Prop rotation and drives
 

On twin bravo outdrives is one drive always pushing up against the top cap?? If you you change prop rotation wouldn't that switch which drive is being "driven" in reverse?? I've heard of people switching drives to even out wear....

Wouldn't switching props be alot easier than switching drives? I have swapped my props from in to out just to see which one performs better. I settled on out, but slow speed idling suffers a little.

I'm talking about which side of the upper gears are engaged. Since the engines turn the same direction one drive needs to running opposite or reverse of the other, Right??

Yes swapping props and shift cables allows you to run on the other side of the upper gears.

Its debatable if its better or not.

The upper gears are always running the same direction....the wear is always on one side of the tooth, whichever gear is reverse will generally have less wear than the gear used for forward.

the lower gears do reverse

Actually that is the opposite in the bravo drive, the shifting is in the upper. However, you are half correct :D There is one gear in the upper that will only wear on one side, unless you reverse the engine rotation.

The upper will push on the top cap on one rotation, and not the other.

Reversing the drives is the best way if you are trying to rotate your gear wear, however some will argue that it doesn't offer extended life on the gears.

Reversing the props and cables is another method, however now your props will spin differently and it can effect the handling of the boat. Some like them in, some like them out. Props spinning in are less responsive around the docks, but offer more top speed and a looser ride in some hulls.

Dont mean to thread jack but I have a single with a stepped hull. Most stepped hull boats are running lefty prop rotation to offset the weight of the driver I think. I have a bravo 1 1994 with that has been spinning right hand rotation for its life.( once again I think) I would like to spin it left. Will this hurt the drive? I only have 640 tq and 600+ hp and the drive is a 1.36R. Max RPM is 5400. Sorry to thread jack just sounds like you guys know this kinda stuff. Thanks in advance.

Main thing will it hurt the drive? Is there a better chance of killing the drive?

Only 600 hp and 600 ft lbs to a bravo drive, only? :D

Some will say switching now is bad for the gears, because they are wore one way. Others will say rotate them and you will be fine. Truth is no one really knows, drive failures are common. I would say the way you are going don't change a thing :)

Running it right, the way you have it puts less stress on the top cap. Fountain ran them left on singles, which he believed offset the rotational torque of the engine and let the boat ride more level

If you are going to run it left, you may consider a before top cap

Yes, the shifting is in the upper, but all 3 gears only contact 1 side of the gear tooth...you flip the top and the bottom gear and the pinion contacts the
same side of the gear as it was in it's former position.

Reversing the engine rotation would put the contact surface on the opposite of all 3 gears, but unless someone makes a clutch shaft where the
direction of spiral of the splines is reversed, a reverse rotation engine wont work on a std bravo

I switched to a LH prop on my single after 200 hrs of running a RH prop. 10 hrs later my upper self destructed. Coincidence? Maybe?

The boat did run good with the LH prop. I am going to get the drive rebuilt when I have the $$ and use it exclusively for LH props.

Thanks for the info. Think I will keep running this drive RH.

THis was kind of the point I was getting at. One drive is pushing against the top cap which makes it weaker, Right?

the real risk i feel is to the lower gears. they have been stressed in one direction for all of their lives. to suddenly push the other way, stressing them back in opposite direction is a bit like bending metal, then bending it back the other way. it is significantly weaker with each direction change.

If its not broken don't fix it driver!!!

I have a question too while we are thread jacking. 1.36 gears compared to 1.50 gears. Are we getting more top end with the 1.36 gear?? What suffers by changing from 1.50 gear.

There is a little more to be had on top end with the 1:36 ratio. a few mph depending on your application. 1.36 ratio is also referred as the stronger gear when compared to the 1.50 being it has less teeth allowing it to have more material. when put side by side the 1:36 is larger than the 1:50. Before xr's were developed they used to use 1.36 quality hd diesel gears in high horsepower applications to keep the drives alive. Its better to spin your wheels faster with less torque than slow with lots of torque. 1:50 may have more acceleration than the 1:36 but also lacks in longevity. If you looking to get the most acceleration out of a big horsepower application and drive like a car down the strip no bravo based drive will stay together.

i believe it is also a way to get effectively more pitch for higher rpm and top speed. once you get up around 30 inches pitch prop options get fewer, so u spin em faster...

Lucky we did jack this and for that I am sorry, but these questions and answers are great and I have learned a good deal. I run a 1.36 with a stepped hull so I dont use anything to get going. I come out slow becuase I dont need to hammer down at all to get going. I care more about mid to top then get up and go.

Great info on the 1.36 and 1.50. I feel better about my drive now. LOL