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-   -   Gear ratio 1:5:1 vs 1:36 (https://www.offshoreonly.com/forums/general-boating-discussion/313000-gear-ratio-1-5-1-vs-1-36-a.html)

QWKRN U 05-29-2014 06:26 PM

Sitting on a lift year round, is there any wear difference lol

Unlimited39 05-29-2014 06:33 PM


Originally Posted by QWKRN U (Post 4129689)
Sitting on a lift year round, is there any wear difference lol

Lol! There's a Dust difference WR!!

QWKRN U 05-29-2014 06:34 PM


Originally Posted by Unlimited39 (Post 4129698)
Lol! There's a Dust difference WR!!

:lolhit:

HabanaJoe 05-29-2014 07:34 PM

It's just math as whether the 1:36 or 1:50 is better for longevity & dependability HP = RPM x T / 5252. As I raise the RPM of the output shaft on the drive the torque goes down. Since the shaft dia and bearing are all equal in size there is less load on it now, higher RPM will increase wear as every bearing has X number of revolutions in it, you now reach that number sooner for the same hours of running. That's the theory and math.

With the diesels we always ran very high shaft rpm's and smaller props. Many of the diesel boats you see people trying to go fast with today have prop issues, they break blades. It was amazing how compared to today props the props of yesteryear were junk yet could run Cowes Torquay Cowes at 100mph and not loose a blade?

I'm just a big fan of smaller and faster than bigger and slower?

BLUEMAGIC 05-30-2014 05:37 AM

With the 1.36 gear there is more surface material compared to the 1.50 making it stronger. Before xr drives were introduced the 1.36 gear was used in big hp applications and more often with Blower motors. This was also seen in the alpha generation as well. With bravo failures all around us and with the cost of new drives continally rising I would think most want every angle they can get. Heat and tourgue kills bravo drives. More rpm and less pitch hooked up to drive gauges will steer you in the right direction.

Unlimited39 05-30-2014 09:15 AM

Appreciate the responses!!!

JRider 05-30-2014 10:01 AM

Probably not worth the money unless you run out of prop pitch options. Although bblades has mentioned that the 34 bravo is a different animal (whatever that means?) and does not perform as well as the 32. It is my opinion that in a high x dimention situation (single engine) that high gear and lower prop pitch can reduce crabbing...i have no data on this.

mcprodesign 05-30-2014 10:31 AM


Originally Posted by JRider (Post 4130037)
Probably not worth the money unless you run out of prop pitch options. Although bblades has mentioned that the 34 bravo is a different animal (whatever that means?) and does not perform as well as the 32. It is my opinion that in a high x dimention situation (single engine) that high gear and lower prop pitch can reduce crabbing...i have no data on this.

Depends on the situation. Here is my take on this. Big gears and little props is for top end. Just look at the ouotboards. Less prop diameter size etc is less drag. Less out of the whole and mid range. Bigger props are the oposite with less top end but everywhere else is better. As far as durabilty. I would say less pitch is better. Plus lots of blades. 4 blade bravo 34's vibrate like crazy on my high x fountain. 5 and 6 blades are smoother and keep the vibration out of the gears making the gears last longer. I know I got side tracked..

GL@PBC 05-30-2014 10:48 AM


Originally Posted by Quinlan (Post 4129599)
I had both 1.50 and 1.36 on my T/S Gun. The 1.36 gears seemed to hold up better. Also seemed to like the lab'ed 30 Bravos A lot better with the 1.36 Vs the 1.50 and 32's.
That was with both stock 575s and after rebuild with about 650 hp. Now I am over 725 and need to try some 34's

All around the 1.36 worked the best for me.

We have a customer with worked over 575s in a T/S who tried 34s, the boat would barely get on plane. We limped back to the dock and put the 32s back on!! Might be time for some 5 blades???

drpete3 05-30-2014 11:30 AM


Originally Posted by Unlimited39 (Post 4129536)
Dr.pete, the boat was running 1:5:1 with 4 blade bravo 1 -32s with stock 575s, the motors were rebuilt- and Dynoed at 683hp @5600, they re geared the drives to 1:36 and spinning the same wheels but 30 pitch- boat GPSs at 96 mph- twin step, so it's set up right I believe, I was just concerned with longevity and dependability of the 1:36 gear ratio?

Very cool. I have been told buy drive guys that the 136 is stronger than 150 and as glass dave pointed out if you went back to 1.50 maybe you would lose performance due to needing bigger props.


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