bravo failure

[boot-e-licious]

i have a situation i would like some feedback. i have a 388 slingshot hustler with twin 525's, bravo xr sportmasters. i had drive showers installed and the starboard drive, which i never had a problem with, did not want to come out of forward gear. so i thought it was a shift cable. so i making my way back to the marina and all of a sudden the drive just goes. so i making home on one. we pull the boat out and the drive shower is hanging over the tie-bar, the finned cap off the top of the drive is missing, there is a chunk out of the prop blades. the holes for the drive cap and shower are not missing any threads,except for one hole, which had about 1/4" to 3/8" missing threads. the drive is trashed. the cotter pin and pivot pin is missing at the shifter linkage.

my thought is that the shower was not tightened down , without lock tite, the bolts vibrated loose, there was only about 8-10 hours on the boat since install, 3 bolts vibrated out and the 4th vibrated out so far and then the water caught the caps and ripped them out. i would think the shop that did the work would be reaponsible for the parts and labor. any thoughts or ideas of what happened. all would be helpful.

[MOBILEMERCMAN]

It may have happened that way, but good luck. I have witnessed a similar failure on a race boat. He had nicked a blade and that side kept cavitating and free wheeling. We kept pushing it until it blow the cap off. The shower stayed in place and you could see all the gears. The gears didn't get chewed up but the housing and all upper components were now junk.

You have heard the expression SHiit happens. The cap may have been loose when you assumed it was the cable and continued to run it.

It is hard to say after the fact. Good luck. If the prop was damaged you may be able to make an insurance claim. DEPENDS ON YOUR COVERAGE Good luck either way.

[t500hps]

OJ got off with alot more proof than you have. You can ask, but unfortunately I don't see them doing anything other than sending you the full bill.

[Rik]

Don't know squat about your Bravo but I know the cure reall well.

[Griff]

If the bolts holding the drive shower vibrated slowly out like you are thinking, I think you would have had a drive lube alarm go off and would have been seeing lots of lube in the water.

I'm guessing that when you tried to pull it out of forward that it may have moved slightly out of forward gear and then you lost the pins in the shift bracket and it was only partially in gear.

Was it the LH rotation drive??? Another possibility is that the bolts were not long enough to start with. A LH rotation drive puts a lot more stress on the upper cap.

[Geronimo36]

One could also summize that the upper gear broke, shot the gear upwards and blew off the top cap and drive shower. While the blades of the prop were still turning the shower smacked down on them.

If it was stuck in gear the floor of the gear may have been broken, then when you kept running it broke the rest of the way.

Was this the port or stbd drive?

[Knot 4 Me]

States in the first post it was the starboard drive. My guess props are turning out so it was the RH rotation drive. I think the drive needs to be torn down before you make any assumptions as to the cause of the failure.

[glassdave]

If it is the drive that turns left (reverse) it puts a load pushing up on the cap. On my Donzi its the stbd drive that spins that way. The exact same thing happened to me last fall, an i mean exact with the exception of dinging the prop. What happens is through time the bolts can stretch a bit from having the load pushing up and than they will just work themselves out. Thats why there is only thread damage in one hole, it was the last to go. Its a good idea to torque them regularly, I forgot this spring and it cost me an upper.

[MOBILEMERCMAN]

States in the first post it was the starboard drive. My guess props are turning out so it was the RH rotation drive. I think the drive needs to be torn down before you make any assumptions as to the cause of the failure.

I think most of them on that boat swing in

[PatriYacht]

Last year it was an upper for me, this year it's a lower. Bravo's just do this. :ack2:

[Mr Gadgets]

How about some pics of the drive and what the gears look like. Was it RH or LH rotation? Lot of speculation without a better look.
Usually the top cap on a LH drive will streach bolts and then the gears will break. How the three bolts worked out without it breaking is strange. All three bolts back out at the same time. Still lifting the cap .200" would let the gears self distruct.
If it were RH and the bolts backed out, I could see how only one set of threads were damaged. But how long did it take for the bolts to back out..??
The floors dont break on the newer gear sets. The hubs will crack off the XR gears and the gear splits in two, but it usually just stops.

I use studs to hold the top cap on. I have seen one that the gears broke and streached the studs, but the cap was still there and three of the holes had thread damage.

How about some pics.. that may help.

Dick

[Expensive Date]

If it is the drive that turns left (reverse) it puts a load pushing up on the cap. On my Donzi its the stbd drive that spins that way. The exact same thing happened to me last fall, an i mean exact with the exception of dinging the prop. What happens is through time the bolts can stretch a bit from having the load pushing up and than they will just work themselves out. Thats why there is only thread damage in one hole, it was the last to go. Its a good idea to torque them regularly, I forgot this spring and it cost me an upper.

What is the torque spec for a Bravo 1 ?

[MOBILEMERCMAN]

Top cover is like 25 or 30 ft/lbs off top of my head

[Griff]

Also, with a chunk out of the prop, it could have all been caused by a submerged object as well.

[Knot 4 Me]

I think most of them on that boat swing inThat would explain why the starboard popped the top off then. Thanks for the clarification.

[Knot 4 Me]

Top cover is like 25 or 30 ft/lbs off top of my headI was told 25 ft/lbs by my Merc buddy but that was for the older, flat top caps. Not sure if it is different for the ribbed caps used on the XR's. Most drive showers I have installed do not state a torque setting for the top cap bolts but the one shower that did (I believe they were from Eddie Marine) said 30 ft. lbs.

[MOBILEMERCMAN]

Also, with a chunk out of the prop, it could have all been caused by a submerged object as well.

That what caused the failure I described earlier. The prop was slipping and ventilating occasionally slipping like in neutral. We would have to back off the throttle and give it a few handfuls to get it to grab again. After 3 or 4 times of doing that it blow the top off.

Our shower had no nicks or damage what so ever. I think if the shower hit the prop it would be evident on the shower. The prop would have to leave a mark.

[ROGUE]

How about some pics of the drive and what the gears look like. Was it RH or LH rotation? Lot of speculation without a better look.
Usually the top cap on a LH drive will streach bolts and then the gears will break. How the three bolts worked out without it breaking is strange. All three bolts back out at the same time. Still lifting the cap .200" would let the gears self distruct.
If it were RH and the bolts backed out, I could see how only one set of threads were damaged. But how long did it take for the bolts to back out..??
The floors dont break on the newer gear sets. The hubs will crack off the XR gears and the gear splits in two, but it usually just stops.

I use studs to hold the top cap on. I have seen one that the gears broke and streached the studs, but the cap was still there and three of the holes had thread damage.

How about some pics.. that may help.

Dick

Dick, do you helicoil the cases to add some pull strength or only if the threads are damaged?

[Geronimo36]

Have't done it myself but I've seen people put studs and spacers on the top cap instead of bolts. Makes sense to me!

[J.T.]

The floors dont break on the newer gear sets. The hubs will crack off the XR gears and the gear splits in two, but it usually just stops.

I had the hub break off of the gear, the gear never split in two,
but there was a crack between the teeth.


Is this a common thing, Dick ?

What are your thoughts on the gear teeth contact area chunking out?
......sh!tty material ?

[Griff]

Have't done it myself but I've seen people put studs and spacers on the top cap instead of bolts. Makes sense to me!

Thats how my Imco upper was.

[Strip Poker 388]

Thats how my Imco upper was.

long time ago I bought a Imco kit, the studs were a larger dia.

Save the old for parts for the next time, sorry:)

[Mr Gadgets]

Rogue,
I normally dont helicoil unless the threads are damaged. I dont like to use larger studs, either, the case is pretty thin in that area and drilling to a larger dia makes it that much thinner. The holding power of the 3/8" studs is sufficient in normal operation of the drive. I like to fill the majority of the threaded hole with stud. I believe it helps stabilize the upper case some. I red loctite them in and use nyloc nut to hold the cap down. Then I install a treaded spacer with bolts in the top to hold the drive shower on. This isolates the top cap fastening from the cap clamping.

If the gears break, it is going to destroy things any way. I have yet to see a top cap come off and cause the gears to break, well when they are studded. In my opinion, I believe the gears break and pop the top cap. But I have never seen one with out streached bolts or undamaged threads. Not saying it doesnt happen, just not seen in in my shop. If the drive is operating properly, I dont see a need to increase clamping load on the top cap.

J.T.
My opinion of the XR gears is not very favorable at present. A few years ago, 1000hp was not an instant drive breaker. Now a days, 650hp in a light boat and the teeth on the driven gears just break off. I had the metal analyzed and no one can match the material up to any common steel offering listed out there. I have also analyzed the Helical gear from Merc and the Bmax upper gear. All very interesting. I am in the process now of attempting to have upper gears made with better material. It is very costly and nothing happens over nite.. We'll see where it takes me.

I have seen a hub seperate from the ring gear (that was what I was refering when I said gear split in two). I have also seen a ring gear break in two, half of it was left on the hub, the other have did some interference machining in the case. All very ugly!

Hope this helps.
Dick

[Geronimo36]

I had the metal analyzed and no one can match the material up to any common steel offering listed out there. I have also analyzed the Helical gear from Merc and the Bmax upper gear. All very interesting.

I'd love to know more about your helical gear findings.

I noticed on IMCO's new SCX drive they went with bigger gears like the BMax but they utilize a straight cut design like an XR. It also appears as though they are using a larger cone/clutch. I also heard a rumor that IMCO's lower unit will bolt up to an XR and vice versa but havne't been able to confirm???

From what I was told the helical can disperse the load better having more tooth contact area. I'm no scientist but it seemed to make sense so long as the teeth had enough meat on them.

[ROGUE]

Rogue,

I have seen a hub seperate from the ring gear (that was what I was refering when I said gear split in two). I have also seen a ring gear break in two, half of it was left on the hub, the other have did some interference machining in the case. All very ugly!

Hope this helps.
Dick


Yeah, this pinion did some fatal damage when it broke.

[Mr Gadgets]

Here is what the XR gear looks like inside. That cavity goes all the way around the gear. That must be where it is welded together and it is a weak point..

[boot-e-licious]

the gears were chewed up , the shaft was sheered in two, the upper is trash. the shop that does my work is going to cover all costs, they already ordered a new upper. last month i replacxed the port drive, it was under warranty. not really sure the exact cause, but it was ugly when they broke it down.

[MOBILEMERCMAN]

the gears were chewed up , the shaft was sheered in two, the upper is trash. the shop that does my work is going to cover all costs, they already ordered a new upper. last month i replacxed the port drive, it was under warranty. not really sure the exact cause, but it was ugly when they broke it down.

That is good news.

Hats off to your shop taking care of you.

[Mr Gadgets]

That is good news!!

[Offshoredrillin]

the gears were chewed up , the shaft was sheered in two, the upper is trash. the shop that does my work is going to cover all costs, they already ordered a new upper. last month i replacxed the port drive, it was under warranty. not really sure the exact cause, but it was ugly when they broke it down.
Wow, that is great news... If you dont mind, for doing the right thing, you may want to make a post in the Good bad and ugly section. I'm quite sure that they would love some more business. also let them know that you did it and how much it is appreciated..

Dick, I blew the gears in my starboard lower and am going through both of them now, I would be interested in your gear findings as well...Rob

[PARADOX]

Glad to hear your shop will take care of you Lenny.

Good news.

[boot-e-licious]

hi guys, the shop is pablo creek marine center and they are very good at what they do. they are here in jacksonville,fl. last year at the jacksonville poker run in june, which is a great run and an area for great boating, a fellow boater in the run blew a water line, still 25 miles from the docks and they met me at one of the docks with the line to bring to this gentleman.

hi pete, how did the surgery go, how's gail? boat will back up next week sometime.