And if you run that bellhousing with the starter in the V8 position you need the bigger flywheel anyway. Just get a V8 flywheel drilled for the slant crank and run a V8 clutch. 10,000 RPM Racing can build you a nice light flywheel and clutch.

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Joshua

Josh has got it...

Personally, I don't like hauling around extra weight, rotating or not.

Lou

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Home of Slant6-powered fun machines since 1988

Too bad my midsection doesn't listen to me on this particular point...

Oh yeah, and someone please get one of these clutches so we can pull the trigger on the group buy...

I wouldn't mind running a 9" clutch, but I believe that no matter what I do the clutch will be my limiting factor and a 10" clutch will be less of a limit than the 9" would be.

I've talked to spec about a 10" clutch and a stage 2 kit for my R154 is only good for 372 ft/lbs. Shaker223 has dyno'ed 345 ft/lbs at the rear tires and run 104 mph in the 1/4, on a stock slant with 340 valve springs, a 4 bbl and a stock GN turbo. These numbers (conservatively) put him about 300 hp and 400 ft/lbs, already exceeding the capacity of the clutch I can buy. Remember, this is with an rpm limiting stock cam and a small valved stock head, imagine what more rpm and some port work would do.

If I go with a 9" clutch, I don't believe a turbo would be worth it as I would have to dial it back so far that an N/A setup would make more sense.

As it is, I don't think I am going to be able to max out a turbo setup with a manual trans, but I would really like to use what I can.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

The clutch disc in my car is for a SHO Taurus.....which weighs considerably more than the Valaint. The weight of the car being moved is more important than its torque output.......


A 10" is not better if it blows yer feet off.....

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Yeah....Im the one who destroyed this rare, vintage automobile.....

Seems reasonable, but the guy I talked to at SPEC seemed to cared more about the torque characteristics of the motor than the weight of the car.

Either way, my bet is that in 3000-3300 # cars, one with 400 ft/#’s is going to need a better clutch than one with 300 ft/#s.


According to MSN.com, a ’94 SHO weighs 3395 #’s and made 222 ft/#’s of torque. Doesn't your Valiant weight something like 3200#?

There are 4 things that are used to calculate the capacity of a clutch; number of friction surfaces (N), co-efficient of friction of the disk (u), cover clamping load (F), and radius of gyration (Rg).

Capacity = (NuF)Rg.

So, the capacity of the clutch cover needs to be thought about. You might be using a disk from a 3400# car that made 222 ft/#’s of torque, but if the pressure plate has only 3/4 of the clamping force of the Taurus one, you don’t have the capacity that the stock SHO clutch has.

And, if the disk is organic, then the only difference your SHO disk makes is that it fits the input splines of transmission and is the right diameter. It doesn’t increase the torque capacity of the clutch, or the weight limit of the car. If it is Kevlar or ceramic, then you’ve got yourself an upgrade.
?

I’m sorry, but your statement of the obvious has me perplexed.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

My car weighs 400 lbs less than the SHO and makes similar torque. The disc is a McLeod ceramic upgrade for the SHO......

If I had a 12000 lb vehicle with 222ft/lb torque I would need a 12" clutch....its about weight or mass.

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I'm not sure what you mean about a 10" clutch blowing up. If I blow a SFI approved 10" clutch to bits then I could do the same to a 9"

But we're not talking about a tow vehicle here, and spec rated the clutch for 300 ft/#s in gmader's car which probably doesn't weight any more than your Valiant. If weight was the defining factor, spec would rate the clutch for vehicle weight, not torque.

Yes, a 12000 lb vehicle needs a bigger clutch for the same torque, but the application is completely different.

Yes, weight is probably a factor (can't ignore physics), but it must not be the defining factor in this application.

Perhaps mass is eliminated as a variable as the application is for a 3000# car, any 3000# car, which reduces the variables down to how much torque is produced. It also makes sense (per physics) that if two different forces are applied to two equal masses, the greater force will require a stronger connection to avoid failure.

I agree that a big motor in a light car may not break parts like the same motor in a heavier car, but I'm talking about a bigger motor in the same car.

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'15 Chrysler 200S V6
'74 Duster 360, factory 4 speed car

I mean there are Factory 10" clutches that blow up.

I also mean that when you are flywheel limited to a 9.25/9.5 or 10" clutch you might not always find the 10" better.

The McLeod site lists 10" mopar clutches that "are not for performance applications"

When I chose driveline components I always consider the GVW of the donor first. That led me to successfully use a 4 cyl 5 speed . My car was 500lbs lighter than the donor. I can use a V6 Explorer rear axle with impunity.


Most guys overbuild stuff.......

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Yeah....Im the one who destroyed this rare, vintage automobile.....

I have wandered about this "10' clutch blowing up deal. Its been my expeirance that the cover of the pressure plate has little to do with a clutch blowing. They do the same thing in the big block set ups using a cover that is slightly cut out to allow for the bigger ring disk in the pressure plate. From our expeirance of racing 4 speed cars its always came down to what the ring/plate was made out of instead of the design of the cover. A cast ring will blow no matter what cover is on it and no cover will hold it if it does blow. This bothers me that they are even making what is considered a performance clutch and not using a steel ring in it instead of a ductil cast ring. Although I would guess a 10" clutch will blow before a 9" simply becuase of a heavier cast ring. With a steel ring it would not blow.

I am wanting to change my 68 Cuda over to 4 speed, but I will not buy a clutch with a cast ring no matter how much torque they rate it to. For now the 4 speed will set on the bench. I have lost exploding clutchs at 7800 rpm on a shift, believe me, I Will Not Run A CAST RING, of any size.


Jess

I believe ductile iron is a different alloy and treatment procedure than standard "gray" cast iron.

Lou

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Home of Slant6-powered fun machines since 1988

I think your right Dart270, but I dont know for sure what the other cast rings are made of ( gray iron, or Ductil) . I feel pretty sure they may already be Ductil iron in most cases becuase of the nature of the application. But I honestly dont know for sure. If not Ductil should be better, enough I dont know.



Jess

Would this kevlar Spec. Clutch be able to with-stand a 150shot of nitrous linked to a 3speed. or is it still going to blow? Would it be tranny failure, Clutch failure or Flywheel failure?

Clutch explosions will be more launch RPM determined than HP level. You might just cause the clutch to slip if the nitrous hit is high.

Lou

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Home of Slant6-powered fun machines since 1988