Wuz up,



So I detonated my motor really bad last summer at the track,(sounded like

a machine gun under my hood for a split second).I was running a nitrous works

kit with a 125hp shot.I didn't know the jetting was too lean until I asked around

and called NOS and NX and sure enough their jetting #'s were consistently fatter

on the fuel jet.I won't make the mistake of trusting a jetting chart again,anyways

the question at hand is,with the detonation I trashed one housing and one rotor.

I need to build a motor to sell this car bu I live in Alaska so parts are few and far between.Can I use a rotor out of a different motor with out having to balance

everything or use different counter weight?The basics of the motor are S5 TII

4 port housing and irons with s5 na rotors,the rotors were out of the same motor so this was never a question before.I do have set of 84 3mm rotors with the counter weight but they are heavy!I need some advice on mixing and matching parts and what is critical for assembling a proper collection of parts,or engine if you prefer,I am trying get this car ready to sell to pay off my 3rd gen....

Sorry the post is soooooooo long...



Thanks

Nick

as long as they're the same year, you can get away with it. optimally, have them balanced though.



don't the rotors have a weight stamp on the side?

They should have the same stamp A-E, but Mazda allows 50 grams difference in stamped sets and still calls them "balanced" so once you pair the rotors they should then be balanced to a closer spec.

Where can you get rotors balanced when re-assembling an engine? I dont think my machine shop can do that, Theyre piston freaks.



Cody



[quote name='89 Rag' date='Mar 20 2005, 08:22 PM']They should have the same stamp A-E, but Mazda allows 50 grams difference in stamped sets and still calls them "balanced" so once you pair the rotors they should then be balanced to a closer spec.


[/quote]

[quote name='SidewaysSA22' date='Mar 20 2005, 10:06 PM']Where can you get rotors balanced when re-assembling an engine? I dont think my machine shop can do that, Theyre piston freaks.



Cody


[/quote]





SDJ MOTORSPORTS, Racing Beat, MAZDATRIX,Daryl Drummond, Paul Yaw and a few other people

Place them on a scale or balance.



Throw the heavy one on a drill press/mill and slowly remove a bit of material on each corner*(same spots) on both sides untill it matches the weight of the other rotor.



If your press/mill has a readout you can take off the exact same ammount of material making it no worse than factory.



Ive done this 2x and it works great.



GregW

Balancing them myself sounds good,I've done this before with pistons.But my question with that is,do you take equal amounts out of each rotor corner on both sides of the rotor?This would be the only way I could see this working but how can you tell if the dynamic balance is okay?Is a close static balance good enough?I've heard 50 grams is what mazda will allow between rotors and that seems excessive!

The input so far is great.Thanks



Nick

[quote name='alaskarotorhead' date='Mar 21 2005, 06:20 PM']Balancing them myself sounds good,I've done this before with pistons.But my question with that is,do you take equal amounts out of each rotor corner on both sides of the rotor?This would be the only way I could see this working but how can you tell if the dynamic balance is okay?Is a close static balance good enough?I've heard 50 grams is what mazda will allow between rotors and that seems excessive!

The input so far is great.Thanks



Nick


[/quote]





Yep, I did both sides and the same ammount on each spot. I use a balance so they end up being pretty much the same exact weight.



Remember, rotors spin way slower than the Eshaft and move up and down as well so having them the same weight is more important than them being individually balanced. As long as you take out the same ammount you should be fine.

Thanks guys,

I was just curious. Not that Im rebuilding right now but it is helpful to know for future reference.



Cody

What were you jetted to?