Real Fiero Tech

Datsun1973 wrote:Will, what clearance issues were you having with the 7.25" setup? With this all installed the HTOB to clutch clearance is .208 or right in the middle of the window of .170 to .230 that tilton recomends. Or are you speaking of radial clearance to some part of the 282 interfering with the larger 7.25" diameter? I know the clutch housing bolts come dang close (>.100") to the transmission bellhousing internal guts.

Titlon recomends using a 5/8" Master with their HTOB's and I have one of their 5.5:1 floor mounted pedal assemblies. All this comes out to a 34lb pedal load and 4" pedal travel. This is based on a release load of 750lbs and a release travel of .180" and free play of .200. However since the tilton HTOB's don't use return springs the .200 free play can be negated.

I laid out the clearance problems in this post: phpBB/viewtopic.php?f=3&t=3376&start=41
The bolts that hold the diaphragm spring to the pressure plate cover go through from the inside, have nuts on the outside and will contact the exterior of the output shaft inner bearing boss inside the bellhousing of the 282.

The thickness limit for the button ends up being something like .450, which is VERY thin for that sort of part.

The dual layshaft nature of the F23 means that the output shaft inner bearing boss does not protrude into the bellhousing as much. This improves clutch packaging with that transmission tremendously.

Well it FITS!!!

The transmission and engine are all assembled and I'm currently fabbing up the mounts for the F23 in the cradle. Once done I should be able to bleed the clutch hydraulics, adjust the pedal stop and see how much pedal force is required and if I have the engagement stack height properly setup.

Excellent! Will you post pictures of your mounts once you finish?

Sure will, although I'm heading out on vacation tomorrow so it may be a bit. I am going to try and get the one mount done tonight. For some reason the engine mount I was using for the front of the engine on my 3.4 DOHC mockup engine didn't quite fit the LZ4 so I had to redo that extensively. The block casting is definately NOT the same. The F23 is a completely different animal too.

Ok well finally got a chance to actually get the new Tilton 5/8" MC installed after getting it from Jegs on 2 month Backorder! Took a full bottle of fluid to bleed all the air but the clutch disenages perfectly! The engine isn't running yet but it should work great, and no puddles under the car too.

The clutch force is about 30-45 lbs (hard to tell). It's definately stiff but not overly so. The clutch in my 370z is just a little bit softer. However, the engagement distance is SMALL, as in, this thing is an on/off switch and not so much a clutch. I am hoping that with such a low rotating mass flywheel that the F23 won't grenade during the ensuing clutch dumps. I am starting to hope the 305 series rear tires won't hook up too much and snap axles.

Just had the opportunity to weigh a QuarterMaster 7.25" dual disk assembly--V6 flywheel, pressure plate, disks and floater.

I never did weigh my stuff. Then again I am sure it's fairly close to what Tilton publishes for the 5.5 rally clutch. I posted a link to this thread over on Old Europe. Needless to say I didn't get much interest. Although i did find about five or six other posts on how there are no quality clutches available for this transmission.

Will, the 5.5 had some a small engagement diameter that forced me to use the 38mm tilton bearing. The stock F23 bearing also interfered with the clutch housing. What is your contact diameter with the 7.25" clutch? I am wondering if the stock F23 HTOB would work with the 7.25" Clutch. Getting the HTOB from tilton to work with the F23 was a LARGE part of the engineering and cost for my setup.

Here are some pics of the Quartermaster clutch that Steven (alltrbo) bought a little while ago.









The flywheel is specifically for the FWD application (I @$$ume Super Duty 4, but also happens to fit V6).

Datsun1973 wrote: Will, the 5.5 had some a small engagement diameter that forced me to use the 38mm tilton bearing. The stock F23 bearing also interfered with the clutch housing. What is your contact diameter with the 7.25" clutch? I am wondering if the stock F23 HTOB would work with the 7.25" Clutch. Getting the HTOB from tilton to work with the F23 was a LARGE part of the engineering and cost for my setup.

Should be able to grab this info over the weekend.

The clutch is only assembled loosely in the picture. I found out when I put it back together that when it's tightened down the diaphragm spring is flat.

From that picture I am guessing a stock F23 HTOB will work. The 5.5 housing is so small in diameter that the HTOB contacted the housing.

That's what you get for trying to be too cool...

NOTE: This post was originally created as a new topic on 2015-01-22 but was merged on 2015-01-23 with the "Tilton Clutch" thread

What's the lightest / lowest moment of inertia clutch assembly I can mate with a 60-degree V6 and an F23 Getrag and hold up to 350 ft-lbs of torque?

I saw a button flywheel posted in the for sale section a loonngggg time ago. Does anyone still make those?

Let's not talk about budget yet. I would prefer an off-the-shelf solution but customizations are acceptable.

I've used many of the standard clutch combinations; stock pressure plate with Clutchnet dual-friction disc, Clutchnet pressure plate and disc, Spec Stage 2, Spec Stage 3... I've also used both steel and aluminum flyhweels... the aluminum flyhweel drops about 7 pounds off the system but the pressure plate and clutch are still quite heavy.

I want to move away from the large pressure plate + single disc clutch system to something with a lower moment of intertia and less overall weight.

This is only going to be used at the track.

Tilton or Quartermaster.

QM used to make a V6/60 button style flywheel with the stock ring gear. I've seen one in person, but they're out of production and rare. Also, I'm not entirely sure they work with the 282.

Here's my thread on installing a Tilton clutch on the Northstar: phpBB/viewtopic.php?f=3&t=3376
All of it should be applicable to the 60 degree.

Everything you get that's based on the 9 1/8" disk will be about 14# for the pressure plate and another 2 or so for the disk. With the stock 14# flywheel, that's a 30# clutch/flywheel assembly. With an 8# aluminum flywheel, that's about 24# for the assembly.

With a well designed button, you should be able to keep the assembly weight for a 7.25" dual disk unit to 12# or so.

If you want to go really crazy, mount a small diameter ring gear to the pressure plate and use a reverse rotation stater on the side of the transmission, then you can even get rid of the large diameter stock ring gear and a sizeable chunk of the MOI.

Follow up... I think the F23's bellhousing is deeper than the 282's, at least according to Indy's thread on Old Europe. So if you are using with an F23 but NOT a 282, then the packaging constraints on the button can be relaxed.

http://www.fiero.com/forum/Forum2/HTML/133518.html

Datsun1973's 5.5" Tilton clutch info will be very helpful to me, since that's the same transmission and engine architecture.

I found a good deal on a 7.25" Tilton assembly; it just has the wrong splines. If the pressure plate and springs are correct, I think it will still be a good deal even if I need new splines (or new discs if Tilton won't redo the splines). It's not as light as the 5.5", but I can't pass up a good deal when the performance is so close!

Next I need to look into the button flywheel + flexplate option.

I'm going to merge this with the old Tilton clutch thread..

For something approaching a full weight Fiero, even with the F23's aggressive first gear, the 5.5" clutch is pretty small.

The thermal mass of the 7.25" helps with a heavier car like the Fiero.

The Dark Side of Will wrote:For something approaching a full weight Fiero, even with the F23's aggressive first gear, the 5.5" clutch is pretty small.

The thermal mass of the 7.25" helps with a heavier car like the Fiero.

I'm not sure my Fiero is going to be full weight for much longer... and the 3.5 first with a 4.41 final drive should be pretty easy to get going. Anyway, I still bought the 7.25" because it was an excellent deal and it should still be a massive improvement over the stock style system.

Anyone need a couple lightly used cerametallic discs with NSX splines?

Also, there's some discussion of lightweight clutches in this thread: http://forums.corner-carvers.com/showthread.php?t=21540

Some dude on Old Europe is actually doing this: http://www.fiero.com/forum/Forum2/HTML/139771.html

His solution to the clearance problem was to use flatheads on the inner ring of screws that would interfere with the output shaft bearing boss. I'm not sure I'd do that until and unless I had a unit in my hands to evaluate. I had planned to flip those screws around. Tilton delivers them with the heads on the inside and nuts on the outside. They gain some clearance by flipping over so that the heads are on the outside. Conterboring the hex heads or installing flat heads results in more clearance. Apparently it's enough more that he was comfortable stacking a button flywheel on top of a flexplate, which is something that wouldn't work if the screws were done the way I had planned on doing them.