Mercruiser Drive shaft spec

[Dumpy48]

Hi,<br />Does anyone have the factory dimensions of the driveshaft splines for an Alpha 1 ?<br /><br />thanks for looking

 

[Don S]

Re: Mercruiser Drive shaft spec

No dimensions, but what are you trying to do?

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Hi Don ,<br />Thanks for your interest.<br />I am marinising a stock Honda Vtec 4 cylinder unit with around 190 bhp .This will be coupled to an Alpha 1 . I am having to fab all the parts ( exhaust , mount brackets etc. ) as there is nothing I can use off the shelf . The current crop of drive couplings look as though with the ammount of work needed to mod , I'd be better off starting from scratch ! I would imagine they are Chevvy clutch plate size but can't afford to guess<br />wrong .<br /><br />Thanx

 

[tommays]

Re: Mercruiser Drive shaft spec

Dumpy<br />just wondering what you doing to EFI to make it marine<br /><br />tommays

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Hi tommays ,<br />Thanx for asking .<br />These Jap motors produce good power with torque with a terrific gain in lower weight .<br />I'll run the motor with the stock ECU /EFI to check power profile and remap if necessary .<br />The stock ECU has a 28 pin DIL chip which is relatively easy to dismount from the circuit board and swap for a socket . I can then download the stock profile to a laptop and run it thru an interface and change ignition /fuel maps to suit marine installation .Shouldn't be to different from stock though and probably similar to that in the Honda BF 150 outboard.I could then produce a chip for low speed eco trolling or flat out power .All component connections are then waterproofed with a contact grease and the ECU is sealed in a protective box . <br />The weight loss over the 'cast iron ships anchor of an engine' should be useful .<br />Sorry about the tech stuff but there are no other words for it .

 

[tommays]

Re: Mercruiser Drive shaft spec

i understand all the tech stuff its just that over here the box would have to meet USCG regs and be tested by a lab<br /><br />the correct rating on the starter and distributer should be intresting also<br /><br />tommays

 

[DHPMARINE]

Re: Mercruiser Drive shaft spec

All that pollution/ fuel/cpu stuff can always be worked on.<br /><br />How are we cooling this idea ?And getting water flow thru it ?<br /><br />DHP

 

[rodbolt]

Re: Mercruiser Drive shaft spec

hello<br /> the late style alpha coupler is a triangle plate that bolts to the flywhell surface. you will have to use the manual shift flywheel and make a bell housing to adapt the engine to the rear mounts. or make an adapter tomate an existing merc engine bell housing mate to the honda engine. nether is difficult just time consuming

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Not a problem here in the U.K. Tommays . The engine will burn as cleaner than any 2-stroke.The little jap starters are particularly torquey and will have no trouble turning the whole lot over and there will be no problem with the stock ignition system as this is an effectively 'distributorless 'system .<br />DHP :The cooling will be closed system borrowed from a 190 setup with a Serck oil cooler , all pipe fittings are 32mm .The fittings lie in a suitable position to hook up to the motor really easy .<br />Hi Rodblot - thanks for that and yes it's a manual motor.The later coupling plate sounds like a good idea and should be easy to adapt as long as the mount holes lie within the starter ring .Do you have a PCD for the mounting holes as they are rather expensive ( about $300 )over here and if I order I cannot return it if it wont work .Is the spline area common thruout the range then ?

 

[waterone1@aol.com]

Re: Mercruiser Drive shaft spec

Dumpy, sounds like an interesting project, and it seams you have thought out things very well. There are a few points that I think I should bring up ( along the same lines as Tommays).<br />1) this is a boat, not a car, the engine and all associated parts are in a sealed bottom area, which is usually enclosed....very different than a car. 2) in most cases, the fuel tanks are in the same area as the engine.....most cars have the fuel tank at the opposite end of the vehicle. 3)One of the biggest hazards in a boat, believe it or not is fire. If you combine all of the above, here are some things to keep in mind.<br />Gas is lighter than water, but gas vapors are heavier than air....not a problem in an open bottom car engine area....BIG PROBLEM in a sealed bottom boat engine room...the gas vapors will stay there. Everything in a production boat is ignition proof or explosion proof.....if it can possibly make a spark, or generate exteme heat, it is totally sealed from the enviroment that it is operating in. The short list would be: starters, alternators, relays or contactors/solenoids, ignition components, circuit breakers, fuse holders....etc. Exhaust components for a marine engine cannot exceed 200 degrees fairenhight, car exhaust components can reach a few times that....they must be wet or water cooled. The list goes on....we all want you and everyone boating around you to be safe. I admire what you are doing....just remember to think about boating safety....it's different than road safety.

 

[rodbolt]

Re: Mercruiser Drive shaft spec

dumpy48<br /> to use the coupler from merc you will have to buy it,take it to a machine shop. have them lay out the bolt circle on the flywheel and drill and tap 3 3/8x16 holes. not had but must be accurate, you will have to indicate the flywheel center them drill 3 holes 120* apart on the correct circle. a first year machinist with a bridgeport can do it. the bell housing adapter is a little more difficult. but by no means impossible. the hard part will be the water cooled exhaust. the altenator and starter should be marine approved as should the ign system. EFI is usually not a worry as its sealed and vapor free. if your system uses a fuel return you will have to add a return line. marine power makes a kit that splices in the fuel tank fill line to return fuel. saves trying to weld on the tank.<br /> here we can run a dry stack exhaust only if the hull has no engine box. interesting project but dont set up something that may burn ya

 

[Bondo]

Re: Mercruiser Drive shaft spec

Ayuh,.......... Sounds like an Interesting Project............<br /><br />Another thing that comes to mind is the proper back spacing of the face of the flywheel in relation to the outdrive/gimbel bearing,+ the adpter that'll be needed to bolt the block to the rear motor mount/flywheel cover............<br /><br />The "Window" to get the proper spline depth is pretty small...........<br /><br />The Input Shaft on All the common Mercruisers are the Same.......Spline count,+ Diameter....... Pre alpha, Alpha, Bravo.....

 

[rodbolt]

Re: Mercruiser Drive shaft spec

the easy way to get the proper distance measurement is to measure the distance from the later style chevolet engine from the manual shift flywheel face to the block at the bell housing mounting surface. you can add or subtract materiel from the bell housing adapter as nessasary. the trick is to keep the face of the fly wheel the same distance fron the gimbal bearing as the original merc unit. this can be accomplished by altering the engine face of the bell housing. you most likely will find it easier to modify the facory chevey bell housing to mate to the honda rather than trying to make a bell housing with the correctly spaced rear mounts. the front mounts should be an easy fabrication. <br /> I was lucky enough to work for some years at a machine shopas an assitant to the R&D dept and a production lead man in the CNC dept. the company also encoraged making things when not on the clock. you would not believe some of the stuff we built nor how much was done "on" the clock.<br /> night shift was great <br />sofarthe most difficlt part I see is the water cooling for the exhaust. if you have a stainless steel fabricator just build a set of headers then weld a water box around them.<br /> when I retire,soon if the property here sells, I may go back to playing with swapping stuff.<br /> would love tohave a bridgeport and a hitachi-seki 4NE 600 lathe

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Thanks Guys ,<br />Lots of useful info here .<br />Can't use the large triangular coupling Rodbolt , as this is much bigger than the flywheel so have ordered the other type on Bondo's info (all the same spline count and size which is 17 X 1.125 " ? )looks like it may be easier to mod - redrill on new PCD.<br />I have got the exhaust in hand as the guy at Technical Tubes here in the U.K. made the 'pipe in pipe ' set up for the inboard V12 Jaguars<br />I'll use all the other info to calculate correct fit out .<br />Be back when its up and running .<br />Cheers

 

[rodbolt]

Re: Mercruiser Drive shaft spec

hello<br /> my thoughts would be to cut the bolt circle down to fit the honda flywheel. a flex plate style coulper will be much easer to machine than trying to modify the bolt circle on the stud crankshaft mounted coupler. if you have access to several couplers most all the diminsions on the alpha,mr R type 1 TRS and bravo drive as well as the volvo sx and the omc cobra was the same. not sure about the starpower marine(bought out by pleasure craft) drives as they used the 71 series inboard clutch wit a outdrive of their own manufacture. but the flange diameter on the 460 OMC cobra was quite large and may have enough area to recut the bolt circle. and the later style one piece crank couplers may have the clearence nessasary for such a small bolt circle. about what is the bolt circle Diameter on your honda engine ?

 

[Bondo]

Re: Mercruiser Drive shaft spec

Another Issue with swapping couplers around is the Set-Back Differences in the Many Couplers that All share the Same Spline count,+ Diameter........<br /><br />This might be an Advantage, or Disadvantage,.... Depending on How you get the engine mounted to the Rear Motor Mount.......<br /><br />The Bravo Style has a Full Circle Aluminum mounting plate.....(rather than the Steel Tri-shaped Alphas) <br />It would be Easy to cut down to fit.........

 

[rodbolt]

Re: Mercruiser Drive shaft spec

could be bondo. would be an interesting project. one day when I retire I may start doing them again myself.

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Thanks Rodbolt . Looks like the choice of coupling is a lot bigger than I first imagined .This opens up a much bigger source ,the 'Boat Jumble' .The Bravo 'full cicle' one looks favourite though . The coupling I odered can go back if it won't work , I have agreed this with the supplier .<br />Your probably right on the machining side of things because I reckon that with this coupling I'll be breaking into the original holes somewhere along the line and we are then into a whole mess of welding and a poor(unreliable ?)installation .<br />I will be using a 'ring' cut from the original ali clutch housing ( the engine came from a wreck with just 9000 miles on it , and the g/box was damaged at the other end ) with the rear mounting lugs welded on once the whole thing is shimmed into the correct position/ relationship with the drive . This will act as a guard for the flywheel and mount for the starter.<br />Shame you guys don't live in G.B. You won't have to wait until you retire.....theres plenty for you to do here !

 

[Dumpy48]

Re: Mercruiser Drive shaft spec

Whoops ,sorry Rodbolt. Forgot the Honda Flywheel details: (as best as can measure)8 X about 2.5" PCD . The flat recessed area for the bolts , is around 3.5" diameter .The OA diameter (from the ring gear shoulder) is just a little under 10.75" .

 

[rodbolt]

Re: Mercruiser Drive shaft spec

dumpy. the rear mounts are critical. would be best to machine the front of a merc bellhousing and manufacture an adapter to mate the chevy housing to the honda. I have made them before on trucks and race cars so its not hard just take a careful measurements a good machinist and a good welder. my macining skills were good my welding skills were marginal so I had a friend that owns a welding shop do the welding. the key is to insure the centerlines of the housing stays the same in relationsip to the crankand the distance from the flywheel face to the transom assy stays the same. or you can hold the factory spec from the flywheel face to the center of the rear mount holes. I go to venezuela occasionally and doa bit of work there. its a true run what ya brung and rig it how ya can place. I love it