Making rod bearing inserts, Attention Machinist

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SquierKA39
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Re: Making rod bearing inserts, Attention Machinist

Postby SquierKA39 » Wed Jun 13, 2018 9:06 am

I think someone said the speedifour had the same size roller bearings? Maybe you could find a set of those.

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Buccaneer
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Re: Making rod bearing inserts, Attention Machinist

Postby Buccaneer » Wed Jun 13, 2018 12:42 pm

dmbono wrote:You can still use my method with a three jaw. The soldered blank is no longer round, but you only need to get the split line roughly centered. I've made many split bushings by this method. No, you don't want the bushing to rotate in the rod. Yes, soft solder is used, not silver solder. That means any type of plumbing solder will do.


Glad to hear this is a tried and true method of making bearings. Thanks!

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Buccaneer
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Re: Making rod bearing inserts, Attention Machinist

Postby Buccaneer » Wed Jun 13, 2018 12:44 pm

SquierKA39 wrote:I think someone said the speedifour had the same size roller bearings? Maybe you could find a set of those.

The lower crank rod journal has a couple of flat spots on it, so probably
better to stick with the bronze bearings than to find roller bearings.

51SeaHorseTN27
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Re: Making rod bearing inserts, Attention Machinist

Postby 51SeaHorseTN27 » Thu Jun 14, 2018 1:36 pm

The fact it has a flat spot on the journal says to take it to a crank shop and have them cut the journal then make the rod bearing for that journal, any slop there is going to egg shape that bearing id and possibly seize or spin that bushing. Lathing that bushing od and split are good ideas. Putting the rod in a vice covered with a rag and putting the insert in the rod, torque it in then ream the id to almost the size it needs to be, then hone the id to nominal size plus the thousandths needed for oil clearence. I was a cnc operator for a few years, this is about the best youll get in a home scenario.
Malcolm
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51SeaHorseTN27
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Re: Making rod bearing inserts, Attention Machinist

Postby 51SeaHorseTN27 » Thu Jun 14, 2018 1:51 pm

Another thought here, if your good with solder and your rods have tang slots you could silver solder tangs on the od of the bushings and dremel them down to fit. But if those rods were designed for roller bearings you wont have tang spots unless the roller cages had tags, most roller cages freewheel as they go around during crank rotoation. Other roller setups use pins to hold the cages, if you had pins in the rod and cap you wouldnt have to worry about perfection or bushing "slip", you could drill holes in the od and the pins would lock it in. In your case the roundness of the torqued rod and cap is the only tension you have to keep the bushing from sliping, make sure you run as tight a side clearence as you can between the bushing and the crank journal wear surfaces on the counter weights to minimize side to side wear it will put less stress on the piston pin connecting rod geometry at higher rpm an reduce the risk of distorting the rod big end and bushing from lateral movement at higher rpms.
Malcolm
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Re: Making rod bearing inserts, Attention Machinist

Postby Buccaneer » Thu Jun 14, 2018 2:10 pm

51SeaHorseTN27 wrote:Another thought here, if your good with solder and your rods have tang slots you could silver solder tangs on the od of the bushings and dremel them down to fit. But if those rods were designed for roller bearings you wont have tang spots unless the roller cages had tags, most roller cages freewheel as they go around during crank rotoation. Other roller setups use pins to hold the cages, if you had pins in the rod and cap you wouldnt have to worry about perfection or bushing "slip", you could drill holes in the od and the pins would lock it in. In your case the roundness of the torqued rod and cap is the only tension you have to keep the bushing from sliping, make sure you run as tight a side clearence as you can between the bushing and the crank journal wear surfaces on the counter weights to minimize side to side wear it will put less stress on the piston pin connecting rod geometry at higher rpm an reduce the risk of distorting the rod big end and bushing from lateral movement at higher rpms.


Malcom, thanks for the excellent ideas. My rod ends do not
have tangs, but pinning the inserts in place would work.
The old inserts were very snug on the width, and as I was
trying to re-fit them by sanding down the mating ends of
the inserts, and reamer the hole bigger for the crank,
I didn't realize the inserts were hanging up on the "fillets",
or raised area, where the journal meets the webs on
the crankshaft. I ended up reaming the crank hole too big,
with no way to correct it as the insert ends were sanded down
as far as they could go. Some simple measuring along
the way would have prevented that. I'll cut a chamfer
on the new inserts to prevent this problem!

51SeaHorseTN27
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Re: Making rod bearing inserts, Attention Machinist

Postby 51SeaHorseTN27 » Thu Jun 14, 2018 2:19 pm

If you have the thickness on the rod and cap and thickness in the bushing you could drill the cap and rod tap small holes and loctite in set screws as pins, i dont like using a pressed in pin design all it takes is a rapid heat and shrink of the rod next thing you know your pin is chewing the crank from dropping out of the rod or cap, as for that flat journal either have it cut or find a good crank, no use in working your fingers to the bone to build a seriously good bushing to put on a mediocre crank that will kill it after a summer on the lake, im a memeber of the do it right the first time club, instead of curse it as its going to the smelter pile club. :ugeek:
Malcolm
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51SeaHorseTN27
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Re: Making rod bearing inserts, Attention Machinist

Postby 51SeaHorseTN27 » Thu Jun 14, 2018 2:24 pm

If your flats arent to bad you could chuck the crank in the lathe and polish those down to round with bands of emery cloth , semi course to microfine, then polish it with compound and a real leather strap. Otherwise crank shop can do the same and if its worse when you get it back its on them.
Malcolm
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Re: Making rod bearing inserts, Attention Machinist

Postby Buccaneer » Thu Jun 14, 2018 3:49 pm

51SeaHorseTN27 wrote:If your flats arent to bad you could chuck the crank in the lathe and polish those down to round with bands of emery cloth , semi course to microfine, then polish it with compound and a real leather strap. Otherwise crank shop can do the same and if its worse when you get it back its on them.

Sure sounds like I need to invest in a four jaw chuck for my lathe some day.

51SeaHorseTN27
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Re: Making rod bearing inserts, Attention Machinist

Postby 51SeaHorseTN27 » Thu Jun 14, 2018 5:30 pm

It would help never hurts
Malcolm
51SeaHorseTN27


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