XR Gear composition
03-18-2014 | 10:09 AM
#21
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From: Oneida Lake NY
No need for popcorn. That gesture was funny though and since I don't post much I guess I had that one coming. lol
In short, been building performance drives for 30 plus years. My Master Mercruiser # is FL0178M . To be able to achieve the "Master Tech" status back then one not only had to excel in all areas of technical professionalism but also had to be voted by the tech reps at that time for entry. Currently all I build is performance drives and lower units, had my hands on my first Bravo drive in 1984. I think you'll find my track record very adequate and hope to earn the forums respect over time.
I've been asking some questions lately to expand some engineering I'm doing on the Bravo XR drives. With some collaboration,not condemnation I believe I can come up with a few improvements that would be beneficial for some on the forum that won't break the bank.
Thanks in advance and hope to get a chance to meet a few of you.
Warren
In short, been building performance drives for 30 plus years. My Master Mercruiser # is FL0178M . To be able to achieve the "Master Tech" status back then one not only had to excel in all areas of technical professionalism but also had to be voted by the tech reps at that time for entry. Currently all I build is performance drives and lower units, had my hands on my first Bravo drive in 1984. I think you'll find my track record very adequate and hope to earn the forums respect over time.
I've been asking some questions lately to expand some engineering I'm doing on the Bravo XR drives. With some collaboration,not condemnation I believe I can come up with a few improvements that would be beneficial for some on the forum that won't break the bank.
Thanks in advance and hope to get a chance to meet a few of you.
Warren
03-18-2014 | 10:17 AM
#22
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From: Oneida Lake NY
Gaz, I'm going to try and stay on task to my original post but will take a minute to agree with you for the most part and I never really took any comments as derogatory so we're good here. I share the frustrations a lot of performance Bravo B1, XZ, XR owners have. I am a Mercruiser loyalist to the core and do believe the engineers for the most part did a pretty good job at listening to the bulk of reasonable complaints. The engineers and inside connections I once had with Mercury have long since retired and the new generation is a little more tight lipped so here I am going to have to do some reverse engineering to get the answers I want.. I will say Kudos to the engineers that took on the task of the original design bugs as these were addressed early on and so for the most part the Bravo drive is a fairly reliable outdrive for purposes intended. Where the loudest noise comes from now are boat owners exceeding the drives intended capabilities and yes playing in the performance field can get expensive. Case in point If someone's not breaking a drive then they're breaking a valve train or wiping out crank bearings etc etc , just hop from the drive forum to the engine forum and I think you'll get my point. Also you do have to throw in some boat owners trying to band aid a problem that should of been fixed correctly the first time. See if you've ever heard this scenario before. The technician feeling bad for the customer succumbed to the crying about the price of a set of gears to do the job right and gets blamed for the job coming apart earlier than expected in the end anyway. I'm sure quite a few techs here on this forum have been in that position before. Its a two way street here and as they say "good deeds never go unpunished."
Some Bravo XR's or XZ's are being pushed way past their HP design limits. For that I can't chastise the Mercruiser engineers they did their part. After all they do have product for the next horsepower jump, its called the NXT or a Speedmaster.
But again and again I still hear the Bravo bashing. Some aftermarket performance drive manufactures such as Imco or B Max and a few others have made some major improvements for this larger horsepower crowd. So if you don't like a Bravo go buy the product intended for the horsepower or task. They are a good products and help fill the dollar/horsepower gap. However these improvements eat horsepower and to be competitive in the classes of racing my niche is involved in the Bravo XR seems to be the best choice. Its the fastest and fairly reliable if built correctly. The Bravo XR's on my build and maintenance plan (minor gear inspection during the middle of the race season) seem to go two full race seasons before the gears finally come to what I deam "end of reliability". As a race only drive this can easily fit into a serious racers budget.
Now for the over 650hp crowd with heavier boats your mileage may vary. But as you know a few hardcore Bravo builders out there see some serious horsepower attached to their work. They're not stock and I applaud there persistence in building a better mousetrap. These are the individuals I'd like to share ideas with as "trial and error" are time consuming and costly.
So I'll wind up here by saying thank you to the ones that have sent emails with their observations
So I said my peace, I hope I didn't offend anyone, my niche is narrow and I'm not trying to solve the worlds problems. I just have a few questions for the serious minds on this forum and I have a few tools, jigs and observations that I made in the past that a few just may find helpful.
Thanks to all
Warren
Now back to the original questions :
Some Bravo XR's or XZ's are being pushed way past their HP design limits. For that I can't chastise the Mercruiser engineers they did their part. After all they do have product for the next horsepower jump, its called the NXT or a Speedmaster.
But again and again I still hear the Bravo bashing. Some aftermarket performance drive manufactures such as Imco or B Max and a few others have made some major improvements for this larger horsepower crowd. So if you don't like a Bravo go buy the product intended for the horsepower or task. They are a good products and help fill the dollar/horsepower gap. However these improvements eat horsepower and to be competitive in the classes of racing my niche is involved in the Bravo XR seems to be the best choice. Its the fastest and fairly reliable if built correctly. The Bravo XR's on my build and maintenance plan (minor gear inspection during the middle of the race season) seem to go two full race seasons before the gears finally come to what I deam "end of reliability". As a race only drive this can easily fit into a serious racers budget.
Now for the over 650hp crowd with heavier boats your mileage may vary. But as you know a few hardcore Bravo builders out there see some serious horsepower attached to their work. They're not stock and I applaud there persistence in building a better mousetrap. These are the individuals I'd like to share ideas with as "trial and error" are time consuming and costly.
So I'll wind up here by saying thank you to the ones that have sent emails with their observations
So I said my peace, I hope I didn't offend anyone, my niche is narrow and I'm not trying to solve the worlds problems. I just have a few questions for the serious minds on this forum and I have a few tools, jigs and observations that I made in the past that a few just may find helpful.
Thanks to all
Warren
Now back to the original questions :
IMO the recent higher X dimension and shorty lower craze has given the bravo a terrible name.
03-18-2014 | 10:27 AM
#23
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From: Sarasota, Florida
Again Mr. Tyce thanks for clearing up the gear analyzed was infact an XR upper. (do you remember if it was an input or a driven gear, not that it probably makes any difference) I found a lab about 30 minutes north of me and I'm going to take a couple of gears there to compare to your findings.
Does any one check the hardness on the gears and if so have you noticed the same reduction in hadness over the years I have?
3rd Here's a quite different question I may be laughed off the forum with. Mercruiser in the XR parts catalogue offers just the upper gear case input gear? Sounds strange to me and why? I have read the polls on previous posts and it appears the uppers gears break 2 to 1 over the lowers. Since Mercury is offering just the input gear , is it my understanding this is the gear that's failing the most?
If it is then here is an idea. The input shaft gear is not that difficult to build compared to the two piece gears with the cone clutch in them. What would happen if a billet XR gear could be made with an alloy that would be compatible with the current near net forgings? Near net forgings are supposed to hold a gear flank tolerance of .0004 but I'm not so sure anymore. The reason I'm not so sure is that even when I get done building a drive to spec with the appropriate Mercruiser shimming tools, I still go back and fine tune the gear sets by using gear marker dye just like the old machinists and rear end builders do. Apart from a twisted gear case (which I have jigs, granite plates, height indicators and all the precision tools needed to do so) I still find some teeth "not consistent". I'm left wondering if a billet gear could be made, that would hold the tooth pattern to a higher standard and possibly be more lubricous than the near net forged gears. There is the possibility the finer grain structure could help with the coarser forged gear sets. Any thoughts?
Thanks in advance
WB
Does any one check the hardness on the gears and if so have you noticed the same reduction in hadness over the years I have?
3rd Here's a quite different question I may be laughed off the forum with. Mercruiser in the XR parts catalogue offers just the upper gear case input gear? Sounds strange to me and why? I have read the polls on previous posts and it appears the uppers gears break 2 to 1 over the lowers. Since Mercury is offering just the input gear , is it my understanding this is the gear that's failing the most?
If it is then here is an idea. The input shaft gear is not that difficult to build compared to the two piece gears with the cone clutch in them. What would happen if a billet XR gear could be made with an alloy that would be compatible with the current near net forgings? Near net forgings are supposed to hold a gear flank tolerance of .0004 but I'm not so sure anymore. The reason I'm not so sure is that even when I get done building a drive to spec with the appropriate Mercruiser shimming tools, I still go back and fine tune the gear sets by using gear marker dye just like the old machinists and rear end builders do. Apart from a twisted gear case (which I have jigs, granite plates, height indicators and all the precision tools needed to do so) I still find some teeth "not consistent". I'm left wondering if a billet gear could be made, that would hold the tooth pattern to a higher standard and possibly be more lubricous than the near net forged gears. There is the possibility the finer grain structure could help with the coarser forged gear sets. Any thoughts?
Thanks in advance
WB
03-18-2014 | 10:41 AM
#24
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From: Sarasota, Florida
4BUS I actually had a chuckle when I saw you're popcorn and no offense taken. We're good , I knew there would be some interesting ideas kicked around here.
As far as swapping the two gears, forward and reverse gears, around that is going to be a one on one basis. The drive gear is still the gear that receives the horsepower ALL the time. So to make a point, in a properly set up out drive, the teeth with the most power/time on them should (and I use this term loosely) wear at the same rate and that should answer the question. BUT
Have I ever swapped a gear around for a customer to help him through the end of a season where it looked like just a tooth on the driven gear side looked iffy, or pitted more. Where the drive gear looked ok, and I thoroughly explained the consequences and documented it. Yes I have
Hope this helps : )
WB
As far as swapping the two gears, forward and reverse gears, around that is going to be a one on one basis. The drive gear is still the gear that receives the horsepower ALL the time. So to make a point, in a properly set up out drive, the teeth with the most power/time on them should (and I use this term loosely) wear at the same rate and that should answer the question. BUT
Have I ever swapped a gear around for a customer to help him through the end of a season where it looked like just a tooth on the driven gear side looked iffy, or pitted more. Where the drive gear looked ok, and I thoroughly explained the consequences and documented it. Yes I have
Hope this helps : )
WB
Last edited by SRQ; 03-18-2014 at 10:44 AM.
03-18-2014 | 11:22 AM
#25
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Posts: 3,648
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From: Oneida Lake NY
4BUS I actually had a chuckle when I saw you're popcorn and no offense taken. We're good , I knew there would be some interesting ideas kicked around here.
As far as swapping the two gears, forward and reverse gears, around that is going to be a one on one basis. The drive gear is still the gear that receives the horsepower ALL the time. So to make a point, in a properly set up out drive, the teeth with the most power/time on them should (and I use this term loosely) wear at the same rate and that should answer the question. BUT
Have I ever swapped a gear around for a customer to help him through the end of a season where it looked like just a tooth on the driven gear side looked iffy, or pitted more. Where the drive gear looked ok, and I thoroughly explained the consequences and documented it. Yes I have
Hope this helps : )
WB
As far as swapping the two gears, forward and reverse gears, around that is going to be a one on one basis. The drive gear is still the gear that receives the horsepower ALL the time. So to make a point, in a properly set up out drive, the teeth with the most power/time on them should (and I use this term loosely) wear at the same rate and that should answer the question. BUT
Have I ever swapped a gear around for a customer to help him through the end of a season where it looked like just a tooth on the driven gear side looked iffy, or pitted more. Where the drive gear looked ok, and I thoroughly explained the consequences and documented it. Yes I have
Hope this helps : )
WB
What I was wondering was swapping drives side to side on a twin application. As you already know the bravo drive determine the final drive rotation. Some claim that swapping the drive from side to side allows you to wear the other side of the upper gears, getting the most out of them. Others claim swapping the drives side to side is not a good idea, once the gears are wore on one side they are effectively weaker on the other side. I don't know if either or any are true, however I am just over 100 hrs on my drives and was wondering if swapping now is a good idea?
Would also like to see some step by step of your inspection process, assuming you are here to share
03-18-2014 | 03:22 PM
#26
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Joined: Dec 2000
Posts: 3,276
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From: Holland, Mi USA.
When you swap from side to side the upper gear set still wears on the same side of the teeth on the input pinion gear, but it is now loading on the other driven gear. But the lower gears will switch sides. I have swapped the lowers from side to side when the gears are worn but not pitting. I have seen some that were pitted and swapped and they die an early death. I believe the pitting is caused by the soft inside (like an M&M) and the outer shell moving.. Once they pit, you swap them and now they M&M squishes to the other side and bingo they come apart. So depending on what your gears look like, it is a crap shoot as to being a good idea or not. I have installed new pinion gears in the upper and then flip the driven gears and that will be a benefit. Or take two reverse gears and a new pinion to make a set. ...
If you run a single, then you run it till it wears out. Same rotation. Does someone that has twins and swaps them get more time out of them? Well it isnt' and apples to apple comparison, so it is hard to tell.
Just what I have experienced over time..
Sometimes the teeth are so far off they are bound to not last. I perfer the helical gears in the upper, but too much power and you are forced to use XR uppers.
Hope that helps.
Dick
If you run a single, then you run it till it wears out. Same rotation. Does someone that has twins and swaps them get more time out of them? Well it isnt' and apples to apple comparison, so it is hard to tell.
Just what I have experienced over time..
Sometimes the teeth are so far off they are bound to not last. I perfer the helical gears in the upper, but too much power and you are forced to use XR uppers.
Hope that helps.
Dick
03-18-2014 | 05:50 PM
#27
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Joined: Jul 2007
Posts: 3,648
Likes: 32
From: Oneida Lake NY
When you swap from side to side the upper gear set still wears on the same side of the teeth on the input pinion gear, but it is now loading on the other driven gear. But the lower gears will switch sides. I have swapped the lowers from side to side when the gears are worn but not pitting. I have seen some that were pitted and swapped and they die an early death. I believe the pitting is caused by the soft inside (like an M&M) and the outer shell moving.. Once they pit, you swap them and now they M&M squishes to the other side and bingo they come apart. So depending on what your gears look like, it is a crap shoot as to being a good idea or not. I have installed new pinion gears in the upper and then flip the driven gears and that will be a benefit. Or take two reverse gears and a new pinion to make a set. ...
If you run a single, then you run it till it wears out. Same rotation. Does someone that has twins and swaps them get more time out of them? Well it isnt' and apples to apple comparison, so it is hard to tell.
Just what I have experienced over time..
Sometimes the teeth are so far off they are bound to not last. I perfer the helical gears in the upper, but too much power and you are forced to use XR uppers.
Hope that helps.
Dick
If you run a single, then you run it till it wears out. Same rotation. Does someone that has twins and swaps them get more time out of them? Well it isnt' and apples to apple comparison, so it is hard to tell.
Just what I have experienced over time..
Sometimes the teeth are so far off they are bound to not last. I perfer the helical gears in the upper, but too much power and you are forced to use XR uppers.
Hope that helps.
Dick
I will inspect again this year, last season was the first season on the bumped up 575s, I was nice to it for most of the year. Then two poker runs to end the season
03-18-2014 | 10:05 PM
#28
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From: Sarasota, Florida
4bus, Mr. Tyce explained that way better than I could have. He is spot on.
I will have to send the answers to your other question tomorrow as its getting late. I will not forget you.
Warren
I will have to send the answers to your other question tomorrow as its getting late. I will not forget you.
Warren
Last edited by SRQ; 03-18-2014 at 10:08 PM.
09-29-2016 | 04:12 PM
#29
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Posts: 140
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From: Chesterfield Twp., MI
Can anybody here identify this steel from the composition?
09-29-2016 | 06:04 PM
#30
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Posts: 4,806
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Whatever lab did the analysis should have a library of metals on hand for a look up. I'm assuming merc isn't using anything exotic. Might be time to find a new lab. This is elementary stuff.
