upper or lower ?
 

what is the weaker point on a bravo1 drive the upper or the lower,, im going to about 650 hp in my 32 active thunder this winter and im going to go to imco lowers and the bravo 1 uppers.

Also have 2 bravo 1 lowers 1 just rebuilt this past summer and the other about 50 hours ago both built by a marina and are working great. 2000.00 for the pr OBO

At 650 hp you should go with the Imco SCX drive. Bravo 1 won't last. If you want to stick with the bravos upgrade to XRs they will stay together a little longer.

uppers are the weak link and even XR's will be slightly under rated at 650hp......I have 630 (but 700TQ) and finally blew an upper after 90 hrs.

Quite honestly you could have gotten by with regular bravo lowers bolted to XR uppers.

Uppers for sure., and the LH rotation drive even more so. I blew an upper on my Pantera and the lower was fine. Bought an Imco upper and bolted up the stock lower. Never had a problem with 300hrs of use behind 550HP.

My thing is i need nose cones on my lowers for my set up and imco lowers alresdy have them built in and from what i here they are faster than stock bravo lowers.

You may need the lowers, but for a different reason.....you may need the nose cones for speed, you need the stronger uppers to keep from having to paddle that thing home! :)

So what do you guys recomend for drives for my application maybe imco lowers and xr upper or just put xr parts in my bravo uppers and go with imco lowers.

650 hp will blow an XR upper eventually, a regular bravo upper won't last nearly as long. The IMCO lower will probably help you run a little faster so you have to decide if you can afford to up-grade both 1/2's. If not, you need the uppers first.

upgrade to what.

I would put minimum XR uppers. Some say the IMCO upper is better than the Merc XR and that something like the SCX drive is way better. I have no experience with anything other than the Merc Bravo and Bravo XR. At 650 hp I just know the regular Bravo upper will be way over it's rating.....hell, that's over the XR's ratings. You could run it like you planned until you blow it up, just don't be surprised when it goes.

Just depends on how much $$$ you can spend and what potentially sitting on the docks in the summer are worth to you. I keep a spare XR ready at all times. Blew an upper this summer and was back on the water the next day (actually it blew on sunday, was on the water the next sat AM). Took a couple weeks til we tore it down and found out what needed to be bought to fix it.......almost everything! :(

I'm putting about 700hp through standard bravos at 5400rpm. The weak link seems to be the top cap. Both of recent my upper failures were WOT in very rough water. One rotating with pressure on the top cap in forward, wiped out the gears. The other with forward pressure on the lower gear, over zealous throttling caused feedback to the gearset and popped it out of gear then WOT back into gear, broke the top cap.

I have also twisted off propshafts in big water. If you are not in big water or you can control yourself better than I, your bravos will live fine with a billet top cap and a good shower. Upgrading the propshafts to 1-1/4 would be wise as well and not all that expensive.

If I were you, I would just put nose cones on the drives that you have and run them. They won't last forever, but should survive a few seasons with good throttling habits.

95% of my running is on a pure flat river and a lake the same, i do 1 poker run where depended on weather conditions can get 3,4 footers, i also baby it onto plane never over 3000 rpms and I ease it to wot, i dont just slam the sticks down. i have good drive showers so you think a billet cap and bigger shafts and nose cones and let her go. my hp may not be quite 650 any how but it will be at least 620 and the boat is not that heavy.

Thanks Rick

I run nose cones on standard bravos. I do poker runs and usually run pretty hard. I run in the upper eighties to low ninties and the nose cones seem to help. I would feel pretty good about my drives if I had the bigger propshafts and better caps. I'll probably work on that next season. The only reason I would pop for the imco lowers would be if I wanted to raise the propshafts 2". But I am already up 2". How about you, could you gain some speed raising the props?

my 32 active thunder has a high x now so i think i need to stay standard length, maybe i should just put nose cones on my bravos and billet caps and let it at that. i was running 87 mph at like 18% slip and in my rev limiters, this year i should be another 50 hp or so and proped right with the nose cones pulling down my slip numbers and i hope to see mid 90s.

I really don't think you'll have any major issues with regular Bravos with the type of boating you do. Stronger top caps couldn't hurt, but I really don't think you'd need them. What you may think about is looking for a deal on a spare drive, just in case. Not because I think you'll need one, but because if something is going to break, it will do so at the worst time and when you can't find a good price on another one.

I also was thinking nose cones on your lowers and start shopping for a spare would be a good idea......ever notice you never need the things your prepared to replace??? Those stronger top caps aren't that expensive and not a bad investment either.

rssteiny,
I have two customers with 32 AT's. One with XR's on stand off boxes and one with XZ's without. Both are running Imco -2". Both in the 700hp range. The one with the XR's wore the gears out.. The one with the XZ's the uppers are still going strong. Not really an apples to apples. But my opinion has always been that if you dont have enough power to snap the teeth off of the helical gears, they will last longer. Both boats have been driven with respect, that is THE most important factor. A properly setup B1 with good top cap, will go a long way when driven with respect.
The lowers are better with the XR propshafts, especially if air time happens and you dont have the feel for driving in that type of water..
XR upper gears have been snapping teeth off in the past couple of years, where they weren't before that. Hopefully someone will solve that problem in the future..
If you want to put bigger power and drive it without respect.. Then you will be better to step up to a drive like the SCX..
But everything will break if you try hard enough..
If you have questions.. pm me or you can call me.
Hope this helps.
Dick

Very true! And then sometimes even when abused.
A friend of mine took both of his mid 90's drives and made his own steel towers for the uppers and also his 1" thick AL billet caps. Studded the housing and never had a drive break yet. He is running huge power (don't know HP, other than it pushes his 32 Fever in the upper 90's) This was a good 3 yrs ago, still going strong. He is also using the original gears, not the upgraded X-gears. Last yr he was makeing a video of his boat in front of our marina and was going full throttle from a dead stop to test the drives and caps. He uses his boat as a test platform since he does the steel tower and custom caps as a sideline of his business. He knows just 1 speed when out running, and it ain't slow. :)

I forgot to mention, I have been installing steel towers in the B1 cases for some time now.. I also can sleeve the snout where the pinion bearings wear into the case.. With the XR ribbed top cap that gives steel towers on both ends to locate the gear stack. External drive cooling and filtering helps keep the lube clean and cool for better operation..

Who has the best top caps for XRs?
I need a pair

Thanks

Buy the stock XR caps from Merc for the XR's. They already have the bearings and race installed. Price is hard to beat too!

With any new cap the deapth of the race needs to be measured between old and new and the race thickness adjusted to compensate or the new cap will affect gear lash.

And use studs on the cap..

Dick

Would this be the case if installing a new Merc cap in place of an existing Merc cap?

Would it be an issue if new cap was part of a rebuild where the entire drive is done with new gears, bearings etc?

This is an issue any time you attempt to just swap caps.. They should be measured. The XR ribbed cap I use has a little bit different depth than a standard XR and lot on a standard B1.
If the drive is being set up with new gears and the lash is done by the new method Merc uses, then the cap doesnt need to be measured, because in the process the gear depth is set by adjusting the shim for proper lash. In other words it takes care of it.

Hope that helps.
Dick

32 THUNDERS RUNNING 2" SHORTS INTERESTING AS THEY HAVE A HIGH X TO START WITH, WHAT KIND OF SPEEDS ARE THEY RUNNING WITH WHAT POWER AND PROPS AND RPMS ARE THEY USING NOSE CONES , THIS WOULD BE VALUABLE INFO FOR ME AS IM BUILDING POWER THIS WINTER. THANKS

Is there a website?

rssteiny
I dont know the full setup on both boats.. I know the one without boxes is 700hp at around 90mph, with 4 blade props. The other with boxes was a tad faster, I think and ran 5 blade props. That is all I can tell you. If you pm me your number I can give it to them and see if they would call and talk to you about it..
Dick

xr caps
 

go on ebay and search bravo xr. they have stainless steel caps that you will never break for under $300.00

fevermarine.com