articfriends

iTrader: (1)

I recently bought a stellings ext box for my single engine v-hull boat. I'm running a blower motor that makes over 950 ft lbs of tq and turns up to 6000 rpm's. I chose a stellings box over the imco box because of the fact it uses a driveline/driveshaft with 2 companion flanges,stub yoke/spline yoke and u-joints instead of a splined shaft and coupler that allow for a height difference between the box and the motor. I am finding conflicting information on how much operating angle is safe to run.Stellings says you can run as much as 7-8 degrees of paralell operating angle,experts say that is not true. I was planning on installing the box in the 1 inch raised position and leaving my motor in its stock position other than small adjustments to make sure crankshaft flange and carrier bearing flange are parralell to each other as my exhaust is very large and rigid and will not allow me to move engine much with out new tailpipes and other modifications. My calculations show me that a 1 inch difference in height between the crankshaft centerline and carrier bearing flange with a 12 inch long driveshaft will put me at 7 1/2 degrees operating angle. Stellings says this is acceptable but everything I'm finding says different.Most driveline specialist reccomend a maximum of 3 degrees and say 1 1/2 degrees is ideal,especially for a shaft thats going to be spinning up to 6000 rpm's.There is another formula I found that says to divide length of shaft by five to find maximum operating angle. 12" div by 5=2.4 degrees. What are others running with same set-up?I don't want to rip boat apart to install ext box just to wait 6-8 weeks for new tailpipes to make proper adjustment and I don't want to install box with driveshaft at 7 1/2 degrees just to blow apart u-joints and damage the boat. I researched alot of past threads on stellings boxes and a common question that goes un-answered is weather you could run box in the 2 inch up position without re-mounting motor higher,I can tell you from my calculations the answer is NO WAY as your driveshaft angle would be 15 degrees.Any one with personal experience please post with your results,ideas and experience,thanks,Smitty

articfriends

iTrader: (1)

To clarify,my question is how much angle are others running on their driveshafts,can you raise the box to the +1 inch position without raising the motor which puts your driveshaft angle at 7 1/2 degrees,Smitty

BenPerfected

My research, which included input from Dana (u-joint manufacture) recommended a max of 2 degrees in a HP application.
A recommendation for more angle might be from someone with a different agenda.
What to do? Change you X-dimension or modify your tail pipes including other adjustments to hoses, wires, etc. that on longer reach...been they done that.
Maybe you can risk 7-8 degrees for 2006 and then re-rig over the winter( I would include new carrier bearings from Stellings in your 2007 budget).
I would also recommend all high RPM runs be for a short duration.

cobra marty

I don't remember but what is the difference in the 3 holes on the box? Are they 1" apart center-to-center that seems too close. So is the center hole at 0 degree driveline angle? What are you trying to accomplish? Setback, raised prop?

articfriends

iTrader: (1)

I'm trying to achieve set back AND raise the prop so I can skip buying a shorty (I have 2 drives,regular one and my spare,and they are both std length). There is 3 sets of holes,top set is considered neutral or stock as far as x-dimension. Middle is plus 1",bottom plus 2". Using middle hole (which is want I want to do first) will put prop carrier bearing/drive input shat centerline 1" above crank centerline. Without moving engine from original position (which would be extremely difficult because I'm running 5 " tailpipes that are EXTREMELY tight) I will end up with a 7 1/2 degree driveshaft angle (from my calculations,might actually be a little different once I actually start installing box) driveshaft will be about 1 ' long installed and going up 1 inch gives you 7.5 degree angle. Stellings says 7 degrees isn't a big deal but researching it tells me 7 degrees is extreme on something so short and spinning up to 6000 rpm's. I know the correct thing is to do whatever it takes to raise engine to get angle down to less than 3 degrees but that means putting off installing the box until after season is over because if I have to get new tailpies or have them seriously modified boat will end up sitting ripped 1/2 apart formost if not all of our short boating season. I'd like to have someone tell me that they went up a inch without moving there motor and it wasn't no problem running a high angle but I'm probably asking for serious problems if I go that route,Smitty

articfriends

iTrader: (1)

Thanks for your answer,pretty much sums up/confirms what I'm thinking too,Smitty

Mbam

Actually, 1" over 12" is 4.76 deg. I have personally run some rather extreme angles (close to 18 degrees), 1000 HP @6000 rpm without a problem. With Spicer 1350 series life of the U joints was only 75 hours or so, when I went to 1480 series I would replace them anyhow at 100-150 hours, but they looked fine. More important to have the 2 flanges parallel. This is not as easy as it sounds, as the angle built into the gimbal housing seldom matches the angle the boat builder put in the transom.

Spicer figures on life spans of multiple thousands of hours and they think in those terms. The de-rating charts don't even get down to the hundreds.

Don't do this on my advice - you can sink the boat if you lose a driveshaft and I'm wrong

ratman

smitty can you fit a 1350 c/v joint on each end of the shaft which will split your angle in half?

ratman

can you fabricate a drive shaft loop to catch the drive shaft if you gernade a u joint?

offshoredrillin

yea this is off of knot rights 46 skater...