speedfever

iTrader: (1)

Do you have to remove the lower unit to replace the prop shaft on a Bravo 1 with a 1" shaft ?
If you do the 1" to 1 1/4 conversion, do you have to remove the lower unit ?

Mr Gadgets

No the 1" shaft will slide back in without problems. If you go to the Merc conversion kit there are new gears in the kit and the lower would need to be removed. If you use a Merc 1 1/4" propshaft you will need to change the gears. If you use an Imco propshaft, 1 1/4" you will not need to change your gears.
Does that make sense??
Dick

speedfever

iTrader: (1)

Yes , that completely makes sense. I thought that was how it worked but I wanted to hear it from a PRO. Thank you for the reply Mr Gadgets. I was hoping that you would respond or I was going to send you a PM.

Mr Gadgets

Glad I was able to help.

US1 Fountain

iTrader: (1)

How are you going to set the preload if you don't separate the lower from the upper?

speedfever

iTrader: (1)

My starboard shaft is twisted and needs to be replaced. I found this when I removed the props. The shaft probably got twisted when the boat got serious air in a race the last time I had it out. 35' Fountain, twin 500hp pushing 540hp. The boat is now in storage. I have 2 options, (1) I can either pull the lower unit myself and take it to my mechanic, (which I am perfectly capable of doing) or, (2) have my outdrive mechanic go to the boat and replace the shaft. Option 2 is better for me if the lower unit doesn't have to be removed to replace the shaft. What do I need to do ???

JMPH

iTrader: (1)

Check the vertical shaft, if prop shaft has twist chances are the vertical is also, mine was on old boat

Mr Gadgets

Speed,
How bad is the twist in the propshaft? I have seen them twist a full spline and not break, but a straight one is better than a twisted one, so it is best to swap it out. The 1 1/4" shaft will prevent spline twisting. But there are a lot of considerations to think about if you are going to go that route.

If I were you, I would pull the lower and inspect the vertical shaft splines. It won't hurt to know if they are starting to twist. As far as having your mechanic visit and install the propshaft without pulling the lower, that would be up to him. If he feels comfortable doing it that way, then he should know how to set the preload without taking the lower off.
Setting the preload with the lower on is possible. Just measure how much the preload is when the nut is tight enought to just start to take the play out of the bearings. Then add the appropriate amount of preload by tightening the retainer nut. Depending on new or used bearings, the setting is different, but it is added to the total by checking it with no preload on the propshaft bearings. The rest of the drag is caused by the vertical shaft preload and any drag the cone is adding to it by rubing in the upper. Make sure the drive is in neutral.
Another quick and dirty way to do it is mark the retainer nut just as the propshaft looses all it slack. The proper preload is usually about 90* more rotation of the nut. There are a lot of things that affect preload and there is a range for the setting. Too loose is bad, too tight is bad.

If you are looking for an answer as to how to handle the problem I would ask your mechanic what he is comfortable doing. I think the easiest/less costly, would be for you to pull the lower and take it to him. If the only problem is a twisted propshaft, then it can be swapped out. But if the lower gears are starting to pit, then I would go with the Merc Kit which has new gears and all the parts needed for the propshaft. It does not come with the vertical shaft bearings, only the propshaft bearings..

Hope that helps.
Dick

speedfever

iTrader: (1)

Thanks for the reply. I am going to make sure that this is done the right way, so I removed the lower unit today. The vertical shaft looks ok and everything feels smooth when I turn the shaft. I will have the lower unit checked out completely and anything replaced if needed. I need to go back with a 1" shaft because my props are labbed Hydromotive and I do not want to spend the money for 2 more props and the 1 1/4 conversions for both outdrives. Thats getting very expensive ! Looking at other post on this site, it looks like the IMCO shaft is probably the best one to get unless someone can tell me of another one to get. Thanks to everyone who posted a reply, The information is priceless !!!!!

Mr Gadgets

I have run the Imco 1" shaft for years and had no problems with it. That is the brand I favor.