502ss

iTrader: (3)

So here is the scenario. I have an 84 scarab with TRS's and I have a set of kaama drives that I really really want to put on the boat. My issue is that I am having no luck finding twin disc transmissions (without spending a fortune) so I am wondering if there are any other options? This is where the out of the box thinking comes in. I am not afraid of having to engineer something that works. Believe me I am far from one of those guys that needs everything to bolt up like a factory install or it can't be done. Unfortunately I don't know enough about the different types of transmissions out there that could maybe be retrofitted into a boat. I know the twin disc are unique in the fact that they can run full power in either direction. I can't imagine that this is the only transmission capable of this?

Anybody have any ideas?

Remember "out of the box thinking is what I am looking for"!

Thanks in advance!

Jim

cheech

Powerglides?

502ss

iTrader: (3)

Don't know a lot about them other then they are still popular in mud trucks and race cars. I am not sure you can put full power to the reverse? Maybe the reverse is a different ratio also?

airjunky

iTrader: (2)

The 72's have been beefed up to handle some girthy hp loads ,flip the pump cover for different rotation needs ,cheap enough you could prob keep a spare in boat somewhere .b&m made some.mini trans like the blactrac back in day outside that its lenco ,ect .should be a interesting project

502ss

iTrader: (3)

Are you saying you can flip the pump and the transmission will run in the opposite direction? Can you run full power like that?

raisingkane

The pump direction on 72s is determined by motor rotation, the counter rotation is in the gear reduction not the pump.

Unlimited jd

iTrader: (5)

When a 72 is used on a counter rotating engine you need to flip the pump. What you need is a drop box reduction gear. I believe there were some made for velvet drives. Also look into the Walter machine company. They make the most compact vee drives and drop boxes I've seen.

airjunky

iTrader: (2)

Brain fart my end ,flip pump for opposite rotation engines .unusual in BBC world .yea if you need gear reduction and low drive centerline its going to be more difficult .may need to flip motors around and have a v drive surface drive scarab .would definetly be outside the box .

Steve H

I will be replacing a pair of Twin Discs mg502 1.5 to 1 ratio with new ZFs sometime after the first of the year. I don't know what they are worth, but if you are interested I would part with them.

They work fine, except under hard throttle they will slip. The issue did not appear until I replaced the 415hp BBC engines with 500hp BBC engines. My boat weighs over 18,000lbs when loaded. I'm guessing there would be no issue in a lighter boat. I have been running it like this for over 150 hours with out any other problems, just have to be careful not to horse it on plane. This boat is a 42' Sport Fish with Arnesons.

Let me know

Steve

CDShack

Velvet drive?