What would cause the shaft in the lower unit to break like this? This is the second lower unit I've replaced and they aint cheap.

What type of motor?

2007 ProDrive

I would call kp at prodrive and discuss with him. He is very helpful and can help you sort it out.

I have called him on a number of issues, and he is always helpful.

Don't know if you have had the motor since 2007 or got it later, but either way you shouldn't be snapping the shafts.

KP will get you sorted out...

Let us know what happens....

That Sucks!!ProDrive don't know what the problem is with the Gearboxes?

Yeah, what kind of feedback did he give you on why it may be happening?

I would figure out the core problem before I kept sinking money in the shafts...

It's not normal....

What were you doing when it snapped?

You stated "The new one has a bigger nuckle, so I assume bigger gears".
Looking at the pictures you provided, I think that I can see a tag that is installed with four (4) rivits into the gear housing itself.
If so, that is one of the old gear boxes; the new ones have the word "Prodrive" casted onto both sides of the gear housing itself. The other way to tell for sure is if there is a bearing atop of the gear that is broke off;I cannot tell from the pictures, it's on the opposite side of the broken shaft side.
I ask because around that time frame (07-08) the gear boxes were up-graded.
The newer ones have more "Robust" gears and incorperate an additional bearing in the design. The driven gear is supported on both sides, unlike the "older" ones that were supported below only.
Now with opposing angular contact bearings, one above the drive gear and one below; the driven gear is better protected from bi-axial thrust loads, and prevent the driven gear from flexing in the area where the drive shaft is pressed into the driven gear, thus breaking the drive shaft just below the driven gear.

If that is one of the "new" ones, it's the first I see broke.

Also looking at the break, did by chance you hit anything rather hard that you can remember??
That triangular "sliver" above the shaft key (in the broken gear), is indicative with rototaional force, and the fact that the break is on plain with the bottom of the key, looks like possible impact.

Just my opinion.

i'm thinking u knocked the fuck out of sumthing and halfway broke the shaft, then kept running it till it finished breaking. if that's not the first one u have broken, i would tend to lean that way.

nothing is indestrucable.

or could be a monday morning motor.

either way, gonna cost a few dollars to fix.


good luck.

Basically ~ I'm gonna leave this one alone and chalk it up as .....

Thangs Brake when yore doin' tha deal !!!!!


I will add this tho ...... belts take 'bout 15 minutes to replace ifin' you have too !!!!!!

Da usally when these ???? are behind a statment its called a Question!!! That is what Jimmy was asking!!! If they know what was causing the problem By the way jack azz how many have you broke!! And yes a belt takes 15 minutes to change!! and the belt is under 100$$ So this is gonna cost this feller 1000$$ to replace it and dam the second one!!

Who knows why it broke. Probably because at some point he knocked the chit out of something. When my prop shaft broke (07 model) I was running clean water but it had obviously been cracked prior from hitting something and took awhile to completely break. And yeh 500.00 for a complete lower unit is more than a 100.00 but you not gonna get around breaking chit on any of these things. Its the nature of the beast with the product you bought. A LU can be changed out in 30 minutes too.

I bet if that shaft is made out of 300M it wont break LOL.
But you think its expensive now for a LU imagine all the parts being some Badass material. Good luck with your repair dude.

i realize that mudbuddy cloned gatortail, but i'll be damned if the gatortail internet rescue team don't sound like leaky, mud doctor, almo, and the rest of the mb team.

lets all go to utah on sunday and wirship the phoobah!!!!!!!

I didn't hit anything out of the norm that day. Maybe from the hard bottom I was hittin the day before. To clear things up that is a 07 LU in the pic. The new one I replaced it with is upgraded/current one.

Did KP give you any idea what caused the problem?

I would really spend some time and energy troubleshooting that before I kept spending money on new shafts...

Just curious-

I have two prodrives and don't want to find myself in your shoes.

Good luck, and thanks for updating us...

Really it sucks to break. But really if you use your motor hard regardless of brand some things are going to break.

I see it alot because I am into 4x4's aswell and your breaking something or changing a bad part before it fails all the time. Its part of the game. The besat way to not have the problems is to not ever buy a toy...

Damn, melted plastic covers...broken shafts....smoked clutches...

GLAD I BOUGHT A GODEVIL.

Carry on.

PS. Sorry for stirrin the pot but this $hit is funny as hell.