Thanks for the idea Fieroguru... I just might try that out.

As for the boot clamps Reallybig... I was thinking the same thing... these clamps don't seem to be able to be tightened enough to work properly. Have you found a source for the good ones?

As I mentioned before, even though I took a bit of leave from posting in here over the past couple weeks, I've been busy nonetheless. While waiting (for forever) for my axles to be re-splined, I got to work researching what I was going to do for the flywheel and clutch. Many moons ago Zac88GT came up with an innovative idea for mating the Northstar to the F40 transmission... in fact, I think he was the first, and I don't believe anyone else has attempted it. He bought a SPEC aluminum flywheel to place the ring gear at the right depth for the starter. Then, he designed an elaborate spacer disk in Solidworks, had it machined out of aluminum, and bolted it to the transmission side of the flywheel. Next, he installed a steel wear plate and the clutch stack to his spacer disk, essentially moving the clutch deeper into the transmission bellhousing where the hydraulic throw out bearing (HTOB) could reach it. His thread is here for those that want more info: www.fiero.nl/forum/Forum3/HTML/000030-2.html

Obviously Zac's solution was my preferred option since it's tried and true, and because he was nice enough to send me his Solidworks file. That was several years ago though and since then, Fieroguru designed a one-piece aluminum flywheel to mate his LS4 to an F40. Fieroguru machined a single aluminum part (with a steel wear plate) based on critical dimensions from an aluminum LT1 Fidanza flywheel, which seemed like an improvement over Zac's two-piece aluminum flywheel with a steel wear plate. If Fieroguru's design could be made to work with the Northstar, it would also cost less since one could avoid buying a SPEC flywheel.

My plan was to contact Fieroguru to see if he would machine a flywheel for me based on the specs for my Northstar engine... but first I needed to get savvy about what I needed. I spent a whole whack of time researching various dimensions of the interface between the transmission, engine, and clutch assemblies and drew up some schematics. The first one shows the key relationships between these components:



The drawing is made from a mix-mash of dimensions that Fieroguru posted in his LS4 build thread, and ones I took from my own flex plate and engine. The amazing thing that fell out of this exercise was that the Northstar is essentially identical to the LS4 for the purpose of mating the F40. That meant Fieroguru's flywheel would only need to be modified for the Northstar crankshaft bolt pattern and the flywheel centering hole. It also meant that I wouldn't have to worry about solving the four key areas that he had to contend with through trial and error. Here's a schematic showing some of the challenges he faced and that I was glad I wouldn't:



In area:
A. the ring gear must be able to fit inside the bell housing diameter and it must be set at the correct depth;
B. the depth of the flywheel, clutch, and pressure plate stack must not exceed the depth of the bell housing;
C. the fingers on the pressure plate must sit at a depth that allows the HTOB to operate within it's range; and
D. the F40 transmission has a differential housing bump that protrudes into the bell housing... the pressure plate must also clear that.

It all sounds easy enough if you've got all the dimensions and drawings sitting in front of you, but there isn't a parts supplier out there that can give you the stack height of a clutch and pressure plate, nor the required throw on the fingers to get full disengagement, nor a whole bunch of other data you need to figure out if it'll work or not. That's why I thought it was appropriate to give credit where it's due. Fieroguru came up with a flywheel design, and a clutch and pressure plate combination that are tried and proven to work with the F40 transmission. He deserves a hearty pat on the back.

The other nice thing about Paul is that to save me money, he figured that it would be much cheaper if I were machine the flywheel up here in Canada and avoid shipping, handling, and duty. So with a gentleman's agreement not to share or otherwise profit from his design, we negotiated an excellent price and he transferred everything I needed to make my own flywheel. Woo-who! This was one of two huge hurdles still left ahead of me and it was solved over a couple days. (The last hurdle is engine management). Next post is when the fun began... I love watching CNC machines do their stuff.

Blooze, you have been more than helpful sharing all your detailed drawings of the 88 suspension (which I have used quite a bit), so sharing the print for my flywheel was one way to return the favor. Hope you like it!

Those drawings are pretty cool and really show how tight everything is within the bellhousing and all the factors one must review to find a workable solution. However, there is another critical dimension not mentioned - the placement of the clutch disk spline hub to the splines on the input shaft.

Also, did you remember to insert the bleeder assy into the HTOB to release the check valve and allow the fluid inside to be removed. If you don't do this, the HTOB will not fully retract and it will throw off the fully retracted measurements... been there, done that...

Let's see some machining pics!

quote Originally posted by Bloozberry: Thanks for the idea Fieroguru... I just might try that out. As for the boot clamps Reallybig... I was thinking the same thing... these clamps don't seem to be able to be tightened enough to work properly. Have you found a source for the good ones?

There are a variety of tools that can tighten the horrid aftermarket clamps. That's what the parts store nincompoops don't know... a tool IS required.

I've used this one:
http://www.amazon.com/gp/pr...1QRQE833QHSCW5C7WAD7

This one looks better, but I have no experience:
http://www.amazon.com/GearW...rench/dp/B0002SRDDC#

quote Originally posted by Will: All of the engines with the FWD pattern (Northstar, 60degreeV6, 3800, 4.9, etc.) are identical in that regard... the crank flange is coplanar with the bellhousing mounting face. A 40.3mm (or 41.275 or 47.625) thick flywheel--even made of aluminum--will be quite heavy. I recommend using a stock flexplate to carry the starter gear, then a steel hub spacer ~27mm thick, but only as large as the Northstar crank flange, then a 10mm thick steel friction surface the full diameter of the clutch, to which the clutch bolts. Assuming the flexplate is 3mm thick at the hub, these numbers add to 40mm. Adjust the hub spacer thickness to arrive at the desired total stack thickness. In addition to being lighter, this will get aluminum out of the equation. I don't like the use of aluminum in a clutch/flywheel application. Aluminum creeps under stress at high temperatures. The heat from friction in the clutch can cause the fasteners that hold the friction surface to the flywheel to relax... it can even cause the flywheel bolts themselves to relax. This is a demonstrated reliability problem on the 2003 Mustang Cobras that had aluminum flywheels from the factory.

Just a note before you go down the road of designing a spacer that utilizes the crank bolt pattern for clamping everything together. Source the fasteners first. I am guessing that the Northstar has a similar flywheel bolt to the LS engines in that it an 11MM thread with a fine pitch. GM performance does not carry any long 11MM fasteners the longest shank is about 1". You may be able to source some studs that will fit the bill, or you may have to get some custom fasteners. Also keep in mind they need to be super strong, if I recall correctly 10.9 spec.

Awesome build by the way.

quote Originally posted by fieroguru: ...there is another critical dimension not mentioned - the placement of the clutch disk spline hub to the splines on the input shaft.

Yeah... I thought about that one after I posted... but then there are lots of other little issues to consider as well like whether low profile crank bolt heads are needed, finding a friction disk with the right number of splines, the correct diameter, and the right offset hub... and the list goes on and on.

quote Originally posted by fieroguru: Also, did you remember to insert the bleeder assy into the HTOB to release the check valve and allow the fluid inside to be removed. If you don't do this, the HTOB will not fully retract and it will throw off the fully retracted measurements... been there, done that...

I didn't need to because I read your thread and got my measurements from your experience. I haven't installed the flywheel yet, though I would imagine I'll need to do as you described otherwise I'll be fighting against the HTOB on the fingers when I try to mate the transmission to the engine.

quote Originally posted by Will: In addition to being lighter, this will get aluminum out of the equation. I don't like the use of aluminum in a clutch/flywheel application. Aluminum creeps under stress at high temperatures. The heat from friction in the clutch can cause the fasteners that hold the friction surface to the flywheel to relax... it can even cause the flywheel bolts themselves to relax.

Unless you're slipping your clutch regularly, I can't see the heat build up as a significant problem. As for the wear plate fasteners relaxing, they're not screwed into the aluminum... the fasteners are through-bolts with lock nuts on the reverse side so I don't see that as a problem either. Your idea of a thick, small diameter flywheel spacer with a larger diameter steel disk to mount the clutch to is interesting but sounds cumbersome with the number of pieces being aligned and bolted together. To each his own.

quote Originally posted by mwhite: I am guessing that the Northstar has a similar flywheel bolt to the LS engines in that it an 11MM thread with a fine pitch....

The Northstar actually has eight M8 x 1.25 flywheel bolts so they're not the same as the LS engines. Thanks for the compliment, BTW.

So, on to the flywheel fabrication. I did a bit of research to figure out the best aluminum alloy to make the flywheel out of and found that 7075-T6 would have been ideal from a properties perspective. The problem with that alloy is that it's not very common around here in 12" diameter billets, and it's not cheap either. After seeing that nearly all the aftermarket flywheels are made from 6061-T6 aluminum, and after finding that the local metal supplier had some in stock, I decided to go that route instead. I ordered up a 2" thick billet from Metals "R" Us and got it the next day for a measly $124 including shipping and taxes.



The Northstar engine uses a 142 tooth flex plate for the starter so rather than attempting to remove the ring gear from flex plate (which I'm not certain could be done anyways), I ordered a new ring gear. For $47 all inclusive, it was delivered within a couple days:



I needed the ring gear in advance because the machine shop would use it to gauge how large the seating surface should be on the flywheel in order to get a nice tight interference fit. Here's the part number for anyone considering going this route:



I spent a couple hours modifying Fieroguru's drawings to change the crank bolt pattern from a six bolt to an eight bolt pattern, and to change the diameter of the centering hole in the middle of the flywheel to match the Northstar's much smaller centering flange. Then, with drawings in hand, I made a trip to my favorite machine shop and watched as the owner's eyes filled with delight as I gave him the instructions. He's up to his eyeballs in "mundane" engine machine work so when he gets a chance to use his CNC lathe and mill for something special, he sets everything else aside. Here's the lathe, and if you look closely, you'll see my aluminum disk already mounted to the chuck:



This particular lathe has an automated head with eight different cutting tools mounted on it for different types of cuts. Only one cutter was used for all of the turning work done on my flywheel though. Here's a close up of the preliminary cut that was made to gain enough clearance for the remaining operations:



From the drawings, the machinist sat at his computer for 15 minutes and programmed the profile of the front face of the flywheel, then stuck the diskette into a port on the lathe. That's when this screen on the lathe lit up and showed the path the cutter would take:



Once that was done, all that remained was for him to close the door...



Start the lathe and the coolant jets, and press the GO button for the cutting head to come alive:



It looked more like an aluminum spaghetti factory in there after a few minutes. Every so often he'd shut the lathe down to remove the strands because they'd start to interfere with the coolant spray pattern. At one point he reached in, grabbed a handful and muttered something like "Bionic Woman's pubic hair"...



As it neared the end of the run, it re-traced its path to clean up any edges and without the coolant jets it made taking pictures a little easier:



Here's the completion of step one of seven... but don't worry, I won't be documenting them all.

but we want to see all of them....

quote Originally posted by mwhite: Just a note before you go down the road of designing a spacer that utilizes the crank bolt pattern for clamping everything together. Source the fasteners first. I am guessing that the Northstar has a similar flywheel bolt to the LS engines in that it an 11MM thread with a fine pitch. GM performance does not carry any long 11MM fasteners the longest shank is about 1". You may be able to source some studs that will fit the bill, or you may have to get some custom fasteners. Also keep in mind they need to be super strong, if I recall correctly 10.9 spec. Awesome build by the way.

quote Originally posted by Bloozberry: The Northstar actually has eight M8 x 1.25 flywheel bolts so they're not the same as the LS engines. Thanks for the compliment, BTW.

As BLooze mentioned, the Northstar has an 8 bolt circle with 8mm bolts.... weird. GM used 10.9 bolts with a 15+50 (IIRC) torque sequence. They are TTY. TTY only takes 50 degrees because the bolts are so short. I use 12.9 hex head bolts from general industry for my flywheel. The standard heads just barely fit under the clutch disk. ARP doesn't have any 8mm thin head flywheel bolts. When I get around to making the button flywheel for a Tilton clutch, I'll enlarge the holes to 10mm for better fastener availability.

quote Originally posted by Bloozberry: Unless you're slipping your clutch regularly, I can't see the heat build up as a significant problem. As for the wear plate fasteners relaxing, they're not screwed into the aluminum... the fasteners are through-bolts with lock nuts on the reverse side so I don't see that as a problem either. Your idea of a thick, small diameter flywheel spacer with a larger diameter steel disk to mount the clutch to is interesting but sounds cumbersome with the number of pieces being aligned and bolted together. To each his own.

Are you going to drive your Ferrari slow enough to drive Miss Daisy?

Even when cold, but especially when warm, the aluminum can flow out from under the bolt heads. Creep means that the material flows so as to reduce the stress on it. As the aluminum flows to reduce the compressive stress on it, this obviously reduces the tensile stress on the bolts as well.

The way the two-piece steel flywheel would have to work is that the hub would be bolted to the friction disk from the engine side. The bolts would be secured with either red lock tite, metal staking or tack welding. The assembly would be trued in a Blanchard grinder and then bolted on top of the flexplate through the hub from the clutch side. The two piece construction means that the hub can be turned from a piece of 4" round bar and the friction surface laser or water jet cut from 3/8" plate... cheaper machines and materials keeping the buy/fly ratio high and the machining time low. The disk could even be plasma cut, but the edge would have to be machined true to ensure balance.

quote Originally posted by Bloozberry: The Northstar engine uses a 142 tooth flex plate for the starter so rather than attempting to remove the ring gear from flex plate (which I'm not certain could be done anyways), I ordered a new ring gear. For $47 all inclusive, it was delivered within a couple days:

Always check The Google:

http://www.summitracing.com/parts/pio-frg-142w

Although shipping to Canada is the great equalizer, isn't it?

[This message has been edited by Will (edited 05-06-2014).]

I want to see all of them too. This is engineering **** , and is highly encouraged around these parts..

------------------


Build thread for my 88 + 3800NA swap

quote Originally posted by Bloozberry: As for the boot clamps Reallybig... I was thinking the same thing... these clamps don't seem to be able to be tightened enough to work properly. Have you found a source for the good ones?

No

quote Originally posted by Bloozberry: As for the boot clamps Reallybig... I was thinking the same thing... these clamps don't seem to be able to be tightened enough to work properly. Have you found a source for the good ones?

I used Mevotech B1000 (large) and B1001 (small) I believe for my CV boots. They're the factory style with the little square that gets crimped to tighten them. You should use a proper crimping tool but I've seen people get away with using a pair of side cutters and a hammer.

quote Originally posted by Zac88GT: I used Mevotech B1000 (large) and B1001 (small) I believe for my CV boots.

Thanks for the part numbers... although I nearly gagged when I saw the prices... $16 for a large clamp and $14 for each small clamp? Hopefully there's something else out there.

Due to popular demand I'm posting a few more shots of the flywheel being machined. Once the transmission face of the flywheel was finished being turned, it got flipped around, the contour of the engine side was programmed, and the machinist let 'er rip again. I could stand for hours watching the progress (in fact I did). There's just something really cool about watching a raw piece of material being turned into a thing of beauty. Anyways, with both sides shaped, the flywheel got transferred to the CNC milling machine for the holes.



Unlike the lathe, in the mill the piece is clamped solidly to the bed and only the machine head does all the moving. Interestingly, the programming for the holes was based on the number of degrees each hole was apart from each other, the radial distance from the center of the piece, and the depth of each hole. It uses fewer programming steps than if it were done using XYZ coordinates. And there were lots of holes... 57 to be exact. Here's a photo of the counter-bores being drilled for the wear plate fasteners:



By this point the ring gear had been installed and all the holes were milled. The ring gear gets heated up in an oven and slipped onto the OD of the flywheel while it's still hot. It cools down rapidly, contracting and cinching itself with an interference fit. For faster spinning engines (12,000+ RPM), the ring gear should to be bolted to the flywheel to prevent it from expanding and coming off due to centrifugal forces... at least that's what the machinist said.



Here's the flip side of the completed bare flywheel. Notice the countersunk groove for the wear plate:



The wear plate is a steel insert made by Fidanza for '91 - '96 Dodge Stealths, part number 221021. It has a 10.25" OD, a 6" ID, and comes with 22 self locking nuts and machine bolts with countersunk heads, although you only need 20 of them. As usual, we Canadians pay about twice what Americans pay for the same part... it was $78 delivered through Amazon. All in all not terribly expensive:



The wear plate gets bolted onto the flywheel using 60 in-lbs of torque. I discovered I hadn't correctly sized the countersunk holes on the backside of the flywheel to the diameter of the socket wrench I needed to torque the nuts with. THe simple solution was to turn down my socket to fit. Here's the flywheel with the wear plate installed:



I started out with an aluminum billet weighing exactly 22 lbs. After all was said and done, the completed flywheel including the ring gear, wear plate, and fasteners, tipped the scales at 12.70 lbs. That's a lot of aluminum left on the machine shop floor! By comparison, the Fiero steel flywheel weighs in at 15 lbs, and according to Fieroguru, the bare LS1 flywheel comes in at a whopping 24 lbs!



Total cost for the flywheel at this stage: $124 for the aluminum, $300 for machining, $78 for a wear plate, and $47 for a ring gear = $550. Not bad for a one-off, custom designed, precision machined, high-tech thing of beauty.

quote Originally posted by Bloozberry: Thanks for the part numbers... although I nearly gagged when I saw the prices... $16 for a large clamp and $14 for each small clamp? Hopefully there's something else out there.

No need to worry, the price looks outrageous because they come in a box of 10, but the parts stores sell them individually.

Oh... well that makes more sense.

quote Originally posted by Bloozberry: I started out with an aluminum billet weighing exactly 22 lbs. After all was said and done, the completed flywheel including the ring gear, wear plate, and fasteners, tipped the scales at 12.70 lbs. That's a lot of aluminum left on the machine shop floor! By comparison, the Fiero steel flywheel weighs in at 15 lbs, and according to Fieroguru, the bare LS1 flywheel comes in at a whopping 24 lbs!

Not bad... better than I expected. I didn't think the back of it was so deeply contoured.

Great Job! Too bad such a nice piece will not see the light of say again once assembled to the car.

BTW I have a small collection of custom made nut drivers, sockets and screw drivers for a bunch of parts I've made over the years too.

Edit: forgot pliers, snap ring and needle nose and many pry bars.

------------------
yellow 88 GT, not stock
white 88 notchie, 4 banger

[This message has been edited by ccfiero350 (edited 05-09-2014).]

I want one!

Charlie

Are you going to rivet that gear ring to the aluminum or something?

No, in fact it's very common for ring gears on street cars to be retained on their flywheels by an interference fit only. The shop that machined the flywheel has some very knowledgeable staff (they routinely rebuild NASCAR engines from the States), so they were the ones who suggested the diameter of the ring gear seat on the flywheel to ensure proper retention.

quote Originally posted by Bloozberry: I discovered I hadn't correctly sized the countersunk holes on the backside of the flywheel to the diameter of the socket wrench I needed to torque the nuts with. THe simple solution was to turn down my socket to fit.

What size socket did you use to torque the nuts (been so long I can't remember)? The drawing shows the counter bore to be 1/2" and I know I had issues taking the LT1 Fidanza flywheel apart because the counter bore holes were too narrow. So I upsized the holes on mine and had a socket that fit the new larger hole, so there were no installation issues. I just want to confirm I didn't make the hole larger than 1/2" and forgot to change the drawing... just another reason I want to pull the LS4/F40 back out to check/verify some things before starting to offer these flywheels for sale. If I compare the picture of the backside of mine to yours, it looks like I might have gone up to 9/16 or 5/8" for the counter bore. Here is the backside of mine:


When I designed this flywheel/clutch combo, I wasn't trying to make it as light as possible, just lighter than the SBC/Fiero pressure plate combo I was used to running. My goal was to keep the overall weight of the flywheel/clutch/pressure plate close to the stock fiero V6 setup. I didn't take the time to calculate the MOI change between the two, but I know this new flywheel/pressure plate does have a higher MOI than the stock 2.8 setup due to the larger diameter pressure plate accounting for more of the total weight of the package. However, it does have a much lower MOI than the Archie SBC setup I was used to and the RWD LS(x) setup.

The LS4/F40 prototype flywheel tipped the scales at 11.2 lbs. Larger crankshaft pilot, larger (but fewer) crankshaft bolt holes, larger counter bores for the wear strip bolts, spring dowels vs. solid, scale calibration differences, etc. all would help account for the lighter weight.

Using my wife's 30 lb postal scale here are the overall flywheel/clutch/pressure plate weights

LS4/F40 flywheel with a used factory ford clutch/pressure plate: 11.2 + 18.4 = 29.6 lbs
LS4/F40 flywheel with new SF964F clutch: 11.2 + 16.52 = 27.72 lbs

For comparisons,
Archie SBC flywheel/Spec clutch is about 42 lbs total and flywheel is about 1" larger in diameter.
Stock 2.8 fiero setup is about 15 lbs for the flywheel and 15.6 lbs for the clutch/pressure plate = 30.65 lbs.
Stock 2000 LS1 is 24 lbs for the flywheel and 32 lbs for the clutch/pressure plate = 56 lbs and this weight is spread over a 2" larger diameter.

[This message has been edited by fieroguru (edited 05-10-2014).]

boot clamps:

http://www.oreillyauto.com/...+clamps+%26+hardware

quote Originally posted by fieroguru: What size socket did you use to torque the nuts (been so long I can't remember)?

I'll send you a PM with the details.

quote Originally posted by fieroguru: The LS4/F40 prototype flywheel tipped the scales at 11.2 lbs. Larger crankshaft pilot, larger (but fewer) crankshaft bolt holes, larger counter bores for the wear strip bolts, spring dowels vs. solid, scale calibration differences, etc. all would help account for the lighter weight.

If you're referring to the reason why mine is heavier, then the reason is probably because you weighed yours either without the ring gear or the wear plate, or both. When I tally up the complete weight of mine including the pressure plate and clutch disk, the assembly weight is nearly identical to yours, as you'll see in my next post.

quote Originally posted by ericjohn262: boot clamps: http://www.oreillyauto.com/...+clamps+%26+hardware

Thanks! A + for you too.

quote Originally posted by Bloozberry: If you're referring to the reason why mine is heavier, then the reason is probably because you weighed yours either without the ring gear or the wear plate, or both. When I tally up the complete weight of mine including the pressure plate and clutch disk, the assembly weight is nearly identical to yours, as you'll see in my next post.

That is entirely possible. I did weigh it a each step of the process and could have grabbed the wrong #... it has been 3 years since I made the prototype...

Just for reference, the Spec Fiero Getrag Stage 3+ clutch (SC883F) and pressure plate weight in at 14.7 lbs. I just opened a new one today and put it on the scale as well.

quote Originally posted by fieroguru: Eventually, I want this flywheel to be SFI certified for 7K RPM, so it will have to sustain 10,500 rpm for 24 continuous hours.

Is that really part of the certification? One spin up, 24 hours later one spin down? That's only one stress cycle. That doesn't say anything of value about the fatigue resistance of the part.

quote Originally posted by Will: Is that really part of the certification? One spin up, 24 hours later one spin down? That's only one stress cycle. That doesn't say anything of value about the fatigue resistance of the part.

I was wrong, its only a single pull for 1 hr of duration. Fatigue resistance isn't part of the testing. Here are the certification requirements for 1.1 (Replacement Flywheels and clutches)

http://www.sfifoundation.co.../Spec_1.1_110901.pdf

quote 5.2.3 PROCEDURE A. Mount the component(s) to the spindle and attach the tachometer. B. The component(s) shall be driven to a minimum rotational speed of 150 percent of the maximum engine speed as provided by the submitting manufacturer and maintained at that level for one hour. 5.2.4 INSPECTION Upon completion of the test, the component(s) shall be examined for signs of failure, such as cracks, by either Fluorescent Dye Penetrant Inspection or Magnetic Particle Inspection.

[This message has been edited by fieroguru (edited 05-11-2014).]

Fieroguru's flywheel was designed specifically for use with the Spec's '93 - '97 Ford Ranger 4.0L clutch and pressure plate. After debating with Fieroguru the pros and cons of using the 3+ sprung hub clutch disk versus the 4+ solid hub clutch disk, I decided to opt for the 4+ after Paul reassured me that its street manners were quite acceptable. He's got about 12K miles on his LS4 with this combination and said he could easily feather it to inch forward in traffic, or drop it hard for max acceleration without slippage. The troubles experienced by several PFF members losing hub springs with Spec's sprung hub disks were enough to make me avoid them.

I ordered up a Spec Stage 4+ (part number SF964F) from Canadian distributor "Steeda" in Ontario, which sells performance Ford parts. The part number isn't listed on Spec's website but it is available. It was especially painful for the pocketbook coming in at $778 after taxes and shipping.



Here's the business side of the pressure plate:



It's the biggest diameter clutch you can physically fit inside the F40 bellhousing. The clamping surface measures just shy of 10" at 9-15/16".



The pressure plate alone weighs in at 11.57 lbs which is within a half pound of the stock Fiero pressure plate for comparison's sake:



Here's the solid hub clutch disk... note that it's a full faced friction surface which helps driveability significantly over the various multi-puck designs of the Stage 4 disks:



It measures 9-27/32" in diameter so it's 13/32" smaller than the wear plate on the flywheel and 3/32" smaller than the pressure plate clamping surface:



The other unique feature of this clutch disk is that the splined hub is entirely offset towards the transmission side. It's deep too giving 15/16" spline engagement:



The clutch disk weighs 4.92 lbs so in all, the flywheel, pressure plate, and disk weigh 29.19 lbs total. Compared to the stock Fiero assembly weighing 30.6 lbs, I'd say the design is pretty darned good. As Fieroguru mentioned earlier, the same assembly off an LS1 engine weighs a whopping 56 lbs!

For fun, I took a couple photos of the disk mocked up on the flywheel to show the relationship between the edges of the two parts:



And again, here are all three parts just stacked on top of each other. These will only get installed once I get around to removing the cradle again, but that will only happen once I take a few measurements for such things as engine torque strut locations and clearances for some exhaust plans.

You won't be disappointed with the solid hub. Our flywheel weights are very close and I thought the driveability was excellent.

Sprung hub and engine mounts both contribute to clutch chatter.

Bump.

Blooz - That flywheel is Automotive Art - it needs to be hanging on a wall for all to admire!

Nice progress, I sent you a PM regarding a related item.

Your thread is on buildthreads.com FYI
http://www.build-threads.co...d-fiero-355-replica/

Nice work

No posts in over a month and a half?!!! I hope all is well.

Thanks for the concern but I've just been overrun with yard and property maintenance, as well as getting ready to host a huge 50th wedding anniversary party for the in-laws. I'll be back on it in a week or so when all the hubbub is over.

Well it's back to the grindstone after having taken a 2 month sabbatical. With the flywheel and clutch ready to install I was seriously tempted to pull the cradle out and git'er done, but practicality prevailed. I knew I needed to get a bunch of measurements for things like where the engine torque struts would meet up with the new cross-car brace; how much I would need to recess the rear bumper bar; how much trunk I would need to sacrifice; and how I might layout an exhaust system. All of this was best accomplished with the cradle still mounted to the frame.

One other thing I needed to check out (but have been dreading) was to mock up Don's rear clip (PFF'er 355Fiero). I'm sure I've mentioned somewhere earlier in this thread that Don "sold" his F355 body to me and Yarmouth Fiero last fall. It was a God-send because even though it is an IFG kit similar to the one I had bought, Don had already done many of the modifications to it to make it a better kit. He separated the rockers from the door bottoms, reshaped and lowered all four wheel arches, realigned the belt line, and on and on.

The only trouble with having reshaped and lowered the wheel arches is that I had based my rear suspension's track width on my un-modified body, which is about 2" narrower. I've known this would be a bit of a problem and hence my reluctance until now to mount his rear quarters on my car. Don's rear quarters were designed for the convertible so yesterday I took the plunge and cut a few notches in the fiberglass to give clearance to my hard top's C-pillars. Then with a little help from my wife, we lifted the quarters into place:



After a little jiggling we were able to get it centered on the chassis left-and-right and fore-and-aft. I couldn't have been happier with the nice newly curved arches and how well they were centered over my wheels from the side view. You did a lot of great work Don.



But, as expected the fenders were wider than my original body so my wheels looked a little sunken in. That's much, much easier to address than had they stuck too far out!



You can't simply cut the original arches off the panel, lower them an inch straight down, then fill the gap with fiberglass or Bondo. That would change the entire curvature of the fender flare. The way to do it properly is the way Don did it... he cut the fender lip off and moved it outboard and downwards along the original slope of the fender line, then filled the gap. That gives a continuous contour from the base of the sail panel to the fender lip:



So, despite my intent to have perfectly offset wheels, I now realize I'll need to buy wheel spacers for the rear to get the tires where I want them. That's a small price to pay considering all the work I avoided by not having to modify my original body panels only to arrive at the same conclusion.



I measured the needed decrease in offset and it appeared that 25 mm's per side was about right. If I were to order new wheels, they would have to be 18" x 9.0" ET 20's rather than ET 45's. So I borrowed a wheel spacer from my 308 kit to mock it up and confirm the new look:



It was bang on:



Here's the top view:



Then I stepped back to get an overall view of the rear end and was finally able to appreciate how far I'd come. If you scroll back to page 1 and see what the wheel gaps were back then, I'm ecstatic with the static stance, the available wheel travel, and the (theoretical) dynamics of the system.

Looks great.



Bob

Blooz;

The rear clip looks pretty darn good on your car..... Glad it worked out. You could sand some of the worst the bondo down with some 80 grit and paint it all one colour of primer and it would really stand out and you can see where any more adjustments might need to be made.

Great work and looking forward to more updates.

Cheers
Don

[This message has been edited by 355Fiero (edited 07-14-2014).]

quote Originally posted by Bloozberry: Well it's back to the grindstone after having taken a 2 month sabbatical. With the flywheel and clutch ready to install I was seriously tempted to pull the cradle out and git'er done, but practicality prevailed. I knew I needed to get a bunch of measurements for things like where the engine torque struts would meet up with the new cross-car brace; how much I would need to recess the rear bumper bar; how much trunk I would need to sacrifice; and how I might layout an exhaust system. All of this was best accomplished with the cradle still mounted to the frame. One other thing I needed to check out (but have been dreading) was to mock up Don's rear clip (PFF'er 355Fiero). I'm sure I've mentioned somewhere earlier in this thread that Don "sold" his F355 body to me and Yarmouth Fiero last fall. It was a God-send because even though it is an IFG kit similar to the one I had bought, Don had already done many of the modifications to it to make it a better kit. He separated the rockers from the door bottoms, reshaped and lowered all four wheel arches, realigned the belt line, and on and on. The only trouble with having reshaped and lowered the wheel arches is that I had based my rear suspension's track width on my un-modified body, which is about 2" narrower. I've known this would be a bit of a problem and hence my reluctance until now to mount his rear quarters on my car. Don's rear quarters were designed for the convertible so yesterday I took the plunge and cut a few notches in the fiberglass to give clearance to my hard top's C-pillars. Then with a little help from my wife, we lifted the quarters into place: After a little jiggling we were able to get it centered on the chassis left-and-right and fore-and-aft. I couldn't have been happier with the nice newly curved arches and how well they were centered over my wheels from the side view. You did a lot of great work Don. But, as expected the fenders were wider than my original body so my wheels looked a little sunken in. That's much, much easier to address than had they stuck too far out! You can't simply cut the original arches off the panel, lower them an inch straight down, then fill the gap with fiberglass or Bondo. That would change the entire curvature of the fender flare. The way to do it properly is the way Don did it... he cut the fender lip off and moved it outboard and downwards along the original slope of the fender line, then filled the gap. That gives a continuous contour from the base of the sail panel to the fender lip:

Awesomeness !!

Do you guys or don have any pictures of the process ? Going to have to do something similar on my choptop.

[This message has been edited by exoticse (edited 07-14-2014).]