[PAUL K]

Originally Posted by taff2

however,that turned down shaft has 90 degree sharp edges where the turned down section meets the original diameter, no one with any inkling of performance sense would turn a load bearing shaft to that form. It's building in a potential failure.

At the end of the day those sharp 90 degree edges worked (accomplished the task on hand) so please explain how they are wrong?

[Tom Vaught]

Originally Posted by PAUL K

Hi Tom, not sure if you are referring to my post but if you are that engine peaked about 7800 rpm. So you think to test the durability of oil pump drive shaft we should pull the engine 10% above peak power for four hundred hours (approximately 8580 rpm) then we would "know" we have a good oil pump drive shaft if it survives the test?

The Keens used to spin their engine to 8500-9000 rpm (2 speed power glide trans) every pass, in the 1998 time frame, and the only issues they had were (in previous posts here), the stem of the cast iron oil pump breaking from cavitation bubbles in the stem of the oil pump bursting.

So 8500 rpm is just a rpm number that my company used as we had lots of track data that matched the dyno data saying we would be safe to run there.

But back on the sharp corners of the modified oil pump shaft for clearance.
Common knowledge from crankshaft experience that you do not cut a crankshaft with sharp corners where the rods are mounted. Always a radiused fillet there. That radiused fillet is there for a reason, which I think TAFF2 is also saying.

As far as what you can get away with in production, If the spring loads on the valvetrain in a Pontiac head were not higher vs the force required to remove the pressed in stud from the head, no worries. But then you have to ask, why were lots of performance pontiacs in the old days running either pinned studs or aftermarket threaded studs vs the press in studs once the spring loads and camshaft lift numbers went up. Same question on why any later pontiac head had threaded studs IF there was not an issue at higher spring loads. So your example/ ouestion has holes in the logic Paul.

Tom V.

[PontiacJim1959]

Why is it that some of these posts turn into pissing contests of who's engine did this and who's engine did that and I knew a guy who.........

Isn't this on a street engine and not a 200,000 RPM race engine using a 500 mega GPH oil pump, 140 weight gear oil, and a modified 3" dia. oil pump drive shaft taper ground in the center and made in China?

Why not just just point out what the HO engine build book shows and make your own shaft that seemed to be the answer for their record holding engines? Man, if Mickey Thompson were alive today............

Moderator, please add a new category titled "Theory, Maybe?" Then some of you can really dig into metallurgy, cohesion, fluid dynamics, hardening treatments, inertia loads at speed, torsional stresses and breaking points of metal compounds, and race engines I have known, known about, or had a buddy who knew a guy who had a race engine.

[Tom Vaught]

Originally Posted by PontiacJim1959

Why is it that some of these posts turn into pissing contests of who's engine did this and who's engine did that and I knew a guy who.........

Isn't this on a street engine and not a 200,000 RPM race engine using a 500 mega GPH oil pump, 140 weight gear oil, and a modified 3" dia. oil pump drive shaft taper ground in the center and made in China?

Why not just just point out what the HO engine build book shows and make your own shaft that seemed to be the answer for their record holding engines? Man, if Mickey Thompson were alive today............

Moderator, please add a new category titled "Theory, Maybe?" Then some of you can really dig into metallurgy, cohesion, fluid dynamics, hardening treatments, inertia loads at speed, torsional stresses and breaking points of metal compounds, and race engines I have known, known about, or had a buddy who knew a guy who had a race engine.

Can't argue with the above post. This is the street section.

The point was use parts designed for the actual application. In this case, another used oil pump shaft might give a bit more clearance vs the one he currently has and then you are done with the exercise.

Tom V.

[1968GTO421]

Originally Posted by Bill Hanlon

Except for Ford Model A rear axles with a key to attach the axle to the hub.

Well lets not forget Studebakers and pre-1966 Mopars (AAAAARRRRRGH)

[SRR]

What about how far it's engaged? Looking at this pic shows it to not be fully engaged. I think a shim or two in the distributor would help.

[NeighborsComplaint]

Shaft is all that stressed. It's running at half crankshaft RPM and cushioned from torque by the compressible oil in the clearance between the oil pump gears.

[PAUL K]

Originally Posted by Tom Vaught

The Keens used to spin their engine to 8500-9000 rpm (2 speed power glide trans) every pass, in the 1998 time frame, and the only issues they had were (in previous posts here), the stem of the cast iron oil pump breaking from cavitation bubbles in the stem of the oil pump bursting.

Not sure what the Keens have to do with this thread but since YOU dragged them into it, did they test their engine at 10 percent above peak power for 400 hours to validate the quality of their oil pump drive shaft?

Originally Posted by Tom Vaught

So 8500 rpm is just a rpm number that my company used as we had lots of track data that matched the dyno data saying we would be safe to run there.

YOU mentioned ten percent above peak power for four hundred hours in regards to quality testing a part.... 8500 rpm happens to be approximately ten percent above the peak power point on the World recording setting engine that's "supposedly" using the wrong oil pump drive shaft. Not sure what "your company" or the Keens have to do with this. They weren't racing in this class and more than likely wouldn't have won the Championship that year either.

Originally Posted by Tom Vaught

But back on the sharp corners of the modified oil pump shaft for clearance.
Common knowledge from crankshaft experience that you do not cut a crankshaft with sharp corners where the rods are mounted. Always a radiused fillet there. That radiused fillet is there for a reason, which I think TAFF2 is also saying.

I'm familiar with a radius adding strength over a sharp corner. I have seen many crankshafts that have had little or no radius on the crank journals and have lived a natural life cycle... Does this make the crankshaft the wrong part for the job?

Same for the oil pump driveshaft with the "sharp corners", is that the wrong oil pump drive shaft for the job? Does all the effort put into winning the Championship that year get disqualified because the oil pump had "sharp corners"?

Originally Posted by Tom Vaught

So your example/ ouestion has holes in the logic Paul.

Tom V.

Please enlighten me what example/question have I put out there that has holes in their logic?


This oil pump drive shaft (with the sharp corners) was designed for a reason. It did it's job and never failed. FACT

[PAUL K]

Originally Posted by PontiacJim1959

Why is it that some of these posts turn into pissing contests of who's engine did this and who's engine did that and I knew a guy who.........

I'm not sure why. Maybe because some guys have a little pee-pee? Maybe it's an ego thing? At all costs their idea has to be the best? Kinda like the kid in class that always raised their hand wanting to be called on because they knew they had the correct answer. Maybe they think they'll get a gold star if their answer is picked.

It's to bad because I believe most of the time the OP is looking for some useful advice.

Remember that thread when the guy was a bit disappointed with his 496 dyno results and there were a bunch of "Interent Experts" giving poop poor, unrealistic, ridiculously expensive, ideas for fixing his issue and most likely their ideas never would've helped.... Sad deal.

[PontiacJim1959]

Originally Posted by SRR

What about how far it's engaged? Looking at this pic shows it to not be fully engaged. I think a shim or two in the distributor would help.

No. Shim or 2 in the distributor may then force the dist. gear into the cam gear - and we know what that means, right? So you want to jam the pump shaft down into the oil pump, maybe tearing up pump gears?

These parts are not designed for a perfect .00001" fit, they can't be. If I had to guess on the shaft pic posted, there is where on that edge because the shaft was working beyond its limits trying to either spin a HD pump, like an 80 PSI pump, thick oil - which is worse when cold/start up, or it had a lot of miles and simply reached peak cycling. Appears the broken side simply twisted off. Looks to be a stock piece.

Bottom line is that ANYTIME you rebuild an engine, replace an oil pump, or simply have an engine out for rework, replace the oil pump and install a new hardened oil pump shaft as insurance - which is cheaper than an engine.

The prices can vary depending on type/style of pump shaft.

[BILL BOWMAN1]

Originally Posted by PAUL K

I'm not sure why. Maybe because some guys have a little pee-pee? Maybe it's an ego thing? At all costs their idea has to be the best? Kinda like the kid in class that always raised their hand wanting to be called on because they knew they had the correct answer. Maybe they think they'll get a gold star if their answer is picked.

It's to bad because I believe most of the time the OP is looking for some useful advice.

Remember that thread when the guy was a bit disappointed with his 496 dyno results and there were a bunch of "Interent Experts" giving poop poor, unrealistic, ridiculously expensive, ideas for fixing his issue and most likely their ideas never would've helped.... Sad deal.

This is why a lot of members just don’t come back here.

[Tom Vaught]

Originally Posted by PAUL K

Not sure what the Keens have to do with this thread but since YOU dragged them into it, did they test their engine at 10 percent above peak power for 400 hours to validate the quality of their oil pump drive shaft?



YOU mentioned ten percent above peak power for four hundred hours in regards to quality testing a part.... 8500 rpm happens to be approximately ten percent above the peak power point on the World recording setting engine that's "supposedly" using the wrong oil pump drive shaft. Not sure what "your company" or the Keens have to do with this. They weren't racing in this class and more than likely wouldn't have won the Championship that year either.



I'm familiar with a radius adding strength over a sharp corner. I have seen many crankshafts that have had little or no radius on the crank journals and have lived a natural life cycle... Does this make the crankshaft the wrong part for the job?

Same for the oil pump driveshaft with the "sharp corners", is that the wrong oil pump drive shaft for the job? Does all the effort put into winning the Championship that year get disqualified because the oil pump had "sharp corners"?



Please enlighten me what example/question have I put out there that has holes in their logic?


This oil pump drive shaft (with the sharp corners) was designed for a reason. It did it's job and never failed. FACT

Have a good evening Paul.

Tom V.

[PAUL K]

Originally Posted by Tom Vaught

Have a good evening Paul.

Tom V.

Thanks Tom! You also

[PAUL K]

Originally Posted by BILL BOWMAN1

This is why a lot of members just don’t come back here.

I agree, sad deal. There is a lot of good information on this sight if you do a search.

[Elarson]

Originally Posted by SRR

What about how far it's engaged? Looking at this pic shows it to not be fully engaged. I think a shim or two in the distributor would help.

That picture looks like it was a pretty brittle fracture....suggesting that it was pretty hard.....maybe too hard for it's own good. Brittle fractures usually start at some sort of stress concentration like a nick or a notch or a sharp edge. If possible, I'd be curious to see the other side of the fractured spot, since it had to initiate from the side facing away from the camera.

With the tangs, it looks like an OEM or Melling shaft?

I recall from my previous days working with OEM parts, that the stock driveshaft had a lengthwise witness mark suggesting that it was made from extruded bar stock vs. the Ram Air/SD engines had a shaft that had subtle spiral colorations which made me suspect it was some sort of rolled alloy steel.

I agree with the statement that on a street engine, the stress should be pretty moderate. I'd wonder if there was an unusual event? For instance, maybe the oil pump ingested a metal chip or something that caused a momentary spike in load?

Just pondering.....
Eric

[scott70]

Originally Posted by Elarson

That picture looks like it was a pretty brittle fracture....suggesting that it was pretty hard.....maybe too hard for it's own good. Brittle fractures usually start at some sort of stress concentration like a nick or a notch or a sharp edge. If possible, I'd be curious to see the other side of the fractured spot, since it had to initiate from the side facing away from the camera.

With the tangs, it looks like an OEM or Melling shaft?

I recall from my previous days working with OEM parts, that the stock driveshaft had a lengthwise witness mark suggesting that it was made from extruded bar stock vs. the Ram Air/SD engines had a shaft that had subtle spiral colorations which made me suspect it was some sort of rolled alloy steel.

I agree with the statement that on a street engine, the stress should be pretty moderate. I'd wonder if there was an unusual event? For instance, maybe the oil pump ingested a metal chip or something that caused a momentary spike in load?

Just pondering.....
Eric

That was a oem shaft with unknown miles. I've probably still have it around somewheres. I have no idea how long it had been like that. Found it by accident on a engine refreshing.

[67Fbird]

wow.......alot of "mine's better than yours"....lol
the broken tang looks to be an anomaly. Yes it happens but without a full "investgation" into the remains of the engine it would be difficult to determine was it the CAUSE of death or the RESULT from something else that failed.

A typical machinist would radius all cuts and edges because it has been proven XXXX times over that ALL edges create stress risers. How much??? who knows..who really cares...its just what we do. As a Toolmaker i've NEVER been accused of UNDER designing something...lol