I fixed my Bravo upper issues with SCX uppers, but now I’m eating lowers on my left hand turner (port side). Two have thrown teeth through the cases, two have broken shafts, and my latest is skipping like a tooth is missing. Prior to changing uppers, my last lower issue was in 2002. Countless B2x upper issues though…. I can’t figure out why I’m eating these up on the left hand side. Using Amsoil severe gear with some Lucas, Powertech BRA23p props. Oil looks fine when I make it to a change interval, they just break. With the Imco uppers, I’m at 2:1. Would it be better to go 1.65 overall? I think Merc makes a special diesel lower that will do that with the Imco 1.5 upper. Alignment is good and mounts are new.

Yep there is a 18/25 (tooth count) lower that will give you 1.65 overall with a 27/32 upper. I am pretty sure we have a new one that I would like to see find a good home. Might even have 2 of them.

To be completely honest you might be better off with a 27/29 upper as it will reduce the torque the lower sees.

Go with the SCX Dual Downshaft and you'll solve the problems with your lowers.

I inspected my Powertech “Cush loc” hub and it’s pretty worn out. Powertech says that they will lock up hard as a failsafe. I’m wondering if that could be the issue. I’m considering weather to convert completely to SCX with a spacer and repropping or trying another B2. How do I get in touch with you Marc? Tried calling Bam, but I can’t find a phone number. Thanks.

Looks like we sold the lower I was thinking of. I will take a look tomorrow and see if we have anything else.

Best way to reach me is email. I don't spend a lot of time near the phone. My name @ bammarine.com

So, I’m currently running under propped to get through with my B2 lowers without breaking. I’m still not sure of the cause, but looking back, my issues all started after a few hundred hours with a set of Powertech 3 blade BRA23p SS props. The Cush loc rubbers were pretty worn, but I’m not sure if that had anything to do with the broken lowers or not. These props are 18-1/2” diameter and perform the best on the boat, other than breaking drives. With the Imco uppers and the B2 lowers, the ratio is 2:1. I’m now running Merc 25p aluminums which are 17-1/4”. I’ve lost 3-5 knots at cruise, and with any wind or chop, they are worse. I’m guessing the slip is good for the lowers though. If I were to switch to Imco lowers, I’d be going 1.5:1 and the biggest diameter props I can find are 15”. Not sure where to start….
with the B2s, I get better performance with the three blade 23ps than 4 Blade Big Cow 24s. WOT rpm is good with both at 4k.