Bronze rod bearing clearance. Spare the rod?

[brownfrog]

Greetings to all; This debacle is about the ever annoying Maytag model 82 engine. Not an outboard but in need of some two stroke expertise. The rod bearing is integral with the rod. The rod is made of bronze and is bored to a bearing fit. The crank is supported on one side with one main bearing. The rod slips onto the crankpin. This example has washed a lot of laundry and has .040″ of clearance. Does anyone have some idea of what bronze rod bearing clearance should be on a vintage outboard? This one makes about 3/4 HP and screams at about 1100 RPM. We are afraid to fire it up as I would expect .001-.002″ of bearing clearance. I suspect we will need to bore and bush the rod. Any thoughts would be greatly appreciated!

[Buccaneer]

It seems like when I was playing with my Maytag engines, there was a dedicated
website to Maytags, with a Q & A forum, etc., but I can’t remember the name of it.

Prepare to be boarded!

[The Boat House]

Back in the day when these we the latest
invention for washing clothes the repair
would have been done by the owner or
possibly a blacksmith. They likely didn’t
even have electricity, let alone a machine
shop to re-boar and fit the rod to the
crankshaft. They would have filed down
the end cap to take out the slop. As most
of the wear in the rod is from top to
bottom you end up with somewhat of a
round hole. There most likely is some wear
on the crankshaft as well but this would be
adequate for these at that time. If they went
too far they would shim the end cap. Its hard
to say how long this would last but that has
more to do with the poor quality of the oil
back then. This would probably work for you
as well but it is not ideal. Filing the end cap
flat so you get a good fit when you bolt it
back together would be your first challenge.
Tubs
https://youtu.be/AE6V6gUHnaw

[Mumbles]

There’s lots of Maytag enthusiasts over at the https://www.smokstak.com/ site and here’s one topic about rod clearances.

https://www.smokstak.com/forum/threads/maytag-92-main-bearing-clearance.98918/

and how to fit the rod bearing by lapping.

https://www.smokstak.com/forum/threads/maytag-92-best-way-to-remove-rod-play.89342/

• This reply was modified 2 years, 7 months ago by Mumbles.

[frankr]

Likewise, back in “The Day”, we had a micrometer and a file. The mic to check out-of-round of the crankpin and the file to adjust the clearance. If there ever were any printed specs for those bronze rods, I never saw them. Consequently, on my first repair job on an engine with a bronze rod (a Jacobson, as I remember), I filed the rod cap down to where it felt about right. Well that wasn’t right because it ran just a couple of minutes or less before it seized up. So, now I had to shim it back to where it felt “loose”. Nope, still seized up. More shimming. End of story is those bronze rods have to be astonishingly loose, even to the point of knocking a bit. Live and learn.

• This reply was modified 2 years, 7 months ago by frankr.

[Tom]

I see that the rod for the Maytag 82 has no end cap, so that route is out. Assuming the crank bearings are good, you might consider checking in with one of the Maytag collector sites on Facebook, or Harry’s Old Engine page. Likely the rod will need to be bored round, bushed, then reamed to fit the crankpin.

T

[need2fish]

Tom, out of curiosity, when you suggest bushing the rod, would you recommend sintering, or using a sleeve ?

[Mumbles]

Sintered metal is compressed powder. No good for this application. If the rod is one piece and needs to be bushed, SAE 660 Bearing Bronze (Roto Bronze) is what you want to use and is a high leaded tin bronze and is considered the workhorse of the bearing bronze alloys. It’s the stuff I use when replacing worn pin bushings in connecting rods.

If your rod is two piece, an automotive machine shop can resize it to your specs if you don’t want to attempt it yourself.

[green-thumbs]

Once had a worn rod with the wrong cap and a broken rod with a correct rod c cap. Aluminum rod with bronze inlays cast into both rod and rod cap.
Rod was 0.008″ oval toward piston end of rod. I filed the mating surfaces
of rod cap and lapped assembled rod and cap on crank pin,

Sounds crude and sloppy. End result is what matters. Used Starret telescoping gage and vernier micrometer to keep check on how
things were going. One thing sure, motor will run better with a rod
than without one.
Louis

Keep in mind that the ancestors of every machine tool were made by
hand using crude tools.

[Mumbles]

And I’ve often wondered how the first lathe was built when there was no lathe to make one with.

Sleep well tonight! ☺

• This reply was modified 2 years, 7 months ago by Mumbles.
• This reply was modified 2 years, 7 months ago by Mumbles.

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