Rob, can you clairify.

Regular HP Merc gimbals.


Yup...no magical recipe can stop it but regular maintenance can save ya from failures! :cool-smiley-011:

Here are my lower gears after 100 hrs of ocean time... Shot peen was starting to wear away, no failures but going to replace with new...:cool-smiley-026:

Tomcei,keep in mind big,heavy boats chew up/blow apart upper gear sets,with a B-max this becomes a non-issue. High horsepower lighter boats (yours falls in between because its fairly heavy for a single vee) tend to chew up lower gears. The B-max (as has been stated) still uses merc bravo lower gears. Rob has told me his boat goes thru lower gears every 20-40 hours. I have over 1000 hp in a single vee but its even lighter then your boat (27 ft baja). My upper gears in my max worx bravo have over 200 hours on them,some at 750 hp,100 at 950 hp and another 25 at over a 1000,they still look like new. I contemplated going to a B-max several times but I chew up lower gears,not uppers so it wouldn't do much for me except slow me down. My lower gears used to last 10-15 hours,with cryo treatment and surface conditioning they are lasting 40-60 hours (1/2 a season). I hear that the new ht B-max has also done something to the lower stock bravo gears to extend the life but with 950 hp especially if you go to a 32 pitch or taller 4 bladeor a 5 blade expect lower gear failure under 100 hours,probably closer to 40-60. I have been working on this problem for 3 years now and have made gains but nothing that lives 100 hours let alone 200 hours. I spent alot of time testing gears the last 2 years,this past year I took it a step further and began testing gear coatings on top of what was already helping. I'm still in the testing phase with the coatings and have partnered up with bob madera/marine kinetics who has the resources and backing of a professional mettalurgist/test lab that is doing destructive testing/non destructive testing and lab analysis testing on our test gears. We are also working with a top gear manufacturer on a set of replacement billet gears that we hope to begin inital water testing on in the spring and bring to market if durable and viable. Our goal is to present a set of merc replacement lower gears that will last 100 to 200 hours with a 1000 hp. These gears would be the answer for guys like me who run modified bravos and for the most part are only experiencing lower gear failure and for the B-max guys who face the same issues of lower gear failure,Smitty

Thank you very much Smitty

I tend to agree... Also, high X-dimensions and step bottoms have the same effect.

If you do go with the BMax, ask them to use a SS prop shaft instead of the Carbon Steel Shaft... Even though the shaft is stronger you MUST keep i lubricated at all times.

I'm looking forward to seeing how the lower gear testing goes..... In 2-3 seasons when I'm ready to R&R these drives again, that may be an added benefit!

What's up w/ that?
Where the prop slides on the splines?

Nothing really up with it....they went with a carbon steel shaft because it's stronger...the downside is it can/will rust. As long as I keep my shafts lubricated it's not an issue. If you don't like to lube the shafts etc then request an XR stainless shaft instead but realize it may not be as strong....

got it :cool-smiley-011:

Just a quick note here.. Imco has a new drive out.. the SCX that looks to be better than the BMax. Larger gears all around. When they are available, I will be offering them to customers.. PM me if you are interested.

thanks
Dick

If the gears are larger, I wonder why the rating is 750 where as the Bmax is 950?

Any thoughts

After re-building a pair of IMCO's (Not the Sc's) on the Whipple boat - the owner decided to go with BMAX HT's.

The first go around wasn't so good as the boat didn't handle worth a flip and lost some speed. After removing the 1 1/2 spacer (running 2 inch shorties) the boat runs like a dream. I'm assuming the difference in weight made the hull ride lower in the back than with the IMCO's. These are 528 inch Hemi's making over 1000 HP and 1000 lb ft of torque. He's running either 36 or 34 pitch 6 blade Herrings on it now and has never had another drive issue........ knock on wood.

now the head gasket is another story in itself........

Capt Ross

I heard about that 2nd hand the other day. I believe there was an ad in Powerboat mag but there's nothing on their wesite. From what I heard they are only rated to 800 hp, which is the same as what the Extreme SC was rated for.

After the way I was treated by IMCO when my Extreme SC's kept blowing up I'll never buy another product from them.:(

The old SSM #3's and #3A's also had steel shafts.

We used to put stainless steel "speed sleeves" on the shafts where the propshaft seals were so the rust wasn't an issue... It was a little trick we learned out in the field... :grinser010:

I have a 26 ft howard cat w/ 1000 hp blown motor and made the switch to Bmax late last summer. Lost a few mph on top end but not blowing imcos any more.. so far im glad I did it. seems to be holding up much better....

Not trying to blast B-max but would never tell anyone to try it. We went through 3 or 4 drives in one year. Tower went once and the bottom went 3 times in one year. We lost a total of 12 mph with there drive and had to fight to get it replaced Deano did end up replacing it but not worth the head ache. Remanufactured xr is still alive through twice the abuse. I believe they had an honest issue with there bottom ends. Just my opinion.