antiSUV

iTrader: (10)

Looking for picture of S4 TII front counter-weight. If anyone has one sitting around they can snap a pic of and post I would be grateful.

Thanks

Black Knight RX7 FC3S

iTrader: (7)

Im pretty sure all S4 front counterweights are the same, n/a or turbo.

antiSUV

iTrader: (10)

That's good information but doesn't really help me. I am an FD guy and I *THINK* I have a S4 TII front counterweight to go with my rotors and flywheel from the same, but I don't know it for a fact, hence my desire for a picture.

TenthYear

iTrader: (1)

here are some that happen to have the front cw included. don't know if it helps ya.
Off my s5 TII

JustJeff

iTrader: (13)

Isn't there a part number stamped on the counterweight? Can't remember if there is one on my S5 or not. Maybe that's the flywheel that has the stamp?

TenthYear

iTrader: (1)

I don't recall a stamp on the counterweight

PvillKnight7

iTrader: (16)

No stamp on the front CW. Only the flywheel. All s4 CW are the same. All S5 and S6 CW are the same. If you have an FD (S6) CW it should look like an S5.

http://www.mazdatrix.com/b5.htm
http://www.racingbeat.com/RX7-1986-1...els/11466.html

There is another way to tell by the number of balance holes (I think, not sure..) It's something like the way you can tell the rear CW apart:
http://www.mazdatrix.com/faq/Rcounterweights.htm

But I can't remember off hand.

K-Tune

iTrader: (26)

S5 and S6 are not interchangeable. The raceway for the thrust bearings makes it incompatible.

S4 and S5 are only distinguishable by measuring the width of the lip or weighing them. Turbo/NA makes no difference.

PvillKnight7

iTrader: (16)

Thanks for clearing that up. I know I've seen the measurements around here and the weights but I can't remember where. I thought it was on mazdatrix...

bumpstart

https://www.rx7club.com/showthread.p...=counterweight

NB

the thickness measurement is the easy method , measure the height of the wide part of the bob edge

83-91 small torrington front masses have a machined chamfer edge on the bob
that is intended to clear aux runner casting if used with a 6p engine

antiSUV

iTrader: (10)

OK, given this info, I DO NOT have a S4 TII front counter-weight.

When I took it apart, my engine had:

- What I think is an FD front counter-weight
- FD flywheel
- S4 TII rotors.

My understanding is that everything in the rotating assembly needs to match, so I bought an S4 TII flywheel recently. (I thought I had an S4 TII front counter-weight)

Now that I know that I NEED to find an S4 front counter-weight, I have another question:

In order to run the S4 front counter-weight, don't I need to collect the thrust bearings and thrust washers that go with it?

bumpstart

correct,, the FD manual uses a front mass with a larger torrington race
the s4 and s5 use the older, smaller torrington size

PvillKnight7

iTrader: (16)

I once made the mistake of running S4 TII rotors with a FD flywheel. Trashed almost everything. Rotors, seals, bearings, sideplates, thrust plates, thrust bearings. Good times. Now I don't forget.

antiSUV

iTrader: (10)

Well this motor only ran for about 45 minutes w/ S4 TII rotors and FD flywheel & front counter-weight, so I don't think it was long enough to mess anything up. This is just one of the surprises my "engine builder" had in store for me.

*Looking for a front S4 counter-weight now if anyone has one to sell*

RotaryEvolution

iTrader: (30)

i only have about 20 of them sitting in my parts bin...

antiSUV

iTrader: (10)

If I run a S4 counter-weight on an S6 engine, does everything behind the counter-weight need to be S4 to make the fit of all the parts work out? Or can I run an FD thrust plate (#1) and thrust bearing (#2) since they don't interact with the counter-weight, and combine that with a S4 thrust bearing and thrust washer in front of the bearing plate (#4), since those parts DO interact with the counter-weight?

Also, why is an S6 bearing plate (#4) different than the previous years?

Ugh.

PvillKnight7

iTrader: (16)

Mine lasted about 2000 miles of half throttle, no boost, >5k rpm driving. I couldn't figure out why I had trouble starting the engine when it was already warmed up. Turned out the seals were binding in the slots because the rotors has been eating the side plates.

bumpstart

different style of clutch

in your dilemma i would be keeping all torrington bearings and races in the small size and also using the s4 spacer set and dizzy/omp drive cog;ie
,, everything in the stack as s4 type

this is so theendfloatt will return to stock as the FD has its own unique spacers
and i think this may be due discrepancies in the torrington and race sets between the series

these bits are not hard to find, many FC enthusiasts will have a shelf full
( i do )

antiSUV

iTrader: (10)

Thanks for the responses so far.

If I have to use an S6 bearing plate due to the pull style clutch, then the idea of using all S4 components in the stack would only work if the S4 and S6 bearing plates are the same thickness.

If the geometry of the hub/keyway area of the counterweight is the same between S4 & S6, I think the simplest way to solve this is to machine the S4 counter-weight's thrust washer seat to the diameter of the FD one. What do you think?

I know that many people have used S4 rotors in FDs before. I wish there was a thread that stated explicitly which components they used.

James

bumpstart

i think that is a very good idea