Honing Wrist Pin Bushings

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Bill Lawless
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Honing Wrist Pin Bushings

#1 Post by Bill Lawless » Mon Nov 04, 2019 3:43 pm

I probably already know the answer to this ...

Can you hone you own Wrist Pin Bushing? I had one that was a little loose so I put in 4 new brass ones from Stoddard.
Can you hone these or are you at risk of getting out of parallel to the Rod Journals? Or is this a machine shop only task?

Bill
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

Martin Benade
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Re: Honing Wrist Pin Bushings

#2 Post by Martin Benade » Mon Nov 04, 2019 3:45 pm

I think machine shop to get it right

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#3 Post by Bill Lawless » Mon Nov 04, 2019 5:14 pm

Thanks..
I found a machine shop that can do them first thing in the AM..

Anybody know how much clearance there should be?
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

Tim Berardelli
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Re: Honing Wrist Pin Bushings

#4 Post by Tim Berardelli » Mon Nov 04, 2019 6:24 pm

Bill,

.0005 or 1/2 of a thousands of an inch . Are they using a device called a "Bearing Master" ?

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#5 Post by Bill Lawless » Tue Nov 05, 2019 8:22 am

Thanks Tim, on my way there now..

Elfrink says .0008-.0014
But I’ll tell them.0005
Thanks
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#6 Post by Bill Lawless » Tue Nov 05, 2019 11:07 am

30D68C75-EF2A-4009-9BD4-F5FEEDAB75A9.jpeg
30D68C75-EF2A-4009-9BD4-F5FEEDAB75A9.jpeg (2.07 MiB) Viewed 1027 times
All done, exact 1/2 tho clearance..
This is the machine they used:
2415BBD2-5A19-4D71-94BB-EC3B81F3096D.jpeg
2415BBD2-5A19-4D71-94BB-EC3B81F3096D.jpeg (2.44 MiB) Viewed 1027 times
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

Tim Berardelli
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Re: Honing Wrist Pin Bushings

#7 Post by Tim Berardelli » Tue Nov 05, 2019 7:12 pm

Bill,

The .0008 spec is for A/B rods.

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#8 Post by Bill Lawless » Tue Nov 05, 2019 7:59 pm

Ahh, Thanks Tim.
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

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Al Zim
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Re: Honing Wrist Pin Bushings

#9 Post by Al Zim » Sun Dec 22, 2019 5:24 pm

You have a used piston pin and a piston that is worn. What are you going to do about the big end of the rod probably being oversize? al zim
 

Martin Benade
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Re: Honing Wrist Pin Bushings

#10 Post by Martin Benade » Sun Dec 22, 2019 5:44 pm

Generally the big end remains in spec.

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Harlan Halsey
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Re: Honing Wrist Pin Bushings

#11 Post by Harlan Halsey » Mon Dec 23, 2019 5:16 am

You have only scratched the surface, so to speak: First clean really clean. Second weigh the rods to see if you have a matched set. Third polish the roots of the cap studs. Now take the rods to a Porsche competent machine shop where they will: magnaflux, check/recondition the big end, same for the small end-rebush if needed, straighten, equalize the lengths, and balance. If the wrist pins don't look and measure new, replace them.
That's the easy part. Porsche pistons are fit to the wrist pins with an interference fit at room temperature. That's why the workshop manual shows an electric piston heater. But you already know that because you didn't have the heater so you heated the pistons on the top with a torch to disassemble the engine. Recovering that fit is sometimes a problem. Even the best machine shops around here insist on fitting the pistons with a slip fit, and honing the valve guides over spec. ( Years ago we solved the wrist pin fit problem by having a wrist pin centerless ground .0002" undersize. Then we have the shop fit the pistons to the undersize pin without telling them that it is undersize. You can hone valve guides at home with the Sunnen electric drill run hone.)

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#12 Post by Bill Lawless » Mon Dec 23, 2019 8:23 am

Harlan Halsey wrote:
Mon Dec 23, 2019 5:16 am
But you already know that because you didn't have the heater so you heated the pistons on the top with a torch to disassemble the engine.
The SPY CAMERA you have installed must of been in somebody else's shop... ****??????****

My engine has been completed and RUNNING BEAUTIFULLY for a while now.... :D
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

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Al Zim
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Re: Honing Wrist Pin Bushings

#13 Post by Al Zim » Mon Dec 23, 2019 10:21 am

Continuing Harlan's write up. The valve guides come in oversize. You should measure each hole and trim the guide to have the correct interference fit. ONE GUIDE DOES NOT FIT ALL. If you are serious about sizing valve guides for proper clearance to the valves, Purchase a new valve guide reamer frequently or go to an adjustable diamond valve guide reamer. As always have your torque wrench calibrated once in a while. al zim
 

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Bill Lawless
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Re: Honing Wrist Pin Bushings

#14 Post by Bill Lawless » Mon Dec 23, 2019 3:52 pm

The Title of this post is “ Honing Wrist Pin Bushings” ?
But Good info. On "Values Guides"
 Thanks,
Bill
65' 356 SC Cab Irish Green :D
65' 356 C T6 Grey
82' SC Targa
81 VW Westfalia with 2015 Forester Engine
BMW R50/2, 2BMW R90/6's, BMW R65, K1200RS

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Jacques Lefriant
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Re: Honing Wrist Pin Bushings

#15 Post by Jacques Lefriant » Tue Dec 24, 2019 11:26 am

Hi
one of the best ways to go about doing this is to use solid bronze bushings that have smaller IDs and have the bushings bored to ensure equal length of the rods. then hone to size.
j
 

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