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Author: Subject: general forged rods question
itsawindupuk

posted on 8/3/14 at 08:27 PM Reply With Quote
general forged rods question

Hiya everyone. Today I got my forged rods, and thought I'd test them by putting the forged pistons and rods together and seeing if there is much free play. The standard pistons and rods have a press fit gudgeon pin. The new ones use circlips, but when I hold the piston and The end of the rod I have a tiny amount of free play. Is this normal as there is non on the oem ones. It is a very small amount but thought id check as I can understand things changing when it warms up.

Thanks

Adam

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madteg

posted on 8/3/14 at 08:40 PM Reply With Quote
Its normal, the hole in the little end will shrink and the gudgeon pin will expand when they warm up.
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redturner
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posted on 9/3/14 at 08:38 AM Reply With Quote
Depends what you call free play. It may well have some end float, but if the free play amounts to being able to rock the piston against the rod, then that's bad news.....
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coyoteboy

posted on 9/3/14 at 09:58 AM Reply With Quote
quote:
Originally posted by madteg
Its normal, the hole in the little end will shrink and the gudgeon pin will expand when they warm up.


The hole doesn't shrink when it warms up, it gets larger too. If the pin and rod material are matched CTE the clearance won't change as it warms up. There should be end play but the 'rocking' play should be so tiny you can bearly detect it. The pistons I just pulled from a 130+k mile engine have immeasurable rocking motion.






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redturner
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posted on 9/3/14 at 10:04 AM Reply With Quote
Exactly, if you can feel it by hand, then it is too much.....
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itsawindupuk

posted on 10/3/14 at 07:00 PM Reply With Quote
Thanks everyone, I took them to two engine builders today and both said it was a little too much, around 3 thou. So, now I need another set of rods for a 2.0 duratec. Are k1 any good? I haven't paid for these rods so im not out of pocket.
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redturner
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posted on 10/3/14 at 07:18 PM Reply With Quote
Why not rebush the little ends, custom and practice....
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itsawindupuk

posted on 10/3/14 at 08:02 PM Reply With Quote
I asked them both and they don't. I called another place and they said 180+ vat which I thought was a lot for a rebush.
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redturner
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posted on 10/3/14 at 08:08 PM Reply With Quote
Thats the price of a new rod nearly, but if it is for all 4 rods it's not too bad.....
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