Bravo 2 to Bravo 3 Swap

[vwmusky1963@att.net]

All, I'm new to the forum and I apologize is this topic has been discussed previously, but I was unable to find out what I am looking for directly!

​I'm looking for a pretty quick answer because my opportunity window is small. I have an opportunity to purchase a 1998 Ciera 2858 (500 hours) with a 7.4l coupled with a Bravo 2 outdrive system for a tiny amount of $ . I have been informed that the lower unit will need to be replaced in short order. In my research for availability and cost, I came across an extremely clean 2010 complete Bravo 3 upper & lower unit with both stainless props, and only 75 hours clocked on it. I'm not sure what the existing Bravo 2 gear ratio is (requested it from owner), but the Bravo 3 unit is 2.2, and it was removed from a 7.4l 454. Are the Bravo 2 & Bravo 3 interchangeable as a direct swap out? Should I change out just the lower unit, or the whole set-up? I have read something about a gimbal bearing, but not familiar with that. The boat does not have a trailer, so I will need to bring it to a marina who will do the work/swap. What is the smartest thing to do here! Any detailed information would be extremely helpful! My window to purchase the Bravo 3 is by the end of the day tomorrow.

 

[Scott06]

Normally when an upper or lower is roached you need to disassemble and clean the other half the drive. I'd swap The Whole drive assuming ratios line up. Question I'd be asking is what else is wrong with the boat. Seems odd some one would walk away from a 28 ft er over the cost of a lower unless they were sick of the boat which most likely means they didn't keep up with maintenance

 

[vwmusky1963@att.net]

Thanks for the reply Scott06. The persons who currently owns the boat has owned it since it was new, and are fellow members of a club that I belong to. Upkeep & maintenance were a concern of mine as well, so I have conducted a thorough inspection and have also had a survey conducted. Other than minor normal issues, and an A/C that needs to be repaired, the boat is good to go! They are getting a little older, and they don't have the time nor passion it takes to continue the upkeep, and continue to pay dock fees, so they want to pass it along to someone who will take care of it. As far as the stern drive response, I'm not sure what you are referring to when you mention "assuming ratios line up​". The boat currently has a 7.4l coupled with a Bravo 2 (upper & Lower). If I replace the entire unit with a Bravo 3 unit (upper & lower as a unit) that also came off of a 7.4l, what would be the concern with the ratio? I know that the Bravo 3 has a 2.2:1 ratio, but I don't yet know what the current Bravo 2 ratio is. Lets assume that the Bravo 2 is a 2.2:1 ratio. Then I could safely assume that the Bravo 3 would bolt up as a direct even swap without having to do anything else. Now, if the Bravo 2 has a 2.0:1 ratio, what will I have to do then? Is this where the Gimbal bearing comes in to play?

 

[wrvond]

The B2 most likely does have a ratio of 2.0 (mine does), but all that means is the number of times the prop rotates in relation to the crankshaft is slightly different between the two and since the props on the B3 are a different pitch and size that's to be expected. I have read the swap is a direct bolt up.

 

[Scott06]

I meant are the drive ratios the same or similar? Most likely if your bravo 2 is a 2.0 vs the 2.2 on the Bravo 3 as mentioned the prop pitch can would take care of it. if the B3 is off a similar size and weight boat most likely the prop set will work fine

 

[Scott06]

Forgot to put include in previous- there is only one gimbal bearing part number for bravo 1,2,3 drives so I don't see an issue there

 

[Bondo]

. I'm not sure what the existing Bravo 2 gear ratio is (requested it from owner), but the Bravo 3 unit is 2.2, and

Ayuh,..... Welcome Aboard,.... The Bravo upper units are the same, so just swap the lower units,.....

 

[thumpar]

The ratios of a b3 and b2 can't really be compared. The b3 is spinning 2 props at the same time and the b2 is spinning a very large prop. Don't use the bearing part # for anything other than ordering a bearing. The alpha uses the same bearing.

 

[alldodge]

As Bondo mentioned, all the Bravo's use the same upper housing, the differences are the gear ratios. The most common for B2 and B3 is gear teeth 32/27 in the upper set, the lower set changes ratio further. That said a 2.20 would have a 30/23 and my guess for your B2 would have the 32/27 upper gears just because they were more widely used from what I've found. If this is the case then you should have the same lower gears of 16/27 which when matted with your current upper will give you the 2.0 ratio.

You could just swap the entire drive and see how the boat performs. If it over revs, then put the lower B3 on the old B2 and it should get you down to 2.00 ratio. Only way to know for sure is to count teeth on the drives, or put them in gear and rotate bay had.

As for the prop differences, the B3 will bite better then the B2. So if you have a 22 pitch B2 and it works great with WOT, then you will probably need to lower the pitch for the same B3 prop pitch set

 

[Fun Times]

1998 Ciera 2858 (500 hours) with a 7.4l coupled with a Bravo 2 outdrive system....
2010 complete Bravo 3 upper & lower....
I'm not sure what the existing Bravo 2 gear ratio is (requested it from owner), but
The Bravo 3 unit is 2.2, and it was removed from a 7.4l 454.
I have read something about a gimbal bearing, but not familiar with that.

If a 2010 Bravo 3 was connected to a 7.4L engine, then it would seem the original drive was replaced at some point as Mercruiser wasn't making the 7.4's in 2010.

If possible + not to late, Have a look or ask the owner what gimbal bearing they installed with the new drive installed along with find out what year the original boat/transom assembly is due to starting in 2000, there was a size change to the U-joint assembly which was bigger and it's recommended that the bearing be changed to a Red Dot for identification purposes as the bearing is thinned down to fit properly. Also the bellows retention sleeve has a larger inside dimension to fit the larger L-18 U-joint assembly for the year 2000 which should of automatically continued upwards with the different U-joint brand manufacturer change that happen in 2004+. In this case, just for all around general purpose you'd be safer to run with the newer bearing installed with the newer drive.

If at all possible 'For possibly for more pr?cised info, try to get as many serial numbers as possible such as all the drives and transom assemblies involved from the original boat and newer B3. Engine serial numbers may help too in order to possibly get an idea of the engine HP's to gear ratio's used.

When replacing a current Bravo Drive with a Bravo One X ... And info below,

 

[HT32BSX115]

I came across an extremely clean 2010 complete Bravo 3 upper & lower unit with both stainless props, and only 75 hours clocked on it. .............My window to purchase the Bravo 3 is by the end of the day tomorrow.

If you have already bought the boat, buy the Bravo III and install it! The performance improvement is reason enough!! You may have to buy a different propset but they're easily found on eBay!

Cheers,

Rick