Krumbsnatcher

OK I have some ?'s on drives. I recently broke my bravo I drive this weekend (i expected it too, just not this early in the season) I was backing my boat off the sand and no avail it started to go but then I head the dreaded sound of my engine spinning and my boat not moving.

I then re beached the boat with some help of friends and put the boat in gear and no avail the prop spun very easy. Now for my questions. How do you know if your drive has failed or your main engine coupler? I know before you can answer you have some questions.

The drive is fairly new Bravo 1 that says Hi performance (standard Bravo later model) the boat is a Magic 29.9 wizard with a Blown 540 that is putting out a de tuned 750hp. I drive the boat very easy on getting her on plane and never hammer the throttle due to the blown engine.

Prior to beaching the boat the lake had about 4 to 5 foot cross chop and severely white capped, so the drive was in and out of the water but not abused over 3800 rpm's.

I removed the drive and placed it on the drive stand and proceeded to do the following tests:

placed the drive into the reverse position by pulling the gear selector (???) all the way out and then turned the u-joint and the prop spun. I then moved the ?? to the neutral position and spun the u-joint and no prop spinning (as expected). Finally i moved the selector all the way in and spun the u-joint and it just spun. I then drained the drive oil to look for metallic particles and inspected the drive oil. The oil was new and did not smell burnt. So I then removed the top cap to see if anything looked out of place, I found nothing unusual (I was looking for broken visible parts found none) so I expect the drive, now I heard someone mention you can not test the drive this way due to some centrifugal clutch inside the drive. I have no clue!

I also checked the alignment of the engine coupler (tool has no splines www.mercstuff.com) and it seemed to be a perfect fit, so I am curious of what to do now. I know I will be purchasing a new drive or building a hardened drive out of my existing one.

What advantages and disadvantages does one incur by buying an XR drive as compared to converting my existing one to all imco hardened parts. All the help will be appreciated, I know very little about these drives

blue thunder

You can tell if the coupler is wiped by looking behind the engine while the engine is running to see if the input shaft to the outdrive is spinning. Obviously this needed to be done before removing the drive. Often when the coupler goes, the splines get ripped out and that is why no outdrive spin. Splines ripped out will leave lots of room for the alignment tool, so the test you did didn't tell anything (if splines are gone). Take a flashlight and sight into and past the gimbal bear inner race (outside the boat) to the coupler. If the splines are out you will see no splines and aluminum shavings all over. It is also possible for the splines to be in tact but the coupler rubber element blown out. Normally you can smell this when it happen as burnt rubber and will see chards of rubber on the underside of your hatch.

BT

Krumbsnatcher

blue thunder

thanks for the info, i did not mention i placed a considerable amount of spline grease on the tool and inserted it and found spline markings all around the tools circumference. I did not find any rubber shrouds or the smelling of burnt rubber particles. I also hooked up ears to the drive and did some more fine tuning on the carb prior to removing the drive, with the engine lid open. So if there was a rubber i surely would of found it because i did go back into the compartment with a flash light. I also inspected the gimbal bearing it was fine and there were visible spliines and in appeared to be intact. I recently put the motor in so the coupler was new to start and it was in proper alignment, i know it took us about 4 to 5 trys with shimming the motor till it was aligned.

thanks for your feedback.

blue thunder

Dang it does ssound like a drive problem then. Usually though, there is a section of splines remaining in the coupler where the input shaft could not reach. I've just had too dam much experience with coupler failure.

BT

Pure Energy

check your coupler again. look straight in, it will be obvious.

formula31

And then theres the rubber prop hub too, if it is that type, Ive blown my share of them. And again, once it cools off it can seem like its ok. You should be able to tell by the smell and appearance.

johnnyboatman

with the motor not running , stick the lever in gear, if it spins the coupler is bad.

mcollinstn

Bravo usually doesn't like to go in and out of gear with the motor not running. The fact that yours is going in and out easily kind of bothers me.

Pull the back cap. drain the gear oil. Take the prop off. Pull the coil wire or yank the kill switch.

With the motor spinning on the starter, have somebody shift in and out of forward and reverse while you watch the action from where the rear cap goes in. You should see where the trouble is.

Many possible routes of failure, one being the floor broken out of the gear(s).

Best of luck

marinetrans

Mcollinstn is on the right path.Sounds like a stomped out gear floor. Usually the bottom gear and not alot of metal would be floating around in the oil because nothing was ground up.

Krumbsnatcher

Ok you guys have been helpful becuase i was thinking it was the drive, unfortunately I am in California and the boat sits in Havasu and the drive is now with me here in Cali.

My dilema is this, I know I need a super strong drive do I buy a standard XR or should i build a custom IMCO with all the hardened goodies in my existing drive.

This is the first time I have broken a drive without going mach speeds, so I believe my casing is good.

Now lets say I do go with an XR, will this be sufficient for my horsepower, or do I still need mods on the XR?

The reason for all these questions is that we are planning a trip over 4th of July to Lake Shasta in Northern California the drive alone is 11 hours. I know the boat will run, but now i have concerns about the drive reliability, I would hate to break the drive again on vacation.

thanks for all your insight and help.