I haven't ordered the Mad Mud Motor plans yet, but I've seen plenty of them built, so I've seen the angled driveline and u-joint that they use. In searching around, I've also seen this:



It's got me wondering whether it's better to have a completely straight driveline, at least on a lower HP motor? I would think it would result in less vibration and wear, but maybe cause the motor to operate at more extreme angles and possibly cause oil/fuel starvation, but since this company is actually manufacturing them that way it must not be that big of a deal. I came up with a cruder design using 4" SCH40 pipe and some flanges to fabricate the housing for the coupling/base of the driveshaft tube. Anyone running motors like this with a straight driveline that like them better over angled?

Ok-here (in series so it's easier to understand) is my "Poor man's Swomp Lite Driveline housing." I'd start with a steel ring fabricated from 1/4" plate and drilled for the outermost holes on Briggs and Stratton horizontal shaft. These take the largest (7/16" bolts) and I think have the mounting holes set wide is probably better for strength. A 6" section of SCH40 black steel pipe would be welded in the center, which will serve as the housing for the coupling. An access hole will be machined into the side (I couldn't figure out how to draw it in Sketchup) so that a removable cover can be fitted. This way the roller chain coupling ( http://www.mcmaster.com/#roller-chain-shaft-couplings ) can be accessed and I can pack the housing with grease:



Next, a SCH40 Black steel flange would be welded onto the end of the pipe with the flat side facing out. Stainless steel studs will be fitted from the backside facing out so that the flange connected to the driveshaft housing can be fitted over top and bolted down with stainless nylock nuts and lockwashers:



Finally, a SCH40 Stainless steel flange would be welded to a length of SCH80 (Because of the smaller ID) stainless steel pipe which would form the driveshaft housing. The full pipe will be 60" long-I just kept it short so it would fit in the picture. The pipe would protrude slightly through the opposite side of the flange into the black steel flange in order to help locate and center it. Even then, the alignment will be hard to get perfect, which is why I opted for the roller chain coupling as they tolerate a little misalignment pretty well.:


Let me know what you all think-the stainless might seem like overkill, but I'm getting a deep discount on the materials. I guess I could build one out of all black pipe first for really cheap and see how it like though? Eveything else about the build would be pretty conventional-three bushings, one top, one middle, one bottom, an automatic grease cup for lubrication, and a seal/retainer cap at the bottom. The shaft will be stainless as well. The boat will never see salt or probably even brackish water, but I figure it will be a good idea in the long run.

I run a straight drive. It starts a lot easier than it did when it was on my longtail frame and seems to have a lot more torque and power. Less resistance being straight coupled than it was angled down with a U joint maybe?

I'm not an engineer but I now spin a 10 x 6 prop vs. a 9 x 6 when it ran as a longtail.