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Saftey of 2.4 flywheel when not used as a friction surface?

MrBill

fige=500Dollar Mistake
300+ Club
Joined
Jan 1, 2006
Location
Southern Maryland
Long story short: I got Eamonn's Getrag setup from his 760. It's a twin disk quartermaster setup that uses the 60-2 flexplate as a starter ring.

He said the twin disc setup was driveable but not really DD-worthy.

My goal is to replace the flexplate with a flywheel. Naturally I'd like a 8.5 with the holes drilled, but they're not cheap. This will give me the weight to drive the car normally on the street but still have that nice holding ability.

I feel a 2.4 9inch flywheel is probably the cheapest option. Then I'd just stack the quartermaster setup on top of the flywheel. Without those spacers on the flexplate, I'd gamble it isn't much thicker, and there looks to be plenty of room.

So...the question is, if using the 2.4 flywheel as simply a flywheel, will it explode at 7500 rpm? My thought is no, but what do I know?
 
So the problem is you want more weight? What about the fact that the twin disc is an on off button?

Cheap? I'll sell my getrag quartermaster twin disc setup never used right now 1200.. You can buy flat stock flywheel with 2.4 holes 300.

I remember RSI used flat flywheel and had holes drilled in it and bolted twin disc right to that. You want more rotating mass? You don't need to hold 750 horsepowers?

Other then that I got johnv billet steel flywheel and I got TVR billet steel flywheel that takes 850r clutch but will only clear m90 bellhousing.. If race car and 7500 then I'd not use dog dish, but they use them in boats aq171's and no clutch touches them..

With the quartermaster twin disc, I thought on the back of the crankshaft you put flexplate first, then little quartermaster steel button flywheel on top of that no spacers at all. Am I wrong? Maybe you could put flat flywheel with 2.4 holes if needed then steel button quatermaster on top of that. Either way, longer bolts needed. Not sure, I'd like to sell my quartermaster setup myself...

I can bust out flat flywheel and quartermaster and see if it's possible if you want.
 
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So I have the twin disc stuff already. It can't have many miles on it, but I got it, the driveshaft, all the swap parts plus a Getrag 265 for a good price (significantly less than $1200)

I also have an 8.5 inch flywheel drilled for 60-2 and 240mm saab pressure plate. I also have a johnv flywheel without the 60-2 I could use for mockup. I don't wish to use either of these for the final install.

I think the thick spacer behind the flexplate is a requirement - maybe for correct spacing for VR? not sure. The thin washer-ish thing for the bolts isn't used I don't think. What I'm a bit fuzzy on is how the unit is centered. If it uses the same step that a flywheel would use, I'm out of luck. I was thinking I could use something like a custom hub centering ring to make it happen.

I understand the twin disc has a harshish engagement, but the flex plate Eamonn had on the car weighs....5lbs? I think a 20-30 lb flywheel would do wonders.
 
I run a twin disc on my DD currently. The flywheel is a full diameter billet steel unit that's about 15lbs. I originally ran it with the quartermaster discs and ultra stiff diaphragm spring they put in all those clutches and it was on the ragged edge of livable on a daily basis but definitely not pleasant in traffic. I've since had the pressure plate rebuilt with a softer spring and replaced the discs with full face organic ones, the clutch is awesome now. Sorta stiff pedal but not unreasonable and really good engagement with no chatter at all. Got the rebuild done and discs from Powertrain Technology.

The extra mass on the flywheel made the insane clutch usable. If you swap to organic discs and soften up the spring I think the button flywheel you already have should work fine.
 
Rebuild was $105 and clutch pack was $286. The discs were special order for a w58 so they were a little more than normal iirc.
 
Okay I did some homework today. I can't say the measurements are exact, but the 'piece of wood under the calipers' trick is close enough to make me think this will work.

So here's what I'm presented with:


Removing the flexplate, I find this spacer. It measures 7.47mm


Using the 'piece of wood under the plate' method, I roughly measure the flexplate at 3.59mm


Using that same procedure I measured my 8.5 inch flywheel. 10.10mm this is about 1mm THINNER than the measurement I got for the flexplate/spacer combination


So why not mock it up. Everything clears here, nothing is hitting, which is a good thing. There is space behind the flywheel, only the mating surface of the pp/clutch assembly touches the 8.5 inch flywheel.
The only current concern is the centering of the assembly. It has nothing to center on, and as far as I can tell, had nothing to center on with just a flexplate. It doesn't have far to move, but it's not like it's sitting on a machined lip like the flywheel is. Not sure if this is okay.


Nut doesn't clear going this way:


But it does this way :) :






Thoughts?
 
Some thoughts:
You could have something turned that goes into the pilot bearing bore on the crank, and then supports the ID of the QM flywheel. You'd just need to find either a small OD bearing for this all to work out, and that bearing would then sit in the adapter/centering thingie.
It could even be used just for setup, like a clutch alignment tool. Bolt the Flexplate and the QM flywheel down and then remove the alignment tool. Install stock pilot bearing and go go go.
 
So why not mock it up. Everything clears here, nothing is hitting, which is a good thing. There is space behind the flywheel, only the mating surface of the pp/clutch assembly touches the 8.5 inch flywheel.
The only current concern is the centering of the assembly. It has nothing to center on, and as far as I can tell, had nothing to center on with just a flexplate. It doesn't have far to move, but it's not like it's sitting on a machined lip like the flywheel is. Not sure if this is okay.

Not having a centering feature is bad juju. The clutch needs to be dead nuts on the input shaft or you run the risk of wearing the discs out very quickly, ruining the input shaft bearing on the trans, or nuking the splines on the input shaft and discs. Tilton calls for a .010" out-of-concentricity allowable on their clutches and the same is applicable to your quartermaster unit. .010" is only about the thickness of three pieces of printer paper, so not much wiggle room. You could conceivably center the flywheel with a dial test indicator and careful snugging of the bolts but i wouldn't recommend it.

Nut doesn't clear going this way:

But it does this way :)

FWIW, the bolts are supposed to be installed from the back of the flywheel.
 
the weight of the clutch isn't the largest driving factor in pleasant-ness of drive-ability.


I can assure you, the twin disc sh<v>it stack I got from SPEC for my evo had plenty of weight on it and didn't drive worth half a fu<v>ck. Easily 10lbs OVER oem clutch/fw weight and drove 10 times worse. A lighter setup *usually* will drive better as long as you don't have some hee-man pressure plate with subergrabber(tm) frictions and unsprung discs... those things work great once a car is moving (i.e. on the race track), but they're not that much fun when you gotta get the car moving.

Additional weight in this application will not resolve the on-off nature of that setup.
 
I'm not sure what Eamon did regarding centering the whole shooting match, but theres apparently a number of manufacturers and transmissions floating around that do not require nor use such things anymore. (though, tbh, I dunno if bmw is one of them, IJS). You would be well served to get one should it require it.
 
Well **** you then.

I guess my goal will be to use the flexplate and see how ****ty it really is. I'm tempted to look into different clutches and pressure plates as Alex has indicated, but my inner cheapskate says '**** it and run it.' I'm only a clutch disc and throwout bearing away from using the saab stuff I suppose. I it sucks I could just 'save' this for a day where I have a redblock that needs this kind of equipment.
 
So I'm clearly over my head here.

Are all these 7.25 inch discs the same? Does a tilton clutch disk = spec = quartermaster?

Can I call anyone and ask for a 7.25 inch for the getrag?

Also, I read it's a 10 spline x 29mm - anyone care to confirm that?
 
for the most part, the 7.25 stuff is all cloned from QM (or maybe it's tilton, I don't recall), but there may be other nuances to keep in mind. stack height, floater width, etc.
 
What throw out bearing you using? I'm bought the tilton one for BMW. Has the rounded part where it contacts the fingers of the pressure plate.

62-021-502x502_zps470d68ef.jpg


9pounder1.jpg


9pounder2.jpg


flywheel2-4.jpg
 
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The to bearing should be the same. I had that discussion with Eamonn and he told me about the rounded bearing that was necessary.

I guess I'll shoot QM an email tomorrow to discuss options for organic discs.
If it's expensive, I guess I'll sell and use the Saab setup.
 
I bought a BMW 240mm clutch disc off Ebay for 50 it was for z3? The convertible bimmer. I got a couple 240mm saab areo johnV flywheels myself. But next up do the freeze plug keepers and put the 16 head on the block then I'll make caddy to put motor on so I can take it off engine stand so I can bolt flywheel and tranny to it.


P1010112_zps37d4f1b2.jpg
 
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