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Soldered Cast Iron Grind Ring in Disposal Insinkerator model 77


I soldered with the new plumbing solder. It took the solder very well.
The ring I cracked when taking apart the disposal. I should have put a vice grip on it and pried it, but I was whacking it with a hammer and cracked it thru in one spot.

I was taking it apart to see why it failed, the base had a plastic liner, and water got under that and rotted the aluminum base. The plastic liner jammed the grinding plate so motor could not turn. I decided i could repair it.

I cleaned all the aluminum corrosion off by scraping, then playing a 1/8 drill bit over the entire aluminum surface, then when clean, I coated with 3 layers of PL Premium Polyurethane construction adhesive using my finger, which is why it looks bubbly, it swells up. This is totally waterproof now.

The inner seal was ok, the grind plate was ok, the cast ring is ok, the motor is ok, so it will work again. Has a 3/4 HP reversing motor.

The cast iron ring was extremely hard stuff, harder than normal cast iron. I could only grind a groove using a grit blade in the tablesaw, ground half way thru the ring. I then rubbed the end of a copper wire hard onto the iron, I heard it can help with tinning. This gave it a slight coppery sheen to the metal.

I put the flux on and heated bottom side with a propane torch, in 2 minutes it was hot enough to melt the solder. The clamp kept it from splitting apart.

It was too tight a fit back into the aluminum housing so I very lightly ground the outer edge, it still needs a press fit into the housing.

The ring I will seal with Rectorseal T plus 2 white teflon paste. I will smear it on the top rubber ring too. a spin on outer housing clamps the whole grinding chamber together, Rectorseal I think will help it slide back together. There are holes in the outer cover, you can make a metal rod hook to grab it and using a 2x4 with rod attached to it, (like those large screw hooks spin it apart, off and on type idea)

I also need a 3/8-24 thread SS nut and lock washer to attach grinding plate. OEM incredibly used a normal nut. It was so rusted, I took a torch to heat it red hot. I plan to use rector seal on the threads. To oil the top bearing, will use 20w- 50 synthetic engine oil and the top rubber seal use a marine grease. Likely West Marine will have the nut.

I can see where the OEM cheaped out on otherwise quality grinder. The plastic inner liner is no good long term, lets in water to the aluminum base. And the standard nut they tried to seal with a plastic cover, it still rusted away. The cast iron grinding ring was in good shape.

Other sealing idea, use an epoxy, but I know the PL is 100% waterproof, its cheap and I had it. The super corroded aluminum base, after it is cleaned up has so much surface texture, epoxy or the PL will have no trouble sticking to it. One clear advantage of PL, it will not crack, an epoxy can crack. You can also embed FG cloth into the PL, even drywall fg tape, which I have done repairing other things..

Garbage disposal generates a fair amount of water pressure when running, I had thought simply seal the crack with the teflon paste, I know soldering it is better, but I think it would still have been ok with just the paste in the crack, and maybe some PL on the outside.



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Re: Soldered cast iron grind ring in disposal Insinkerator model 77

Nice to see stuff getting repaired instead of pitched. Would guess that the flimsy plastic and plain steel nut was the designed in failure point. :rant:

Reversing eh? Does it reverse on every start, or is there a separate control?

How old do you think it is?


Re: Soldered cast iron grind ring in disposal Insinkerator model 77

It reverses every time it turns on. There is a momentum switch in the base, when motor starts spinning one way, it follows the rotation, then when shut off the switch is set to spin motor the other way. Autoreversing is helpful in case it jams.

I am not sure how old, this was in our parents house, when he passed, the thing stopped being used for several years, then it refused to work. Had built up terrible amount corrosion in the aluminum base. Likely over 10 years old.

Yes, most people will toss out disposals. My daughter's house needs one, now if I can talk her into putting this is in...

We don't need it. I repaired a Sears disposal given to me by a friend, has all SS internal parts, that one the top bearing locked up due to it running out of grease. Some of these things are worth fixing, some are made so bad, not worth fixing. If it does not have SS grinder plate, not worth fixing. I dont like to see good stuff get thrown away and I can have some fun , it is a challenge to fix old things.

Crazy cheap is a SS nut, local hardware has it for 50 cents.
I had to torch it loose with oxy-acetylene, heat it up to break it loose, what little was left of it.

Insinkerator plans for these to fail, they want you to get another, most of the time the motor itself is still ok.


Re: Soldered cast iron grind ring in disposal Insinkerator model 77

True Value here in Grafton VA had the nuts, and they also had acorn nuts in that 3/8-24 size. So I bought an acorn nut as it will seal the top of the motor shaft. Acorn nuts are harder to get and pricier, paid $3.50 for one while a standard ss nut is 0$.85. So very happy to get that Surprised West Marine had nothing I could use.

Back together so it works.
T plus 2 sealer, am very happy with that stuff. it allowed the outer coller to slip on by hand, and the outer cover and screw keeps it locked together, rather better than bolts maybe.

The bearings, I oiled with 5w-50 and marine greased the top seal, then used T plus 2 on the nut threads.
On this one, the upper bearing has slots and is filled with something like sawdust, so you can sort of refill the bearing. Some bearings do not have that. I t helps provide extra oil over the long haul. Lower one may be similar, I filled best I could both and smeared a little grease in there also. I also wiped the stator and armature with a little grease to keep it from rusting.
I took a SS flat 5/16 washer and opened it to slip on the motor shaft for under the nut, this will totally seal the shaft as the nut was not wide enough to seal over the motor shaft slots. The cast grind ring, I lightly tapped home after smearing the T plus 2 onto it and the aluminum housing. T plus 2 seals and lubricates. I also use it on hose bibs to keep rubber hoses from sticking on the boat engine.


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The outer collar slip fits on extremely easily sliding over the T plus 2, so saved me trouble, coming off it was a pain.
one pic shows how the screw secures the locking collar. Even without the screw, the outer plastic cover wont allow you to twist it apart.



Had to start using it, been working great.
The SS sears one we were using needs fixing. Water has I suppose gotten to the upper bearing and motor squeals when it runs. We had some sink clogs and I think that stresses the upper motor bearing with water pressure. The Sears disposal is all SS inside, grinding chamber etc...
What's interesting is the form factor is identical sizes, all pipes simply fits the same.