aa piston install no markings

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jpryorx2
Posts: 34
Joined: Tue Oct 02, 2007 3:50 pm

aa piston install no markings

Post by jpryorx2 »

hey guys i bought a set of aa 92mm forged thick walls and they have no markings to tell which way goes to the flywheel. i've had people tell me would be a mark on the inside by where the wrist pin goes through and to put that too the flywheel but again theres nothing there i've tried calling and emailing AA and got no response at all. so can anyone tell me which way they go in or does it not make a difference? ive never had a piston for a vw that didn't have an arrow on it
thanks
jason
Bruce.m
Posts: 453
Joined: Sun Aug 11, 2013 1:44 pm

Re: aa piston install no markings

Post by Bruce.m »

Get a set of measuring calipers and measure the distance between the piston pin bore and the outside diameter of the piston, on both sides.

Stock pistons have the pin offset to one side so that force of the combustion pressure is not just on one side of the piston/cylinder. The offset also reduces noise (probably the main reason for having it).

Some aftermarket piston have no offset so can be fitted either way. Some have no offset and still have the arrow marked so that the customer is not confused, but it has no purpose.
jpryorx2
Posts: 34
Joined: Tue Oct 02, 2007 3:50 pm

Re: aa piston install no markings

Post by jpryorx2 »

thanks it's looking like measuring it is going to be the only way to figure it out as they still haven't responded
jpryorx2
Posts: 34
Joined: Tue Oct 02, 2007 3:50 pm

Re: aa piston install no markings

Post by jpryorx2 »

so i measured 0 offset then just to be sure i was gonna try to call them again but went and read the description and it does say 0 offset s i guess they can go in either way.maybe i can actually get them in today and hope that the online calculators are right fr my barrel shims and head gaskets
thanks
Bruce.m
Posts: 453
Joined: Sun Aug 11, 2013 1:44 pm

Re: aa piston install no markings

Post by Bruce.m »

Good luck!
User avatar
sideshow
Posts: 3428
Joined: Mon Oct 27, 2003 11:00 am

Re: aa piston install no markings

Post by sideshow »

Its common/standard to not off set the pins in aftermarket parts. The arrow or bosses in the pins are common to OEM parts, because they are off set.
Yeah some may call it overkill, but you can't have too much overkill.
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