The Stovebolt Site Forums The Shop Area Engine Shop Crankshaft dilema needs help

Have a '61 261 that I'm in the process of rebuilding, not hopping up. Took the crank to the machine shop to have the nose drilled and tapped for a 1/2x20 damper bolt and they put the hole in the flywheel end...yes they did. Fortunatly the hole did not intersect the crankshaft rear main oil passage nor did it break thru the "cheek" of the #6 cyl crank throw. It was close. I know all the engine torque "funnels" thru the rear main and am concerned about the integrity of the crank in this area. All comments are appreciated

they owe you a new crank

Bill

I'd be VERY reluctant to rely on that one! There's no difference I can think of between a 235 and a 261 crank, so they shouldn't have much trouble finding you a good-quality replacement shaft. Don't let 'em weasel out of their responsibility!
Jerry

Get your new/replacement crank, and then leave. Don't let them work on anything else.

If that wasn't so messed up, it would be funny...

What was the reason they drilled the wrong end? Is this an automotive machine shop or a tool and die machine shop?

It was a tool & die shop. I suppose they dont know the diff. Eh? Whats done is done. No offense but I was hoping for more than "who shot Willie" comments

the first comment took care of it all, they owe you a new crank. the rest is about Willie.

What is a "who shot Willie" comment? Something about the theme of a Boogie Smith song?

"All comments are appreciated."

I'm a country boy and I know this much, to keep my ears wide open and my big mouth shut.

I'm just askin . . .

question: "am concerned about the integrity of the crank in this area"
then: "Whats done is done"

so you're not concerned anymore now that folks here identified Willies killer, or you've accepted the shops mistake?

maybe you were hoping folks would give you "Don't Worry, Be Happy" comments? or a makeshift solution like asking the shop to fill the hole and do it on the other end? a tool and die shop should have some threaded rod around they could jam in there

did you have them drill the right end as well? what was their response when you pointed out the mistake? or did you not point it out? maybe just paid up and took the damaged shaft home?

no offense back, but if you gave them explicit instructions, they're liable for correcting their mistake .... if your instructions were vague or incomplete, you're the one who needs to bite the bullet, either way folks here have voted to reject the crank

Bill

I shot Willy.

It maybe fine to run like that. But then again do you want to use it as an experiment? When the manufacture does changes like that, they test. Some times the tests are purposely to break the modified part, to prove it will handle the load and endurance.
Some times removing material can make something stronger or more durable, ie counter intuitive. In the end its still just a test, on your dime. So its your choice.

The machine shop owner (who is my brother-in-law in good standing) was very apologetic and immediately correctly redrilled the crank, and yes I was shopping for a "don't worry-be happy" comment or two. After all, isn't this what it's all about. Anyhoe, back to the issue--I popped the xmission input shaft bushing out of the end of the crank to get a better look at the situation. To my suprise, the bushing hole which is 1 1/8 dia extends into the rear of the rear main bearing journal about 3/4". This tells me that the amount of steel area available to transmit "funnel" engine torque would be the cross sectional area of the rear main brg minus the cross sectional area of the bushing hole (1 1/8"). I'm thinking that the 1/2" dia drilled hole has no effect on the structural integrity of the crank in this area because it is forward of the much larger bushing hole that was put in by the factory. Again, any don't worry-be happy comments or others are always appreciated

There is little doubt you are ever going to put the maximum load/torque on your crank, unless it is in a big truck, so I'm with you, run it.

If the hole is already threaded, how about putting an Allen-head bolt into the hole, torque it snug, and secure it with red LocTite. That will minimize the distortion and possibly prevent a crack or a break from getting started. Good luck!
Jerry

What Jerry said.

I would:

1. Run a bottoming tap in it to get the threads as close as possible to bottom.
2. Locate a bolt with thread length equal to or greater than that in the pc. and chamfer/square up the end comparable to the tap to insure bottoming out.
3. Dip it in green loctite (bearing retaining compound)before torquing it in 25-50 ft. lbs.
4. Mill away the remaining bolt head/shank.

ok if the hole does not go into oil galleys it will not hurt a thing I am asuming they drilled hole behind where pilot bearing goes. we build 850 hp engines with a hole that goes from back of crank to the front main for lightning about 1 inch dia. you should also use a smaller bolt size they probably saw snout dia and it would weaken to much with a hole that big. 3/8 will work. the Honer