I am in the middle of swapping gears from the old Bravo over to the new IMCO case. I have some observatuions so far, Man the races or a ***** to install . this case is TIGHT. All the macine work seems to be spot on and the vertical shaft is quite a bit stouter. I am thinking that if I had to do this again I would make a set of set up beariings for this job, sure would be a lot less a pain... the Merc drive guy I am working with he is teaching me how to set it up, was short one tool so I will not be able to finish for a couple of days.

On a side not people have said to plug the speedo hole....why?


Also good news my bearings, gears, propshaft splines etc.... are all like new, no wear on the gears at all. I did however find that the pinion nut on the verticle shaft was only torqued to a bout 10 lbs if that, all it took was a little bit to start it and then I could finish it with my hand on the shaft, good thing I went in there.
I wiill keep you posted.

Bryan

This is good information as I am considering doing the same thing. How much did you pay for the cases? What type of boat do you have? Any idea on the speed increase you are expecting?

Let us know how this turns out.

I had a Imco nut back off and trashed the lower gear set . I use red locktite from then on.

Keep us posted on the speed change

rob

Ever Try Putting The Race In The Freezer First. That Shrinks It Down Quite A Bit And Will Slide Rite In.

Front Gear race was super tight....Put it in the freezer for an hour AND heated up the case inside a bit to help....it went in but it did not just drop in....
The reason I was talking about set up bearing was that I used to set up a lot of DANA 60 and 80 Differentials when I had the rock crawling bug and made a set of bearing and races that would just drop in tightly and dnug then do the set up and then when everything is right install all new bearings and races and check again...99% of the time bingo , spot on. it was just an old set that I took a few thousands off to fit that way....

Not sure what kind of speed gain I will see if any ....
it is going from the driveshaft 8 inches deep to 6 inches deep.

Should help but how much ?




Red locktight for sure....could have been a problem, good thign I went in there.


How in the hell am I going to keep this thing clean? Satin finish

Bryan

be sure to post before and after results
what are the boat specs power, stepped hull or not length and what is the curren x dimension?
I will be doing the same this spring

27' Donzi twin step hull
power is a 500 EFI
X dimention not sure but the nose of the bullet is 8 inches below the pad.

currently runs a best of 71 GPS verified and a consistant 70

Bryan

I also had a 27' donzi no step with hp 500 carb with Ho bravo one, x was 1-5/8 below, the best it ran 78.9 also no interior cabin. My donzi wt 4620 lb dry

Bryan,
I just learned how to set up Bravos this winter. I also have set up quite a few automotive rear ends before. When I saw how the lowers were set up, the first thing I did was make a set up race from my old front bearing race in the lower. It worked perfectly just as you would imagine. I even tought an old dog here on oso a new trick with that very same idea. Right Mr Gadgets....

thats really hualing the mail.....what prop/ rpm and who set the boat up? motor must have been really high in the stringers....