Real Fiero Tech

I'll start a new thread for discussion relevant to installing a QuarterMaster clutch in a Fiero.
This thread will remain for installing a Tilton clutch: viewtopic.php?f=3&t=3376

I recently bought this from ALLTRBO:







As you can see from the photo of the back, the flywheel has 141 teeth. I haven't figured out what P/N it is, though. I *DO* know it's one of the PN's they've offered over the years that bolts up to the Super Duty 4/Iron Puke and works with the Muncie transmission.
You can also see from the photos of the top that it's been used with the wrong throw out bearing, which has damaged the diaphragm spring fingers.

I had it on the surface plate because I was using some fancy QC gear to measure the height of various features on the clutch.
The tips of the diaphragm spring screws are 2.377" above the surface plate.
The flywheel friction surface is 0.764" above the surface plate.
2.377 - 0.764 = 1.613"

Per this post: viewtopic.php?p=50199#p50199
(The drawing that post links is now here: http://tiltonracing.com/wp-content/uplo ... 1-2-pl.pdf
*BUT* the drawing has been updated to reflect Tilton's current practice of using flat head screws installed from the outside to hold the diaphragm spring pivot to the pressure plate cover, as opposed to their former habit of installing conventional screws from the inside).

The depth of the 282 bellhousing is 2.425 over the output shaft bearing boss. This means that the QM unit would *BOLT RIGHT IN*. Horry Sheet! Although... not entirely unexpected. It is made for the Muncie application, after all.
Also per the above, the tips of the Tilton diaphragm spring screws are (were) 1.98" above the friction surface. Compared to the corresponding value of 1.613 for the QM, the Tilton was almost 3/8" taller in the same screw configuration! Again Horry Sheet!

The height of the NEW Tilton units is 1.706 above the friction surface with the flat head screws. The new Tiltons are STILL 0.093" *TALLER* than the QM's. Still Horry Sheet.

Flipping the diaphragm spring screws on the QM drops the height of the heads down to 2.245, *BUT*, the top surface of the pressure plate is 2.337", so that's as shallow as the clutch gets. Still PLENTY of clearance, though.

QM's pressure plate cover is stamped steel, while Tilton's PP cover is either cast or billet aluminum. That explains some of the difference in thickness. Fundamentally the QM is just packaged that much better. I am officially impressed.

The QM flywheel 506630 is still listed on their website, so I might even be able to order one. Their main tech guy sent me a (surprisingly) detailed drawing of it. I need to tweak the forum settings to allow .pdf attachments before I can upload it here. The crank flange mating surface on that part is too small for a Northstar (or LS) crank flange, so I wouldn't be able to plug & redrill it. QM's min run size is either 5 or 10, so I may be able to redline their drawing and have some parts made *WITHOUT* a crank bolt circle. That way one could be drilled for a Northstar or LS4 or LLT or even, God forbid, a 4.9.

Also, the part pictured above has an impressive number of speed holes, but the drawing does NOT show speed holes. That's one of the reasons I'm not exactly sure which part I have. The PN is not included with the part mark either (WTF?!?) The spec thickness per the drawing is 0.760; mine being at 0.764 means that it's original and has never been resurfaced.

Plan B is still to roll my own. That's even easier with the QM's better packaging.

Here's a quote about QM PN's from the Tilton thread:

The Dark Side of Will wrote: ↑Thu Nov 20, 2008 9:37 pm Quartermaster clutches:
http://www.racingclutches.com/~rclutch/ ... _Guide.pdf

506630 is listed as "FLYWHEEL PONTIAC FIERO 7.25". I guess that's what coinage has.

296626 and 296630 are listed in his application list as 2 disk clutches for 1 x 14 spline.

236626 is listed as "RELEASE BEARING FIERO L-4" (probably just means for the Muncie 4 speed).

296626 is still listed in the current application guide under "2 Disc 7.25 Pro-series clutch and flywheel" as "Clutch Pontiac L-4 7.25 1x14".

296630 isn't listed in the current app guide.

I wonder if any of these parts are actually still available.

Anybody know how the crank bolt patterns and flywheel pilot diameters compare from the Iron Duck to the 2.8?

Very cool. Like to see where this goes

Anything new?

Haven't heard anything from QM in response to my email, but didn't really expect to. However, I have not yet called them back.
I can make a puck for 6 bolt patterns: V6/60, LS, SBC and another for 8 bolt patterns like the Northstar. Anyone know what crank bolt pattern a 3800 has, right off?

I'm also looking at what the thicknesses have to be to make a puck that can be welded into a flexplate to work with a 282, sit on top of the flexplate in an F23 and then work with a spacer in an F40.

Any ideas on throw oit bearings that will work with this qm?

I have ideas, but I need to collect dimensions. Fundamentally, we'd have to use a mechanical TOB provided by the clutch manufacturer. I'll have to design a custom TOB carrier for each transmission to make that work. I sketched one for the 282 a few years back, but I don't think I still have the sketch. The form is simple enough, I'll just have to re-figure the numbers.

I have an F40 for the high feature V6, a bunch of 282's and a Muncie. There's an F23 for the V6/60 nearby that I can grab for $100. I need to get all these on the bench next to each other and start figuring this out.

The SBC, LS, V6/60 & Caddy 4.9 all use six bolt flywheel patterns; the Northstar and 3800 use eight bolt flywheel patterns.

Does a factory 282 to bearing not engage the pp flingers in the correct spot? Why wont it work? I guess I need a visual

Look closely at the wear on the throw out fingers in the pics I posted above. The edge of the stock TOB digs into the fingers when the clutch is released. That's why it needs a round faced bearing such as the clutch MFGs sell

So the throwout bearing from from the mfg is no longer available? This has been verified?

Also are you sure the factory to bearing caused the damage and not that a bearing failure at one point in time caused the damage?

Perhaps a bearing failed for coinage that caused that damage and not the bearing face itself.

I looked at a pic of a to bearing in a 282 and I dont see what part of it would be creating the groove

Shaun41178(2) wrote: ↑Tue Nov 06, 2018 12:05 pm So the throwout bearing from from the mfg is no longer available? This has been verified?

Not sure where you got that idea, but QM and Tilton make PLENTY of release bearings.

Shaun41178(2) wrote: ↑Tue Nov 06, 2018 12:09 pm Also are you sure the factory to bearing caused the damage and not that a bearing failure at one point in time caused the damage?

Perhaps a bearing failed for coinage that caused that damage and not the bearing face itself.

I looked at a pic of a to bearing in a 282 and I dont see what part of it would be creating the groove

I'll check with a 282 TOB, but the diameter looks about right.

The fingers on the production clutch go from "up" to "flat" when the TOB releases the clutch. The fingers on the Tilton & QM units go from "a little up" to "a little down". When they're a little down, the outside corner of the 282 or Muncie TOB digs into the fingers as pictured.

Well if the to bearing is still available from qm for the 282 then that seems like the way to go instead of making your own

Oh, that's what you meant.
I don't think QM ever made one for the 282. I'm not sure what they used for the Muncie...

I picked up an F23 to use for clutch design purposes. I already have an F40 for the 3.6 V6... I might as well just grab one for a 2007 Pontiac G6 (MU9 gearset) so I have all the same bellhousings to work with.