Beefing up a Bravo 1
12-14-2011, 09:54 AM
#21
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Poker,
It is ok to run the XR lower. The lower cases on the B1 and XR lower are the same size. The only difference is the propshaft, bearing carrier and lower gears (driven gear has a larger hole in it to fit the tapered splines on the XR propshaft).
There was a short bullet on the 88 drives, but since they made it longer, the dimensions have stayed pretty much the same.
Hope that helps.
Dick
It is ok to run the XR lower. The lower cases on the B1 and XR lower are the same size. The only difference is the propshaft, bearing carrier and lower gears (driven gear has a larger hole in it to fit the tapered splines on the XR propshaft).
There was a short bullet on the 88 drives, but since they made it longer, the dimensions have stayed pretty much the same.
Hope that helps.
Dick
I destroyed an xr as easily as a bravo1. For me it's just easier to have a couple extra b1's laying around then fix the xr. I can get b1 in good shape for 800 to a grand. That's two for the price of an xr rebuild. I use an imco shorty now so the lower question was more for the orig poster having one on his b1. I have seen some guys think they are helping their drives.
12-14-2011, 10:35 AM
#22
I have been running IMCO SCs on my boat for 64 hours now. I have 900HP aside and i have not had a problem yet. I turn them to 6000RPM every time i go out. 1.36 ratio 36 pitch props. My season is over now and would like to have someone tear my drives apart and see what should be replaced. When i emptied the drive oil there was alot of shavings. I live in Windsor Canada and was looking for someone within a couple hours drive. Any drive experts near me.THANKS
12-16-2011, 07:10 PM
#23
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Drive Identification
The reason I recommend the helical gears is because of the poor track record the XR upper gears are having these days. My theory is, if you dont have enough power to knock the teeth off the helicals, stay with them. A Procharged 950 hp 24' Checkmate is running the helicals without problems. Others in the 800-850 range are also. I agree, if you can find a good set of XR upper gears, they are stronger, but if they last 10hrs, well not such a good deal. They used to last 250hrs on a regular basis, not now. I have a set (XR) I pulled out of my personal drive with 300 on the driven gears and about 270 on the pinion gear that show no signs of pitting.. They were made around 2002.. Ran approximately 700hp through it.
I would rather see someone buy a B1 X upper.. add an XR ribbed top cap (well built comes with bearings and relatively cheap) with a stud kit, and you have a good drive. 550hp is not that much power these days..
Dick
I would rather see someone buy a B1 X upper.. add an XR ribbed top cap (well built comes with bearings and relatively cheap) with a stud kit, and you have a good drive. 550hp is not that much power these days..
Dick
Thanks.
12-16-2011, 10:47 PM
#24
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I have been running IMCO SCs on my boat for 64 hours now. I have 900HP aside and i have not had a problem yet. I turn them to 6000RPM every time i go out. 1.36 ratio 36 pitch props. My season is over now and would like to have someone tear my drives apart and see what should be replaced. When i emptied the drive oil there was alot of shavings. I live in Windsor Canada and was looking for someone within a couple hours drive. Any drive experts near me.THANKS
Mr. Gadgets is a GREAT guy and I trust all his advice. He does good work on drives also.
But 900hp will break any bravo based drive, and if they don't break they will wear out much faster.
OP, Mr. Gadgets can set your drive up to last though. Especially if you run his oil, bravo shop oil, something better then the mercury oil!
12-18-2011, 09:14 AM
#25
Charter Member #601
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Inspector,
The XZ had the old style input shaft ujoints (with grease fittings). So that is one other difference between the newer B1X. The XZ serial would start with OM.. Not sure when the B1X came out, so it could start with OM, but OW would not be an XZ. OW's are hump backs.
If you have a drive with 1" propshaft, and it uses the XR upper case (retainer nut on the input shaft has holes instead of tabs), then it is a good bet it is a B1X. Same XR upper case with old style large unjoints (grease fitting) and 1.25" propshaft, could be an XZ or XR. You would have to pull the back or top cap to look at the teeth on the gears.
There are some that can look up the serial number and give more details, I dont have that info.
Best way to determine what you have is to open it up and inspect it. Decal sets usually head you in the right direction, but they can be misleading is some cases.
A stronger upper case, well in my opinion the B1 is stronger because the input snout is thicker where the retainer nut threads are. But you have to add a steel tower to the case to finish that statement. The newer the cases are (mid 2000's) the more meat they seem to have. So if you are shopping there a lot of things to look at. I have seen one XR upper case that the tower pulled the threads out of the case (all I saw was the case, not sure what caused it). Merc towers thread down 1" into the case. When a tooth snaps off the XR upper gears, it can push the pinion out the front of the case and in most cases the snout is cracked right at the thin spot on the threads. So nothing is bullet proof. They all have weak spots. And that is what the chase is all about, fixing the weal spots.
Hope this info helps.
Dick
The XZ had the old style input shaft ujoints (with grease fittings). So that is one other difference between the newer B1X. The XZ serial would start with OM.. Not sure when the B1X came out, so it could start with OM, but OW would not be an XZ. OW's are hump backs.
If you have a drive with 1" propshaft, and it uses the XR upper case (retainer nut on the input shaft has holes instead of tabs), then it is a good bet it is a B1X. Same XR upper case with old style large unjoints (grease fitting) and 1.25" propshaft, could be an XZ or XR. You would have to pull the back or top cap to look at the teeth on the gears.
There are some that can look up the serial number and give more details, I dont have that info.
Best way to determine what you have is to open it up and inspect it. Decal sets usually head you in the right direction, but they can be misleading is some cases.
A stronger upper case, well in my opinion the B1 is stronger because the input snout is thicker where the retainer nut threads are. But you have to add a steel tower to the case to finish that statement. The newer the cases are (mid 2000's) the more meat they seem to have. So if you are shopping there a lot of things to look at. I have seen one XR upper case that the tower pulled the threads out of the case (all I saw was the case, not sure what caused it). Merc towers thread down 1" into the case. When a tooth snaps off the XR upper gears, it can push the pinion out the front of the case and in most cases the snout is cracked right at the thin spot on the threads. So nothing is bullet proof. They all have weak spots. And that is what the chase is all about, fixing the weal spots.
Hope this info helps.
Dick
