3.0 Piston pin

[outsider347]

Need the Piston pin tolerances for 3.0
Bore-
Shaft-
Clearance fit-

I have Waynes book but the above info is N/A

tks
ed

[Mark Henry]

For what? Installing and sizing the small end bushing?
I'd never do it that way.

You need to take the rods, bushings and pins you will be using to your machinist.
This is a high tolerance slip fit, there should be absolutely no pin rock or slop and at the same time it can't be tight.
Not something you want to ballpark.

Clearance will be tight, something like .0005"

[prschmn]

+1 without a doubt

[outsider347]

agree with above

still need the dimensional info

[Mark Henry]

22mm

[outsider347]

Originally Posted by Mark Henry

22mm

Tks Mark
22 mm - shaft dia?

Would you know the clearance fit as well?

Tks for your response

[arbita1]

Funny you ask this. I'm going to be dropping my rods at the machine shop for rebushing. My machinist told me he needs a good pin also when I bring them in. It got me thinking how do I know if the pins are good. I looked in Wayne's book and Bentley and couldn't find any info. I was thinking of putting each corresponding pin with each rod and let him decide if he should use one for all or each individually. Maybe I'm over thinking.

[Mark Henry]

The pins are hardened steel, the rod bushing is bronze (alloy), the bushing wears before the pin ever will. So likely your old pin are fine and in tolerance. If you are getting new pins I'd wait till you have them in hand before going to the machine shop.

I didn't reply to the OP because any engine machinist worth his salt has a reference book(s) right at his desk and should be asking for a pin.

Also this is not a job you do on a mill, it takes several special machines/tools and experience to do a top notch rod rebuild. One degree off will put side loads on that will prematurely end your engine.

Not a 911 but this will give you a good idea of the work involved.
https://youtu.be/lzUa8kYLSRU

[prschmn]

Mark is quite right that the bushings are the "sacrificial" material.
If you look at your pins now there are two spots that don't ever ride in the piston
or rod. they may have a stain even. if you can detect any bump there you've
got wear-got a mic?

[manbridge 74]

If it helps, industry standard on floating pin type is gravity. Yes, no typo. You let the pin fall through the bushing under its own weight. Slips right through, too loose. Doesn't move, too tight. Slowly moves through, just right. Oiled surfaces.

Of course, comparing the above to brand new Porsche assembled parts would be best. Or if Henry wanders by he might have some input.

[Trackrash]

Bush new, 22.033 - 22.020mm inside diameter

Clearance 0.020 - 0.039mm

I just took an SC motor apart and the original Male piston pins measure 21.996mm