Re: What broke in my outdrive?
 

I agree a 1:50 would improve all around.

Re: What broke in my outdrive?
 

Is the gear reduction in the upper or lower?

If i go to a 1.50, everything after the gear reduction will see that much more stress. They put 1.36's behind the 502's for a reason, i figure. That's their band-aid for weak components, if i take off the band-aid it might start bleedng.

Re: What broke in my outdrive?
 

The 27 in my shop has a
1:50
502
23p
jumps out the water and runs good, not sure of rpm or speed ?

Re: What broke in my outdrive?
 

The new XR's change it in the lower I believe.

Higher gear ratio is better on the drive due to less torque load, you may also see a speed increase.

I did the IMCO thing last year, had the same results. :(

Re: What broke in my outdrive?
 

That would be the approximate equivalent of running a 20.8" prop on my boat. I'm running a 21" Mirage +. I highly doubt the hydrodynamics are so wildly different between a 21" and a 23" prop (of the same type, of course) that i would see significantly different results by going to a 1.5 ratio and a 23" prop.

That said, there's definitely room for improvement in my setup, and i don't believe a Mirage + is necessarily the right prop for my boat. But i think the only thing i'll gain by going to a different ratio (i'm not, by the way, i'm cheap) is a better selection of props, and i think it will put more stress on certain (expensive) outdrive components. Definitely more stress on everything after the gear reduction.

What does the boat you're referring to have for torque? Is it a stock 502? (mine's a stock 502 mag, carbed).

What kind of prop is it running?

What's your idea of "jumping out of the water"? What kind of load? What kind of tabs, and how much are they used?

is it a step hull? Mine's a 1991, non-step.

What does it top out at? I'm getting 61-62 mph, might have another 1 or 2 in it if i get out there by myself on low fuel.

I'm not trying to be a dick here, i'm serious, i'd like to know more about the setup on that boat and how it performs.

I can get my boat to "jump" out of the water if it's just me and a friend, with a reasonable fuel load (less than full, more than half), and i put the drive and the tabs all the way down. Sometimes i like to slow down for a second though, just to grab something that fell off the dash or something, then get right back up on plane. Putting the tabs down to get on plane is easy, but it's a pain in the rear to pull them back up, adjust the drive, steer, and adjust the throttle all at once when the boat comes on plane. Given the cost of outdrive repairs, though, i think i'm just going to make sure the tabs are all the way down every time i get on plane, to minimize stress on the drive. In the same light load conditions, i can get it on plane at just over 1/2 throttle with all the tab and the drive all the way down. With a full load on board, it's a different story, though.

With 4 people on board, completely full fuel (filled it to weigh the boat / trailer setup) and a tool box in the cabin, not taking the time to put the tabs all the way down (leaving them at a good cruise setting, puts the tips below the hull at least a couple inches), it takes a lot more to get on plane.

Re: What broke in my outdrive?
 

You should only go to a 1:36 unless you run out of prop i.e. 34pitch. I would say 90% of bravo BBC configurations are 1:50. Did you just get the boat? Maybe the previous owner had big power in the boat, therefore the need for the 1:36.

Re: What broke in my outdrive?
 

It's not my boat but I can find out some details, I know it's stock

Re: What broke in my outdrive?
 

Clymers manual says in 1991, they put 1.36 drives behind 502's and 1.50 drives behind 454's. Best i can tell, it's a stock 15 year old drive.

A previous owner did have a blower motor in there, though. I couldn't tell you if this was the drive it was attached to or not.

I called merc and ran the serial numbers before i bought the boat. Drive and transom housing are 1991 vintage. Block was originally a 1994 MPI motor.

Re: What broke in my outdrive?
 

Your drive in a 27 ft fountain should last at least 300-400 hours behind a stock 502. I ran 625-675 hp in a similar weight boat for over 125 hours before shearing floor out of stock bravo upper gears and I was running a 26 pitch 4 blade prop w/ 1.50 gear ratio. Drive broke the first ride out after going to a 28 pitch 4 blade and some other improvements. Was your coupler aluminum or steel splined? You probably already been told this but if not insist on the xr type coupler with longer snout on it,they support the shaft real nice and last ,Smitty

Re: What broke in my outdrive?
 

thats the same thing I was thinking,had biger power :D

Re: What broke in my outdrive?
 

Glad to hear the 300-400 hours thing. Too bad the boat has 530 hours. I hope the drive's been gone through.

I called the shop today to see what kind of coupler they were putting in it. They said it's an XR coupler.

And again... 1.36 was STOCK behind a 502 in '91.... Merc said they didn't have a HIN # associated with that drive S/N for warranty purposes and that probably meant it was sold to a boat manufacturer.

Re: What broke in my outdrive?
 

I never pulled the engines out to change a coupler, I just used a 4x4 and chained the back of the engine via the cylinder heads to the 4x4 and yanked the drive, pulled the bell housing off and took off the coupler, Alot of labor for not that much work in my opinion.
Good that you are improving the coupler with a better one, hopefully you wont have to revisit this situation in the future.
Good luck
J

Re: What broke in my outdrive?
 

I did almost this way to change out a flywheel, but the motor had to come forward a bit.....

Re: What broke in my outdrive?
 

Standard bravo? Single or twin? You should be able to get the flywheel and the coupler out without having to move the engine anywhere.
Now if you leave your engine hatch on it will make it tougher to do the job, Take the hatch off and not have that stuff in your way, you should have no problem.
J

Re: What broke in my outdrive?
 

How do you get the bellhousing to clear the coupler if the motor doesn't come forward any w/o getting wedged against the inner transom plate?

Re: What broke in my outdrive?
 

take 2 of the 3 motor mount bolts out, Loosen the big nut holding it on the stringer, Chain winch or come along strap on back of engine, rachet it up, slip out the bell housing (move it around a little bit and it will come out) you have to get the bottom part with the little 7-8MM bolts shroud off the bottom of the bell housing first.

Re: What broke in my outdrive?
 

Well they called me and said it's ready. $1530. They said they couldn't use the XR coupler, it wouldn't fit. It's too long, and there's almost no room in front of the engine on my boat. They said they couldn't get the motor in with that coupler on there, they couldn't move it forward enough to clear what it needs to clear to drop in place. d'oh. They said the new piece is still an improved design over the old one, and if the old one is as old as i think it is, i should be fine.