available

the big reason I'm even reconsidering this is because of how far off the material was between what was promised and what was delivered. a sprocket of the proper material can probably handle this type of load just fine.

A quick way to check to see is a material is the right strength is a Rockwell hardness test. It's very cheap and easy and many fabrication shops will have one. If you can't find a hardness tester a scratch test could help. If you have something laying around that is about the hardness/strength you want, see if it will scratch the suspect part.

I Googled your Ti-moly alloy and it looks like is is supposed to be a steel. If so, I don't understand how the ads can claim it is 3X harder than stainless (some grades of stainless are hard, many are not) and yet 35% lighter than stainless steel. For that strength/density you'd have to be using a titanium alloy, not a steel with a dash of Ti in it. One post noted that it resists bending better than steel, and I don't believe that since other than for all practical purposes the stiffness of all steels are the same and on top of that stiffness is not related to strength or hardness. In fact, if they think they have a super hard material and so can used thinner stock, the part will be even easier to bend.

Can you ask your vendor what the standard alloy designation is? I'm beginning to think this is something fishy because I can only find the alloy mentioned on motorcycle sites and on eBay and other cheesy sites selling titanium steel jewelery, but not at any aerospace or metals sites.

Edit - I found a Chinese site that sells the material, but they listed it as a titanium alloy, and a legit casting site that finally did mention titanium steels as steels containing 0.5-2% titanium plus usually Ni, Cr, and other elements.