Johnrude v-8 lower unit

[bluess02]

What can be done to make the gear case stronger, or what gear case is the go to for these engines when making 350-400hp. Triple engine configuration on a CC v-bottom.

TIA

[FUJIMO]

...What can be done to make the gear case stronger?

TIA
...nothing...

[25two.stroke]

What can be done to make the gear case stronger, or what gear case is the go to for these engines when making 350-400hp. Triple engine configuration on a CC v-bottom.

TIA

Merc 3.0L sportmaster.

[bluess02]

Merc 3.0L sportmaster.


that was the direction I was thinking I was going to have to go.

[David]

Don’t some people pin the carriers?

[Instigator]

Don’t mind fujimo, he just has a bad attitude and hates everything non black but……

Yes, pinning the carrier is a big part.

Also starting w/known, good, 35 yr old cases and gears (mo) is a good start.

Like the rest of the motor, if they’re worn and tired when you add 50+ HPs to them and Jack them to the moon, probably won’t end well.

Even if they’re black.
But, being 35+ yrs old, and still running, they won’t be.

[bluess02]

What is “pinning” entail?

[25two.stroke]

The omc carriers were not retained well. Not necessarily that mercs were much better...but the omc carriers were not held in well at all. Pinning the carrier is just that, drilling and pressing a pin through the carrier to keep it from spinning or backing out. Some people put a countersunk screw through the side of the case, some press a pin in, some drill and tap the case and then put a set-screw in it to push against the carrier. Theres ways you can make your omc case hold up, but there also less people out there willing to build a high hp omc case vs. a modern merc sportmaster.

[Instigator]

Not a good pic but if you look close you can see how most/all of us do it.

Four 1.4” x 20 flat head bolts counter sunk into housing and oriented every 90* around case.

The bolts go through the middle of the prop shaft carrier and clamp to the housing, making it act as a single assembly.

I’ve done a bunch of them, abused them all and had 100% success.

The pic of the unit by itself is one I doubled the size of the OEM housing the greatly improved handling and also greatly reduced crabbing at speed.

The Merc case is a far superior case, for strength and the Sporty is better all the way around but w/some elbow grease you can make an OMC fast and dependable.

[MattGreen]

An M2 Magnum (aka SLE) gearcase from ETEC 3.3/3.4L G1 motors can be adapted to a V8 fairly easily with a moderate amount of work to the shift and drive shafts. There's a thread I started on this a couple years ago, where Al Stoker (Racer) provided the details. I've gathered the parts for this and will be chipping away at doing this conversion next year. The M2 has a press-fit propshaft bearing carrier so the pinning process is not needed. It also has much beefier gears than regular OMC V6 cases. A significant problem with V8 cases at this point is the scarcity of good housings. That case has a tiny little skeg too so really not a great starting point. Remind me then and I'll post some updates on the M2 conversion project.

Matt

[rude tim]

I think one of the best things you can do is never shift them into gear with the engine running, start them in gear for both forward and reverse. With bigger SS props many with solid hubs the shock when putting them in gear is hard on the gears. I have found Royal Purple gear oil does not burn as quick as Mercury Racing gear oil.

[wfowahoo]

Ive broke three cases. None since I stop running surfacing props.

[Dave S]

If you can't find old cases......aren't cobra I/O cases the same ?