Engine Balancing

[frankoporsche]

Anybody know if there are any Machine shop close by Seattle iWashington does complete balancing for 911 engine?
Balancing Crank /Rod/ piston/flywheel...Thanks

[grotvik]

Try Chris' German Auto Service in Redmond. He has a good reputation. If he doesn't provide balancing services, I'm sure he will be able to recommend someone.

Chris's German Auto Service: Service and Repair for All Porsche Models in Redmond, WA

Greg

[frankoporsche]

Originally Posted by grotvik

Try Chris' German Auto Service in Redmond. He has a good reputation. If he doesn't provide balancing services, I'm sure he will be able to recommend someone.

Chris's German Auto Service: Service and Repair for All Porsche Models in Redmond, WA

Greg

I will check it out ..thanks

[Walt Fricke]

Afterburn - I think the boxer configuration reduces balance issues compared with an in-line motor or a V motor. But the reciprocating parts (pistons) and rotating parts (crank), and both (rods) still need to be balanced, which Porsche does (or did) by grouping parts of roughly equal weight together - some engines had heavier rods, some lighter, for instance, though all in any engine were within some spec of each other' weight.

I'd venture to say that for ordinary street driving, if you rebuild a 911 engine and the pistons are good you don't need to have them balanced. If the crank measures out, it doesn't need to be balanced. Rods might benefit from balancing if you have them reconditioned, but the shop might well have that in their normal price for that work.

One thing you can do is line up your parts so the heaviest ones are closest to the flywheel, and then get lighter as you go out. I don't know if that will work on a straight or V motor, though

If you are going to hot rod the motor, well of course you will have everything balanced to a gnat's ass - that's just what we do, whether it makes much of a difference or not. Though if you are going to spin a 6,000 rpm motor to 8,500 rpm, a better balance job is a pretty good idea..

[Trackrash]

From what I have been told the cranks are usually good to go. As long as the flywheel hasn't been machined that only leaves the pistons and rods. Those can be DIYed if you have a good scale. The rods should be done end to end. There is a lot of info if you Google.

[Neil Harvey]

When you measure your pistons, make sure you add in the clips.

[Trackrash]

My JE pistons were perfect just by swapping around the piston pins. All within a gram anyway....

Turns out my rods were also spot on.

[Trackrash]

Yea, I could have gotten out my triple beam balance.... The new digital scales make it so much easier. Porsche's tolerance is 9grams on the rods, so I figure I'm good.

[2jmotorsports]

Might be of value to this thread. Necessary to balance an aluminum pressure plate?

[Walt Fricke]

Balancing the pressure plate depends. Where did it come from? Is it new and the manufacturer balanced it, or used with an unknown history. Makes sense to balance it.

I prefer to zero balance the flywheel, and the pressure plate. That way you can swap out one or the other without sending both back to be balanced together.

But some prefer balancing things as an assembly, which could include the crank.

I am dubious that clutch disks need balancing - they look pretty uniform and symmetric to me. But maybe someone has had one balanced and learned it was, indeed, out of balance enough that balancing was worth while?