problem with mud motor prop nut

the threads ended about 1/4'' away from the bearing cap. so the nut spun itself past the threads. i really don't know how, but i was turning that prop litterally as hard as i could so i don't doubt it. Mud Buddy seems to think, if you can't get it to spin, just use bigger cheater pipes and it will turn eventually...Were gonna try and cut the nut off with the grinder and have a new nut machined i think is the plan...if i mess it up, i'll just get a new shaft i guess.

thanks
 
Dont know what paticular u joint the machine has, but can you loosen the set screws where the shaft goes into the u joint then grab onto the shaft with something like a nut on it . Pull it out of the u joint 1/4'' or so just enough to take the presure off the nut. Just another idea???
 
OK, can't resist but be advised I am not a mud buddy expert. Since I have built a few of these, why can't you un couple the shaft from the u-joint at the top near the motor and then slide the shaft out of the shaft housing (pull through shaft housing at prop end)? This will allow you much better alternatives to remove that nut I would think. This is how I get my shafts out when my motors need attention.

There may be a shaft collar on the top (near the motor end) of the shaft and if this is the case, and by looking at your pictures, you would not be able to slide the shaft up far enough to remove the shaft collar. Pray there is no shaft collar.

Mark W
 
Mark,

I could be all wet on this as I am going off memory but,,,,,


I believe there is a thrust collar contained with-in the lower bearing housing. That way the thrust is against the bearings in the lower end and NOT against the u-joint ( and thus transfered onto the engine crankshaft)

If indeed I am remembering correctly, that means the bearing housing would need disassembled to remove the drive shaft.


A lot of the early mud motors (maybe some still do) only had bushings, which allowed the prop thrust to transfer all the way up to and against the engine crankshaft. That was not real good because most engine crankshfts are not designed to handle end thrust.
 
Hi Dave -

I understand what you are saying. My question back is if what you say is true, how does the drive shaft get assembled? How do you lock the thrust collar onto the shaft if it is contained within the bearings? I know when I built mine, the bearings had to be put into the tuber prior to the shaft being installed. If you tried to put in the shaft AND the bearings at the same time you would be one frustrated individual. Granted, I am not as smart as the pro's in this area and I'm certain Mud Buddy knows how to build these things way better than me.

I would think that with a ujoint design, the ujoint would take some of that thrust and not the motor. I know that I leave a little bit of play in the driveshaft so that the thrust of the prop never gets all the way to the motor itself. Rather ingenius I thought.

Once again, I'm not the expert.

Mark W
 
Mark,

I can't answer your questions right now. I know at the time I purchased mine, Mudbuddy showed the bearing housing set up on their web site. I was impressed with the engineering behind it and that swayed me to purchase their product. I have searched their site and checked my filing cabinet and I don't see any info on the design details for their setup on the longtails.

If I have to take mine apart I'll take photos. I am pretty sure there are two bearings, plus a double seal system, plus a seal guard/spacer contained within the housing. It is a little more elaborate than what you have in yours. Not that there is anything wrong with what you have done.

The bearings are ball bearings and I think they do slid in as a unit along with the shaft. Unlike yours, they are a slip fit and held in place and kept from rotating by the threaded bearing cap. The bearing housing itself is threaded to the end of the tube. The housing is much larger than the tube and allows for bigger bearings and everything else in there.

Sorry I can't be more specific but I am not taking mine apart just to look!! ha :>) :>)
 
so after getting in contact with Dave M, he stepped up and got me going forward. He cut the stuck nut off and is going to machine a new one. The prop had definately ridden past the threads and would not budge.

so thanks again

i'll get some pictures of when the boat is finally up and running

rob
 
while i got your guys attention, another issue i got with this thing...Anybody know where i have to run the wires for the killswitch go? obviously ones a ground but the red one? I had to get a new one and it came with no instructions. just don't want to get thrown out and see this thing drive a mile away from me

thanks

rob
 
Mark,

If I have to take mine apart I'll take photos. I am pretty sure there are two bearings, plus a double seal system, plus a seal guard/spacer contained within the housing. It is a little more elaborate than what you have in yours. Not that there is anything wrong with what you have done.

The bearings are ball bearings and I think they do slid in as a unit along with the shaft. Unlike yours, they are a slip fit and held in place and kept from rotating by the threaded bearing cap. The bearing housing itself is threaded to the end of the tube. The housing is much larger than the tube and allows for bigger bearings and everything else in there.
Click to expand...


Hey hey don't short change what I've done :) I actually have bearings in my most recently built unit along with a couple bushings. I actually have two seal guards on either side of the lower bearing. Mine is more pressure fit than slip fit bu I have helf mine in place with set screws to keep the bearings and bushings in place and to prevent rotation as well.

I love to see your motor apart some day Dave just so I would know how to build the next one. I'm thinking a surface drive with a 2 hp motor driving it. I've got the plans drawn, just need the time.

I've got the mud buddy patents if you would ever like to see them. They fully explain their bearing system.

Mark W
 
Morton,
I can see it now..... "Mortons Mud Motors" Your Quohogs aint got nothin on our MUD Machines.......


Glad you got a grip on that thing and have it apart without exploding something.

Rob
now that you got a huge fix out of the way, take the time to fill out your profile. It is a tradition around this site and as you have found a lot of good guys hang out here.


Looking forward to seeing the rig up and running with a full roostertail!
 
Bob ,

I love the sounds of that !!!! It was the 1st one i have seen in person we repaired a tiller for one a few years back the shop for a guy in NY state but these are cool motors !! The nut was spun up the shaft real good , we tried all the ideas posted here with no results , so i cut it off with a small cuttoff wheel mde 2 cuts to take a chunk of the nut out which releived the pressure and allowed us to back off the nut .


Rob ,

Nice meeting you last night , real cool setup for sure .

Picked up the stainless tonight and will have the nut done this weekend i hope i will call you when we are all set .

Dave M
 
sounds good, came across another problem today with it. one of the ignition coils crapped out so had to order another one...maybe monday or tuesday it will be running again so no rush dave haha...glad im running into these problems now and not in december in the middle of nowhere
 
Dave was something missing to allow the nut to get so far past the end of the cut threads? Or was it just a case of way tight.
We have gone to using red locktight on prop nuts on shafting for Bronze Propellers. It keeps the pal nuts locked for sure, as long as the taper is lapped and the key is not bound up.
I am assuming this is a straight shaft and not tapered. Does it use splines to keep the prop from spinning?
We always have the luxury of a "Hot Wrench" in the shop so cutting off nuts with a wheel or fire is an option and the Red Locktight gives right up with some heat applied. But if a field\swamp replacement is required it might be too much hold.
Do they use a cotter pin or a tab lock washer to keep the nut from going off?

Cool Motors and for sure, look like they go places no other can.
 
They say not to use any sort of lock-tite. You are suppose to use marine grease or anti-seize. When the prop hits something in the water, it actually tightens the prop a little everytime. This size motor is suppose to have a 9x6 prop on it and the old one was worn down to 7 1/2". Here is a pic of go-devils setup, its similar to the mud buddy. The props are threaded on. The mud buddy sequence is forward prop nut, brass washer, prop, brass washer, nut, and nylock nut.

next year i'll probably get a new drive shaft, u-joint, bearings and seals. This year im just going to run it.

prop.jpg

 
Just wanted to give a quick thanks to all the guys that helped. Thanks to Dave M for cutting the old and machining the new nut I needed.

Taking a ride tommorow morning with it for some fishing and see what we get with the gps. Been putting in alot of work on this motor so hopefully it pays off. Will try to get some pics...

thanks

Rob
 
Rob ,

I am glad it worked out for you,please let me know how you make out in the morning .



Dave M
 
Dave,

Knowing what you do for a living, I'll bet you've seen worse "rebuild and repair jobs" than a jammed prop nut. :>) :>)
 
Dave we both do the same line or work and we know how things can happen and be a royal pain to fix but this was an easy fix turned a piece of Stainless for Rob to replace the nut we cutoff , i am always happy to help with things like this .


Dave M
 
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