I have a 353 fastech formula with 525's, Bravo XRs, stellings boxes. I was running 5 blade 30 pitch maximus props. I have had repeated failures on my port drive. Yoke seal failed twice, Upper gears failed (replaced), prop shaft broke(replaced), and then the entire drive was destroyed after pinion gear sheared off. Drive shaft was twisted upon disassembly inspection. Just had the entire drive rebuilt including upper housing. I have never had an impact on either drive, but it is possible that the original owner may have struck something at some point and had the prop repaired. Is it possible that the 5 blade props and the stellings boxes are contributing to the drives failures? Is it more likely that the drive encountered some solid object damage in the past? It is my understanding that there is no drive coupler with the stellings application. Could it be that the heavy five blade Maximus without a drive coupler could have caused this massive damage to my drive? I have switched to 4 balde bravo 32p props. Just trying to avoid on another drive failure. Thanks!

Starboard drive will incorperate same pto style non rubberized flywheel mount. That and a solid hub prop will not be impact friendly.wouldnt be a bad idea to get into the top cap look see bottom plug pull and sample oil in morning ritual with xr's of unknown lineage

Could of been a "just fix it so i can sell it quicky by previous owner on compromised drive too
xr goods are pricey.

My Stellings were my biggest problem w XRs too I believe. With the direct bolt to flywheel and no give.

Take out guts and have longer shaft made and go to drive coupler.

At least make sure everything is dead nuts on alignment and tight before your next outing..thats the driveline equivalent of the old 750 lift solid cam valvetrain . (Or the orig hp500)

Most likely the biggest problem is the 30 pitch 5 blades w/ a heavy boat and extension boxes , do you need a lot of throttle to get on plane, or does it float out relatively easy, like maybe 1/3 throttle or so ,do you have any ventilation holes around the props to let them slip a little on launch, and , have you been launching over big waves getting air under you, that You don't need impact damage if they are constantly over worked , that destroys drives fast.
A friend of mine has destroyed 2 XR's in 1 year because he is over propped, has a heavy boat, and must pour the coals to it just to get on plane, I just finished rebuilding his 2nd. XR today, if he doesn't get less prop it will break again.

had the same problem on my 35 motion stelling boxes with driveshafts you have to put a different bellhousing with merc coupler to absorb the harmonjcs call me and i can tell you what i did like a whole different boat bill 401-841-5866

Please tell us the secret. I have been pondering something to absorb shock for a LOOOOONG time.

If you have one drive constantly failing and the other drive is still together it sounds to me like there is deflection in the case. Not saying the rubber merc coupler is a bad idea. But you may want to swap your parts into a new case.

X2 building a 30 cat whit new xr s and 500 hp would like them to last !