Today I separated my uppers and lowers on my bravo one drive.When I removed the coupler on the down shaft I noticed the splines on the down shaft where twisted and starting to crack,what would cause this?What is the best way to upgrade the lower to help prevent his from happening again?I have new motors with more power coming for spring and can't afford to upgrade complete drives as of right now.What about Imco internals,any one use them with any success?How much are we talking?

Thanks Nordic95

What type of Bravos do you have?

1991 bravo ones 1:36 ratio.

A drive is only as strong as Its weakest point, I have used imco parts and have never been disappointed, check out the imco site the have a nice replacment pinion shaft ( upright shaft )

What is your opinion on what I should do.You are around these things all the time and must have an idea on what should be replaced with the down shaft.Where would the next weak link be?

Thanks Nordic95

I broke an Imco vertical shaft this year. Maybe they are somewhat stronger than Merc, but they still break. I would be concerned about the tower in the upper and the helical cut gears with their weak floors. XR drives have addressed these issues with better success.

What causes it.. AIR time!! In and out of the water with the throttle on will twist the vertical shaft. I new vertical shaft, I use Imco also and have had good luck with them. They have revised the shaft to eliminate the oil hole that checkmate454mag shows. Depending on time on the drives, new bearings and the vertical shaft would be recommended and proper setup of the gears if they are still in good condition..

Hope this helps.
Dick

I have noticed some of your replys about bravos and there set up.Do you do this as side work or just for your self.If you are interested in setting mine up send me a p.m. please

Thanks Nordic

Dick,
I hope that new shaft holds up better. Unlike the last guy who did it, I hope I set this drive up right. Time will tell I guess.

Nordic

Call Dick "Mr. Gadgets". He has built 8 or 10 drives for me and I have been very happy. He also did the one on the 1150hp 109mph Baja at LOTO.