Question for the brain trust.
Is the factory balance of the fan 'good ' or should it be rebalance on a rebuild?

Thanks in advance for your suggestions.
oh is so, where in the La area to do that?

Rebalance.

European Motorworks or Fat Performance should be able to do this.

Thanks for suggestion..

Peter, if you're taking it apart (to clean, blast, paint, etc.), make note of where the factory installed balance weight is on the pulley in relation to the timing notch in the cast fan part. It should go back together in the same position to avoid a big rebalance job (ask me how I know)

Have the whole rotating system balanced (crank, flywheel with clutch and pressure plate, and the fan/pulley all attached). Have the shop balance your pistons and rods as well. You'll be glad you did in case you ever over-rev the motor



Hi Mike.

Balance everything.
If you have one part out of balance, you wasted you time and money having the rest balanced.

That's my line of thinking

We don't really offer the service anymore (even though its still on the site) but this link will give you some information to support why everything needs to be balanced.

http://www.aircooledtechnology.com/index.p...namic-balancing

Jake,

Your comments, you are well regarded on my end.
Most of the outfits that I've contacted mentioned that it's not needed as it's already balanced from the factory. Today, I found and dropped off my fan at Auto Dynamic Balancing in Baldwin Park Calif # 626-962-9136 for them to check / balance. Well.... it was almost 1/2 once OFF....YA factory all right! Now, if it were I and I just rebuilt a type 4 and just bolted the fan back on...I would take if off and send it to Rod the owner so he can balance it for you. FYI.. we learn some thing every day!

Have you balanced the stock pistons.

funny as I bought a digital scale to check how close my new JEs were. They were all spot on with a Zero gram difference!

Everything is "balanced" if the tolerance of balance is great enough.

Anyone who tells you that the stock crank doesn't need to be balanced is totally off base. They are ASSUMING a lot, and in engine machining and building assumptions are not made- ever.
Everything is quantified- ALWAYS.

Consider this:
1- What if the unit was previously dressed, or attempted to be balanced by an idiot?

2- What if Klaus had a bad day at work 40 years ago.

3- What if someone removed the fan ring and did not have a jig to re-center it? If this happens the fan is greatly imbalanced and can often never be re-installed "true".

Cooling fans are the second most imbalanced T4 component that we interface with, the only thing worse is a new Sachs pressure plate, which isn't even round- none of them are.

Nothing is ever good enough, especially when it comes to dynamic balancing.

Jake, it's awesome when you share the science of building engines! Quantification indeed.