Speedmaster 5s
#41
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iTrader: (3)
I have new straight cut, near net forged, polygoned upper gears for the #4. The gear is the same as the #5, only the "shank" that the polygon shaft fits into is sized for the #4 polygon shaft and the bearings for a #4. It is a definite upgrade from the stock #4 upper gear. I only have them in a 1.31:1 ratio though. Combined with a 1.125:1 lower gear set, the overall drive ratio will be 1.48:1. I can supply new "big shaft" 1.75" dia. propshafts for the #4 drive also. I would not recommend changing any of your internal pieces for these, unless it is time for a complete rebuild of your drives.
Let me know.
Gary
Let me know.
Gary
#44
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Years ago, merc had the #3 drive, used in racing. Then the competion began using surface drives, and merc's response to that was the #4. As time went on, the #3, evolved into the 3A, and the #4, evolved into the #5. The 3A and #5 were stronger than their predecessors.
Not exactly sure when the 3A and V drives came out, but many of the big power raceboats of the early to mid 80's were running regular old #3 drives with success. The #6 drive pretty much elminated the need for all of them. The nice thing about the IV and V drives, is that on some hulls, they gave the clearance needed to run high drive heights. You will see some older fountains with III's or IIIA's installed, and to get a higher x, the transom assemblies were pretty much cut into the rear of the deck joint. My older fountain, has ssm IV's, and they actually lowered the engines, when they re-rigged it from TRS, and my propshafts are about a inch below the bottom. I am able to run blowers, under my stock hatches. There would be no way to accomplish that on my hull using a #3 or 3a, especially with my molded in swim platform.
#45
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So, would you guys chose a #5 over the new Imco SCX stuff on let's say a 38' boat with 900 HP? Would it be basically trading speed for reliability? Meaning the #5 would be a faster drive but may give you problems with this combination of boat/HP versus a more reliable SCX that robs several MPH.
#48
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Yeah, trs through #6 all use trannies....basically a bravo type drive is the only drive that shifts in the drive itself. Yes they all use the same basic trannies but the more power you run the more mods have to be done to it.
#49
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Well I am running well over 1000 hp thru mine, they dyno'd at 1077 and 1084 when we freshened them up this spring and I have never had a problem with the drives, I did have tranny issues until I went with the Huber HM1450's then that problem went away. The drives as far as I am concerned are bullet proof.