darin

I have a baja 272 with a 540 with an 8-71 blower and supper chiller. I started out with an imco extreme 1.36 ratio and it lasted a couple months and then broke the upper shaft in it. I switched to an imco extreme with 1.50 ratio and broke it the first time out. ANY SUGGESTIONS ON WHAT TO TRY NEXT ?

articfriends

How much power are you making and what prop are you trying to turn? I have the same boat and have ran big power in it for years (my blown 540 made 944hp/967 ft lbs of tq 3 years ago) and am now running over a 1000 hp in it ( haven't really started beating on it super hard yet with latest motor set-up). I usually run a 30 labbed bravo up to 6000 and run 90 mph,run a 32 labbed at 5700-5800 when running light and see 92.5 to 92.8 (gps) and plan on mid 90's to low 100's with the new power but haven't been there yet. I was chewing up lower 1.50 gear sets every 10-15 hours but have cured that,have sheared off 1 max worx billet prop shaft but it had over 200 hours and I was trying to run a 5 blade maximus prop. Sheared off a max worx billet vert shaft a few years ago driving like a retard torque loading the boat repeatedly from a slow rolling start but for the most part my Max machine worx drive has the same upper and most the same lower parts in it that I bought years ago. Give us some more info and some dyno and speed gps numbers if you have them,I can tell you I never broke a prop shaft ever even with all the tq my motor makes until I bolted on a 5 blade prop then it only took a few (about 10) passes and I sheared one right off,I stay away from 5 blade props,Smitty

fastlane40

Smitty every post of yours i read mentions this 5 blade phobia.Man your scaring me.I just unpacked my new Maximus.Makes my XR look like an alpha.You'd swear it has twice the surface area of my 34 Bravo.Are they really that bad?

Wild Card 09

Smitty´s right, you know. I´ve got two Maximus´s here. A labbed and an unlabbed 26", and although the midrange pull is amazing and the labbed prop comes pretty close on the 80 mile top end of the Bravo, it feels like the there is a giant octopus hanging on to the back of the boat and the motor is trying its best to break free.
Its an XR killer for sure. I´ve only run the five blade on one poker run and two test sessions, but will stick to 4 blades in future.

Coincidentally, both my XR and the Imco extreme on my buddy´s Aero Tek have died in the last tthree weeks. Both have around 120 hours on them.
The Imco has thrown a UJ out of the side, when running at 90 mph.

The XR suddenly spilled all its drive oil into the belows and on into the extension box, last weekend. We are stripping it down, this week.
Definite, lack of drive, here!

Mr Gadgets

The 8-71 will help you make lots of torque when the hull is at it's wettest point. That load is very hard on the drive, wheater it be an XR or Imco Extreme. They use the same gears and other parts internally. That fact has to be kept in mind when operating a boat with a blower.
Anything that puts more torque or load on the drive is potentially a drive killer! Plain and simple!

Like Smitty says, give us more info. You may be able to go to differnt type of drive or modify your driving habits to help the situation. Plain fact is, you have too much torque for the Bravo style of drive, comprimises have be made in order to get any kind of servicable life out of your drive.

Hope this helps.

D*ck

Bad Influence

...is there a difference in torque / load on the driveshaft or
vertical shaft between 1.36 and 1.50 ratio?

Bad Influence

RBeyer

I did my share of homework when I purchased my B-Max. If you are under 950 ft lb and hp they will warrat uo to two years. I am almost thru 1 year with no problems. Procharged and modified 280 Velocity.
Bob

articfriends

I talk to alot of guys on the phone in regards to getting their gears treated,I hear time and time again where someone has a single with fairly big power and drive is semi-reliable (like mine),they bolt on a big azz maximus and next thing you know they are breaking parts they have never had a problem with before. Alot of these single engine boats run anywhere from 15-25% slip,the big 5 blades drop that to below 10%,there isn't really any top end gain,just mid range but the stress on the drive is definately higher. I have talked with alot of guys running cats and twins though with higher x-dimension's that are running labbed 5 blades without major constant problems,I think its the single engine vees that don't like it,and thats only my opinion,i'm no expert by any means,Smitty

articfriends

Any more info yet?? I'm interested to hear your set-up being I have a very similar boat,Smitty
You can call me at the number on my signature too,I'd love to hear the details on your 272

Croozin2

Not pointing fingers here but that was going to be my question. We didn't get a lot of info on setup and driving habits. You really need to be prudent with the throttle if you want to make a Bravo-style outdrive live with big power, no matter what the brand.