911S piston balancing

[246jaenick]

Can anyone help?
I have a set of original Mahle standard size pistons that need balancing.
What I am trying to find out is the "correct" way and where to machine them.
I am not keen on "drilling" the underside of the crowns method.
Regards,
Jim.

[uai]

I'd go for the wrist pin.
I had the issue with a NOS set of pistons where i would have had to remove quite some volume to get the weight off.
After asking around it was quite clear that machinig the wrist pin was the way to go.
So I had 3 machined to scheme a and one machined to scheme b
Be sure to use a collet chuck - not sure if that's the correct term - when having it on the lathe.

[SIMI BOB]

First thing to do, measure all the pistons and the wrist pins separately. Match the lightest piston with the heaviest wrist pin and so on. Then measure pistons and pins together and see what needs to be done.
Bob B

[304065]

Unless it's a race motor-- in which case rather than matching, machine everything to the same (match to lightest) weight. That way if you blow one thing you can replace just that thing without having to rebalance everything. Which isn't to say you won't have the case apart to clean it after a blown motor, it's just one less thing to do.

[246jaenick]

Thanks very much for your reply.
The 911S I have is purely a road car. The pistons have a weight difference of 3.2g and the conrods have a difference of 3.0g.
If I mix and match the pistons/conrods and wristpins I can get the combined weight difference down to 0.9g.
Do you think this mix and match method would be OK for my road car?
Regards,
Jim.

[uai]

Well I wouldn't mix up the conrods and weighing them is not enough - you need to Balance them - it is not that difficult, or have that done by a professional it's not expensive and they usually check for angulatity and dimensions too. it's 55$ for the set @ ollies so that's a no brainer.
http://www.olliesmachine.com/uploads/Ollies_List.pdf
Balancing pistons is 55/set too.
There are lots of manuals for this on the net.
e.g. http://www.angelfire.com/ca4/CorvAIR...odBalance.html
You need one stamp/kitchen scale a little fixture and a grinder (I do it with two scales fixed on a base)