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40' Outlaw Upgrades - Twin 900Sc to 1000hp Duramax Diesels

Old 05-04-2021, 10:11 PM
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Originally Posted by kidturbo View Post
Love the 3d work. Being how we twisted that 1480 slip yoke off when the gearset exploded, CV shaft gonna need scaled up to like 2" dia.. I've see a lot more half shafts twisted off in cranked up trucks than I have Spicer yokes. But it does solve most of these type issues pretty easily.
this little printer has been great for test fitting custom Parts before machining, I usually come up with extra features or small tweaks that make the part much better or easier to install without having to pay/wait for the real ones. You are totally correct the 934 stuff is too small for your application, I have thought a spline coupler like funny cars and industrial machinery run could work but Iím not sure how it would survive prolonged runs with a less than perfect alignment.

Originally Posted by cheech View Post
Nice work on the 3D stuff.
Otherwise, if both joints are good what kind of slop are you seeing in your double cardan?
without hijacking too much... the sae spline on the drive input shaft to yoke is sloppy. I have tried a few yokes and after reviewing the sae spline info out there they just seem to be an inherently sloppy older design. I think my drives input shafts were machined for a bolted on yoke like a differential pinion shaft, and a driveshaft with a slip joint, but I only have room for a DBL cardan that bolts to the 72c trans output and leave the yoke free to slide on the sae drive spline. The boat was originally rigged like this and itís just not right...

I may just reverse engineer the input shafts and have them cut for a better spline that yokes are available for but Iíd rather not
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Old 05-04-2021, 11:52 PM
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Originally Posted by boostbros View Post
they claim thats what started the statement turbine fire a cv joint let go spewing white hot balls that ignited wherever they landed
I knew that was driveshaft failure stated, but not that it was CV related. Result sounds totally reasonable. I've picked up a few blue pieces of metal from drivetrain and CP3 pump carnage already.
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Old 05-05-2021, 12:08 AM
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Originally Posted by sailtexas186548 View Post
I think my drives input shafts were machined for a bolted on yoke like a differential pinion shaft, and a driveshaft with a slip joint, but I only have room for a DBL cardan that bolts to the 72c trans output and leave the yoke free to slide on the sae drive spline. The boat was originally rigged like this and itís just not right...
That's what I'm trying to avoid ending up with. Part of the reason behind new boxes. The 6 yoke sticks out through the transom, or extension box edge, as where old setup was several inches back inside the transom box. So a 12" extension box actually might need be 14" deep to make this fly.. I'm gonna mock it up again once the extension box end plates are cut an tack in some tubes to let us check things before finalize and wrap the boxes.

Know where I could find a dfx or dwg of a #6 pattern? I can't even find the PDF with transom assembly dimensions now. Had all that saved at one time.
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Old 05-05-2021, 06:41 AM
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Originally Posted by kidturbo View Post

I don't have any really good pictures from original #6 setup that shows where prop shaft was set factory.
Please PM me your cell, I have some photos that may or may not help.

Ryan
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Old 05-05-2021, 10:48 PM
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i have to ask, if the boat was originally rigged with #6's, why did you not go with these from the start? driveline angles can be exaggerated if you were to, length permitting, increase the number of cross bearings on the driveline. i.e. each cross is good for 3 degrees of range so a typical drive line with two crosses = 6 degrees. increase the cross count and you increase the operating range of deflection. a center support bearing would be required for a shaft with greater than two crosses. fairly simple idea and execution. cv joints are good if the rpm are within the operating range of the cv. they are however costly in comparison to a cross bearing drive line.
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Old 05-06-2021, 10:23 AM
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The original 6's were plug-in style, with a 1.50 gear ratio. I was told they were dry sump, but after all I've learned, believe they were wet sumps. But either way, going with 2-spd transmissions would still have demanded moving things back for clearance. The ability to easily change up the gear ratio was a good selling point on the W's..
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Old 05-14-2021, 02:29 AM
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So I took a 3 day walk about into the mountains of WV along with my wife to relax and contemplate this new driveline setup. Got all serous, laid out the new cardboard templates on a picnic table, dug up all the pictures and measurements from our original designs, and stated working on the dimensions. But I needed something to hold down the templates.

I also brought along a fifth of 92 proof rum, then we picked up a half dozen bottles of wine, and some tasty tenderloin steaks. Things get a little fuzzy, I wake up in a hot tube, and this strange drawing is on my computer.. Have no idea what it means, but believe the answer I'm looking for is in there somewhere.. Please let me know if ya spot it.








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Old 05-14-2021, 04:26 PM
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your making a big intermediate standoff box that covers the stock 6 hole and raises the stock box, t-assy and drive.
somewhere in there maybe the factory box has 3 mounting locations any of which have acceptable drive line angles.
the whole set up will net the prop within an inch distance from transom and 1-2 inches in elevation.

That's my w.a.g. but would really like to some pics looking sqaure at the transom @ approx crank centerline.
smart money says you cyphered it all out.
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Old 05-14-2021, 07:47 PM
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This may be very old within the OSO community but I hadn’t seen it until recently.
When my small brain saw your diagram, I immediately thought of the Turbo Encabulator.

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Old 05-15-2021, 12:37 AM
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Your both right. There was a lot of alcohol involved in that drawing ..

I've been trying to weigh the options before we start welding up aluminum plates. It's a tough call, and I'd forgot how much math went into the original design. What doesn't help is more that slight differences between the W's and 6 Mercs. The driveshaft carrier flanges on 6's are about 4 inches lower and 8 inches forward of the W's before you add boxes. As you can see in pics below. Not to mention change in height from the gimbal ring pivot / input-shaft centerline to prop-shaft centerline. The W's are a 15" drop, where the 6's are 18.6" before you add spaces..

So while our drive-shafts are getting much shorter, drive side flanges are also lower, and then we are limited to 3" max shim spacers on lower uints to recover what gets taken up in these new Jacked Up Boxes. We have to raise the 6's a minimum of 2",, and add 3deg of downward tilt, just to run a std driveshaft. Option B, was run a Double Cardan joint, which requires matching the [pinion] / drive side flange angle to the driveshaft. Which would jack all the lower angles out like 8-12deg in the opposite up direction. While common in 4x4's, not really desirable in boats.. Also see CV pic below..

But we got a break today when received pics showing we actually have 12" between the transmission flange and the outside of transom. Adding 4.6" back to what I had calculated in the centerline drawing above. Every inch counts, and if using 12" extension boxes may just get our driveshaft angle in a happy condition. According to my driveshaft guru up here, a Spicer 1480 single cardan can safely operate up to about 12deg fully loaded. Preferably under 10deg, but not constrained to the 4deg I estimated above. Next to figure out how much down trim angle #6 lowers are capable of. If going this route, we'll be robbing 3deg of down trim in the extension box.. Plus our final prop height will land about where the W's are set now, even with those extra 2" shim plates in there..

Back to the Rum..















Why Double Cardan Doesn't Work.








Where I hope to land..



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