RotaryEvolution

iTrader: (30)

the front bearing stack is held in place by the front hub bolt, not the rear flywheel nut. you can spin the engine, beat on the e-shaft, do whatever you want and it won't fall out with just the flywheel loose.

vibrations can't always be compared one on one due to bearing wear and minor less imbalance issues such as rotor weight for example.

RacerXtreme7

iTrader: (2)

Your right, not sure what I was thinking.

I personally think its his counter weight. If it has s4 rotors, why in the world use a s5 counter weight? The builder might have gotten lucky and had the absolute lightest s4 rotors (don't recall the stamps on the rotors to determine weights per series A,B,C?)and front counter weight, then found the heaviest S5 flywheel and it worked, but unlikely... but the stamp on the fly wheel does mean its meant for a S5..weird....

You CAN however tell which series rotors are in the engine WITHOUT breaking it down. Pull off the exhaust manifold and look through the ports and see if the rotor dishes are machined and uniform (S5) or ill-regular (not really symmetrical) and have a cast finish. This may be difficult to see due to carbon build up, so run the engine till its warmed up and let it pull some fresh water into it via vac line and revving it to 4~5k and holding it there for 10 minutes or so with a constant supply of water (just enough to keep it from stalling) before pulling the manifold off.

OR.... the simple solution is to put your stock flywheel back on it and drive the damned thing lol.

~Mike............

Roen

iTrader: (2)

I vote buy a S4 counterweight from somewhere on the forum....easiest way to test.

Supercharged FC

iTrader: (7)

I ran a Camden supercharger for may years and they are hell on front bearing, plus I pulled the rear stationary gear, which I thought would allow enough play in the essentric shaft to upset the thrust bearing, (I could be wrong)

RotaryEvolution

iTrader: (30)

you cannot upset the thrust bearing unless you remove the front hub. not sure how many times i have to say it.

MazdaMike02

iTrader: (4)

I still don't understand how using an aftermarket lightweight flywheel and a stock counterweight would work. Someone enlighten me I don't like spreading false information.

farberio

iTrader: (7)

I would listen to this guy, but that's just me...

Supercharged FC

iTrader: (7)

So I asked some reputable companies to weight in.

The guys at "beat" said they thought I had put a S4 counterweight. I sent them pictures today to verify.

Their words

"I assume you saw "N370" on the stock flywheel you removed from the engine. Since the engine did not exhibit any notable vibration, you can assume that the balance with that flywheel was OK. The N370 number is used on '89~'91 RX7's - not the '88. Therefore, it is reasonable to assume the assembly is an '89~'91. The correct rear balance weight for that model is our part # 11466. This part has no identifying marks. The weight for an '88 - our part # 11463 - has a groove cut in the side of the eccentric mass on the "clutch" side of the counterweight for identification. I suspect that this is the weight you are using. If correct, changing the weight will fix your problem."

The guys at that fad diet place said I should check my transmission mounts, assuming the counterweight was correct.

Their words

"check the transmission mounts..
if the trans mission mounts are broken than that is the problem..
Engine will be fine long as the CW weights are correct for what set up you have plus it ran 9 years with no problems till now."

PvillKnight7

iTrader: (16)

It would be very nice if it's just bad transmission mounts. Let us know what you find.

cone_crushr

iTrader: (18)

^ Agree you should check your tranny mounts (and rotor pockets), but I suspect that's not your core problem since the vibe appeared during the clutch/flywheel upgrade.

If you've got counterweight pics's why not post them for us forum fans to inspect?

Presuming the vibes are engine speed related as you noted in your original post and you've got the right CW, my vote is to remove the flywheel & Pressure Plate and get them balanced as an assembly. That's my next step.A serious auto machine shop should be able to do this since when flywheels get resurfaced, a rebalance is typically recommended (although nobody does this .

Supercharged FC

iTrader: (7)

Check out page one...

Here they are again.



Thanks for your vote, I agree balancing the flywheel and clutch would be a good idea while I have them out.

Supercharged FC

iTrader: (7)

So I have a S6 rotating assembly and noticed there are no part numbers on the front counterweight (also the machined pocket you guys mentioned on the rotors)

How can I identify my front counterweight?

Also who rents a borascope? I would like to inspect my intake and ID my rotors.

Thanks again for all the responces

Supercharged FC

iTrader: (7)

Update from the "Beat"

"I just measured a '87~'88 rear weight outer flange at 13.70mm and a '89~'91 rear weight flange at 13.90mm. I do not believe that this technique is valid to establish what model weight you have - at least when that is your only criterion.

Front weights have not had part numbers for a very long time."

I take that as you have a S4 and you need a certified S5

Supercharged FC

iTrader: (7)

I hate to be getto and end up in the same boat again but will my S6 counter weight work if I have a S5 rotors?

farberio

iTrader: (7)

It should be fine, S6 ad S5 had the same weight rotors if I recall.

cone_crushr

iTrader: (18)

Your symptoms sounds bizarre and don't compute. And you pulled the rear stationary gear - uh oh, this thread needs a do over. Your vibe peak is 2000RPM, drops from there and never recurs? This doesn't sound like a simple imbalance problem.

farberio

iTrader: (7)

^ I agree with you.

For reference this is my S4 counterweight.


Hey SFC? The counterweight you are using is not the same one I put on my car at first right? The one I bought off of you?

RotaryEvolution

iTrader: (30)

most rotating assembly balance issues will have a harmonic rate, which basically means if you notice a vibration at 2k then you will notice it again at 4k. something such as worn bearings will not exhibit the same vibrations as a balance harmonic issue due to friction and other variances due to engine speed. if you only have a vibration at 2k and all the mounts, u-joints, tranny bearings etc all check out then you may actually have worn rotor bearings. counterbalance issues generally are noticable at 3 and again at 6k RPMs.

i do suggest you guys inspect the parts you removed as thoroughly as possible though, if the problems were never present before the light clutch installs then i still would think it is something in those assemblies that isn't adding up. the counterweights aren't impossible to distinguish but it doesn't mean that it is still out of the equation for being incorrect. i never did like how mazda did not stamp them with a part#.

Supercharged FC

iTrader: (7)

It's the same one, thought that experiment proved it was an S5.

It's going into the scrap bin after this.

farberio

iTrader: (7)

Yes, that c/w is a certified S5. Which means all this time you said you had S4 TII rotors makes more sense right now.

Supercharged FC

iTrader: (7)

SO I have a digital camera boroscope for tonight only!!!! How can I make sure I'm looking at the combustion chamber????

I figured if I see an apex seal on one side the other side should be on a combustion chamber. Does this make since????

Let me know before the clap-on guy takes his tool back!

Supercharged FC

iTrader: (7)

So I try aligning the apex seal on rotor 2 and looking through rotor one but I could not tell.

The features I can see are the apex seal and transition into the combustion chamber. On my S6 rotors the transition is machined (as is the whole face), from pictures I noticed the transition on S4 is cast.


So I found the transition and took a ton of pictures, here the best one.


So the transition has machining marks on both sides so I must have S5 rotors. Let me know if you agree.

This leads me to believe my counter weight is garbage, and or I damaged my stationary gear bearing while removing it. Either way I’m changing both when I take the trany out.

PvillKnight7

iTrader: (16)

I see the machined feature on the rotor in the picture. That's S5. Check those transmission mounts and inspect the rear stationary gear bearing. Check the engine mounts too while your're under there...and the shake the drive shaft and check the u-joints.

Supercharged FC

iTrader: (7)

Engine mounts, drive shaft/U-joints, and trany mounts (except center one) are good.

I'll post the stationary bearing once I pull it.

PvillKnight7

iTrader: (16)

I'm running out of possible causes. While the transmission is out , before you pull the flywheel to check the bearing... check the end play. This video shows how to do it:

http://www.rebuildingrotaryengines.c...tting_end_play

If you don't have a dial indicator there is another method described in the FSM that uses a bolt. It's worth taking a minute and checking while your staring at the flywheel.