GMON

Does anyone know how this is done. Do you need some sort of machine similar to a tire balancer. Is this something I can do on my own with a couple of scales and some head scratchin?



Gregory

Lynn E. Hanover

The shaft alone needs nothing done unless you have lightened it. The rotor are done at the factory. The counter weights are matched to the rotor weight.



The weights are used to take out the rocking couple caused by the rotor offset.



The rotors are numbered in sets. Some have the actual weight stamped on them.

Some rotors of the same year/model have a paint dot to show the range of weight.

The paint dot is gone after running the engine.



If you replace one rotor, and you don't have a scale to compare it to the old rotor,

just get a stiff stick. Drill a hole through the center. Put a long nail through the hole. Measure from the center hole to each end of the stick. Drill a hole at each end the same distance from the center. Make two coat hanger hooks using the same amount of wire. On the corner of a table set up two 3/8" drive sockets and set the nail across the sockets. You can guess most of the rest.



Balance the rotors with dimes set in the rotor bearing. Put a stop on the drill press and drill into the area near the apex on the side of the rotor. Look where the factory drilled the original balance holes. Set the stop for a very shallow hole. Start with 1/16" deep at the full diameter of a 1/4" drill bit. Try to stay in the same place on each apex. Plan ahead for this.



If you have a damaged rotor, practice on that. Notice how much material is drilled out to equal one dime. (Not much). Drill an equal amount from each corner. If you need more, flip the rotor over and take some off the other side. Drill three holes each time you remove any metal. Even if you have to go a tiny bit too light to get that done.



The rotors get various amounts of oil from time to time, and end up changing weight while running, and nobody takes notice of the obvious imbalance. Since the rotors are so heavy the ratio of imbalance is always high, so that is good for us.



So if you brake hard, the rear rotor may drop more oil, and the front rotor may hold some extra oil for a few seconds. Both out of balance, but you cannot feel it.



If you take anything to a balance shop, take it all, including the front stack, the front bolt and the big nut for the rear weight, and the keys to keep things aligned.

Balance the whole thing together.



If you screw up and poke through in a place, just TIG the hole shut with mild steel filler rod. Works fine.



Lynn E. Hanover

1Revvin7

Sweet! Thats exactly along the lines of what we had discussed.

ColinRX7

That's awesome Lynn! I didn't know you could do that..

Silver Ninety Three

I'm having my rotating assembly balanced right now

RONIN FC

When a shop balances the assembly, do they take the oil that is supposed to be in the rotors into account? Do they balance the rotors independantly, assemble it to the shaft with counterweights, then balance the assembly?



This has always confused me, it makes me wonder if it is even worth balancing the assembly

kahren

i was always wondering that if balancing is so important, and the oil that is in thre can mess things up so much then why do we even bother balncing the rotors, i mean they should all be "good enouf" to use. i think this is especailly true in a rotory engine for reasons lynn has stated above, i think in a piston engine there is more control of the weight in the assembly and oil doesnt play as big of a role.i could also be mistaken and i dont have any evidence but the oil in the rotor has some centrifugal force that keeps in inside the rotor while its spinning, so it would be intersting to see how much of that oil actaulyl leaves the rotor and under what loads from the car, brakign accelerating and so on.



just my .02c

ColinRX7

How can they?

RONIN FC

I dunno. Maybe they can weigh the oil capacity of the rotors and then compensate for it. Granted if the oil in the rotors is always at a consistant level. Thats why im asking, cause to me the whole assembly balancing thing looks like a waste of time and money.