Okay, I have one S5 rotor stamped E, another stamped A and I'm looking to buy one stamped C.

The E and A rotor were both originally together, but E is dead so i'm looking at C. Anyone know if they're compatible?

 

stamps should be within 1 letter of each other so you would need an A or B stamped rotor.

 

But i had A and E originally running together in the engine and A is the one that's useful.

Are you saying that to replace E because it was the original i would need D or E?
Anyone have a chart ? Maybe it's in the FSM...

 

edited, and just because they were in there doesnt mean they were properly matched in the first place.

 

So C would be better then E?

 

wow, never knew there was different letters. what do they mean?

 

yes c would be better than e, but the point is to have no more than 1 leter difference, or 2(IIRC). That vert looks just like mine.... same wheels and everything... ITs like a miror immage only mine is s4. And yea it looks nice...

 

I doubt it you were running an "A" and an "E" rotor.
On the "E" rotor, look for another letter - either "A" or "B".

English "E" looks amazingly like Japanese Katakana "yo" (backwards).
The rotor sides are stamped with Japanese Katakana characters.


-Ted

 

Nope, it was A and E. Pic:

 

Nope, you're right (as usual )
I scrapped off some more grease from one of the corners and found a B. Thanks!

 

Here's a hint - Japanese Katakana characters are used to denote rotor faces - they are stamped as close to the center of the rotor face as possible without hitting the side seal groove.
If you see just one stamp all by itself close to the center of the rotor face, that's not it.

The "A" - "E" denotation are usually more towards the apex seals grooves, although your pic shows the "A" *VERY* close to the center.
If you see two stamps, one will usually be the "A" - "E" designation.

BTW, your "A" rotor has a Japanese Katakana "wa" next to it.


-Ted

 

So uhh...anyone have an A or B rotor?

 

thanks for the hint reted..but what is the difference between the letters?

 

"A" is heaviest, "E" is lightest...............the difference is measured in grams.

 

Wow...I never knew this!

Man I love all the info on these forums!

 

I never heard of this either. Do they have to be a letter apart or can they be the same letter? What kind came in which fc?

 

Yes, "A" denotes heaviest, and "E" denotes lightest.
Letters are "A" through "E".
Rotors are "matched" with either identical letters or ONE letter difference.

So, a "C" rotor can be matched with either a "B" or a "D" rotor.
You are NOT supposed to run a "C" and an "A" or an "E" rotor.

I know fanatics that have a stash of "E" rotors!

If I remember correctly, the weight difference is like 2 grams for each letter - but don't quote me on this!
So the difference is very minimal...


-Ted

 

2 grams on the whole rotor? lol, thats probably the difference in the mass of the metal etched out to make the letter itself.

hahaha.

 

sorry for resurecting the dead like i usually do, i understand A-E stamps E being the lightest. Now s5 is lighter then s4 so is A-C s4 and C-E s5 or is there a letter stamp for every series like s4 has A-E and a s5 has A-E? sorry i just bought s5 rotors and im afraid there s4 rotors. They look to be machined and are both stamped B id prefer a E stamp but if there the 9.7:1 compression ill live.

 

weight it....

 

http://www.mazdamotorsports.com/weba...ject=balancing
That *MIGHT* be informative, not sure.

 

https://www.rx7club.com/showthread.p...5&page=2&pp=30

This is my logic, tell me where I have gone wrong:

I weighed these two rotors:

"B" 4377.57g (9.650lb)
"D" 4343.67g (9.576lb)

The “2-letter” weight deviation of this pair seems to be 33.9g. Half of this value must be the “1-letter” deviation, which is 16.95g. Mazda letters rotors from A to E, which is (4) “1-letter” deviations in weight, which is 67.8g.

Given the above 2 values let assume that the mean rotor weights are:

“A” = 4394g
“B” = 4277g
“C” = 4360g
“D” = 4343g
“E” = 4326g

That means the lightest pair of rotors is:

2 x 4326 = 8652g

And the heaviest pair of rotors is:

2 x 4394 = 8788g

The difference of these is:

8788 – 8652 = 136g

There must also be an allowable range for the weights of counter weights (drilling them brings the rough casting into this range). Let’s be conservative and assume all of the counterweights are exactly the same weight.

If Mazda does not dynamically balance every engine, and Mazda does not stamp counterweights to be used with their matching rotors then Mazda must allow rotor pairs that range over 136g in weight to be used with the same counterweights. Right?

So how does my removal of 60g (30g x (2)) make my setup any worse than what Mazda ships out the door?

Justin

 

You really thought about this, eh? It's quite possible that you are weighing rotors that have been worn over the years, and one might be substantially lighter then it would be stock. From the factory, they are probably much closer...even wear is not possible.


Nonetheless..I was a set of E rotors for my T2 :P

 

I didn't weight those. Click on the link.

 

you are kidding right?
because a non-wear item would get lighter over years.

maybe if there was detonation....