full balancing of e shaft rotors and counterweights assembled

[dubber91]

theoretically. so long as the rotating radius of the counterweights and Centre of gravity of each rotor doesnt change

[Timrxmotors]

My 12A has never been balanced,12A rotors with a 13B rear counterweight.You will know as soon as you start the engine if it is far out.I did find a company called \'Vibration Free\' who would have no problem balancing a rotor assembly.

Latest is,my engine does need balancing,mainly because I have a \'D\' and a \'B\' weight rotors.I have come to the conclusion there are 2 ways to balance the rotating assembly.
The first way is to balance the shaft with counterweights and rotors.It appears Mazda do this with the RX8 engine,they inject a gel into the rotor to make up oil weight.There are no balance holes in the rotor,they are balanced by adjusting the counterweights.I don\'t know how they attach the rotors.Other people use a bob weight to replace the rotor.
The second way is the way I will have it done.To balance the shaft first,then balanced with counterweights.The rotors will be made exactly the same weight,then balanced individually.It appears Mazda balanced each RX7 rotor,but were not weight matched,just close,within 50g.
The result should be a far better balanced engine than I\'ve ever had!
I did speak to \'Vibration Free\',he balances the whole built up block,so I guess the rotors are dragged around with no proper lubrication.He has done Carl\'s 4 rotor and 3 rotor engines this way.Think I\'ll pass on that one,the bloke is not very helpful at all.

[oldone]

We have always balanced the eccentric shaft,rotors,flywheel and balance weights as a unit.The rotors were lightened to choice weight first to within 1 gram of each other.

[Wankeltrim]

Hi
The right way to do this is that you get two rotors with same weight and then you made bobweight that is matched to your rotor weight including oil and all seals and springs and put them on the shaft. If you have a light weight flywheel then you first balance the shaft with balance weight but without the flywheel and when this is done then you put the flywheel on and balance your flywheel ( after that you can put your clutch on and balance the clutch for it self ).
We have done this for more than 20 years and i got all information from a japanese that we meet at MazdaRallyeTeamEurope when Mazda compete with the first gen Rx7 in Gr-B. This japanese was a engine technician that work at Mazdaspeed in japan so i think he knew how to do.



/Jörgen Blennow
Rotary Performance
Sweden

[stuart wizy]

i can turn bob weights with the corect bore size and od as a rotor and face up 1 end to get the required weight but how do you stop the weights spining of the shaft when balancing?  I thought of 1hole drilled and tapped from od throgh to bore so a grub screw could be used to hold the bob weight on the journal, is that how you do it?
cheers
stu

[Wankeltrim]

YES .....
But the bobweight dont have the rotor shape

[stuart wizy]

what sort of revs have you run up to with your balaced assembly in a motor and did you use a centre bearing type e shaft?
cheers
stu

[Timrxmotors]

Hi
The right way to do this is that you get two rotors with same weight and then you made bobweight that is matched to your rotor weight including oil and all seals and springs and put them on the shaft. If you have a light weight flywheel then you first balance the shaft with balance weight but without the flywheel and when this is done then you put the flywheel on and balance your flywheel ( after that you can put your clutch on and balance the clutch for it self ).
We have done this for more than 20 years and i got all information from a japanese that we meet at MazdaRallyeTeamEurope when Mazda compete with the first gen Rx7 in Gr-B. This japanese was a engine technician that work at Mazdaspeed in japan so i think he knew how to do.



/Jörgen Blennow
Rotary Performance
Sweden

If it is done with the bobweights,all balanced fine,then if the bobweights are removed would the remaining shaft and counterweights be in balance? Put another way,are the counterweights at all balancing the rotors,or do the rotors balance each other?

[Wankeltrim]

what sort of revs have you run up to with your balaced assembly in a motor and did you use a centre bearing type e shaft?
cheers
stu

The balance has nothing to do with the rev limit. It\'s the weight of your rotors that sets the limit.
Mazdas 13G rotor that was the lightest rotor that was produced has a weight of 3750g without bearing. With this rotors they had a rev limit that was 10.400rpm so with the production rotors the rev limit should be around 9-9.500rpm.

No i dont use 2 piece shafts becuse there are no reason to do that if the balance is done well.

[Wankeltrim]

If it is done with the bobweights,all balanced fine,then if the bobweights are removed would the remaining shaft and counterweights be in balance? Put another way,are the counterweights at all balancing the rotors,or do the rotors balance each other?

The counter weights are balancing the rotor weight.