Changing drive

[ericcarr2000]

Ok guys. I currently have a 90 sundancer with a 330 hp merc 7.4 motor with a bravo 1 currently on her. Lately I noticed that I'm having problems getting her up on plane. I believe it is the original drive on her. I guess my question is does anyone recommend a switch to either a bravo 1 or a 2 and will they mount directly to the transom?

 

[thumpar]

If you are going to switch I would go to a bravo 3. The bravo 2 is longer and would not be setup right for the hull. Just make sure you get a drive ratio that matches your engine/boat.

 

[Bondo]

and will they mount directly to the transom?

Ayuh,..... The difference 'tween the BI, BII, 'n BIII is the Lower Units,.....

The Uppers are the same,....

 

[ericcarr2000]

So which one would you guys recommend according to my setup

 

[burtonrider11]

Ok guys. I currently have a 90 sundancer with a 330 hp merc 7.4 motor with a bravo 1 currently on her. Lately I noticed that I'm having problems getting her up on plane. I believe it is the original drive on her. I guess my question is does anyone recommend a switch to either a bravo 1 or a 2 and will they mount directly to the transom?

I am certainly not an expert and some of the more wise members of this forum may have other opinions than mine. However, my concern would be that switching drives is masking a problem. You say lately you noticed trouble getting on plane. This implies that at one time that boat accelerated and planed satisfactorily. A prop switch would be cheaper than a drive swap. If you run aluminum now, consider stainless or going to a smaller pitch prop.

My bigger concern would be, what has changed with the boat to get it to stop performing like it should. Bad gas? Dirty bottom? Is the carb in need of a rebuild? When is the last time the boat has had a tune up? What about a fuel filter change?

To me, the last option would be to change drives, but that's just my opinion. Drives will run somewhere in the 1000's. Props would run in the hundreds. Fuel filter and a tune up (if you do it yourself) should be around $100. I'd start there first, good luck!

 

[harleyman1975]

To answer your question the bravo 3 lower unit is the one that will help you get up on plane the fastest due to the counter rotating dual propellers. Also the most expensive solution...just sayin'.

 

[ericcarr2000]

Ok so I can put a bravo 3 lower unit on a bravo 1 upper? What performance Gaines would I get by upgrading to a bravo 3 lower unit, if possible? And do I necessarily need to use a dip prop?

 

[Bondo]

And do I necessarily need to use a dip prop?

Huh,..??

The BI is a single prop drive,... the BIII is a dual-prop drive,.....

The BII runs a HUGE prop,....

 

[ericcarr2000]

So if I go with a 3 I'll have to get a new duo prop then I'm assuming?

 

[thumpar]

If the lower doesn't come with a prop set then you would need to buy them. They are specific to the B3 and not cheap.

 

[ericcarr2000]

Od351140 is my drive serial number. What ratio do I currently have, and should I stick with that ratio?

 

[Scott Danforth]

I'm 99% sure its not a drive issue. You may have a fuel issue, a motor issue, or a hull issue. Changing drives would only make sense if you upgraded to a B3 drive. However that will not help a fuel or motor issue

 

[ericcarr2000]

I'm not so sure about that because the motir was running great at around 4600 rpms, then it just wouldn't get on plane and the slipped out of gear. So with it slipping out of gear, I'm pretty sure it has to be something with the drive right?

 

[thumpar]

It could be a shift cable or linkage problem too. Keep in mind the clutch on a Bravo is in the upper so changing just the lower may not fix the issue if that shift problem is in the drive.

 

[ericcarr2000]

Gotcha, I didn't know it was in the upper. I should just replace the whole thing then.

 

[alldodge]

Gotcha, I didn't know it was in the upper. I should just replace the whole thing then.

NO Gee wiz, you have an issue and maybe it is going out of gear and maybe it isn't, you need to find out what the problem is first
After you know what the problem is then you can try other things. You have a 25 footer and a B1, while your boat is a bit heaiver then mine (23.5 ft rinker ) the B1 will get it up and move, mine does 60mph with the 300hp 7.4). The B3 would bring you out of the hole faster and may save 2$ worth of gas, but find out what the issue is as Scott mentioned. Your all over the place trying to fix the issue and still have not found out is it the prop, coupler or drive

 

[Scott Danforth]

^+1. What AllDodge said. Find the problem first, then formulate a corrective action

 

[ericcarr2000]

I agree with you guys saying find the problem first, but the problem is like I said before I pulled the boat out for the season so I can't really do any testing I guess. The one thing I do know is I had an issue getting her up on plane, first time ever and it did slip out of gear. I know it has the drive from the factory on it so I just figured I guess it's time for an upgrade.

 

[alldodge]

Need to try to find out why it slipped out of gear. The Bravo drive would not do that unless something is really wrong. Drain the lube and see if you can see any metal. Pull the top and rear covers off the drive. The top one will show the cone clutch and see if anything looks wrong. The rear cover will expose the shift mechanism and spring loaded detent ball.

If no metal is found, and everything else looks good, then it did not come out of gear by the drive, something else happened to cause it, or something else is the issue. If all looks good and you want a B3, then just get a lower section and swap with the one you have

 

[ericcarr2000]

Gotcha, guess I found out what my new winter project is now, .