Reducing the pin hole size of a press fit rod

[Super_Stock]

Just curious. What will be the wall thickness of the bushing?

Around .085, also this is virtually a stock application. I'm going to set some up at various stages and then use my shop press with it's pressure gauge to see what gives and when it gives. I'm also going to cycle some heat though them to see what that does as well as knock them around a little.
I guess it's really more of a sleeve than a bushing at this point.

[Dave Koehler]

Just curious. What will be the wall thickness of the bushing?

Let me rephrase this. What is the diameter of the Mopar pin?

[Momus]

...
Question is...Has anybody done this with any success? I think I saw MadBill elude to this once in a post..

[Smokey Yunick is quoted as saying: "Bleeped if I know where those (pin) forces come from!"]

The minutes (or even seconds) of an arc the pin/piston /small end bore/crank are out of alignment under heavy dynamic load is my thought.

[Super_Stock]

Let me rephrase this. What is the diameter of the Mopar pin?

Old pin 1.094, new pin is .927

[Super_Stock]

The minutes (or even seconds) of an arc the pin/piston /small end bore/crank are out of alignment under heavy dynamic load is my thought.

Well if the sleeve sticks in the rod like the pin and the pin sticks in the sleeve like in the rod, then I don't see a problem.

[Dave Koehler]

Let me rephrase this. What is the diameter of the Mopar pin?

Old pin 1.094, new pin is .927

When this started I was thinking a much thicker bushing.
I have done similar projects on some industrial stuff but the wall thickness was substantially more.
1.094 to .927 gives you a bushing with only .080 wall thickness. Not particularly crazy about that.
If you go forward with this I would increase the press fit to .002, maybe more if you are feeling froggy.
However, in review I think your best bet for genuine, predictable success is to go the free float ampco bronze route. Piece of cake.

[Super_Stock]

Yeah, I understand your concern Dave.
When I first started looking at doing something with this clunker I have here, I had a bunch of options. I could have had some custom pistons made, or bought some aftermarket rods with the right bushes already installed, I could even have offset ground the crank or put a stroker crank in it and went with a a different rod. Then there was just bushing a stock rod with suitable alloy bronze.
But then I got to thinking about the steel sleeve, and it just peaked my curiosity.. I wouldn't be bothering if the sleeve was only a real thin one, like most rods have.
I'll do a bit of testing and see where I go from there.

[Super_Stock]

Hey Bill, this is the one I'm thinking about.

Whatever you do, don't try to press fit them into brass/bronze bushes. The pins will eventually work themselves to one side and cause the mayhem described by falcongeorge...

I know this thread is more than a decade old, but JIC someone else is facing a similar dilemma, per above one solution would be to make up steel bushings to replace the bronze ones and size them for the correct press fit.

It's all your fault !!! LOL!!!!

[Dave Koehler]

Sadly, I have been pondering this thin wall bushing deal off and on and came to this conclusion.
To pull this off a lot more press fit is required than seems logical.

Procedure goes like this.
1: Hone rod ends a couple of thou over and to the same size.
Chamfer the hole if needed.
2: To avoid the problem of installing the bushing to the proper depth the first time a special bushing is to be made.
This bushing will be T shaped with just enough thickness to act as a stop. .060?
Bushing ID should be .002 under size
Bushing OD should be .005 -.006 larger than the rod hole
Bushing should be slightly chamfered on the OD.
3: Induction heat the rod and drop the bushing in.
Machine off the excess T portion
Chamfer the bushing ID.
4: Finish hone or bore for .001-.0012 pin press fit
Make sure there are no nicks or burrs however small, on the pins.
My thinking is that is will take less heat than the bush to install the piston pin and this can be pulled off.

Optional procedure (and probably a good idea.)
.080 wall isn't all that much and would be no problem if it was a free float bronze setup.
A bit more thickness for press fit with steel could prove to be a good thing.

Honing is no fun so I would bore the rod .040 - .060 oversize and make the bushing to match.
This is probably overthinking it but my minds eye says the dodge rods are pretty thick on the top.
This much has to be bored out anyway if you were to bush the rod for a bronze bush at the oem pin diameter.
Boring also gives you the option to blueprint the C to C length.
IF the hole is a bit offset (happens a lot) in the forging you can also move it sideways a bit to center the hole better.

Closing thoughts:
Consider dry ice to freeze the steel bushing for installation. Need all the help you can get.
Resize the Big ends before doing any boring of the small end.
Rods should be spiffy clean and dry before induction heating.
Bronze bushed free float is a lot less work.

[Momus]

The minutes (or even seconds) of an arc the pin/piston /small end bore/crank are out of alignment under heavy dynamic load is my thought.

Well if the sleeve sticks in the rod like the pin and the pin sticks in the sleeve like in the rod, then I don't see a problem.

That was a reply to Mad Bill.

[Momus]

Sadly, I have been pondering this thin wall bushing deal off and on and came to this conclusion.
To pull this off a lot more press fit is required than seems logical.

Procedure goes like this.
1: Hone rod ends a couple of thou over and to the same size.
Chamfer the hole if needed.
2: To avoid the problem of installing the bushing to the proper depth the first time a special bushing is to be made.
This bushing will be T shaped with just enough thickness to act as a stop. .060?
Bushing ID should be .002 under size
Bushing OD should be .005 -.006 larger than the rod hole
Bushing should be slightly chamfered on the OD.
3: Induction heat the rod and drop the bushing in.
Machine off the excess T portion
Chamfer the bushing ID.
4: Finish hone or bore for .001-.0012 pin press fit
Make sure there are no nicks or burrs however small, on the pins.
My thinking is that is will take less heat than the bush to install the piston pin and this can be pulled off.

Optional procedure (and probably a good idea.)
.080 wall isn't all that much and would be no problem if it was a free float bronze setup.
A bit more thickness for press fit with steel could prove to be a good thing.

Honing is no fun so I would bore the rod .040 - .060 oversize and make the bushing to match.
This is probably overthinking it but my minds eye says the dodge rods are pretty thick on the top.
This much has to be bored out anyway if you were to bush the rod for a bronze bush at the oem pin diameter.
Boring also gives you the option to blueprint the C to C length.
IF the hole is a bit offset (happens a lot) in the forging you can also move it sideways a bit to center the hole better.

Closing thoughts:
Consider dry ice to freeze the steel bushing for installation. Need all the help you can get.
Resize the Big ends before doing any boring of the small end.
Rods should be spiffy clean and dry before induction heating.
Bronze bushed free float is a lot less work.

That 005 to 006" on the interference might be a bit tight on an 1.090" bore Dave?

[Dave Koehler]

Sadly, I have been pondering this thin wall bushing deal off and on and came to this conclusion.
To pull this off a lot more press fit is required than seems logical.

Procedure goes like this.
1: Hone rod ends a couple of thou over and to the same size.
Chamfer the hole if needed.
2: To avoid the problem of installing the bushing to the proper depth the first time a special bushing is to be made.
This bushing will be T shaped with just enough thickness to act as a stop. .060?
Bushing ID should be .002 under size
Bushing OD should be .005 -.006 larger than the rod hole
Bushing should be slightly chamfered on the OD.
3: Induction heat the rod and drop the bushing in.
Machine off the excess T portion
Chamfer the bushing ID.
4: Finish hone or bore for .001-.0012 pin press fit
Make sure there are no nicks or burrs however small, on the pins.
My thinking is that is will take less heat than the bush to install the piston pin and this can be pulled off.

Optional procedure (and probably a good idea.)
.080 wall isn't all that much and would be no problem if it was a free float bronze setup.
A bit more thickness for press fit with steel could prove to be a good thing.

Honing is no fun so I would bore the rod .040 - .060 oversize and make the bushing to match.
This is probably overthinking it but my minds eye says the dodge rods are pretty thick on the top.
This much has to be bored out anyway if you were to bush the rod for a bronze bush at the oem pin diameter.
Boring also gives you the option to blueprint the C to C length.
IF the hole is a bit offset (happens a lot) in the forging you can also move it sideways a bit to center the hole better.

Closing thoughts:
Consider dry ice to freeze the steel bushing for installation. Need all the help you can get.
Resize the Big ends before doing any boring of the small end.
Rods should be spiffy clean and dry before induction heating.
Bronze bushed free float is a lot less work.

That 005 to 006" on the interference might be a bit tight on an 1.090" bore Dave?

Not with induction heating. Cold press would be iffy.
The idea is to have more press on the bushing when heated up just enough to allow the piston pin to be installed.

[Super_Stock]

Thanks again for the advice Dave, I appreciate it.
One thing I was a little worried about was having the bush move when installing the pin. I thought if I put a chamfer on the end of the rod and then leave a small riser on the end of the bush, then that would stop the bush bushing through the rod when inserting the pin. I would just have to make sure the pin was inserted from the correct side. I guess I could even flare out the ends of the bush into some chamfered ends on both sides of the rod.
Having said that, realistically, the pin should pass though the bush with minimal effort once the rod is heated.

[Dave Koehler]

Having said that, realistically, the pin should pass though the bush with minimal effort once the rod is heated.

Yup, you only get one shot so prep is key.
It will take less heat to install the pin so the bush should not move due to the heavier press fit.

[Super_Stock]

Well, if it all goes to crap, then I'll just chock it up to experience... It wont be the first time.!!!! LOL