Wow, I haven't seen that far out, but we NEVER build any type of engine here w/o balancing. As someone else mentioned factory weight tolerances are horrible...

 

Adam you are taking my replys the wrong way. I'm not calling you ignorant. Did I ever say "You" are ignorant. Don't think so. I completely understand that 99% won't have a problem (which is why I said most wont notice the difference) with the counter weights. I'm just stating the facts as when you compare the internal weight differences that one counter weight can't "perfectly" balance a rotating assembly when it has 5 different internal weight combinations. This is what I'm trying to get you and everyone else to understand. The facts regardless if you feel the differance or not, the factory counter weight all have holes drilled to more accurately balance the engine. Switching them around will infact change the balance as is the case for me when I swapped out a completely different set of heavier rotors (A & B ) to 2 lighter "C weights. If one size fit all I wouldn't be having the vibration problems I'm having.


Oh yea nice pulling out the dictionary. It's odvious I used the word "through" in an ebonics sort of way. Everyone else knew what I was talking about except you. It's also odvious you didn't comprehend what I was saying by taking things way too personal. No big deal! Peace!

 

I wouldn't doubte that. The factory balance I speak of are the new factory engines that originally came with the car. Mazda of Japan does these the right way. There's no telling what the guys over at Williams Technology are doing when they rebuild these engines. They are probably using Mazda's 2 letter rule when they replace damaged rotors with new ones.

 

FYI, adamc has been known to make more than a few "tongue-in-cheek" comments... The problem is you can't see his facial expressions when you read them!

Dave

 

^ LOL! I met Adam about 3yrs ago during sevenstock 7 so I can't remember any known facial expressions. It's damn near impossible to put the right expression or tone when using words. It's all good!

 

Yep .............. it's all good!! I'm "threw" harassing you

 

Of interest the FRONT auto counterweight on the FD is 1.6mm thicker than the equivalent manual version. Whether you should install one when you install a rear auto counterweight and light flywheel.....dunno.

 

im having the same concerns regarding lightened flywheels. 30-40k with a 9.5lb and i think a oem auto counterweight.. the main bearings are worn to one side and i do notice some wobbling when the engine is revved. now that im rebuilding due to a coolant seal im hoping to figure out this off-balance issue.

 

Thx for that info, didn't know that. It sounds like TpCpLaYa basically just has a auto engine converted for manual usage. If this is the case bolting on a lightened flywheel to the already present rear counter weight wont effect his balance since the original rotating assembly ( both front & rear counter weights and original rotors ) are still present and haven't been switched out. But regardless you do bring up a really good point about the thicker front counter weight.

 

There are 2 very different scenarios that different people are talking about in this thread:

1. You have a running engine in your car, and are replacing the flywheel.

2. You are putting in a new/replacement engine in.

Under scenario 1 (which I was talking about), almost no one is going to pull the engine, and ship it to someone to have everything balanced. The cost will far outweigh the benefit.

Under scenario 2, the engine is already at the shop that can easily balance everything. If the engine is already there, the cost to balance the entire assembly will be minimal, and well worth the few extra bucks to get it done.

I hope no one is going to argue with that

 

I guess I am just another lucky one as well.... Car is smooth as can be with the auto counterweight and exedy flywheel.... It really runs better now than before the clutch change...

 

 

HAHAHA!!!

I damn near fell out of my chair on that one.

 

forgot all about this while doing my rebuild. i have a auto counterweight installed on my car with a fidanza flywheel. its been ~23k miles since its been installed and when i tore down the motor and both front and rear bearings did show uneven wear. even before tearing down i did notice that the engine wobbles when reved. it bugged me especially after test driving a rx8 and noticing 0 vibration through the entire rev range. i think T-von is right about the disparity between counterweight / rotor weight causing uneveness.. for reference my rotors are both D weight.

maybe this is crazy, but i also wonder if off-balance engines can ultimately lead to failure. for example by loosening the tension bolts slightly? or causing some kind of sheering force between the housings. i don't know lol. but my engine did fail b/c of coolant seals.

 

so all thats needed for the balancing is the e-shaft rotors the front counter weight the flywheel and rear counter weight?

 

I think it true to some point that the counter weight and lighten flywheel do effect the motor balance, but i also think it all pend on how light is the flywheel is. A few kg different might not seem much to us, but to a engine it might mean life of death because all motor have spec for the clearances and it in thousand of an inch, too the our eye we dont see the different, so you can be the judge if is cause the bearing to wear uneven or not.

 

i think its been mentioned before that the flywheel itself doesn't factor into the balancing. reason that adding a counterweight is necessary is to balance out the rotors. stock manual flywheel has a counterweight built into it. obviously when you remove one, u have to replace it sad part about it is i guess there are different counterweights for diff weight rotors. so either u get lucky matching the right counterweight to your rotors, or u end up with a mismatch. too bad the counterweights don't come labelled A B C D E F for easy reference. maybe some kind of database can be started, with what exat weight counterweights(i assume lighter counterweight for lighter rotors lol) work well with what rotors.

 

I'd be interested to know where you got that info from, considering the "manual version" is built into the flywheel itself.

 

he's talking about the front counterweight. u're talking about the rear being built in

 

Gordon, you want to have the ENTIRE rotating assembly balanced, including the clutch & flywheel for optimal performance. But it may be a bit too late now if you're engine's already finished...

 

Gordon, as this thread has shown, you CAN fare well w/o balancing the entire rotating assembly. But this thread has also shown that you CAN see uneven wear. Now if you factor in the longer e-shaft and not two but three rotors & housings, plus the power levels you're going through, my personal opinion would be anything short of balancing the assembly would be unfinished/incomplete.

As for shipping, once the Mazdaspeed order arrives w/ us, we'll be shipping the parts over.

~Ramy

 

Any more ya's or na's on this topic? I'd like more opinions from anyone with experience; My 2 cents I picked up a spare core a bit ago with low miles with a blown bearing; so I took it apart and and sure enough the front main bearing was shot to hell but no other damage to the block. Now I didn't run the block or know a hole lot about it but it did have a lightweight fly on it and it did spin a bearing which is not too common, but could have been reused bearings as well like I said I don't know all the facts on it just putting up findings and stoking the fire. Anyone else?

 

How many miles were on that block?

 

Sorry didn't realize this question was asked. Since all factory 20b Cosmo engines are auto, adding a light weight aftermarket flywheel to a 20b (or any auto rotary)really doesn't effect the balance any since you will be reusing the auto counter weight that came with the engine. The light flywheel is just like a heavier pressure plate. You could even add a 100lb flywheel and the engine would still be in balance. This is because aftermarket flywheels are balanced with-in themselves around the perfect center of rotation. So their weight isn't the issue. It's the counter weights counter balance that's in question as this is what conter balances the uneveness of the rotating assembly. Remember in a 13b the rotors are off center and 180 degrees apart. In a 20b they are off center and 120 degrees apart. This is why all counter weights are designed to be off center.

Gordon since you changed out your rotors to hi compression, all you would really need to do is match the newer set of hi compression rotors to the same weight as the rotors that orginally came with your 20b.

My 20b came with a matching set of "C" weight 9.0 compression rotors. Since I am going hi-compression also, I've purchased a matching set of 9.7 S5 "C" weight rotors to help keep things near perfect factory balance. Since S5 nA rotors and Fd/20b rotors are the same weight, matching the letter code should keep me from having to balance my rotating assembly for everyday street driving. At some point I will re-open the engine and get everything perfectly balanced when my desire for a higher red line is reached. Untill then, I'm trying to keep my cost down as much as possible till I get it actually running.

 

It had 9 k on it and went out wile Kan tunned it according to the seller, I had it spec'd by a machine shop and they said everything seem to be almost to new spec so I will lean towards that it did have 9k on the housings and plates but I don' t know about the bearings if they were reused or not and being the front bearing it could have been a O ring but nothing looked too bad when I opened it up; but doesn't mean that the O ring didn't fail.