There's a number of threads on this site that discuss the problems of repowering a Pearson 365. There are many nice motors our there like the Yanmar and other Westerbekes with the Hurth gearbox. All these motors are a problem because they require a 1:1 gear ratio RV-10. I actually have one BTW, but feel the best solution is to find a motor gearbox combo with 1:1 gear reduction. The best advice from an engineering viewpoint is to leave the gear reduction in the V-drive were it belongs.
The Velvet Drive 71C seems to be the direct drive transmission of choice, provided you can install an engine with a small enough diameter so that the center line of the motors crankshaft can be brought in line with the 15 degree angle of the RV-10 V drive. In my case with the W58 the engine cannot be made to align with the V-drive.
I concluded that the Velvet Drive 5000A, which comes in 1:1 and has input to output shaft offset is the best solution. You will be upgrading to a gearbox that is currently in production with parts available around the world. Here's my engineering drawing showing a Velvet Drive 5000A as it fits into a Pearson 36 with the Westerbeke W58.
(http://i1121.photobucket.com/albums/l505/banjoband/hullandmotor.png)
With this gearbox, I can restore the RV-10 shaft angle to 15 degrees and stand the motor up 8 degrees from where it was. As you can see I am going to have to do some carpentry to clear the transmission. Unless I can move the entire engine forward (not easy).
I am putting an R&D high deflection (HD) damper plate in there. That will reduce the low rpm vibration I was getting in the old worn out drive train. The RV-10 will get all new bearings, seals and gaskets.
There are two remaining problem areas. Turns out the Paragon SAO hole is bigger than the velvet drive by 5/8". So I will need an SAE#4 to Velvet drive bell housing adapter with less than .5" offset. The adapter ring I had was for velvet drive but was machined out for Paragon. And I still need to find the telescopic drive shaft from Walter Machine.
I knew I was going to have trouble making sure my damper plate splines get fully engaged in the switchover to the Velvet Drive gearbox. The old adapter ring has a different pilot hole diameter.
(http://i1121.photobucket.com/albums/l505/banjoband/gearboxes2.png)
The bell housing cover on the velvet drive is a stock Perkins 154 cast aluminum part and was to good a deal to pass up ($75). It's a perfect fit to the Westerbeke SAE5 Bell housing and the Velvet drive 8.25" dia" hole pattern. Only trouble is it has about 1" of offset.
Making that up will be difficult. I can fly cut .2" off the bell housing cover and somehow put spacers between the flywheel and damper plate. Does anyone know of a source for flywheel spacers? In my case I'm looking for a 1/2 -3/4" thick spacer ring to fit a standard SAE10 flywheel/damper plate hole pattern (15.25" diam.) Could I use round spacers and longer Grade 8 bolts? Or is that a recipe for disaster?
Or I can probably machine the recess into the steel flywheel adapter that's on the old Paragon but it weighs a ton and that will require access to a 16" lathe. (But could possibly be done a vertical mill) They left an 8.25" diameter lip that could register the velvet drive from when they machined it out for Paragon. Maybe this is a better solution in that it makes my engine/gearbox shorter also.
Pete
Pete,
The way I am reading this is that you have two separate issues? One being the pilot hole difference between the two and the other being the offset dimension. If that is correct, a new spacer could be made on a CNC vertical machining center from a flat plate thickness of your choosing. Think of the maching center as a bridgeport with all of the axises computer controlled.
You would first have to have an accurate drawing which I know you already can do. A program would have to be written by the machine shop that allows the machine to self calculate all of the profiles into X - Y positions, so your round outside dimension is generated by simply positioning the tool in minuet X -Y adjustments. Of course the Z axis dimensions will also be entered for all of the hole depth or even threading.
If the machine program control is good you will not be able to tell the part was not turned on a lathe when it is finished. Around these parts, (your costs will surly be more) programing and machine time approach $100/hour but the actual machining time will be but a few minutes. Writing the program and setting up the machine will account for the majority of the cost. Fortunately the program does not appear to be that difficult as everything is a mirror of the last so many degrees around the circle, so it is a kind of a cut and paste.
Two jobs ago we used to do this stuff all the time and like anything different from the day to day, we would have been thrilled to make something different for a change. We also typically ran the first one out of wood or cheap plastic just to make sure before we "modified" the actual material.
Shop around, you might find someone looking for a "different" part to make and cut a deal, or they already do this all day long and can just tweak the dimensions in a few minutes off of a canned program routine.
Keep me in the loop.
Dale
Hi Dale,
For simplicity you could say I only have one issue. Its one of those mysteries of life we all ask ourselves while we are motor sailing. And that is: "Are the splines of my transmission shaft fully engaged with the damper plate?" You have no way of knowing because once you hang the gearbox you cant see in there to know. I'd bet most retrofits out there are not fully engaged. The SAOD I pulled was only 50% engaged which explains all the wear.
I have 2 different bell housing adapter rings and both have this issue to contend with. I'd like to use the Perkins cast aluminum ring because it's an exact fit for my bell housing and the velvet drive and its light weight. The only way I can see to ensure full engagement (I've done all the measurements and math) is to fit a 3/4" spacer ring between the flywheel and the SAE10 hole pattern damper plate.
I have found some discussion of this on-line and it appears to be a real thing that is routinely done on marinized engines. The problem exists because you are removing a clutch housing and pressure plate and replacing all that with only a damper plate. So there always seems to be a need for some kind of spacer in there because the bell housing is now bigger than it needs to be. I could build a spacer but anytime you add some ring with mass you have to have it balanced. If I minimize the mass and go with 8 individual spacers I might introduce some weakness to the drive train. Longer bolts to shear off and all that. But the diameter is 10" so there's a pretty decent torque arm so that seems unlikely to me.
So if there is no remedy for the Perkins part I'm looking at machining the big heavy steel adapter ring to counter bore a hole large enough to sink the velvet drive housing into and then install a backing ring from the inside surface to support it. In this approach my offset from velvet drive flange to bell housing deck goes from 1" (with Perkins ring) to 0".
I'm going to visit a shop tomorrow that I think has a big enough lathe. That will be cheaper than setting up an CNC mill.
(http://i1121.photobucket.com/albums/l505/banjoband/vdadapter.png)
Thanks again and good luck with the business. I assume you'll stay at the Niagara St location. Pete
I can now conclude that I have the recipe for re-powering a Pearson 365 with a larger motor. By using the output shaft offset and 8 degree down angle you get from substituting the Velvet Drive 5000A 1:1 for the 71C you can upgrade to a motor with a larger bell housing diameter. In my case a Westerbeke W58. Here's the SAE4 bell housing adapter that needed to be counter bored to achieve 100% spline engagement. Counter boring to clear the gearbox casting OD also makes motor/gearbox shorter. This minimizes the amount of carpentry you will need to do to accommodate the longer motor and gearbox.
(http://i1121.photobucket.com/albums/l505/banjoband/5000a-adapter.jpg)
That grove that was ground at the bottom is to provide clearance for a web in the 5000A casting. Its that close. Below is a measurement showing the target depth for full spline engagement and a clos-up showing the 5000A installed into the counter bore of the adapter ring.
(http://i1121.photobucket.com/albums/l505/banjoband/bellhousing1.png)
Here's the W58 bell housing with an R&D High Deflection damper plate installed. The engine was pre-aligned to be spot-on to the v-drive shaft by using a plywood template of the gearbox. Note that no modification of the engine bed cross brace is required. There are welded engine mount brackets that fit into slots cut into the mounting weighs however.
(http://i1121.photobucket.com/albums/l505/banjoband/rampdDamper.png)
Here is the final installation of the Velvet Drive 5000a. The 15 degree V-drive shaft angle is actually 14 degrees because the prop shaft on my boat -1 degree down. By angling the motor to achieve 6 degrees of tilt plus the 8 degrees down angle, the 5" velvet drive flange angle comes in at 14 degrees. Using some trigonometry I calculated the final motor/gearbox flange to v-drive alignment error to be .95 degrees. Walter says this alignment error must be less than 3 degrees.
(http://i1121.photobucket.com/albums/l505/banjoband/5000A-install.png)
All I need now is to install the transmission cooler and a drive shaft.
Transmission cooler installed and motor to drive shaft alignment completed and custom drive shaft installed. Video taken at 900 rpm.
(http://i1121.photobucket.com/albums/l505/banjoband/BoatVideo/th_W58-500A-900rpm-1.jpg) (http://i1121.photobucket.com/albums/l505/banjoband/BoatVideo/W58-500A-900rpm-1.mp4)
Pete s/v Tartanic, Hull #6