My Mini Mud Motor build so far

The purpose of the 90 weight against the grease in the bushing is to supply something to fill the void of if and when your grease evaporates. It escapes the seals as a gass and draws water back in unless that void is immediately filled as the gaseous grease goes out. This is why you also need a atmospheric pressure vent as well.

Mark
 
Ed,

I have a fill hole which is just a 1/4" thumb screw with a rubber gasket. Can't say if there is a vent. I'm not aware of one but I haven't looked it over real real close, nothing that is obviously a vent tho.
 
I finally have everything sitting on the bench. Any words of wisdom before I start cutting and grinding? Seems like the bushings are going to require an arbor press as the tubing is a bit tight. Did you guys turn the bushing down any? I haven't touched anything yet. May just be a burr when they used their cut off saw.

Thanks,

Ed L.
 
Ed, Good luck. The bushings for Mark's motor were just a bit tight so we just used a bolt and nut as an arbor, chucked it in the lathe and used a file with careful fitting until they just slid in. The seals were snug too so with the help of a seal driver (short piece of pipe) we just tapped them in w/ a hammer. Pretty loow tech but it seemed to go together fine. Hind site I would have put grease zerks in the bushings as a set screw and direct grease. I am still not sure what the best theory for lube is but some one will chime in there I'm sure. This project has my interest but not my time commitment. Go for it guys and let me know what not to do!! yukyuk. And that is what I know about that. I need to get away from this darned machine for a bit..
 
I would do a few things differently.

1. I would replace the bushing at the top with a sealed bearing. Might even have replaced the mid bushing with a sealed bearing as well. I don't think these are going to see water and if they do, you have bigger problems than water rusting the sealed bearings.

2. I would put the shaft collar in between the grease seal and the bushing at the top and throw a bunch of grease in-between. I know you are thinking this differently and are concerned about the set screw coming out and causing havoc. With the tolerance of the shaft collar against the ID of the tube, that set screw is never going to come out.

3. I would put the bottom bushing back a couple of inches from the last grease seal. I would then pack that space with grease to act as a water barrier. I would then fill the tube in between the bottom and middle bushing, and the middle bushing and the top bushing with lube oil or some heavy weight lubricant. Would definitely use synthetic for cold weather performance. I'm thinking that only part of the space between the bushings needs to be filled as the motor will be tipped and the oil will be against the bushings.

4. I would end machine the driveshaft prior to installing in the drive tube. Not a big deal but it saves some time later.

5. With your Bolens motor, you will need to dremel, or somehow grind a slot in the top to fit into "the key" in the motor housing. I'm not using the right words here but you know what I mean. It would have been far easier to cut this groove first and then attach the skeg verses attaching the skeg first and then having to align the groove to the key in the motor housing.

6. The 60 inch drive shaft and the 58.75 inch drive tube are incorrect. Our motor attaches differently than the motor "Ripped Off" must have used. The drive tube needs to be cut an additional 1.25".

I keep thinking the next motor will take 1/4 the time of this one now that I have gone through it once. Next up, we'll have to try a bigger motor.

Call me Ed if you have any questions (651) 738-2180 (home). or (651) 283-4643 (mobile)

Mark W
 
Ed: I fit my bushings with a .004-5 interference fit with the bushing houseing. I put a greese zert in the middle of the bushing for grease. I don't think that a set screw is necessary.

In the past I have squeased the bushings in with a piece of all thread that was longer than the drive tube. Connecter nuts work better than regular nuts for the pressure involved. I have since made a hydrolic press for this task. If you don't have access to a lathe you can use a drill press and a file with paying attention to detail with a mic. The simplist thing to do is to find a lath in someones garage and go get aquainted.

Mark F. Cheney
 
Thanks for the info. Wasn't a good weekend to work on the motor after all. Warm weather amd sinus problems had me down all weekend. Go figure. Stuff is still sittin on the bench. I did get a peice of all-thread to assemble the bushings with. Sounds better than banging away with a hammer and a piece of dowel rod. Thanks Mark C.
 
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