View Poll Results: Bravo XR drive breakage
Broke upper gear set
71
82.56%
Broke lower gear set
15
17.44%
Voters: 86. You may not vote on this poll
Bravo XR drive breakage
12-21-2012 | 07:57 PM
#51
Banned
Joined: Nov 2012
Posts: 59
Likes: 0
From: Pitt
6's very seldom break, and with 600-850hp you wont have to worry about any problems as long as you keep the oil changed. Bravos simply will not hold up period,
12-21-2012 | 08:57 PM
#52
Neno the mind boggler
Joined: Sep 2001
Posts: 13,080
Likes: 320
From: toledo oh
Again this is all because marketing takes precidance over engineering, pretty much standard practice these days. Its also worth noting nearly all CEO's of just about all major companies like these are out of marketing as well.
Couple things boys. I have a 1994 STD Bravo.. 500+ hours with a 454 mag. No problems. none, But no serious HP and high revs. However. The XR's problems are not in the gears. It's in the overall design specifically in the upper driveshaft. Some time ago (not sure when) merc changed the upper niddle bearings and also hardened the driveshaft etc. Now. You got more "niddles" in the bearing but less of them. Also the port wher the lube gets to the bearings and shaft is too small. So the niddles/bearing digs a groove in the shaft and stuff gets out of alignment, viboratin then failure. Merc. wont tell you this, but I have discussed this with merc racing staff and during some "casual" talks they will admit it. I am pissed at Merc also, so I have no reason to keep it out of the arena. I had great relatinship with Merc, untill the CMI issues. (old stuff). I had both the 525's XR drives upper shaft replaced, seen the problem but I cought it in time so no break downs, to date. Close. The gears are not an issue. Change the niddle bearing to the old style, if you can get them , machine the lube hole out to get more oil in the bearing and shaft areas and the XR will last longer. (unless you bolt on some 850 HP crazy stuff. 
I will see if I can dig up the driveshaft pictures one of these days. But at the end of the day, it's called planned obsolesance, faulty parts, designs, more new parts and service sales. Merc's integrity is gone long ago.
I will see if I can dig up the driveshaft pictures one of these days. But at the end of the day, it's called planned obsolesance, faulty parts, designs, more new parts and service sales. Merc's integrity is gone long ago.
__________________
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
Throttles- Cleveland Construction 377 Talon
08 OPA Class 1 National Champion
08 Class 1 Geico Triple Crown Champion
08 OPA High Points Champion
10 OPA Class 1 National Champion ( happy now Ed! )
Last edited by glassdave; 12-21-2012 at 09:02 PM.
12-21-2012 | 09:05 PM
#53
Registered
Joined: Mar 2008
Posts: 3,613
Likes: 375
From: Traverse City MI
Lets also remember the older gears were forged a little better where the new gears are junk. Yes there are a few things you can waste money on that will gain a tiny bit of strength. My drives have all of the current upgrade parts available and STILL break!
Looking forward to your new product Smitty! Thanks for sharing
Looking forward to your new product Smitty! Thanks for sharing
Last edited by offshorexcursion; 12-21-2012 at 11:40 PM.
12-21-2012 | 10:44 PM
#54
Thread Starter
VIP Member
Joined: Apr 2001
Posts: 4,213
Likes: 0
From: Chicago il
I highly doubt that a needle bearing is the cause of a failed/damaged upper gearset. I have done testing on stock gears and have proven without a doubt that the way the gear is shaped at the end, creates a stress riser and with enough torque, will cause it to fracture and then the teeth break off.
Again, all I am looking for right now was to see the percentage of upper failures versus lower failures. Reason is, should I also be trying to make a better lower set while I am at it.
Again, all I am looking for right now was to see the percentage of upper failures versus lower failures. Reason is, should I also be trying to make a better lower set while I am at it.
__________________
Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
Want your ECU tuned right?? Call Mark at Precision www.pmefi.com
12-22-2012 | 06:59 AM
#55
Registered
Joined: Jul 2011
Posts: 821
Likes: 0
From: mirabel,qc
I highly doubt that a needle bearing is the cause of a failed/damaged upper gearset. I have done testing on stock gears and have proven without a doubt that the way the gear is shaped at the end, creates a stress riser and with enough torque, will cause it to fracture and then the teeth break off.
Again, all I am looking for right now was to see the percentage of upper failures versus lower failures. Reason is, should I also be trying to make a better lower set while I am at it.
Again, all I am looking for right now was to see the percentage of upper failures versus lower failures. Reason is, should I also be trying to make a better lower set while I am at it.
lead to more lower gears breakage?
BTW,i salute your efforts/research,Smitty...
Jack
12-22-2012 | 09:03 AM
#56
Registered
Joined: Jan 2008
Posts: 2,357
Likes: 2
From: San Diego
How does the xr differ from the bravo 1? I am building a new 600hp motor for my 280 velocity that has a b1 and have heard of guys running 700 hp with stock b1 with out to many problems. Is it due to the 280 being a light boat? I'm still new to this, but was under the impression the xr drive was an upgrade to the b1.
In my industry we have transmission failers when using stock gears behind the high hp bike motors we build. Years ago we started cryoing gear seats and found that to extend the amount of power the gears would hold by about 10-15%. Still in need of stronger gear sets we started having complete billet gear and output shafts made up. The billet seems to be about 50-55% stronger than factory gears. Are there no options like this for boats? Or has it been tried and doesn't work.
For the bolts stretching problem. Why not have arp make up a set of bolts. I'm sure they can make a stronger option. I have an account with them if someone were interested in experimenting with having a bolt made.
In my industry we have transmission failers when using stock gears behind the high hp bike motors we build. Years ago we started cryoing gear seats and found that to extend the amount of power the gears would hold by about 10-15%. Still in need of stronger gear sets we started having complete billet gear and output shafts made up. The billet seems to be about 50-55% stronger than factory gears. Are there no options like this for boats? Or has it been tried and doesn't work.
For the bolts stretching problem. Why not have arp make up a set of bolts. I'm sure they can make a stronger option. I have an account with them if someone were interested in experimenting with having a bolt made.
12-22-2012 | 09:47 AM
#57
Charter Member #601
Joined: Dec 2000
Posts: 3,276
Likes: 5
From: Holland, Mi USA.
Prior to 2006 a friend of mine was running 1170hp in a 25' Baja. He ran it very hard and never broke any teeth off the upper gear set. The upper and lower gear sets would both be pitted at 60-70hrs of hard runing. I think he went through 3 sets of uppers and lowers while he owned this boat and combination. That was with an OW upper gear case and Imco SC lower case. During 2006 and since then, I have had numerous friends fracture teeth off the upper driven gears. They used to be much better, and case flex was not really a problem in most situations. On a friend's 50' Hustler, it probably came into play, but that boat could break just about anything in the drive.
If Smitty can make a better one, it will improve the life an XR!! Just my .02.
Dick
If Smitty can make a better one, it will improve the life an XR!! Just my .02.
Dick
12-22-2012 | 10:27 AM
#58
Gold Member
Joined: Jul 2008
Posts: 3,748
Likes: 869
From: Delray Beach, FL
We are all trying to make these drives do something they were never designed to do.
12-22-2012 | 04:52 PM
#59
Registered
Joined: Dec 2005
Posts: 2,798
Likes: 13
From: Florida
The politically correct answer is Fatigue Analysis, CAE Durability Prediction or Product Lifecycle Performance. Mercury doesnt have a team of engineers in a back room trying to screw you. Dont forget, just like anything else there is a very fine line here for cost of manufacture and durability of the product. Realistically, Mercury can handle 700 HP, its called the NXT or MORE with the #6 which are obviously the next drives up in the family of drive products. The only questionable engine an XR is behind is a 525. From there, the builder or the buyer specified the power/drive combo. Who's fault is that? Not Mercury.
We are all trying to make these drives do something they were never designed to do.
We are all trying to make these drives do something they were never designed to do.
12-22-2012 | 05:00 PM
#60
Registered
Joined: Jul 2007
Posts: 2,640
Likes: 14
From: MI
The politically correct answer is Fatigue Analysis, CAE Durability Prediction or Product Lifecycle Performance. Mercury doesnt have a team of engineers in a back room trying to screw you. Dont forget, just like anything else there is a very fine line here for cost of manufacture and durability of the product. Realistically, Mercury can handle 700 HP, its called the NXT or MORE with the #6 which are obviously the next drives up in the family of drive products. The only questionable engine an XR is behind is a 525. From there, the builder or the buyer specified the power/drive combo. Who's fault is that? Not Mercury.
We are all trying to make these drives do something they were never designed to do.
We are all trying to make these drives do something they were never designed to do.
