V-drive gear change?

[TimbrSS]

I was reading one of the other posts about the new boats with 1.7:1 or 2:1 and got me thinking.

I have 2006 8.1 247 with the oddball 1.21:1 gears. Every other wakesetter (except early LSA with 1.25)  has had 1.5 or higher (numerically) gears.  I mostly surf and rarely cruise. I have GSA/Wave control, running 1000# each locker, 1450 factory ballast, 500# lead and have 1000 for bow triangle. Plus wedge. Mid 11's mph. I think about 2700-2800rpm. I'm running 2419 prop: 15x12 .075. It will do all that I'm asking of it, but feels like we're about at the limit. So I'm considering a swap to 1.46:1 Looks like a gear set is $500 or so. Should be an easy swap. Has anyone swapped? Any reason why I shouldn't consider it?

Also I'm at 760' elevation.

Edited May 8, 2018 by TimbrSS

[hethj7]

Hmm, interesting idea.  I am interested to hear the downside of this from others since swapping gears in cars has always been a quick way for more "power". 

[Bill_AirJunky]

So your ok with the boat topping out at 30 or 35? What is top speed now?

Depending on what lake we're on, we might ride miles away from where we launch. And miles away from the restaurant. And miles away from a buddies house. So to limit that speed could limit how far we might go to do something.

[MadMan]

The reason for these higher numerically gear ratios is to increase the torque multiplication, so there is enough torque to use a larger prop.  I don't know the numbers, but I would think the 8.1 would have enough torque without having to resort to these low speed gear ratios.

[85 Barefoot]

9 hours ago, TimbrSS said:

I was reading one of the other posts about the new boats with 1:1.7 or 1:2 and got me thinking.

I have 2006 8.1 247 with the oddball 1:1.2 gears. Every other wakesetter ever has had 1.5 or higher (numerically) gears.  I mostly surf and rarely cruise. I have GSA/Wave control, running 1000# each locker, 1450 factory ballast, 500# lead and have 750 for bow/walkway. Plus wedge. Mid 11's mph. I think about 2700-2800rpm. I'm running 2419 prop: 15x12 .075. It will do all that I'm asking of it, but feels like we're about at the limit. Could possible be OK with more bow weight to get nose down and some more MPH. So I'm considering a swap to 1:1.5. Looks like a gear set is $500 or so. Should be an easy swap. Has anyone swapped? Any reason why I shouldn't consider it?

are you positive on that ratio that you currently have?

[TimbrSS]

6 hours ago, Bill_AirJunky said:

So your ok with the boat topping out at 30 or 35? What is top speed now?

 

90% of the time, I drop the boat from the lift, fill ballast  while the engine warms up and Idling out of the no wake zone, then we go straight into surfing. There really is no cruising most of the time. I'd say top speed now is 39.9 on the paddle wheel. 

[Sailvi767]

There is no real comparison between a auto and boat with regard to gear ratio since on a boat the prop also functions as a gear and it's the combination of both that actually determines the true ratio. The reason to change ratio's is to allow for the most efficient propeller sizing. The general rule of thumb is prop diameter and pitch should be close to each other for best efficiency. You also don't want propeller tip speeds getting to high. I suspect that if your pitch is within 3 inches of prop diameter there would not be much gain with a gear set change. Going to a 1.5 to one would slow the prop down and could reduce noise. 

[Bill_AirJunky]

1 hour ago, TimbrSS said:

90% of the time, I drop the boat from the lift, fill ballast  while the engine warms up and Idling out of the no wake zone, then we go straight into surfing. There really is no cruising most of the time. I'd say top speed now is 39.9 on the paddle wheel. 

And thats how it is for us on my home lake. But when we go on long weekend camping trips to Pend O'reille or Coeur d'Alene, which are much larger lakes, we don't ride near the dock where the boat is kept.

[TimbrSS]

Ok. Getting ready to swap V-drive next week to 1.46. I still need to get a new prop, and  I think I will start with ACME 2277. 15 x 15.75 .150 cup. Anyone have any opinions on that?

[Wes24781]

 

     Was the transmission a ZF 63C. Do you have a link to the 1.46 gear set. I think I have the same transmission in my 06 247 8.1

Tag on tranny says Model ZF 63C

A.ratio 1.00

B.ratio 1.03

Not sure if this is the same 1.21:1 transmission. 

[Wes24781]

Ok I found the other ID tag on the v-drive it is a Walter 1.21:1 ratio. Do you have the part number for the 1.46:1 kit?

[hunter77ah]

On 5/8/2018 at 3:59 PM, TimbrSS said:

Ok. Getting ready to swap V-drive next week to 1.46. I still need to get a new prop, and  I think I will start with ACME 2277. 15 x 15.75 .150 cup. Anyone have any opinions on that?

Did it work?