For the belt drive I'm Going to use a cvt torque convert which give it I believe 10:1 underdrive and also in theory be capable of 10% over drive For the spur gears I'm going to be using gears I bought out of Mcmaster carr, for the housing I'm going to use 6x10 aluminum tubing, The drive tube will be 3" od 1.5" ID aluminum tubing The jack shaft and drive shaft will be made of 303 series stainless steel the steel flanged mounted bearings will also be purchased from mccmaster carr. I am going to attempt to run special sealed wheel bearings for the drive and locking collars to hole the drive shaft in place. Oil seals will be purchased from a local auto parts store, I bought a transom mount off of ebay. This is kinda where Im at I will begin to post pictures of the build asap.

 

my ol' brain havin trouble following this..... top gear goes counter clockwise.... and depending on which small gear meshes with top/bottom they both will turn clockwise spinning the bottom counter clockwise.... :huh: :huh: :huh: :huh: :huh: :huh:

 

You will need two small gears on one side of your setup. Otherwise you will never get in reverse. Also you need to check the rpm limits for those spur gears (I assume they are straight cut gears). The gears will need to be enclosed and lubricated and you will need to incorporate a clutch in there somewhere.

Not trying to burst your bubble b/c I have been working on the same thing for a few months now and its a little more complicated than one would think.

Also a CTV setup sounds good on paper but you need to have a STRONG motor to make them work. Not very many CTV setups in the marine world.

 

ah....

 

ah crap.... now I thinking aboot it fer my motor...lol

 

You will need two small gears on one side of your setup. Otherwise you will never get in reverse. Also you need to check the rpm limits for those spur gears (I assume they are straight cut gears). The gears will need to be enclosed and lubricated and you will need to incorporate a clutch in there somewhere.

Not trying to burst your bubble b/c I have been working on the same thing for a few months now and its a little more complicated than one would think.

Also a CTV setup sounds good on paper but you need to have a STRONG motor to make them work. Not very many CTV setups in the marine world.

I was thinking about using a 20 hp motor with electric start. I had already thought of enclosing the geared section I knew it needed to be lubed if you will look at the drawing their is a divider seperating the cvt from the gears and their is also screw plugs in the side for filling the housing and a screw plug in the bottom to drain it.

 

guywithhat excellent design I think if you dont care i will use your design for my reverse.

 

lol... not mine.... i just went to the google trying to figure out how a reverse gear box works and found em on a dune buggy page... seemed relevant and the handle setup seemed good so I posted em.... I don't think I could fit that setup in my tiny chaincase... but if your going with a 20hp Iam sure your setup will be larger.. Make sure you post pictures of the build.... looking forward to seeing it.... as for my rig... I am going to simplify mine... less parts...

 

guywithhat If i were to use something like this i could could get rid of the chain slack all together and then it would shift into reverse smoothly.

 

there suposta be a large gear where the bottom hole is? looks like it... with top/bottom gears same size... input/output RPM would be the same... both large gears would have to have a chain gear or belt pulley attached to them to transfer the power from engine and to shaft....

 

Yes there is i just removed it so I could see how it was made a little better. Yes the top gear If you look at my assembly drawing would be connected to the torque converter via a jack shaft the bottom gear would be mounted to the drive shaft both gears would be the same size so it would be 1:1 ratio as far as the spur gears are concerned and that would let the torque converter handle the the gearing down and gearing up according to the strain on the motor and drive shaft.

 

Rough Materials List:
Item# Qty description From Price
1 1 Transom Mount Ebay 50
2 2 3x5x1/4 12 inch long aluminum angle Ebay 31
3 3 1x1x1/4 12" long aluminum angle Ebay 21
4 1 10x6x1/4 aluminum plate Ebay 15
5 3 1 ID oil seals Auto parts store 21
6 1 Drive shaft 1" stainless steel Ryerson
7 1 Jack shaft 3/4 stainless steel Ryerson
8 2 Sealed wheel bearings Motion Inudstries 55
9 2 locking collar Mcmaster Carr 20
10 1 Prop Ebay 150
11 1 Sandec electric tachometer Ebay 40
12 3 steel flanged mounted ball bearings Mcmaster Carr 100
13 1 6x10 Aluminum Tubing Ebay 115
14 1 4x8 sheet metal Ryerson 63
15 1 40 series Torque Converter Ebay 288
16 1 5"x1" Aluminum round stock Ebay 12
17 1 Motorcycle handlebar grips Ebay 3
18 1 1"x10 emt lowes 7
19 1 throttle assembly Ebay 9
20 misc. nuts bolts and sealants local hardware 100
21 2 16 pitch 14 tooth spur gear Mcmaster Carr 42
22 2 16 pitch 60 tooth spur gear Mcmaster carr 125
23 1 4" OD Aluminum round stock Ebay 24
Total 1,283

Realisticly I expect this build to cost me somewhere around the 1500 dollar mark.

 

torque converter would have a built in clutch I am assuming... wouldn't want to shift for/rev with it moving..lol.. you'll have to run some numbers on the torque converter to determine you output RPM.. floyd hopkins told me the 9x7 I purchased from him is best ran in the 3800-4200 rpm range... you'd want to be sure you don't over spin your prop at the top end ... and end up wasting power... I was just one the ebay looking at martin spur gears.... now you got me thinking...lol..

 

150$ prop on ebay? with a 20 hp... your going to be looking at a larger prop i'd be guessing...

 

That is the plan as of right now.

 

I had a little time today so I worked on the drive tube and the housing. I rough machines the bores for the bearings I left .050 in them to finish machining after the flange is welded on to the shaft. Once it's welded I'll put the assembly between centers and turn the flange and outside of the all true with one another then ill chuck on the outside and indicate the it in to the outside and turn the counter bores true with the outside. I drilled and tapped holes to mount the transom mount and to mount the motor mounts. Tomorrow ill get the bottom plate welded and then ill drill and tap to mount it and ill finish the motor mounts.

 

hot damn dats some fancy work right thur...makes my welded water pipe look like poo.. think I might go have a beer and cry about it...lol keep the pictures a comin tho...

 

Thanks guywithhat if I progress far enough tomorrow ill post more pics

 

I got a little work done on the motor yesterday. Welded the flange to the drive tube. Drilled and taped the bolt hole pattern into the housing. Ill work on the motor mounts today

 

lookin good.... just be sure to support the tube while trailering... my buddy wilgosh didn't... and he used the cast outboard mount too... it split at the top and he dropped his 16hp Vtwin and shorttail setup doing bout 80-90km/h....
I keep my 1232/6.5hp on a tilt n' load utility trailer backwards with the tube strapped down to the trailer tongue. also makes it easier to unload into a ditch or creek... just tilt trailer bed, and kick the boat in... I load it nose first then spin it later on the trailer. actually the same buddy who dropped his motor tried putting his into the same mud hole as me.. but transom first... the transom dug in and he had to drag it off and pull the trailer out from under it.. then try to turn it around and get the nose pointing up the creek... not as bad if you have reverse I guess.

 

Speaking of reverse I've also solved that problem as well I think. I'm going to use a planetary gear set up its small compact and effecient. Very similar to this kind it set up.

 

My forward reverse gearbox some of my bearings and pulley came in the mail today.

 

Well I had some time this morning so I decided to bore my drive tube for the bearings and thread the ends for the locking nuts and end cap. I also made my motor mounts this morning along with the locking nuts and end cap and pressed the seal into the end cap.

 

pictures continued

 

That thing is starting to look great. How much hp is that planetary setup rated at and how much hp do you have? I looked at those alot but wouldn't hold the hp I was putting out. Are you running a clutch of any kind or does that planetary setup have neutral?