Has anyone run a rotary with the wrong counter weight on it? What noise does it make?

I have just gottenb everything together with my S4 13B and there was a question about the counter weight.

Well, the enginbe make a strage werring noise. Kind of like a throughout bearing noise, but different. (Yes, I did change the throughout bearing).
Thanks

 

rotating assembly would be unbalanced and engine/car would shake a lot, especially at high rpms.

counterweights must match the rotating assembly: rotors and e-shaft.

 

do u have the correct amount of e-shaft end play? i would suspect that if u were too tight on the thrust bearings that it would make some kinda noise.

 

does anyone have a correct counter wight and flywheel chart for 12A engines?

This is something that i am sure menbers can use.
The weights below for the fwheel were taken from the mazdatrix site.

1985 12A.
Counter weigth = weight LBS _____?
Flywheel weight lbs ____26_____?


1984 12A .
Counter weigth = weight LBS _____?
Flywheel weight lbs _____26____?

1983 12A
Counter weigth = weight LBS _____?
Flywheel weight lbs ___26______?

1982 12A .
Counter weigth = weight LBS ____?
Flywheel weight lbs ____23____?

 

MAZDATRIX has rotor weight stuff on their website also.

Quick snapshot: 79-80 are by themselves, 81-82 have light flywheel and heavy rotors, 83 has heavy rotors and flywheel, 84-85 have heavy flywheel and light rotors. Hot ticket is 81-82 flywheel & c/wt on 84-85 rotors and e-shaft.

On the whirring sound; are you sure the front thrust bearing didn't get pinched when the counterweight was off? Easy to do, I understand. I understand a quick check is to see if the front e-shaft pulley is lined up with the water pump pulley; if it's off an appeciable amount either way then the thrust bearing is furschnorkeled.

 

'83-'85 have lightest rotors and 27LBS flywheel. '81'82 heavy rotors and lightest flywheel. '79-'80 have heavy everything.

peejay, am I right?

 

I know the weights are just an ounce or so differnt, so the shake may not be massive.

Has anyone run an engine with the wrong weight?

 

rxtasy, I still have the same endplay that I started with. I do know what you mean about the thrust bearings, I crushed them on my last engine.

 

I have came across the counterweight problem,
I had a 86 13b in a 82 GSL with light flywheel
and when I put it together I ended up using the
front and rear counterweights off a 84 GSLSE motor
by mistake and It had a harmonic vibration and
once in a while it would over rev by itself so after
not even 20 miles on it I bent the shaft and started
to backfire through the carb.Now I have a 12A with
the light flywheel and the rear counterweight from
mazdatrix.

Alexis

 

Sounds about right.

The difference in rotor weight isn't "an ounce or so". It's *much* different.

 

OK, so I have put the stock flywheel back on and I still have the strange "werrring" noise. I still have endplay and I am worried about doing damage if I run it. Any ideas?

 

Ok, I swaped out the trany and I still have the noise. I can't figure this one out. I have swaped out just about everything and I still have the same noise. Well, I think I will be seeing the Atkins folks next week. I will ask them what they think. I will post the results.

 

So, I think that we have figured out the noise. When I pulled the engine I took off the metal cups under the motor mounts. They just looked like extra peices, but noooooo.
They dampen harmonic nvirbrations between the engine and the chasis - ie noise.