Engine: 289 crankshaft undersize limits

[MChance]

How far undersize can you go with a V-8 crankshaft?
(I have an .030 undersized 289 crank that's questionable ) should I toss is or??

[PackardV8]

If you have the room, save it. They're getting more difficult to find all the time. For a stock build, .040" and .060" under bearings used to be available, but I haven't bought any lately. Welding up throws aren't that expensive if the alternative is buying a $300 crank which may have its own issues.

jack vines

[Dan Timberlake]

Are there any journals with dark/discolored cheeks?

http://i56.photobucket.com/albums/g170/Smokebombb/motorcycleposts/IMG_1205.jpg

IF so, it was so bad it probably had to be welded AND ground 30 under. Or suffered a major rod bearing failure. Either way Not a good candidate for resuscitation.

Before having a crank welded ( or even using a used crank ) I'd have it checked for cracks, etc by someone familiar with the wet fluorescent magnetic particle inspection.
I don't want the shop that says " oh we've never seen a cracked Chevy/Ford/anything else crank". Or that uses the dry powder method. Or that advocates the "ring" test, except maybe as a first step before REALLY crack checking (MagnaGlo-ing.)

I'd also check the crank for straightness . All it takes is a block with #1 and #5 bearing half insert installed, and a dial indicator. Or, wooden V-blocks in place of an engine block.
Before grinding I'd check all the main journals, the cranks snout, gear seat, crank flange, and seal surfaces. If there was much more than 0.002" TIR or so on the non-main journal surfaces I'd suspect the crank was welded, or similarly distorted by massive messy bearing failure, and again, not a good candidate for repair.

After the crank was welded and ground I'd want to magnaflux the crank again, paying special attention (just like the first time) to the radiused fillets at the journal edges.
It is not unheard of to MX a nice shiny looking freshly ground crank and find a string of transverse "indications" similar to the "row-of-dimes" pattern so admired in finish welds.

http://image.slidesharecdn.com/dyepenetrantinspection-141220000824-conversion-gate02/95/dye-penetrant-inspection-ndt-30-638.jpg?cb=1419055803

Or, indications along the edge of the weld.

Or, grinding "checks" (cracks !) on the journal surface.

http://www.wilcoxengines.co.uk/images/crakcrnk1.jpg

More than one crank grinder has said, after being informed their freshly ground crank failed magnaflux, "oh, those are just weld cracks" or, "oh, those are just heat checks" and "won't hurt anything."

Tain't so. An indication in a highly stressed area is going to propagate, and someday fail all at once.

[jclary]

I suppose I'll show my ignorance by commenting...but here goes...Is there a place for plasma spray, or brush plating, to build up a crank?

Another limit to what you can turn a crank has to be determined by what standard size bearings are available.

[Alan]

John, Plasma spray is good for .010" or so, but I would not try .030" +. Submerged arc is best and with a dedicated machine there is no problems building up .040"-.060". It is all in the operator. There is a guy near me that welds up and grinds to standard a .030" crank for $190. He is at R&C Cranks 3400 Union Pacific in L.A.

[Mike Van Veghten]

Hard chroming is also possible.
The crank I have for my hot rod 299 has had the bearing surfaces hard chromed.

Hard chroming is just an application of "chrome"...without the copper and the bright nickle, both of which are much softer than the chrome. The chrome itself is in the 65 to 67Rc range, which is harder than the crank metal.
Normally done at more industrial type places.

Mike

[Alan]

The most you can build up hard chrome is .015", any more than that and it starts getting holes. I used to have cranks that had to go to .020" chromed. But the last plater in the L.A. area was done under about 20 years ago. Plating is not cheap. Back then it was by the pound. A Stude crank ran $300 just for the plating in the 1990's.

[Mike Van Veghten]

Hey Alan -

In my experience, more than .015" is doable by a good shop, but depending on the crank/rpm/main web strength, the chrome can crack. While this isn't too big a deal depending on how the cracking has formed, "many" aircraft (piston driven) cylinders are chromed, then artificially cracked, then finish honed to prevent...uncontrolled cracking. And no, no idea how the chrome is artificially cracked..!

Mine was over plated then ground back to about .010" thick.

I also had a motorcycle steering neck plated up a few years ago to be able to be tight into a different manufacturers lower steering head clamp. A place in Whittier. Don't know if they are still there.

Mike

[Skybolt]

Mike and Alan, do you know of any places still in operation that do hard chroming? I have some parts, not cranks, that I would like done.

Len

[karterfred88]

I'm not an expert in this area, but if there are so many concerns with welding on a crank shaft, why do they bother to make expensive equipment dedicated to doing it, even adding lots of material to create longer stroke cranks? Some of those modified cranks are in engines producing 1000+ HP. Doubt any 289 Studes will get that much stress in everyday use.

[MChance]

If you have the room, save it. They're getting more difficult to find all the time. For a stock build, .040" and .060" under bearings used to be available, but I haven't bought any lately. Welding up throws aren't that expensive if the alternative is buying a $300 crank which may have its own issues.

jack vines

The room to store it is not an issue, I just have no use/need for it. (I have 3 extra complete 289's) it came out of a seized engine that was in a 56 Power Hawk parts car.

Are there any journals with dark/discolored cheeks?

http://i56.photobucket.com/albums/g170/Smokebombb/motorcycleposts/IMG_1205.jpg

IF so, it was so bad it probably had to be welded AND ground 30 under. Or suffered a major rod bearing failure. Either way Not a good candidate for resuscitation.

Before having a crank welded ( or even using a used crank ) I'd have it checked for cracks, etc by someone familiar with the wet fluorescent magnetic particle inspection.
I don't want the shop that says " oh we've never seen a cracked Chevy/Ford/anything else crank". Or that uses the dry powder method. Or that advocates the "ring" test, except maybe as a first step before REALLY crack checking (MagnaGlo-ing.)

I'd also check the crank for straightness . All it takes is a block with #1 and #5 bearing half insert installed, and a dial indicator. Or, wooden V-blocks in place of an engine block.
Before grinding I'd check all the main journals, the cranks snout, gear seat, crank flange, and seal surfaces. If there was much more than 0.002" TIR or so on the non-main journal surfaces I'd suspect the crank was welded, or similarly distorted by massive messy bearing failure, and again, not a good candidate for repair.

After the crank was welded and ground I'd want to magnaflux the crank again, paying special attention (just like the first time) to the radiused fillets at the journal edges.
It is not unheard of to MX a nice shiny looking freshly ground crank and find a string of transverse "indications" similar to the "row-of-dimes" pattern so admired in finish welds.

http://image.slidesharecdn.com/dyepenetrantinspection-141220000824-conversion-gate02/95/dye-penetrant-inspection-ndt-30-638.jpg?cb=1419055803

Or, indications along the edge of the weld.

Or, grinding "checks" (cracks !) on the journal surface.

http://www.wilcoxengines.co.uk/images/crakcrnk1.jpg

More than one crank grinder has said, after being informed their freshly ground crank failed magnaflux, "oh, those are just weld cracks" or, "oh, those are just heat checks" and "won't hurt anything."

Tain't so. An indication in a highly stressed area is going to propagate, and someday fail all at once.

It doesn't appear to have any "blueing" indicating a spun bearing at one time.

Anyone want a free 289 crank? I just hate to scrap it.

[Alan]

Len; I will check around and see. I used to take my cranks to Loyd's Crank grinding in Lakewood. He would grind a .010" under crank to .015". Then I would take the crank to the plater that was in Bell Gardens next to Del Rio off of Florence Blvd. Then take it back to Loyd's for finish. The total cost for a crank was around $500. The final grinding was the most expensive, since Loyd said that he wore out one of his $100 wheels grinding the chrome. Loyd retired to Bullhead City 20 years ago. The plater wanted to retire about the same time, so he tried to sell his shop. The EPA inspectors came in and said he could not sell the shop, but had to remove the building and test the soil 6 feet deep for any chrome.

[PackardV8]

Anyone want a free 289 crank? I just hate to scrap it.

Thanks for the offer. I'm going to be over that way soon, so if you've got room, hold on to it for me.

jack vines

[Alan]

Len, Barkens Hard Chrome, 239 E. Greenleaf Bl.,Compton CA., 310-632-2000. Although there should be some out there by you.

[Dan Timberlake]

Haven't a couple of folks here reported having V8 cranks break in passenger car service?
I don't recall feeling like we were "getting to the bottom" of why they failed, but I'm guessing a crack initiated in a rod journal fillet/radius. It is a pretty safe bet the crack initiated from some stress concentration, like a material defect, or poorly ground radius either by Studebaker or a crank grinder. There are plenty of tales of other makes' cranks breaking, even "forged steel" usually with the explanation that the crank had been ground too far undersize. I have seen gorgeous looking freshly ground cranks riddled with weld "checks" and cracks and even porosity in the highest stress regions. "Diesel fitter."

Not all shops take much care in what they do, relying on the law of averages that high positive cash flow can offset a come-back every now and then. If they even KNOW what to do.
Back in the 1980s, One grinder that I complained to about snout, timing sprocket journal and flywheel runout, and WHOPPING unbalance (all of which pretty much guarantee he welded a bunch of the crank journals, and then started grinding away) said something like " I never ground a bent crank. " In the sense the main journals ran nice and true, he was correct. But he had whittled those journals from a badly bent core, and the un-ground original reference surfaces were not concentric with the new mains.

This is typically how a crankshaft is held by the crank grinder.

http://www.rtsalesinc.com/web_quotes_english/crankshaft_camshaft_equipment/PHOTOS/0-stock-0075-p02-d-w0700-h0427.png

The tip of the snout, and the flywheel pilot on the extreme ends of the crankshaft. Unless the operator checks the runout of the features I'm whining about before and during the crank grinding process, he can not possibly know what they are.

http://crankshaftrepair.org/welding/