gregga

Hey guys,

I've never really messed around with the Speedmaster III or IIIA drives. My question is can someone school me on these drives?? Like what their hp rating is, how the transom assembly is different, the difference in gear ratios, just anything about these drives. Thank you guys.


Gregg

wannabe

The 3 and 3a drivea are generally good for 800 hp or so. Some people put more through them. The 3a has a bigger shaft. They are discontinued so parts are tough. Talk to Speedmasters inc in Florida. They know these drives.

Wannabe

gregga

Thanks bro, I appreciate it.

RMPRam

iTrader: (1)

The #3A has much more than "a bigger shaft". Everything internally is "larger" and stronger than a #3 and in my opinion a #3 is not "good" for 800hp. I don't want to start an argument, but to compare a #3A to a #3 is comparing apples to oranges.

tcelano

+1. Listen to Gary. He knows these things. I had a set of upper gears taken out of a SSMIII that had run 850 hp, and they had broken a couple teeth already.

SSMIII was "Capable" of 800+ in a racing environment with frequent rebuilds and attention. In everyday use, it's probably more like 650-700. It will still outlive a Bravo though, and they fare much better pushing big heavy boats. If you are in the market, IIIA and V's are still viable drives, and will get you more drive for the money than pretty much anything else. You can scavenge III transom/gimbal parts, then just bolt up a IIIA leg when you can find it.

The other weak area of the III/IV was the trim pins. The original was a rather absurd (my opinion) staked design. I've retrofitted a total of three #III gimbals with IIIA/V style pins. It takes a bit of machining, but well worth it even if they havent gotten totally sloppy yet.

Going back to the original post- III's and IV's are based off the same hardware. Virtually everything was the same except X-dimension and cases. These had the 1-3/8" 19 spline shaft. It is hard to find four-blade props for these. There is a pair of III's right now on E-bay that comes with four sets of props. They are the newer style III's that had a crescent lower gearcase compared to the original straight leading edge case. I don't know how many years they produced the crescent III before going to the IIIA.


There was a fuzzy time when some of the IV's were equipped with larger prop shafts. Ultimately, the IIIA and V were released, which got stronger gears, bigger shafts, the better trim pins, larger trim ram shafts, and a beefed up gimbal housing. The offical HP rating for these was 750. They've been run reliably at well over 1000. I've heard of people trying to pass off big-shaft IV's as V's.

IIIA's and V's can run the same propellers as VI's, just with a different insert (1-3/4" shaft vs. 1-7/8"). Both use the same 26 spline pattern. That reminds me, if you do start off with a III or IV drive, you can buy 26 spline props, and get adapters from Arneson. That way, you not only increase your prop selection, but you can keep using the props if you do upgrade to a IIIA or V drive. That's what I did. Needless to say, props for these are very spendy ($2000-$4000 a piece) compared to Bravo props.

gregga

tcelano- Thank you very much that was very informative and I really appreciate the help. One question though, if the boat is outfitted with a bravo is it really worth the extra money and parts to replace it with a III or IIA? I know these drives have to be run with a transmission so by the time you add up purchasing a drive, transom assembly, transmission,props, and various parts, and labor... would it almost be worth it to stick with a built bravo or even a BMAX if we could find a used one?

RMPRam

iTrader: (1)

In my opinion, if you are contemplating using big power, now or in the future, I would never consider a Bravo or any of it's derivatives as a choice for a drive. There are probably guys on OSO using Bravo's with big power, but I would bet they are or have experienced drive failures. You can break anything.

tcelano

Agreed. I wanted to do mildly big power, not nearly what some people are running. And nothing says more than putting your money where your mouth is. I rigged SSM V's and would not even consider Bravo setups. In fact I made a commitment to myself to never own a Bravo boat. I am on my second SSM boat, and I've never even had a drive whimper, and definitely no failures after 9 years.

That's why there is a whole cottage industry for Bravos, and the SSM parts are all just reused from one guy to the next.

gregga

What would be your thoughts on an Imco setup?? That way we don't have to mess around with changing the transom assembly and moving the engine forward ( which we don't believe we have the space for that as is) and getting into the whole customization aspect.

RMPRam

iTrader: (1)

Like I said, in my opinion, I would not have a boat with a Bravo derivative, which is what an Imco is. They will not hold up to big power, no matter what you do to them. If you plan to upgrade to more HP stick to the Mercury #3A (or #5) or a #6. This is only my opinion!