GY6 139QMB piston arm replacement, possible? By crazedfox (Read 569 times)

[crazedfox]

Ok.
Got a good 139QMB Crank,
& a separate good 139QMB Piston-arm.

I'm wanting to combine both to get
a solid crank & piston assembly.

Has anyone removed a Piston-arm
from a Crank, & installed it on another?
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[alleyoop]

Sure you need to take out the circlips on the side of the piston holding in the wrist pin.
Alleyoop

Here is a video for you:

[skyrider]

Ally, if he is talking about a connecting rod doesn't the crank have to be pressed apart and back together?

[alleyoop]

Skyrider, MY BAD I read it wrong(HAHA), and yes he would have to have it taken off and pressed on another crank as well as new bearings .
And there are not to many machine shops that do that anymore and it would cost more than a new crank.

So it is not worth the trouble and money just get a whole new crank..
Alleyoop

[crazedfox]

Alley,
I don't think a prepped crank would cost more a few dollars to just go out & have them press the arm-pin out then one back in.

Sure a new crank would be better.
But I'm just wanting to save a crank,
Cus' I have the parts to make use of it.
-
Waste not, Need not.
Yes?
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[crazedfox]

So anyone accually do this?
Or am I the only one to ask/try-this?
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[skyrider]

I wonder if you understand the physics of pressing a crankshaft apart and , more importantly, pressing it back together properly aligned. The crank pin is not splined or otherwise keyed to go together perfectly straight. Any misalignment would cause the shaft to "wobble" and cause all sorts of problems.

[crazedfox]

I'm familiar with needing to keep things in align while being pressed back together.
I've rebuilt my share of pressed parts on my own cars, & trucks.
Even had some fun doing the
heat a front-knuckle, &
freeze the race-bearing to
be able to drop it in for a solid straight fit.
( Got to be quick on that one!)

- If I owned a press I'd be doing it myself. -
I'm fairly picky about my Alinements/Measurements.

Like my wood projects, an 1/8'th of inch out,
I don't like to deal with if I can prevent it.

I do Own a 6" ruler that goes down to 64'ths an inch.
& used that plenty.
But I prefer metric now, easy on the math.
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[alleyoop]

Yea you definitely will need a press to press the Pin in through the two counter weights.
Alleyoop

[crazedfox]

Yep, very true.
-
Now I want a bench top press…
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[crazedfox]

I have a few tools…


The Apt. manager sighed when she first saw this in my dining area.
All she asked was;
is that attached to the wall?"
Me;
"No.., would like me to climb it to prove so..?
Manager;
"no…"
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[crazedfox]

I think Apt. Management might freak-out at the sight of this in my living room.

Then ask me "How the heck I got this up to the 2'nd floor?!"

[crazedfox]

At what place on the crank dose one "measure" the crank, to ensure its the correct size?
-
I want to be sure it's not going to be the wrong stroke length for the P-arm I'd like to put on it.
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[crazedfox]

Bump.
I'd like to know to measure a crank & piston-arm.
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