93BlackFD

I was over at rick engman's shop and he revealed some interesting new insight on remanufactured motors.

He does rotor balancing/rotating-assembly-balancing over there and has been noticing, mazda is placing front counterweights in the motors without balancing them. Meaning, they are raw, 100% factory weight counterweights, unlike the ones you typically pull out of the engine that has the dimples on it where weight was removed to balance against rotors.

So i guess when mazda deems that a reman needs a new counterweight, they order it, and replace it. Straight from the supplier....no balancing is performed.

This is VERY interesting to any of us trying to build high horsepower motors...he said the weight can be off as much as 10 grams, which when rotating, is a LOT of force.

comments: GO!

ejmack1

oh boy....

So how hard is it to check the counter weight? you have to actually tear the engine down right?

93BlackFD

it gets complicated basically, it increases wear with it being out of balance. Even if by a little, it will just shorten the life span of the motor, and certainly this risk increases with revs.

counterweight can be accessed from the front cover, so technically you don't have to take motor apart to check, however, you do have to take motor apart to balance, because it's balanced against your rotors.

Also, for those of you who use low compression (86-87 rotors) you need a front automatic counterweight. They are slightly heavier, and allow for compensating for the increased weight of the low compression rotors.

In short, do not hesitate for balancing. I believe it's about $200 to get it done, I'll do it on my next motor. Ideally, do a rebuild, get a lightweight flywheel, have the rear and front counterweight balanced to rotors, new rotor housings, new bearings, and you're set

But that's in a perfect world.

Here's some low compression rotors with the balancing service performed, front automatic/rear automatic counterweight, and the bearings received the same "break-in" that rick's 26B's get (he pre-breaks them in on a lathe before installing)

awesome eh?

drool!

t-von

iTrader: (8)

So if I wanted to have my motor balanced during a rebuild, would I just have to send the rotors and counter weights off? What about the e-shaft?

93BlackFD

i take my stuff to rick, he did my e-shaft for me- if he wasn't so close i'd mail him rotors/shaft/weights, get a packaged deal

before
http://www.1131.net/pics/brian/DSCN1211.JPG

after
http://www.1131.net/pics/brian/DSCN1242.JPG

dubulup

FAWK! more time until my motor is together...

definitely worth the wait.

(you pick up my e-shaft while you were over there?)

WHO in the world would use 86-87 rotors in an ever so elite (totally above that) FD???

Mr rx-7 tt

iTrader: (5)

If memory serves me Mazda's tolerance between rotors is up to 50 grams. On continual high reving (9000-12000 rpm) race engines it makes a difference on a street car it doesn't really matter.

93BlackFD

^ very true, but sometimes "she's a female" isn't good enough for some of us, she's gotta be perfect

RotorJoe

Great info, Thanks

FormerPorscheGuy

Arn't the remans actually made by AC Delco which is a General Motors company. That was on the label last time I was over at MAZMAX here in Houston and they had some fresh remans in. Very interesting all the same though.

93BlackFD

i will call and ask ray crowe who/where they are made

j9fd3s

iTrader: (3)

they are delco/remy remans now. they are doing a better job than the previous people

FormerPorscheGuy

You have got to love the global economy at work here,

RX-7 is a Mazda vehicle,
Mazda is a Japanese company
Ford has a 30% stake in Mazda, but
Mazda remanufactured engines are made by Delco
Delco is owned by General Motors.

I have a Japanese car that is tied to Ford but yet runs a General Motors engine.

I love the irony of it. hahaha