Ok so I found a balance in the attic and started going through my rotors. None of the pairs matched from the factory were even close. One of my rotors ate part of an apex seal so I need to find it a new partner. I ended up finding one that was very close in weight. Does anyone have any suggestions on how I could remove some material from the rotor to get them dead on.



Also, Any info on balancing the rotors? I was thinking of hanging the rotor from the center of two of the corner seals and on the third using a scale to take readings of the different apexes. Then you just spin it arround till you have all the info then remove some material and retest.....Thoughts...





Gregory

What were the weight #s you got?

I just did the balance thing. The scale part of the balance does not go that high https://www.nopistons.com/forums/pub...O_DIR#>/11.gif



Gregory

The rotating assembly on this engine (from mazda) had a B and an E. The E is heavier than the B. What gives? And yep they are spotless. The E is 1.5 side seals heavier than the B.



Gregory

unless you have a peice of papre that says something different the letters (a, c, e etc) dont mean anything. as far as mazda is concerned they have a part number for an application (ie all s4 na rotors are ithe same) and they are all interchangeable

https://www.nopistons.com/forums/index.php?...pic=22992&st=25





Look at the post by BDC. I hope he will chime in and tell us where he got that info.



Gregory

https://www.nopistons.com/forums/pub...IR#>/smile.png Use a postal scale and try to get the weights matched perfectly for optium use.



mazda does have a scale of being able to use some letters with others, I would need to check my tech manual at work for the proper sequence. But the rotors can vari with in the letter types.



Hope I didn't confuse the issue

the rotor are different there is B, C, D, E



they can be no more than one letter off from each other, like:



b, b or b, c

c, c or c, b or c, d

d, d or d, c or d,e

e, e or e, d



hopefully that makes sense the best rotors to have are either C or D cause they work with a wider range of rotors...

My B weight rotors were off by the weight of a 1/3 or so of a sideseal

where is this written down in a mazda manual?

Funny how mazdtrix does not list weight tolerances!

One and a half side seals in a 9 pound rotor?



Close enough.



The rotors never have the same amount of oil in them anyway, so they pass each other in balance as you brake and accelerate. The rotors balance each other (just about) and the counter weights just take out the rocking couple. The wiggle in the shaft caused by the rotors not being exactly opposed on the shaft.



Use the rotor. No problem.





Lynn E. Hanover

Thanks for all the replys on this https://www.nopistons.com/forums/pub...1047683894.gif



Gregory

believe it or not, having different letter rotor doesn't make enough difference to do any damages to the engine. Mazda specifies 50 grams in tolerance so if you take everything into consideration, pretty much anything and everything is interchangable and still within spec.

9 pounds, damn. I got 10.8 on a S5 N/A rotor that was polished spotless w/ the sideseals still in it.

ok i finally got off my ass and looked up the letter thing.



its in the r100 shop manual, and the 74-75 rx4 manual, but by 77 its gone. in the 77 and 83 books they dont even give any kind of balance wieght.