Allison Gears

[CapetaniosG]

A friend of mine overseas has a busted Allison M15 gear with a ratio of
1.5 to1.He wants to use an Allison M20 with a ratio 2:1 to replace it, since he can't repair the M15 or find a direct replacement locally (Greece). Can he do that? The vessel has twin DD 8V71N engines and it means one engine will have M15 Gear and the other an M20.

I got a quote from Pacific Torque of $6,169 for a rebuilt M15 Gear. Is the price fair? Thanks for your input.

CapetaniosG

[StratPlan61]

Call Kalamazoo Marine Gear @ 269-345-0629, they may be a big help. They are located in Kalamazoo, MI

[Brian Degulis]

If he replaces a 1.5 to 1 ratio with a 2.1 ratio the prop shaft will be turning slower on the 2 to 1 at the same engine RPM.

Brian

[REBrueckner]

Running two different gears on the same boat is perhaps ok for a temporary fix, but the 2:1 engine will rev too high and never develop it's HP....as Brian posted...unless the prop is changed.....It's not a good idea as a long term solution. for example if he runs via synchronizer, the boat will pull towards the 2:1 side...to get equal thrust, he'll have to run engines at different RPMS...

On the other hand, if your friend has room to increase prop diameter, going 2:1 makes that possible and should increase efficiency a bit....but in the long run he'll want to change both transmissions....

[CapetaniosG]

Thank you guys for your input. As always you're the greatest bunch.
I'll be with Lady Ntina on 8/5/08. I can't wait.
Have fun and a great boating summer of what is left.

capetaniosG

[mike]

Call Acadian Marine, they are straight up to deal with and are about as reasonable in price as you are going to find. They do a lot of the offshore oil-rig supply boats and know their Allisons very well, and usually have units in stock ready to go.

Acadian Marine
21 Burgess Dr.
Broussard, LA 70518
337-837-3636
Brian Lemmon