Lower unit thread repair?

[riverrunner114]

Any one know who might be able to fix the threads at the back of a lower unit case? I am talking about the carrier spanner nut threads.. about half of them are gone and I dont believe theres enough to hold. I have also heard of some folks pinning the nut/carrier in place... any luck with that? Anyone ever done that themselves? Thanks for any advice, john

[rock]

We had a guy up here doing a spray weld process and it worked quite well. I will check and see if that service is still available. As far as pinning goes, I have done it many times. In my opinion it is not the best thing. It will weaken the case and could crack. I haven't had that happen but I think it could. I have broken several carriers due to the drilling. I would suggest contacting a good welding shop down your way and see if they can do the welding deal.
Rock

[riverrunner114]

We had a guy up here doing a spray weld process and it worked quite well. I will check and see if that service is still available. As far as pinning goes, I have done it many times. In my opinion it is not the best thing. It will weaken the case and could crack. I haven't had that happen but I think it could. I have broken several carriers due to the drilling. I would suggest contacting a good welding shop down your way and see if they can do the welding deal.
Rock

thanks rock, john

[Bruster]

Any one know who might be able to fix the threads at the back of a lower unit case? I am talking about the carrier spanner nut threads.. about half of them are gone and I dont believe theres enough to hold. I have also heard of some folks pinning the nut/carrier in place... any luck with that? Anyone ever done that themselves? Thanks for any advice, john

Henry Smith propellers in Eastern Michigan makes that repair. I am sure there are propeller repair shops in every state that do it. Chase the threads, this is not the first time for this question ~ good luck!

[Hottrucks]

I still cann't figure out why someone hasn't come up with a Nut and chase that is 1/16th bigger so they could be re threaded theres a millioin cases that could use this????

[riverrunner114]

I still cann't figure out why someone hasn't come up with a Nut and chase that is 1/16th bigger so they could be re threaded theres a millioin cases that could use this????

and a millionare is born... theres a million guys that would pay to have that tool...I'll take one!:)

[The Big Al]

I had a XR6 gear case going south, put set screws in the outside of the case going into the spaner nut.

It would have worked perfect, but my treads were so for gone I could not get the nut tight first.

If you can get it tight, I mean 4 ft pull handle stand on it tight.

Then drilling, taping, and installing a set screw would be a great idea.

Al

[Hottrucks]

I cann't beleive there's not a machinest that could make something up????
Maybe one of the goverment jobs at work??

I may look into it??

[staylor]

...due to the size of the thread diameter it's got a lot of area. Any good machinist can make a part that has the thread cut to the same threads per inch but with a pitch diameter that's about .02 to .03 over the original pitch diameter. He will need a good sized thread pitch micrometer to do this- but a good machinist will have this tool available. Then, he can hand taper the first 1-2 threads down to the stock diameter and mill/file a couple of chip grooves to make this into a self-tapping thread. This was done in several different sizes for the fuel inlet threads on Holley 4-bbl carbs so you wouldn't have to scrap the ex[ensive castings from a simple fuel leak. Somebody needs to get a machinist to volunteer to try this. You take a scrap case and try it with .01, .02, .03 progressively oversized threads till you get one that will hold the final thread torque on the nut without stripping.
Doug

[Hottrucks]

I'm NO machinest but A quick look at your lower and you will relize that if you go larger it will have to start at the top edge of the case... no big deal ..also I would think that making the the top of the new nut threads the same as the bottom as the old ones it ( what ever the thread hieght is) would have to work since you are useing the same amount of thead area.... and you wouldn't have to worry how bad the case is...Most Junk cases I have seen are only worn enough not to hold but not completely gone...

Just read that ??? hope someone undestands it???

[SlimDaddy]

I haven't rebuilt a lower myself but, looks like my Dad's on his 2.5 200 carb motor is going to need some repair soon.(too much backlash) I've been machining and doing tool and die work for 15+ years before I started engineering, when we pull his apart I'll give it a look and see if I can come up with any ideas. :confused: It seems to me that the major hurdle would be the major internal diameter hence the spanner nut's pitch diameter due to thinning the housing possibly making it weak,I'm not 100% on this since I haven't taken any measurements yet but I already have one Idea that I think could work:rolleyes: but I'll have to put some more thought into it to be sure.
If I come up with anything I'll let Ya'll know. :)

[staylor]

I agree that it's thin, that's why I think this can be done by just going about 02 over on the pitch diameter, essentially making a plus .02 bastard thread. If I know Merc, they've probably got more than that in the allowable runout for the thread relative to wherever they guess the center of the bullet casting is.
Doug

[riverrunner114]

After disassembling the unit today, I belive that in the case of this'case' the threads will survive to fight another day, however I have several that are as stated above, not completley gone but too far gone to use...and I am telling you guys, there is money to be made here on this subject... how many merc cases you think has found thier way to the junk pile because of these threads... How much does a new case cost? I am willing to bet it ain't cheap... allmost any other damage can be easily fixed on these except for the carrier threads... a slightly deeper thread and a corisponding nut will make some one rich sooner or later...something that can be done by the local marine mechanic (me) and not have to go to the machine shop will pay for itself in gold...get those brains to working and when you come up with the tool/nut, I'll take the first one... thanks for all the great responces from all of you and good luck, john

[Hottrucks]

John you hit the nail on the head and I'm looking into it as we type!!

[airentrapment]

River runner 114, Call Mark at Aluminun Doctor in clearwater Fl he has been reringing lower units for 15 years or more. He was the welder at Precision MFG in clearwater almost the whole time they were in business...727-447-7346 I hope this helps you...:D

[LakeRacer99]

I think Precision Marine in FL. sells the tap if you can get someone to weld some meat in there to cut into.

[NZ Sidewinder]

492161
Not difficult.
Just a thread cut in medium carbon steel then fluted.
This one could do with more flutes and relieving of threads leading to the chasing edges (clearance angle) although this one chases the threads well enough