drive height
 

hi i just bought a 1994 topgun with bravos and 800hp sc and it has a notch hull. Am looking to see if changing the drive height will help. The drives are 5 1/2 lower then the back of the hull now. any help would be great thanks

we are raising the x and adding boxes on my 92 gun. should raise the drive a bunch by the time I'm done. but its a TRS boat and raising the x on a trs boat can yield large gains. i know carter38 raised the x on his bravo cafe, not sure the gains.

I would think about changing the drives instead of the height, 800 hp in front of bravos on a gun wont live long.

what he said ^^^^ but if you want to keep the B-1, you might try some speed master or Imco shorties lowers

I not changing the x height. Am thinking imco or sportmasters lowers. just don't know it 2 or 3 shortie would work.

I not changing the x height. Am thinking imco or sportmasters lowers. just don't know it 2" or 3" shortie would work best.

I don't have any real world numbers for ya, I sold my bravo TG before I started messing with that, you can start at -2 -3 and always shim down, but like said before if your gonna run it hard those B-1's wont last behind 800 SC's

while on the topic... many are nay sayers on bravo style behind bigger go fasts... but if they are so bad, why are so many new boats, having XR's ? i found a set of XR and was going to convert mine for a bravo and everyone was against it... but if they are so bad, how come so many new guns, with 525 efi, or merc 700's and the like have bravos? 388 hustlers etc... never really understood it. if they are so bad why are the manufactures doing it?

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Merc doesn't offer XR's with 700's.....they have a hard enough time surviving behind 525's

Because manufacturers like to sell boats (bravos are cheap) and mercury likes to sell parts.I bet theres some real sweet mark up on a $1600 upper gear set.

Are the drive XR's or regular bravo's? Pics of the set up?

1 poker run, wasn't rough, 2 boats, moderate power 3 wrecked bravos. They're great.... For drive shop business

I've seen guys with moderate power less than 700 get Bravo's to live for a little while on larger heavy boats. Usually replacing lower gear sets every other year. If that is reliable then your right. But do a couple poker runs running hard in rougher water and those gear sets may last a season. The 800sc will eat a bravo alive due to the torque not the horsepower. Raising the "x" will only make things worse. Your best bet would be to go with and Imco SCX drive which can take the high power and torque.

I know this isn't what you want to hear, but after 4 or 5 drive rebuilds and your wife screaming at how much money this thing is costing you will be ahead.

Going with the IMCO SCX uppers and -2 lowers would likely be the hot ticket. You might be well served with the SCX-4, but I suspect you'd want to space it down a hair.

I agree with the the others, B1/XR uppers will not last long on that boat with 800SC's!!!

they reg bravos

I cant see why a bravo drive with a beefup upper case and a sprortmaster or imco lower wont lasts

You're going to be eating B1's like they are are popping out of a Pez dispenser! Strengthened case or not, they still use tiny junk gears which are the weak link in a B1/XR. The SCX uses a much larger gear set. Switch to the SCX while you're B1's can still be sold as functional drives and have value, this will take a lot of the sting out of paying for the upgrade. If you don't change the drives, prepare to be this guy...


http://img.escapade.co.uk/SALEHIRE/Large/4160.jpg?2

take the blowers off, put intake and carbs on and enjoy your ride

Maybe they will survive, keep us updated I'll be the first one to tell you I was wrong.

Homer Glen ? That means you`re going to be boating on Lake Michigan?

I read that STIHL Offshore Racing will be running DriveGuardian's this year. In theory it sounds like it might help a Bravo last longer (maybe not with 800s), but 500-700s maybe??? Think it's worth the money?? $2495 each. Has anybody run this setup??http://www.marinedesigncorp.com/our-products.html

Yes

I went from TRS, to Konrads, to SSM dry sump Sixes. 800 Chiefs were the constant power. I broke; TRS, Konrads, and transmissions. The failures would happen while cruising at 3500, 50 mph. The TRS were 5.5 inches below bottom, Konrads 3.75 below bottom. 6A's 1 inch above bottom. Same power, 6A was 12 mph faster. Bam 1350 transmissions now. I don't run mine fast. 62-63 mph at 3500 cruise now, up and down the coast of Florida.
Do yourself a favor and listen the guys on this forum. They know what they are speaking of. Bravos XRs are a great product up to 500 hp. Iffy at 600 hp, after that keep a spare in the bow. The Bravos on 800 plus hp are good if you idle.

I am now in the process of converting a #5 drive, staggered, 90 mph edition boat, to 6A SSM on extension boxes

Maybe we`ll see you around, you could jump on I80 and be in Portage in no time, that`s one of the launches we like.
I also have a guy in Homer Glen that does all my fabricating, (built new gas tanks, will be making my tails, Jason can do pretty much anything with metal/stainless etc.)
btw, Lake Michigan is not nice on drives, I had a 600CS in a 25' AT and in 2 years I went thru 2 drives.

Thats a good mph @ 3500 rpm, my Bravo TG was about 8 mph slower than that @ 3500

For now I have to stick with the bravos money wise. I guess the best way to go would be to put surface drives on . The motors have 70 hours on them since rebuilt and never broke a drive. I guess is it how you drive it the main question is will 2" shorty help with more top speed. The drive now are 5 1/2 deep

From my experience, I wouldnt worry about going 2 in higher. If your not going to do a drive upgrade then I would leave it alone. You might gain some speed but you might not. What are the possible losses if you go higher?

am in hammond marina

I plan on going with some gear mods I can get a pair of sportmasters at a good price. Just need to work something with the top gears.

17 3/4" x 32 x 15 rake merc 5 blades,

Just my opinion, but you should not buy a Cig to try and go fast. Just enjoy the ride, they are great quality boats, that run rough water when needed. The styling is timeless. The history wonderful. But it takes a lot of $$$$ and personal time to make one go fast. My Skater is faster than my Cig, but I love both. Different animals, for different days.

Cruise speed is usually where most bravos break. You are in the heart of the torque curve so the load on the drive will be the highest as the boat is not really aired out. That is the range where the drive temps will be the highest as well.
Good luck with the build. If you are looking for improved gears talk to George at All American Drive Service. They do CRYO and REM polishing of gears.

All American Drive Service
Shipping Address:
563 E. Chicago Street
Bronson, MI 49028
TOLL FREE: (877) 283-5465
Fax: (517) 858-1043
[email protected]

ZERO,

Which 90MPH did you pick up. I would love to do one of them someday.

That was my next call

Not mine, Mr. Picketts. Lock and Load, #4 of the 5. It lives here with mine.
We have the transom recut and the drives at paint. Waiting on driveshaft fabrication.

Hey Zero , do know what Mr. Picketts is dong with the hardare he is removing from the boat ?
On another note is the X dimension the same with the 6's as it was with the 5's ?

Rick G.

The boxes, #5 drives, steering, all went to someone in Michigan. The x was a pain in the ass. The 6a,s are longer than #5s. We had to use 12 " ext. boxes on the sixes to get the driveline to connect, or you move engines, buy new tailpipes again, fight hatch issues, etc. The sixes will be 12 " back farther than the 5s on boxes. So the height has to come up. Without exceeding max drive shaft angle. It took a little time to mock up, and some advise from John Pompi ( marine performance), and Chief Performance (Tommy), to arrive at a template location. We then drilled and recut it, filled all the old steering holes, #5 holes, airfiled it, and repainted. Then reassembled the six boxes and measured for new driveshafts. They are being built now.

Those drives will not last on lake Michigan with that setup. Unless of course you only take it out on calm days and baby it ever so gently. I wouldn't install shorties on that setup. Lake Michigan is rough. Bringing the props closer to the surface will just let them break free more often, and lead to more frequent drive failures. Going 85-90mph and having the drive let go sucks. Especially if you snap a standard bravo gimbal ring , which is a reality on a heavy top gun in rough waters with decent speed capability. I've seen boats sink and nearly sink because of that.

I would strongly recommend at minimum the SCX drives with the heavy duty transom assemblies. There's a reason cigarette ran #6s or #5's with that kind of power.

Been there and done that myself back in 93 south of grand haven. Not a good time. In fact one of the very few what consider down right scary moments,

I just bought a pair of IMCO SC totally rebuild -3 shorty I can always space them down

Calm days it is.