Putting 8 holes on a 6 hole flywheel

I've used Tilton's, APs and Quartermaster 7" clutches and I wouldn't want to use any of them on the street... but it it'll rev quick!

That's not true. I've run OEM style clutches on race cars revving to 8,000 RPM with no problem. Of course, if there's no stock or aftermarket flywheel readily available for your motor, then it doesn't matter much, other than usability on the street; you're still going to have to have a flywheel made.

Peter

I'd contact Craig Taylor at Taylor Racing in Plano TX. He's engineering drivetrains for everything from formula cars to Bonneville LSR cars. Good guy to talk to, first-rate work, fair prices.

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||>> here are the pix: ||>> dissassembled clutch ||>>

||>> close ups of both... I need the 8 hole pattern on the 6 hole ||>> flywheel ||>>

||>> I have a miller 135 mig welder, and countless drill sand airtools at ||>> my disposal... what do you eple reccomend? ||>>

||>> Jay ||>

||Steve, yours is the second reply I have seen that states a dividing ||head or index is required. ||There is another option. If you draw it in AutoCAD, you can pick off ||the X-Y coordinates of each hole. If you make the center the 0,0 ||point, then you can locate the flywheel with a centering gauge and ||move to each hole position. A DRO is a big help, here. ||As to the old holes, can't they be welded up and faced off? || ||Jay, this is definitely a job for a machine shop. || || ||Ron Thompson ||Was On the Beautiful Mississippi Gulf Coast, ||Now On the Beautiful Florida Space Coast, right beside the Kennedy Space Center, USA || ||

Rex in Fort Worth

Hi Jay. I make flywheels for racing applications, and what you need to do isn't that hard.

First, cast iron is a bad material for a racing flywheel, steel or aluminium is much better. Aluminium is stronger, pound for pound, than steel, steel doesn't need to have a friction surface installed. Both can be very good choices.

I use 6061-T6 for my flywheels, and I use 1040 steel for the friction surface disc. I make it .25" thick, hold it with 12 10-32 screws and locking bolts, or with 12 10-24 screws loctited in if the flywheel is 1/2" thick at that point - some are, some arent't. The tilton/quartermaster

I normally use stock ring gears, shrunk on to the OD of the flywheel with .015" interference per 10" of flywheel OD. I heat the ring gear to .025" greater diameter, put it on, and let it cool. the ring gear almost always have a little wave in them, so I then tap or press them to a firm fit onto the locating step. I hold them in place with three button head 10-24 screws as they can walk a bit with engine vibration.

A rule of thumb for Tilton style clutches is 250 hp 250 Ft.lbs of torque per disc, with a lot of latitude depending on the clutch cover/spring installed. You may find that a triple is overkill. The downside is they do not tolerate slipping at all. You can kill a clutch putting a car on a trailer one time. The discs have a ear tolerance, they start out about ..100" thick and you just measure them with a micrometer to see how worn they are. Quartermaster, at least, sells fabric discs designed for use on rally cars, they are a lot more like a street clutch. A big benefit of a metalic clutch is that they tolerate a lot of oil on them before they start to slip.

I make flywheels and sell them for about $400 US for a typical application, so this shouldn't be a big deal. I budget 10 hours and $100 material not including ring gear.

Brian

How long do the fabric discs last? What material is used on the discs? Would they be durable on a street car?

Peter

I would say that yes they would be good for a street car. I don't know details, I just saw them in a catalog or on a web site. The interesting thing is that I actually own such a disc...it came on a 1967 race motor that was still very original. It was a Porsche Carrera clutch and disc, identical in almost all ways to a tilton, but with the thicker fabric disc. The disc itself was solid, no little springs or anything.

Brian

Is this motor out of a Carrera 6 or 8, or out of a 911 based car? I always thought that the Carrera 6 was one of the better looking race cars around...

Peter

locking nuts ??

or with 12 10-24 screws loctited in if the flywheel is 1/2"

So I take it you have countersunk screws with the heads in the steel ring, just under the surface, and the threads in the aluminium yes ?

Dave Baker - Puma Race Engines

Hi dave. Yes, they are locking nuts - jet nuts, in fact, with countersunk head screws. I use those where the guy wants a very light flywheel, on the order of 6 - 7 pounds or so for a Ford 1600 type application. If a slightly heavier flywheel is used, then I can thread the aluminium and use the countersunk head screws. I also use a light press fit on the insert, if the design allows that. If a stock type clutch is used, then the insert is faced off flush and you need to put the locating dowels in, etc.

I've seen extremely light flywheels with no insert using a hard anodised friction face, and I've heard of plasma sprayed finishes. My field is vintage cars, so I mostly see BMC and early Ford motors, althought I did make one for a genuine Austin Healey 100 Sebring last year. Lathe swing was barely enough to hold the blank in the four jaw. I don't always go for the lightest flywheel possible because these guys usually like the motor to idle, and a little bit of flywheel helps that a lot.

Brian

this sounds like good advice. Doesn't a flywheel actually fail from the center outwards when it explodes? I'm not near my old textbooks, but I seem to recall this is the case. Can anyone confirm?

Seeing as how the is the very area in question, I think it's worth looking into.

D.