BMAX or IMCO
 

Looking for a new drive for 29 single 525efi any input? THANKS

Bone stock 525?.........stay with merc XR, and be easier on it. Uprade internals if you must.

F the XR i want to drop the hammer and still have it last!!! The 525 can handle it, y can't the drive....

I have some imcos in the classifieds for sale.

Droppin' the hammer on that engine (or any BBC for that matter) all the time will blow out just about any drive eventually. Gotta be easy, unless you wanna strap a #6 on the back of that thing.......but that doesn't necessarily mean be a wuss either. I talked to a very reputable engine builder a few weeks ago and said he had a guy running twin 770's on Stock Bravo 1's. Over 100 hours, no issues. Drive failures more often than not are a result of operator error. Remember, they're all gear-REDUCTION. my 2c

Just want to run WOT for 30 miles and not boil the oil, i'm not running wot in 4'+ water and not backing off.

I had outdrive failure las year so please explain do you not hammer it at all or jus till you plane out? I cant make another $1800 mistake.

had a friend who went through 3 sets of bravos on his 36 OL. He switched to Imco 3 seasons ago and hasnt had a problem. He drives fast but doesn't beat on them.

I wait until i plane to drop the hammer, just tired of replacing bravos after 80-140 hrs. 1-2 years for a drive isnt acceptable

What prop you running?
How many rpm at wot?
Do you have a halo style drive shower?
What gear lube do you use?
What part of your drive keeps breaking?

Prop is 23 Hydromotive 4 blade, turns left hand
WOT is 5300 rpm
I do have halo style drive shower
I use Mercruiser Gear lube
sheered a tooth off of upper gears.
I DO NOT RUN MY BOAT HARD!

Do you ever get put in gear above idle speed?
You change out the gear lube every season?
Always check the Halo for clogs, a floating piece of wood gets in there from time to time.
I'm also trying the Cryo treatment on the gears, should make them a bit more wear resistant.
I would open them up every 2 seasons though.
Everything checks out with your application, switch to a GL-5 Grade lube....The Merc stuff is out dated.

Please explain GL-5 lube

Best examples...

API Category GL-4 designates the type of service characteristic of spiral-bevel and hypoid gears in automotive axles operated under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications.

API Category GL-5 designates the type of service characteristic of gears, particularly hypoids in automotive axles under high-speed and/or low-speed, high-torque conditions. Lubricants qualified under U.S. Military specification MIL-L-2105D (formerly MIL-L-2015C), MIL-PRF-2105E and SAE J2360 satisfy the requirements of the API GL-5 service designation.

API GL-4 and API GL-5 products typically use the same extreme pressure (EP) additive system, with the API GL-5 having about twice the concentration of a API GL-4. In service, these additives become active under extreme load and temperature when the protective oil film can be squeezed away. EP additives work by forming wear-resistant compounds with the metal of the gear tooth surface. As the gears mesh, these compounds shield the gear teeth from direct metal-to-metal contact that would cause wear and damage to the gears. If too little of the active additive is present, proper protection would be compromised.

Is the viscosity the same? Flow through the oil journals and flow from the resivior bottle in bilge? I know these are dumb questions but I want to be sure. Thanks for the information!

Actually it flows better because it appears thinner and is more stable at higher temps.
GL-5 Marine Lube
http://www.amsoil.com/StoreFront/agm.aspx

I'm going to try this one next
http://www.amsoil.com/StoreFront/svg.aspx

Sticking it from 3,800 rpm to full WOT with one jab is just as hard on them as coming out of the hole hard, if not worse, as you're way up there in the torque curve then. It is possible to accelerate like a banshee and still not risk drive failure/gear wear. Smooth is fast.

Hey Back4More have u had any problems w/ your bmax, i like the fact you can get a 3 year warranty no body else will step up like that.

Have a friend on the board here that has a 29 with a Tyler Crockett blower motor. Got tired of braking bravo's and went with Bmax also, broke that also then had warranty issues with Bmax, didnt want to stand behind it. It also slowed the boat down by a few miles per hr.

I switched to Royal Purple, had the lowers cyro treated when I went with the shorties. But I still really watch the stock Bravo uppers. We'll see how long they last.

You have a friend? :D:D

Sorry 'should have clairfied that, I had 1 Friend:cool-smiley-011:

b-max's WILL be slower, do break, and also in a 525 application will move the weak link to the gimbal ring and/or helmet due to the "added strength" and x-tra weight.
i would suggest an XR sportmaster shortie from merc with a good drive shower or even the drive oil cooler thats on the market. imco over the bmax as well for the same reasons.

I 've had others say IMCO will slow me down also, just tryin to find a bravo style drive that will last. Thanks for all the info

max machine werx?

depending on the speed of the vessell, bulett style cases usually dont have much of a positive effect until the 90 mph mark. same holds true for shortie or not.
imco on a personal back to back to back test on same boat same ratio and so on yeilded highest speed from the imco with most stability coming from the merc sportmaster lower due to skeg.

The boat only runs 80, I've heard that the bullet style lower will slow you down cause the 29 single likes more trim. Dont know I never tried one.

U running Max Machine ?

I Run the Bmax uppers with IMCO -2 lowers...
I have a non step and like the IMCO lower design better than the Merc Sport, don't need the oversized case and skeg slowin me down.
The lower is the weak link with the vertical shaft bearing and the XR gear set.