I borrowed a 32 labbbed Bravo from a buddy to test this weekend. The good news is I picked up 5mph over my 30. Bad (or good) news is I have to much side clearance on the prop shaft. I didn't put the dial indicator on it, but it's at least .010-.015. Just looking for some info on if I should atttemp to fix it myself and what would be needed. I've done a lot of engines, but I have been lucky with drives and never had to buy the tools or repair any, but I'm not opposed getting them amd learnig to fix them. I am a big fan of replacing wear items when I take something apart. The drive has around 250-300 hours, so should I just go ahead and replace all the bearings, and what about the gears even if they look good?
Looking at the schematic on IMCO's site it doesn't look like it uses a crush ring like the bravo. Do the clearances get set with the shim kit they have listed? Shim kit (Carrier bearing) 01-2011.
It looks like I would need a 91-840393 carrier retain nut wrench to pull it apart, but If I should have it all gone through it looks like it takes a lot of different tools to set all the clearances, disassemble and reassemble, so I might be better off sending it to some place for the repair.
Thanks for any help you can give me.

Rockie

Rockie,
There should be no free play in the proshaft. Bearing preload should prevent any slop. The shims do set the preload on the bearings. Something might have moved (a bearing race not seated properly, etc) but it should be looked into. With that many hours a rebuild would be a good idea. Anytime the preload shows tapered bearings that don't roll smoothly, they should be replaced. Generally the metal that is generated by a bravo drive, circulates with the oil and damages those bearings, so usually they all need to be replaced if you find one set, but not always.
And yes, there are a lot of tools needed to do a bravo rebuild properly.
I hope that helps.
Dick

Thanks Dick, I was hoping you would chime in and yes it helps.
Are you saying that the whole drive should be rebuilt, upper and lower if I find a bearing going south? If so I might remove the drive this weekend. And when you say rebuilt, what all should be replaced? All bearings, Gears
I am going to drain the gear lube this weekend and see what comes out or shows up on the magnet, so i can update what I find. Once the gear lube is out, I will see if I feel any rough spots while spinning the shaft.

At least I have the whole winter to either try the repair or send it off to be gone through.
Rockie

Typically if the gears give off metal ( pits in the gear teeth), all the tapered bearings get replaced because of the circulation of oil through the drive along with the pieces of metal. What upper gears do you have? Are they XR or helical (bravo 1)? The XR gears will pit also. The helicals last a long time unless you have enough power to snap the teeth off.
The magnets will tell the story pretty much. The bearings need to be preloaded and spun to feel any rough bearings. Unless the propshaft bearing preload is set to spec you probably won't feel it with your hand. It is unusual for a propshaft to loose it's preload by that much. Spin easy, yes, wobble around, no. So at least that shaft needs to come out and see what changed inside.

Dick
Let us know what you find on the magnets..

The top is an XR upper 1.5. I bought the complete unit from Mark at BAM so it has the same amount of hours on it. I guess it has held up pretty good for pushing 650-700hp to it. Any idea what would be a typical rebuild cost assuming new gears and bearings, $4-5000 sound about right?
I will get more info when I drain it this weekend and post!
Rockie

I drained the oil and there are maybe a few more metal filings than normal, but nothing terrible. I also had a bigger magnet that I placed in the back so all the oil had to run over it while draining and it had some very small metal fillings, but nothing big at all. I think I will buy the tool to remove the prop shaft and see how bad it looks inside and then go from there. I know in a perfect world there shouldn't be any fillings. Here is a picture of the plug. All of the stuff on it are an accumulation a bunch of small fillings.
Thoughts?

[IMG][/IMG]

Say Dick, I got the prop shaft removed and I don't see or feel anything wrong with the carrier bearing or race. I haven't pulled the vertical shaft, but I don't see any pitting on the gears from the distance looking through the housing. Can something with the front bearing cause the extra play? This unit has the load ring in it, so is there any possibility that it has just had too much play for a long time and the preload wasn't set right, or the nut backed off slightly. I guess further inspection is needed, and then maybe change bearings, seals and reassemble.
Rockie

That magnet doesn't look too bad. Looks like a couple of flakes. If you see no pitting on the lower gears, then take a peek at the uppers. The metal came from somewhere, but it could have been in the case when it was built and worked it's way out. Not usually, but I have seen new drives (no run time on them) with metal pieces floating around in them. Keep looking, just to make sure.
Put the propshaft back in without the .105" shim and load ring and Oring. Tighten the retainer nut until you feel some preload. Rotate the propshaft with a socket and ratchet (usually use the torque meter) and see if you can feel any roughness. Rotate a few times, then tighten the nut a bit more. If it rolls smoothly then the bearings are ok. With used bearings, sometimes you can keep adding pressure to the preload and it doesn't increase too much, you don't want to get to that point when you do the final setup. But without the load ring you can test the bearings to see how they feel.
What color is the bearing carrier? Red, black, gold, blue? I had some Merc carriers (blue) where they either didnt press the race all the way in or it was completely missing right out of the box. So I always take a mirror and check to see if the race is fully seated in the carrier. Otherwise it may have been setup wrong from the begining.
Usually the middle bearings on the vertical shaft will show dents. Take a smooth 600 grit or 1500 grit wet/dry paper and make a few swipes around the race, if there are dents they will show up with a bit of polishing..

Hope that helps..

Thanks Dick, Interestingly enough, I have the blue carrier. So on the middle bearing are you saying that is how you can determine if the bearing needs replaced? Agreed, the metal came from somewhere and I was really expectiing to see the problem in the lower since the shaft was lose. We'll get the rest of the lower apart and clean up stuff to see if we can determine where the metal flakes came from. If we don't find anything I guess I will pull the upper off the boat and inspect it. I'd rather mess with it all now instead of having a failure next summer.

All the tapered bearings have preload on them, if they roll rough, then they need to be replaced. On the vertical shaft you clamp a plate on the housing that presses on the spacer, that puts preload on the center two, vertical shaft bearings.
Tightening the retainer nut will put preload on the propshaft bearings. If they roll rough, again, replace them.
With the Blue carrier (Merc) they may not have pressed the race all the way in. You run the boat for a few minutes and the race seats, bingo, loose propshaft.