what to do to keep Bravo 1 alive at 525hp?
09-30-2005, 10:25 PM
#31
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Re: what to do to keep Bravo 1 alive at 525hp?
Rage,
You still out there?
Was hoping I would get some comments from the crowd???
PatriYacht,
I finally finished the drive oil fill pump we talked about. Are you still interested, or should MsPatriYacht be looking at it for a Christmas gift??
Dick
You still out there?
Was hoping I would get some comments from the crowd???
PatriYacht,
I finally finished the drive oil fill pump we talked about. Are you still interested, or should MsPatriYacht be looking at it for a Christmas gift??
Dick
10-01-2005, 07:30 AM
#32
Registered
Re: what to do to keep Bravo 1 alive at 525hp?
Sure Dick, I'll take one. I have both drives off the boat now. Have to talk to you soon about upgrades. That thrust washer fix you did lasted just fine. Got us through the rest of the season and another poker run.
10-02-2005, 11:08 AM
#33
Charter Member #601
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Re: what to do to keep Bravo 1 alive at 525hp?
PatriYacht,
I will put your name on one and when you drop off the drives I'll have it for you! I am glad to hear that all went well for the rest of the summer!! I am starting a winter schedule, so give me a call when your can and I will make an appointment for you.. Thanks
Rage,
Did we lose you on this thread?? Even if you dont want to ship your drive this way, I would like to give you as much info as possible so that you can make a good decision on what to do.. If you want, give me a call.
Dick
I will put your name on one and when you drop off the drives I'll have it for you! I am glad to hear that all went well for the rest of the summer!! I am starting a winter schedule, so give me a call when your can and I will make an appointment for you.. Thanks
Rage,
Did we lose you on this thread?? Even if you dont want to ship your drive this way, I would like to give you as much info as possible so that you can make a good decision on what to do.. If you want, give me a call.
Dick
10-04-2005, 03:40 PM
#34
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Re: what to do to keep Bravo 1 alive at 525hp?
Originally Posted by Mr Gadgets
Rage,
The upper case has to be milled to accept the new steel tower. I have worked closely with a local machine shop to have this done.
When I say the gears have thick floors, I mean that all the gears have it. There is actually only two different gears. The helical cut gears (I call them X gears) are all the same. They are used in X and XZ drives. The standard Bravo starting with the OM serial number uses the same driven gears, but the pinion gear has a smaller splined input shaft. It is the driven gears that Merc made the floors thicker. In doing so they use a shorter bearing in the gear, which in turn makes the towers shorter (one in the case and one in the cap). The XR gears are straight cut gears, not helical. They are stronger but softer, so they wear faster.
There is some interchangeability between the gears, but lots of things need be considered. I run a standard Bravo (pre OM ser #) with XR gears in it. So things will fit, but certain things need be considered. When I put a tower in an older drive, it can use X gears or XR gears, but a lot of things need to be matched up. I hope this helps.. without pictures it is hard to describe.
Here are some pics of my tower mods..
The upper case has to be milled to accept the new steel tower. I have worked closely with a local machine shop to have this done.
When I say the gears have thick floors, I mean that all the gears have it. There is actually only two different gears. The helical cut gears (I call them X gears) are all the same. They are used in X and XZ drives. The standard Bravo starting with the OM serial number uses the same driven gears, but the pinion gear has a smaller splined input shaft. It is the driven gears that Merc made the floors thicker. In doing so they use a shorter bearing in the gear, which in turn makes the towers shorter (one in the case and one in the cap). The XR gears are straight cut gears, not helical. They are stronger but softer, so they wear faster.
There is some interchangeability between the gears, but lots of things need be considered. I run a standard Bravo (pre OM ser #) with XR gears in it. So things will fit, but certain things need be considered. When I put a tower in an older drive, it can use X gears or XR gears, but a lot of things need to be matched up. I hope this helps.. without pictures it is hard to describe.
Here are some pics of my tower mods..
Dick,
Sorry for the slow response, I had to work for a while.
Thanks for taking the time to fully explain the nuances of Bravo drives. Obviously very valuable and hard won information.
If I understand correctly, the latest Bravo1 starting with the OM serial number has the same thicker floor driven gears as the Bravo X and XZ with only the pinion gear being different in that the Bravo 1 pinion has a smaller diameter hole for the splined input shaft.
Is the most likely drive failure point the driven gear or other?
I see other comments about drive thrust washer failures. Is this mostly a problem with the real high HP/torque with Bravo 1 /XR drives or is 525hp also a high risk configuration for this problem? Are there also upgrades in the Mercury system for this problem as well?
Thanks!
10-04-2005, 04:34 PM
#35
Charter Member #601
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Re: what to do to keep Bravo 1 alive at 525hp?
If I understand correctly, the latest Bravo1 starting with the OM serial number has the same thicker floor driven gears as the Bravo X and XZ with only the pinion gear being different in that the Bravo 1 pinion has a smaller diameter hole for the splined input shaft.
Rage,
You are correct in what you said about the gears as stated above.
There are several weak points in the Bravo. But a properly setup drive will go along way in a NA motor, if it is driven properly. Depending on what type of boating you do, the operator has the most control over failure. Torque is the killer and how much torque your motor makes and at what RPM is the key factor. Getting on plane with a heavy load is hard on them. Big boats with big props compound the problem. A lighter boat should have little problem in that area, if the throttles are advanced accordingly. How much?? Well just enough to get the boat on plane and using tabs is big help. Next is acceleration from 3000rpm. Most boat motors make their big torque numbers mid range, so acceleration from mid should be gentle. In your case 525hp.. is not a drive breaker unless it is driven too hard. Common sense will keep the drive on the back of the boat, rather than the drive shop.
I used to run a 25' Checkmate with 690hp and 680ft of torque. My best prop was a 3 blade Mirage. I would accelerate from 3500 with a steady motion right on up to high 80's. Now that was a stock Bravo 1 with all the weak parts. I ran that boat hard on Lake Mich.. and never had drive problems. The 3 blade prop would slip on acceleration so it was easy on the drive. My theory is that anything can break, but it doesnt have to.
I have seen teeth come off either the drive or driven gears when a blower motor is in front of it.. Then it is time to step up to XR gears and good shafts.
Thrust washers dont usually go bad. Tower alignment can cause wear on things unevenly and that may be an answer as to why they fail. In most cases things are gettin old and should be replaced anyway..
I hope this helps.. any more??? Be happy to help..
Dick
10-05-2005, 11:13 AM
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Re: what to do to keep Bravo 1 alive at 525hp?
Dick,
I am out of questions (for now) but I can assure you I will be back after I make some decisions.
Thanks again you have obviously been a tremendous help in getting me up to speed on Bravo drives!
I am out of questions (for now) but I can assure you I will be back after I make some decisions.
Thanks again you have obviously been a tremendous help in getting me up to speed on Bravo drives!
10-05-2005, 09:34 PM
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Re: what to do to keep Bravo 1 alive at 525hp?
I have a 88 b1 drive that I run in the ocean with I think I HAVE ABOUT 600 TO 700 TOTAL HOURS ON IT been running about 600hp from 95to99 then went up to647 hp and627tq 99to 03 just ran it it sat after 2yr rest and I use to get a lot of air 
I must be doooo, I'll look for a used newer drive in the spring , good idear 
cause you now the knock on wood is going to go BANG real soon 
I must be doooo, I'll look for a used newer drive in the spring , good idear cause you now the knock on wood is going to go BANG real soon
10-06-2005, 02:44 PM
#38
Charter Member #601
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Re: what to do to keep Bravo 1 alive at 525hp?
AirTime,
Seems you have gotten your money's worth out of that one.. I would find some wood to knock or quick run get another one.. LOL!!
Dick
Seems you have gotten your money's worth out of that one.. I would find some wood to knock or quick run get another one.. LOL!!
Dick
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