Topic: broken teeth of crankshaft

[Retro Rocket]

the rubbers in the primary are new also all bearings in the complete engine I fink it would by a good idea to weld this 2 sprockets together but i am not sure if the sprocket on the primary side are good to weld i will take to sprocket out of my stock make a chamfer on the lathe and weld it  and test it afterwords. i don't send a crank to cyclex its to expensive for me i am from Austria Europe so i have to pay +50 dollars. I am not sure but i don't thing that ken check the crank with magnaflux for cracks. When i have this problem again a will make a billet crankshaft out of 34CrNiMo6 Europe (4340 SAE USA).

If i were going to the trouble of having a cromo 4340 crank made, i'd build the whole bottom end like the old RSC endurance racers, a full gear drive bottom end...



I would love one of these....

[MRieck]

Me too. In fact ....I'd take 3

[Retro Rocket]

Me too. In fact ....I'd take 3

How hard would it be to build Mike...?  Did you get my K8 crank case with back cut gearbox....?

[754]

The real hard part of that will be finding the machines to cut the sprocket teeth and gear teeth.. The rest is home shop type stuff.

[Jerry Rxman Griffin aka MuthaF'er]

KMB69, would that be hard to find?

[teebee67]

I'd be buying at least one as well.

[PeWe]

I am sure you checked the teeth before assembly?
..i keep getting this nagging thought that that is the kind of damage that would occur if you had clamped down on the teeth (even if you used a shim) on say a milling machine.... Perhaps that cracked them, then in running they broke off..............just thinking out loud..

I got that feeling too when I saw the photo. Teeth cracked were the crank is milled. The teeth seems to be the highest point and might be rather vulnerable.

[MRieck]

Me too. In fact ....I'd take 3

How hard would it be to build Mike...?  Did you get my K8 crank case with back cut gearbox....?

yes...a few days ago Mick. It's an assembled lower halve. It almost went right through the shipping box.....thing is heavy to ship in a box.

[PeWe]

Me too. In fact ....I'd take 3

How hard would it be to build Mike...?  Did you get my K8 crank case with back cut gearbox....?

yes...a few days ago Mick. It's an assembled lower halve. It almost went right through the shipping box.....thing is heavy to ship in a box.

Heavy crank?
....back cut gearbox....I'm dreaming about that

[Retro Rocket]

Me too. In fact ....I'd take 3

How hard would it be to build Mike...?  Did you get my K8 crank case with back cut gearbox....?

yes...a few days ago Mick. It's an assembled lower halve. It almost went right through the shipping box.....thing is heavy to ship in a box.

Thanks Mike, I'll be in touch...

[Retro Rocket]

I'd be buying at least one as well.

Group buy...?  I wonder what it would cost to make say, 10 of these gear driven bottom ends, i'm sure they would fly off the shelf...

[kmb69]

The real hard part of that will be finding the machines to cut the sprocket teeth and gear teeth.. The rest is home shop type stuff.

Not so sure about that "home shop type stuff" Frank. That intermediate gear would need to be substantially mounted. That crank would be trying to rip that gear right out of there. That gear appears to have no support from the top case. Not sure if Honda machined a custom crankcase casting or mounted it in a modified stock case. I have looked at this picture many times thinking about it. Wish I could find some more pictures with different viewing angles but this is the only one I have ever seen. Pretty sure Honda won some endurance races with this setup. This modified SOHC lower also had a DOHC 4 valve head. These were essentially the early prototypes going to the DOHC's in 79.

KMB69, would that be hard to find?

Pretty sure my machines would do all but the journal grinding but I am up to my nose on a VERY HOT project (Jr's) right now.

[754]

The worst part is you probably. Cannot find a forged blank..
 We had a forged blank unmachined BBF crank, that we did a lot of work on with a Bridgeport type mill, the rest on the lathe and crank grinder.l
 The gear or sprockets. Has to be one piece with the crank, so the teeth cutting probably is a gearshaper job..
A lot of setup for a short run as far as the gearshaper guys think..
 Same reason nobody is cutting the replacement gears for RC distributors.

[Retro Rocket]

The real hard part of that will be finding the machines to cut the sprocket teeth and gear teeth.. The rest is home shop type stuff.

Not so sure about that "home shop type stuff" Frank. That intermediate gear would need to be substantially mounted. That crank would be trying to rip that gear right out of there. That gear appears to have no support from the top case. Not sure if Honda machined a custom crankcase casting or mounted it in a modified stock case. I have looked at this picture many times thinking about it. Wish I could find some more pictures with different viewing angles but this is the only one I have ever seen. Pretty sure Honda won some endurance races with this setup. This modified SOHC lower also had a DOHC 4 valve head. These were essentially the early prototypes going to the DOHC's in 79.

KMB69, would that be hard to find?

Pretty sure my machines would do all but the journal grinding but I am up to my nose on a VERY HOT project (Jr's) right now.

Honda won a lot of endurance races with this set up, championships too, considering they were endurance races, i'd say it was a pretty solid and sound set up...   I'll post a link with the story on the race bikes...

http://www.vf750fd.com/Joep_Kortekaas/honda_endurance_history.html

Listen to the gear drives scream.....

[scottly]

Lots of hot motors have gone for thousands of miles without the crank sprocket failing. The only recent failure I can recall is the cyclex drag bike, which was most likely stressing the drive-train a bit more than an 836 road-racer, and maybe Bear's 120+ HP alcohol swilling side-hack?
Something odd happened here.... 

[Aurel]

I don´t no i think the teeth had so small crack befor i used it. Hopefully the new crank will life longer.

[kmb69]

The worst part is you probably. Cannot find a forged blank..
.....

It would probably have to be a billet crank. A set of forging dies even amortized on 10 pieces would be quite costly.

I'd be buying at least one as well.

Group buy...?  I wonder what it would cost to make say, 10 of these gear driven bottom ends, i'm sure they would fly off the shelf...

Lots of folks would probably want one until they had to cough up the $jack$.
Billet crankshaft, 2 additional gears, crankcase mods, plus other related hardware - even a 10 piece build would be  E X P E N S I V E !!!

[Retro Rocket]

The worst part is you probably. Cannot find a forged blank..
.....

It would probably have to be a billet crank. A set of forging dies even amortized on 10 pieces would be quite costly.

I'd be buying at least one as well.

Group buy...?  I wonder what it would cost to make say, 10 of these gear driven bottom ends, i'm sure they would fly off the shelf...

Lots of folks would probably want one until they had to cough up the $jack$.
Billet crankshaft, 2 additional gears, crankcase mods, plus other related hardware - even a 10 piece build would be  E X P E N S I V E !!!

Ball park figure...?   

[Jerry Rxman Griffin aka MuthaF'er]

The worst part is you probably. Cannot find a forged blank..
.....

It would probably have to be a billet crank. A set of forging dies even amortized on 10 pieces would be quite costly.

I'd be buying at least one as well.

Group buy...?  I wonder what it would cost to make say, 10 of these gear driven bottom ends, i'm sure they would fly off the shelf...

Lots of folks would probably want one until they had to cough up the $jack$.
Billet crankshaft, 2 additional gears, crankcase mods, plus other related hardware - even a 10 piece build would be  E X P E N S I V E !!!

Have toys, MUST play! good project for an expert machinist I'd say. You on it?

[kmb69]

Ball park figure...?   

Like Frank mentioned earlier, setup cost amortized across 10 pieces would be $ H I G H $
Just guessing, a minimum of $7.5k, maybe closer to $10k. That kind of serious machine time ain't cheap.
And...You probably got to make a minimum 50% deposit up front. How many you want? 
Brent's modified DOHC head is over $5k and you get to supply the valves, springs, retainers, buckets, and cams for example.
He also gets 50% up front.

Have toys, MUST play! good project for an expert machinist I'd say. You on it?

Whaa chu tawkin bout Willis? 

"Then it wouldn't be a Honda" is what you always tell me when I share my hybrid ideas with you. 

[Jerry Rxman Griffin aka MuthaF'er]

Honda outside, Keith inside. Get to work sucka.

[MRieck]

Ball park figure...?   

Like Frank mentioned earlier, setup cost amortized across 10 pieces would be $ H I G H $
Just guessing, a minimum of $7.5k, maybe closer to $10k. That kind of serious machine time ain't cheap.
And...You probably got to make a minimum 50% deposit up front. How many you want? 
Vince's modified DOHC head is over $5k and you get to supply the valves, springs, retainers, buckets, and cams for example.
He also gets 50% up front.

Have toys, MUST play! good project for an expert machinist I'd say. You on it?

Whaa chu tawkin bout Willis? 

"Then it wouldn't be a Honda" is what you always tell me when I share my hybrid ideas with you. 

People usually change that word to "hairbrain"when I talk about stuff.

[Aurel]

Her are the pics of the chain.

[kmb69]

Thanks for the pictures Aurel. That's the Classic Cycle City (Thomas') chain, correct?

[kmb69]

People usually change that word to "hairbrain"when I talk about stuff.

Yes, but you got hair. Me, well...............