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V drive torque brace

Blown72GN

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Is there any rule or guidelines on length and angle when bracing tour drive to tour stringers? I was goimg to go from my mid plate close as i can to the case half to the outer edge of my drive shaft saftey collar cross brace seeing how it crosses my stringers and block me from going further back towards the tranny mount/ rail plates... this ends up giving me a brace length of 9-1/2"at a 30° angle.... im using 3"×3/16 6061 plate
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SoCalZero

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Not sure if there is any guidelines. Maybe it comes down to space in some instances. Here is my boat in the top picture and a boat a year older the braces are forward. I believe they did battery under seat so braces wouldn’t fit going back.

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Blown72GN

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Thats what i kind of thought. As long as there triangulated to the stringers and support the drive closest to the center as possible. Its been almost 6 years since the lew larson 572 has been in it and 1000+ hp through a unbraced drive are starting to show. Its eating the top bearings in the drive and theres slight signs of movement on the vdrive mounting feet on the stringers... definitely need to do something
 

Blown72GN

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The biggest job of the bracing is not the rotational movement from the motor but to restrict the forward force of the prop shaft that wants to screw into your boat.
Thats what talkimg about... boat wasnt originally rigged for big power... really needs a major re-rigging.
 

BamBam

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Thats what talkimg about... boat wasnt originally rigged for big power... really needs a major re-rigging.

I agree with your statement. Your other statement in the Gearing thread about it being a handful over 80 makes a lot of sense now that I see the v-drive placement and angles. Fast boats with big power will have that shaft angle much lower and the v-drive will be a couple feet further forward. That will make your boat carry better and handle the speed without being as much of a handful.
 

Blown72GN

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I agree with your statement. Your other statement in the Gearing thread about it being a handful over 80 makes a lot of sense now that I see the v-drive placement and angles. Fast boats with big power will have that shaft angle much lower and the v-drive will be a couple feet further forward. That will make your boat carry better and handle the speed without being as much of a handful.
9° strut 12° hd split case 1-1/8 shaft 3 blade 11.75 ×16 (could be a 15p) radiece. Prop is stamped radiece and cant make out the other stamping...11.7....... then it fades away. Pulls hard to 7400rpm with 32's in the box. Being stamped radiece would make it a tom Bentley prop right? (Kindsvater?) Not a menkens?
 

Blown72GN

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9° strut 12° hd split case 1-1/8 shaft 3 blade 11.75 ×16 (could be a 15p) radiece. Prop is stamped radiece and cant make out the other stamping...11.7....... then it fades away. Pulls hard to 7400rpm with 32's in the box. Being stamped radiece would make it a tom Bentley prop right? (Kindsvater?) Not a menkens?
Still a few old skool nicson bronze parts down there as well... tiller arm, shaft log, rudder stuffing box, turn fin, and 😬 yes... glenwood bolt on strut... although it is braced.... not a race boat by any means more a quick beer hauler/sand bar hopper... but..... still not the desired equipment for triple digit speeds and yes ive been 107.6 with the current setup..🤐
 

vdcruiser

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What hull is this? and you definitely need to attend to the rigging, strut location and angle if you are going that fast. I run a 7.5 deg strut in my 21 Howard and the V drive is much further foward than yours.
 

Blown72GN

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What hull is this? and you definitely need to attend to the rigging, strut location and angle if you are going that fast. I run a 7.5 deg strut in my 21 Howard and the V drive is much further foward than yours.
Its a 1972 Howard 20' GN deck. You are correct...The 9° strut and 12° drive dont help high speed stability at all. Ive been looking into a fabricated strut as bronze is a big no no with the power im making... bought it that way... i didnt really want to move the strut forward, change the angle and fill/move/ re-drill the shaft opening as well as move the drive or change to a 10° box. I just dont have the time or money to under go such major changes right now... but my plan was to have connelly marine copy my current strut with a cromoly one. Also currently looking for a new rudder now swapping the GN/cruiser one for a wedge. I already have new 3/16 t6 cav plates that are 4 inches longer...current ones are 12" past the transom ( 1/8" plate) as well as adding 2 more turnbuckles in effort to lessen plate deflection. and lastly add some gear to try to bring the cruising rpm down around [email protected] 50~55 mph. My end goal is a quick river cruiser that will comfortably seat 5 run the river all day at 55 and be able to touch 100 on the big end. My poor mans version of a 21rc lol. Wish this thing would ride like my 20' mandella.
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Nailhead

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We’re rigging a 24’ Campbell with about 600hp. I had all the under water gear fabbed out of stainless and moved the strut where it should be and did away with the single cable steering. Plans are for more HP once it’s up and running. You just can’t trust the old bronze underwater gear with lots of power.
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oldschool

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