Bravo 3

daviscfad

Petty Officer 2nd Class
Joined
Jun 22, 2008
Messages
143
Re: Bravo 3

yeah i have one i was trying to put in today but it would not go in my housing it would get about an inch from going in all th way and would go no further.. I dont know what to do i figured maybe its not interchangable
 

TilliamWe

Banned
Joined
Dec 21, 2004
Messages
6,579
Re: Bravo 3

The one thing I can think of is that the 1988 does not have the place for the reservoir bottle to push into the drive. It is possible that is holding it up. But more likely it's a gimbal bearing issue, or your 1988 "driveshaft" has an extra o-ring that isn't required.
Because the external dimensions and the bolt pattern are the same.
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
Re: Bravo 3

Ayuh,...

Another alternative is to swap Just the Lower Units....

It's a Plug,+ Play swap, I believe....
 

daviscfad

Petty Officer 2nd Class
Joined
Jun 22, 2008
Messages
143
Re: Bravo 3

The one thing I can think of is that the 1988 does not have the place for the reservoir bottle to push into the drive.
you mean where you can oil the outdrive right?? I dont think that is holding it... Its something like at the top of the unit i beleive holding it up... I am gonna try again today
Another alternative is to swap Just the Lower Units....

It's a Plug,+ Play swap, I believe....
I am not sure what you are talking about bondo
 

Bondo

Moderator
Staff member
Joined
Apr 17, 2002
Messages
70,464
Re: Bravo 3

I am not sure what you are talking about bondo

Ayuh,...

Outdrives consist of 2 units,...
The Upper gear case,+ the Lower Unit....

On the Bravos,.. The Upper gear cases are the Same.....
The differences in the Bravo Is, IIs,+ IIIs is just the Lower Unit......


Have you checked the Gimbel Bearing Alignment,..??
You might be fighting a Different Issue...
 

TilliamWe

Banned
Joined
Dec 21, 2004
Messages
6,579
Re: Bravo 3

davis, on the right side of the "housing" that is attached to the boat, between the mounting studs, is a little plastic "nipple" of sorts that sticks out. That nipple mates up to a spring loaded metal ball in the outdrive on Bravos made from about 1989 or 1990 through current. This is what allows the reservoir bottle in the boat to gravity feed the outdrive, should it leak. But your 1988 drive doesn't have the spring loaded ball in it. So it's possible that the nipple is hitting a solid flat spot on the drive and not allowing it to slide the rest of the way on.
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Bravo 3

Yes you can just swap the "lower"

See http://www-alt.mercurymarine.com/mnetdata/SERVICE/CRUISER/Servmanl/11/11covr5x.pdf (right click and "save as")


Depending on the engine and props you may have the wrong ratio in the upper. You probably have a 1.5:1 upper now.

Mine is a 1.81:1 drive and I am using 26p props. I get almost exactly 4600 RPM at WOT. (exactly where the carbed, GEN VI 454 wants to be at WOT)

1.5 might be a little steep if you're using an SBC or even a 454. With the stock 454 & 1.81/26p I am propped about right.
 

daviscfad

Petty Officer 2nd Class
Joined
Jun 22, 2008
Messages
143
Re: Bravo 3

I am thinking it might be that gimbal bearing alignment bondo speaks of... Isnt there a tool for that??? This outdrive must be newer than an 88 b/c it has the spot for the oil nipple... I am really leaning towards an alignment issue.. Thats nice to know that you can just swap the lower unit and have a bravo 3 drive I did not know that thanks...

HT32BSX115
I am not sure what the ratio is on the unit.. Its My uncles unit and he need to do a lot of work to his boat so he just told me i could use it until i can find one... I think it has a 24 pitch prop on it.. I have just a stock 454 also so i should maybe go with something like you have since its basically the the same... Does that Bravo 3 really make a difference?? I thought i read on here somewhere that you got the boat from your brother and it did not have a 3 on it
 

HT32BSX115

Supreme Mariner
Joined
Dec 8, 2005
Messages
10,083
Re: Bravo 3

Mine had an OMC boat anchor in it (460 King Cobra)

The 460 was rated at about the same crankshaft HP as the 454.

With the Bravo III it just ROCKETS out of the hole (probably twice as fast as the previous OMC did) and is about 3 mph slower than with the OMC. (those were my brothers words....he bought the boat new and he used to get 60 mph running it at 5000 rpm.....OMC suggested max was 4800)

Using this prop slip calculator, I get the predicted performance with 4600 rpm, 26p, 1.81:1 ratio drive, 8% slip. (about 57mph)


If that drive is a 1.5 you would need 22p props to get approx the same performance. (if you build up the HP in your engine you might get more and be able to run 24p props)

24 might be a little tall pitch wise. You may not get your engine to turn more than about 4000-4200 or so. Don't lug the engine for too long...


Good luck ....post your results!




Rick
 
Top