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Dynamic Balancing Rotax 912

Amadeus

Amadeus

Well Known Member
I've had the same leaking radiator issue as many others with the Rotax 912iS and am trying to eliminate any and all potential causes....one of which is possible propeller vibration.

I thought I had a location lined up to balance the prop on my -12iS but then he just backed out of performing the dynamic balance over concerns that the engine and the propeller turn at different speeds and that because of the gearbox he wouldn't have holes on the flywheel to place balancing weight.

Has anyone actually had their propeller dynamic balanced on the Rotax 912 powerplant?

If so, where were the weights placed?

My thought is that a hole could be drilled in the spinner backplate and a bolt with washers and a lock nut be installed for the balancing weight in the location identified by the dynamic balancer. Is this method not a possibility?
 
Amadeus said:
I've had the same leaking radiator issue as many others with the Rotax 912iS and am trying to eliminate any and all potential causes....one of which is possible propeller vibration.

I thought I had a location lined up to balance the prop on my -12iS but then he just backed out of performing the dynamic balance over concerns that the engine and the propeller turn at different speeds and that because of the gearbox he wouldn't have holes on the flywheel to place balancing weight.

Has anyone actually had their propeller dynamic balanced on the Rotax 912 powerplant?

If so, where were the weights placed?

My thought is that a hole could be drilled in the spinner backplate and a bolt with washers and a lock nut be installed for the balancing weight in the location identified by the dynamic balancer. Is this method not a possibility?
Click to expand...

Yes, it is, and I have done lots of them that way and many many owners have had it done as well.
To be blunt, if the person you contracted gave you the response they did, you are probably better off having it done by someone else.

I think all balancing units come with instructions prescribing a procedure for adding balance weights to the aft spinner bulkhead. That is the procedure that is used on a Rotax 912.
 
If you don’t have them, here are the DynaVibe Rotax-specific balancing instructions.
 

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rvbuilder2002 said:
To be blunt, if the person you contracted gave you the response they did, you are probably better off having it done by someone else.
Click to expand...

My first thought, too. Thanks for confirming.


Bob Y said:
If you don’t have them, here are the DynaVibe Rotax-specific balancing instructions.
Click to expand...

Thank you! Is it possible to rent a DynaVibe anywhere? I'm thinking it my be best to just do it myself.
 
Amadeus said:
My first thought, too. Thanks for confirming.




Thank you! Is it possible to rent a DynaVibe anywhere? I'm thinking it my be best to just do it myself.
Click to expand...

Standby, you're probably in luck. I don't want to speak for anyone else but there is a solution to this that circulates the RV-12 community thanks to a builder.
 
DynaVibe Classic

Amadeus, I have used the DynaVibe Classic very successfully on our legacy RV-12. If you decide to rent or buy one there are some things to consider. It is the least sophisticated DynaVibe balancer so I suggest you go to the Web and download the users manual. I found that there were things that needed to be done before you can actually use it. You can PM me and I'll get back to you with more specific observations.
 
Yes Jayson/Nate!

I'm running a special on my Dynavibe now :) .. thanks to a lot of $100 donations in the past.. it has paid for itself and is now "owned" by the RV-12 community.

It is currently in Alabama with GatorsR1. He's done with it and can send it to you when you're ready for it. You can use it and hold on to it until the next builder asks for it.. you just pay for the shipping to him. Usually you will want to have an assortment of AN3 bolts (shorter sizes), and a bunch of washers (the thick and thin types), and an AN365 nut (maybe a AN364 too) on hand so you're not waiting for an Aircraft Spruce shipment while you have the unit.

Just drop me a PM if you want it.
 
At what RPM should the balancing be performed?

I assumed that since the engine spends more running time at cruise, about 5000 RPM, propeller speed 2076 RPM, that is where it should be measured and corrected. In the DynaVibe user manual there is scribbling and calculations at 500 RPM. I'm confused.
 
Amadeus said:
At what RPM should the balancing be performed?

I assumed that since the engine spends more running time at cruise, about 5000 RPM, propeller speed 2076 RPM, that is where it should be measured and corrected. In the DynaVibe user manual there is scribbling and calculations at 500 RPM. I'm confused.
Click to expand...

Valid assumption. You should balance at your intended cruise RPM. It's not a big deal if you don't get it exact, but you should try to get close to it.
 
DynaVibe

There is a DynaVibe instruction manual specifically for Rotax 912 engines.

"DynaVibe Procedure for Rotax 912 Propeller Balancing
RPX-AFA-RO-912-00-B
December 2020"
 
azonslow said:
There is a DynaVibe instruction manual specifically for Rotax 912 engines.

"DynaVibe Procedure for Rotax 912 Propeller Balancing
RPX-AFA-RO-912-00-B
December 2020"
Click to expand...

Do you know where that manual can be obtained ? I tried a basic web search but didn't find anything.
 
rob,
i talked to you in the past 10 days and have sent you my address. the current user has been in contact with me and is sending it to me next. if you e mail me or however you do it i can send it to the next in line.
 
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