Yes the S* center hole is the same as the 4.0. But my caliper does not read in fractions, can you mic the holes in mm. From center hole edge to bolt hole edge, hole to hole (next to each other) and inside edge to inside edge of two holes that are oposite sides from each other (furthest apart from each other)
Thanks.

quote Originally posted by Rickady88GT: Yes the S* center hole is the same as the 4.0. But my caliper does not read in fractions, can you mic the holes in mm. From center hole edge to bolt hole edge, hole to hole (next to each other) and inside edge to inside edge of two holes that are oposite sides from each other (furthest apart from each other) Thanks.

I have a nasty cold and am under the influence of medicine... I hope this is what you're asking for
the calipers i am using are the $20 digital ones from checker auto. i doubt that they are very accurate.

I got an e-mail from David and here is what he said:

Sounds good, Robert. Also, we had sent Charles Morris a unit that had a .141 too large center hole bore size (made off the incorrect sample we received) by accident. So we shot him out another unit. Don’t think any others of the 14 we’ve shipped were accidentally sent that way, but I wanted to let you know that we have the correct specimens on the shelf, and will save one for you.

------------------
Bobby from NW Indiana
93 Northstar and 5 speed Getrag
thespeedshop@sbcglobal.net
My build thread

quote Originally posted by GSXRBOBBY: I got an e-mail from David and here is what he said: Sounds good, Robert. Also, we had sent Charles Morris a unit that had a .141 too large center hole bore size (made off the incorrect sample we received) by accident. So we shot him out another unit. Don’t think any others of the 14 we’ve shipped were accidentally sent that way, but I wanted to let you know that we have the correct specimens on the shelf, and will save one for you.

WOW!! I am really happy that I got the only one like that! I am no real hurry so no problems here. whew!

So there was only one made with the wrong center hole diameter?

I can make a concentricity ring that will press into the center of the incorrect flywheel and make it correct. If anyone else has that problem, I can do the same for them as well.

I'm tired of putting up with mistake and incompetence, one after the other...
Even the incorrect flywheels ought to be used, since these dam things were so hard to get made in the first place. It would be a shame to have a salvageable flywheel disappear back into the abyss at SPEC when someone could be getting use out of it.

------------------
Turn the key and feel the engine shake the whole car with its lope; Plant the gas pedal and feel in your chest neither a shriek nor a wail but a bellowing roar; Lift and be pushed into the harness by compression braking that only comes from the biggest cylinders while listening to music of pops and gurgles. Know that you are driving an American V8. There are finer engines made, but none of them are this cool.

Luck, Fate and Destiny are words used by those who lack the courage to define their own future

quote Originally posted by Will: So there was only one made with the wrong center hole diameter?

That is what I understand. I am being shipped a new correct flywheel and am shipping back the incorrect one. I wish I could have this kind of luck with the lottery!

Yeah, thanks! Those are exactly the deminsions I was looking for. My measurments are very
close to your measurments. The differance is maybe your caliper and my cheap Harbor Frieght caliper.

I only have one more question about your flexplate. What is the part # on it?
Mine is TU2640 and is found on the torque converter side outer area between two rivits.
From the looks of the deminsions you've given me, they are exactly the same.

+ for you cptsnoopy, thanks for the hard work, it's not easy pioneering!

Thanks Rickady88GT!

The only two numbers I could find on the aurora flexplate are on the engine side. There are no rivits on this flexplate. Does your flexplate have a balance weight on it?

the first number is black lettering about 3/8" tall. "60092"
the second number is light blue lettering about 1/2" tall. "3544671"

this is a neutral balance flexplate as far as i can tell.

This is a picture of the flexplate, front and backside. The flexplate is neutral balanced. I guess they are not rivets, they are very deep stamped spot welds that hold on what looks like a thin metal piece, not sure exactly what it is for. I guess it may make the outter edge thicker and stronger. I used scotch brite to clean off the rust, the part number is stamped.

my flexplate does not have that ring welded on it. i looked closely and there is no stamped number on it. my guess is that yours is different because it is a newer model.

Well crap....figures something is wrong on these, I'm not all that surprised. David just thinks a couple are wrong, but I'm willing to bet they're all wrong. My center hole is the wrong diameter as well, and I'll be calling Spec tomorrow to get it taken care of.

cptsnoopy: You said you didn't order the lightweight pressure plate, I did, and ours look exactly the same from what I can tell. Can you tell me what your receipt says for the part number? Mine says SC94A, and also has an additional $69 tacked on for "Lighten"....20 bucks more than David said it would cost. I'm not going to argue over the 20 bucks, but I do want to know what the difference is between our pressure plates.

Referencing the pictures of the standard Spec clutch compared to the lightweight Spec clutch for different styles of clutches, there's an obvious difference in how they're built. I think David might be taking me for a ride on this one, as there's no discernable difference between mine and the one cptsnoopy showed. If this is the case, I'm not going to be all that happy. I've tried to get away from Centerforce because of their false claims, and this is the last thing I expected from Spec based on the reviews I've heard here on PFF.

I will say this flywheel is LIGHT! I feel like hercules tossing this thing around...sweetness! Too bad it's not going to work as is.

Bryce
88 GT

I think you guys are making a mountain out of a molehill on this whole oversized hole.

Think about it.

When the flywheel is bolted down the flywheel isnt being supported by teh crank at all. All the load is on the bolts.

As long as the flywheel is centered it doesnt' matter if its not resting on the crank or closer to the crank

The bolts take all the load!!!

it doesnt' matter if the hole is .2 of an inch too big or whatever the measurement was. As long as the bolts holes line up and its neutrally balanced thats all that should matter

I think you guys are making too big of a deal about this whole thing.

I know I was redundant here but still, its not a big deal.

SH

------------------
JM / SH

I am The Punisher and I approve this message
Opinions are like ‘The Punisher” everyone has one ™
Member of the Redbar Brigade

quote Originally posted by The Punisher: As long as the flywheel is centered it doesnt' matter if its not resting on the crank or closer to the crank The bolts take all the load!!! SH

Think about it a little more; I've seen what happens when inputs and outputs don't line up, it's not pretty.

The bolts DO take all the load, but they are not meant to center the flywheel. If they were shoulder bolts or similar, they could, but they aren't. The design of the flywheel is such that the center hole is just big enough to slide over the crankshaft. The center hole of the flywheel and the pilot shoulder on the crankshaft are both manufactured to be as close to centered as possible. If one of these circles are not centered in relation to the other one, then the flywheel will not be properly centered. If the flywheel isn't perfectly centered, either is the pressure plate or friction disk. If the friction disk isn't centered, it's constantly putting load on the input shaft bearings. It can also cause some pretty nasty vibrations.

So, you obviously understand what happens if the flywheel isn't centered. Using the bolts as the only centering mechanism will allow the minor slop in the holes to cause the flywheel to be off center. This situation is just as bad as a pilot hole being drilled off center.

If they didn't need the right size hole, they wouldn't bother with it at the factory and they wouldn't bother with it at Spec. There's a reason it's there.

Bryce
88 GT

then what about measuring the distance around the flywheel from teh crank.

If the distance is the same all the way around then that means the flywheel is centered and no need to worry

SH

quote Originally posted by Nashco: cptsnoopy: You said you didn't order the lightweight pressure plate, I did, and ours look exactly the same from what I can tell. Can you tell me what your receipt says for the part number? Mine says SC94A, and also has an additional $69 tacked on for "Lighten"....20 bucks more than David said it would cost. I'm not going to argue over the 20 bucks, but I do want to know what the difference is between our pressure plates. Bryce 88 GT

I show SC94A also. I do not have any additional charges. the setup looks like it will be top notch when it is correct. I hope they get yours straightened out. I sent the incorrect one back today. I am expecting the next one by Friday or maybe Monday. I would risk using it with a high quality concentric ring but still prefer it cut correctly the first time. Tomorrow I will try to weigh the pressure plate but I don't have a very sensitive scale. I'll take a pic of the friction side and post that too.

quote Originally posted by cptsnoopy: I show SC94A also. I do not have any additional charges. the setup looks like it will be top notch when it is correct. I hope they get yours straightened out. I sent the incorrect one back today. I am expecting the next one by Friday or maybe Monday. I would risk using it with a high quality concentric ring but still prefer it cut correctly the first time. Tomorrow I will try to weigh the pressure plate but I don't have a very sensitive scale. I'll take a pic of the friction side and post that too.

If you could weigh yours, that would be great. I've got access to a pretty accurate force meter, so I can weigh mine and compare. I, too, would use the flywheel with a centering ring, but at the same time I wanted this flywheel instead of a modified Fiero one so I didn't have to worry about piece-mealing such a critical part.

Bryce
88 GT

quote Originally posted by The Punisher: When the flywheel is bolted down the flywheel isnt being supported by teh crank at all. All the load is on the bolts. As long as the flywheel is centered it doesnt' matter if its not resting on the crank or closer to the crank

The bolts do NOT take the torque load. The torque load is transmitted by the friction between the crank flange and the flywheel. That friction is provided by the clamp load of properly torqued bolts. The bolts are loaded in tension, NOT in shear.

As for centering the flywheel... you need a VERY small eccentricity between crank flange and transmission input shaft... eccentricity of less than 0.003" or so. Can you do that without a precise pilot? Theoretically you can if you use a dial indicator... and even then it's a HUGE PITA as you'd have to rotate the crank a couple of times with every step in torquing the bolts... I've had to tap things concentric in lathe chucks using a dial indicator... trust me, it's NOT something you want to try on a flywheel.

I'll restate that I can make a press-in concentricity ring (IE press it into the flywheel once and forget about it for the rest of your life) for anyone who wants one. The issue with the modified Fiero flywheel is the bolt circle, not the pilot diameter.

------------------
Turn the key and feel the engine shake the whole car with its lope; Plant the gas pedal and feel in your chest neither a shriek nor a wail but a bellowing roar; Lift and be pushed into the harness by compression braking that only comes from the biggest cylinders while listening to music of pops and gurgles. Know that you are driving an American V8. There are finer engines made, but none of them are this cool.

Luck, Fate and Destiny are words used by those who lack the courage to define their own future

quote Originally posted by Nashco: If you could weigh yours, that would be great. I've got access to a pretty accurate force meter, so I can weigh mine and compare. I, too, would use the flywheel with a centering ring, but at the same time I wanted this flywheel instead of a modified Fiero one so I didn't have to worry about piece-mealing such a critical part. Bryce 88 GT

approx 10lbs. just about the same as the flywheel.

I'd like to hold off on ordering mine until I hear that the center hole size is irrelevant.

It's NOT irrelevant.
However, it is easily fixed.

What I think happened was that somebody screwed up and made a couple with the N* bolt circle but V6 pilot diameter. The mistake was apparently caught as they say they have correct ones on hand. However, a couple of the incorrect flywheels have apparently been shipped.

I have no doubt that SPEC can deliver a quality product...
It's their ability to do a custom product in a reasonable time and get it right first try that has been shown to be lacking.

Well, I called David and explained my issue. He's sending me the correct flywheel and UPS is supposed to be picking up the one I have. He said they have correct ones on hand, and only the first few made had this issue.

On the lightened pressure plate, he said it's a slightly different material and slightly different design on the friction plate portion of the pressure plate. He told me to send him some pics and he can tell me if I got the correct (lightened) pressure plate or not. I asked if there was an easy way for me to tell, but he said it's easiest if he just looks at it and tells me.....we'll see what the story is. I weighed my stuff last night (don't have the numbers in front of me right now) and the pressure plate was about 9.7 pounds as I recall.

Bryce
88 GT

quote Originally posted by Nashco: Well, I called David and explained my issue. He's sending me the correct flywheel and UPS is supposed to be picking up the one I have. He said they have correct ones on hand, and only the first few made had this issue. On the lightened pressure plate, he said it's a slightly different material and slightly different design on the friction plate portion of the pressure plate. He told me to send him some pics and he can tell me if I got the correct (lightened) pressure plate or not. I asked if there was an easy way for me to tell, but he said it's easiest if he just looks at it and tells me.....we'll see what the story is. I weighed my stuff last night (don't have the numbers in front of me right now) and the pressure plate was about 9.7 pounds as I recall. Bryce 88 GT

Wow , they told me it would be 8 weeks before they would have the right ones.....

Im starting to get leary of spec.

JM

quote Originally posted by The Punisher: Wow , they told me it would be 8 weeks before they would have the right ones..... Im starting to get leary of spec. JM

At this point, I'm hoping the product is as good as they are trying to make it seem. David has been pretty helpful, and Spec's reputation is a heck of a lot better than anyone else in the Fiero world. I'm hoping for the best.

Anyway, what are your options? Throw that car together and tell us what happens!

Bryce
88 GT

i should be getting mine back today or Monday. I'll let you know how it fits.

edit: just got word that it has not shipped yet. so please disregard that last statement...

[This message has been edited by cptsnoopy (edited 10-15-2004).]

For those interested, these are the weights I got from my parts:

3.34 lbs - Friction Disk Assembly
8.00 lbs - Flywheel Assembly
9.56 lbs - Standard Pressure Plate Assembly
0.40 lbs - Included Hardware

21.3 lbs total

I'm pretty skeptic about the "lightened" pressure plate, we'll see what David has to say about it when I send him the pics on Monday.
*edit: Pressure plate turned out to be the standard pressure plate, see post below for lightened pressure plate info.

Bryce
88 GT

[This message has been edited by Nashco (edited 10-26-2004).]

------------------
Bobby from NW Indiana
93 Northstar and 5 speed Getrag
thespeedshop@sbcglobal.net
My build thread

quote Originally posted by cptsnoopy: i should be getting mine back today or Monday. I'll let you know how it fits. edit: just got word that it has not shipped yet. so please disregard that last statement...

I sent David an email requesting a tracking number this time. last time I was not in town when it arrived and had to make arrangements with the neighbors to sign for it. I was told the replacement would ship today but my gut feeling is that it is either already enroute or it will be awhile, one way or the other...

quote Originally posted by Nashco: For those interested, these are the weights I got from my parts: 3.5 lbs - Friction Disk Assembly 8.2 lbs - Flywheel Assembly 9.7 lbs - Pressure Plate Assembly 0.5 lbs - Included Hardware 21.9 lbs total I'm pretty skeptic about the "lightened" pressure plate, we'll see what David has to say about it when I send him the pics on Monday. Bryce 88 GT

wow - now that should rev quick and make shifting hella-fast
the rev drop should make revmatching very fast - nice setup guys

Did Dave write you back or call you today?

------------------
Bobby from NW Indiana
93 Northstar and 5 speed Getrag
thespeedshop@sbcglobal.net
My build thread

quote Originally posted by GSXRBOBBY: Did Dave write you back or call you today?

I did not receive an email or a call from David. I get the feeling he may have gotten sick or something. He was not in last Friday when I tried to get a tracking number. that is when another guy informed me that the flywheel had not been shipped yet.
I am not sure what the status is.

I got an email reply from David yesterday afternoon. He said that the picture of my pressure plate does *not* look like the lightweight version, and that he is shipping me the correct part with a call tag to return the first one. So, the assembly should be a bit lighter, still! I'll make sure to weigh the lightweight one so you guys know how they compare.

In theory, I should be receiving the corrected flywheel and pressure plate this week. I'm going to call David tomorrow if I haven't received the flywheel yet, as UPS should only take a couple days to get here.

Bryce
88 GT

I called David today and found out why things seemed a little wacky. They are in the process of moving from there current location to a new fabrication plant and it's added some confusion to daily operations. He said my flywheel has shipped and I should get a tracking number later today or tomorrow.

edit: got the tracking number and it is scheduled to arrive on Friday

[This message has been edited by cptsnoopy (edited 10-19-2004).]

Good to hear your going to be all set Friday there Snoopy.

------------------
Bobby from NW Indiana
93 Northstar and 5 speed Getrag
thespeedshop@sbcglobal.net
My build thread

Good news! I got the new flywheel today, looks to be the same diameter center hole as cptsnoopy indicates it should have. I should be getting the lightened pressure plate in the not too distant future. I sure wish I had a Northstar laying around to mount it up and check fitment for those of you needing to verify that. I have a spare trans, but no engine.

Bryce
88 GT

quote Originally posted by Nashco: Good news! I got the new flywheel today, looks to be the same diameter center hole as cptsnoopy indicates it should have. I should be getting the lightened pressure plate in the not too distant future. I sure wish I had a Northstar laying around to mount it up and check fitment for those of you needing to verify that. I have a spare trans, but no engine. Bryce 88 GT

Hi Bryce,

I don't remember if you're already driving a N* fiero or have one in the works? congrats on getting the correct goods!

quote Originally posted by cptsnoopy: Hi Bryce, I don't remember if you're already driving a N* fiero or have one in the works? congrats on getting the correct goods!

Now that I have a complete clutch and flywheel assembly, I'm about 0.08% done with my Northstar swap.

Bryce
88 GT

lookin good! the replacement flywheel showed up today and I promptly went out and measured the center hole.

this is the old one:

and this is the new one:

I won't have the trans off for a little while so I can't check the fit but it looks great!

Latest news on the lightened flywheel, which actually does exist and has arrived. Good news is that it is different and is lightened, bad news is I don't think it's all that great of a deal. Here's a pic and the measured weights of the stage 3 pressure plate, you be the judge to determine if it's worth $79. I weighed things with a force meter calibrated to +/- .02 lb, so the weights can be considered very accurate....I edited my prior post to reflect these more accurate measurements.

9.56 lbs - Standard Pressure Plate
9.10 lbs - Lightened Pressure Plate

20.84 lbs - Total With Lightened Pressure Plate

Bryce
88 GT

.46 lbs of lost rotating mass IS an improvement and you'd see it in a side by side test but i'd think that the weight would have been better when lost tward the OUTSIDE of the plate ring, thus lowering enertial forces.

as for the extra 79$ charge, i would think a good machine shop could do that for about half that cost.

-Arty