another new one to me, 2 pounds is A LOT
doesnt sound right?

 

That's why you can only use one letter difference together in the rotating assembly which is half a pound.

I'm referencing this from a post where Kevin landers aka rotary resurrection weighed s5/s6 rotors

 

i've never seen any factory documentation on the weight difference between letters.

secondly they grade the rotors by batch, so an A rotor from 1986 isn't going to weigh the same as an A rotor from 2012, even though they are the same part numbers. in fact new rotors have some changes, so they are lighter

thirdly, every replacement rotor is a C, how is that possible, if the spread between an A and B is half a pound?

its not. the letter thing is bogus, it ONLY matters if you have two rotors from the same batch.

if it was so important why isn't it in the shop manual?

 

they are under the assumption that you're using the same rotors and not replacing them?


I was wrong about weight difference its .05 of a pound difference. Sorry for the wrong info I read the information I read earlier wrong, honest mistake.

Originally Posted by RotaryResurrection:
Just for you, I weighed a few s5/6 rotors while rearranging/cleaning some for the shelf.

A 9.7lb 4400g
B 9.65lb 4377g
C 9.6lb 4354g
D 9.55lb 4331g
E 9.51lb 4314g

A few of these I had more than one rotor of each letter of, and I noticed that within each letter there is still a tolerance of 0.03lb one way or another. So a C could be anywhere from about 9.58 to 9.63. As i've stated before, the letters are just a tolerance scale, and not absolute. For instance, the general rule is to stay within 1 letter when doing a build, like C and D, which should be something like 9.55 with 9.6, a variance of 0.05lb. In reality you could have a light B and a heavy D that would mate up just fine, like 9.63 and 9.57, still a tolerance of 0.05, but not within the "rule" of 1 letter.

 

Could you imagine how desirable A weight rotors would be if they were 2 pounds lighter, lol

 

yeah that cant be right. Rotors are around 9 lbs from what I know....So rotors would range from 7-11 lbs? that doesnt sound right.

 

I corrected myself its .05 of a pound which is 5 hundredths of a pound

 

Kevin and i are basically saying the same thing. the letter codes only mean something at the factory the day a batch of rotors came out of the oven.

Mazda has made S4 turbo rotors from 1985 to 2014, there is no way a rotor made in 1985 is going to weigh the same as a rotor made in 2014.

 

Best way to check is a digital scale imho