Advice on 5.5” Race clutch Options

[BlueRidge914]

I vintage race a 2.0L six single plug narrow body 914, and for years used a Patrick Motorsport “901” style flywheel and Centerforce 215mm clutch package. I would like to go to their 5.5” clutch and ultralight flywheel, and I understand all the advantages, but I don’t know if that’s offset by lurching around the paddock and in and out of my trailer, and shorter clutch life. Will I forget about that on the track?
Thanks for the advice,
Gavin

[brant]

They are hard to get rolling
The clutch is an on-off switch.
So it’s typical to kill the motor when you try to get rolling

But Once it’s on track you will never notice that.
No lurching
No problems

I’m also a 2.0/6 with a narrow bodied car

[stownsen914]

I've driven a 7.25" clutch. The small clutch + super light flywheel takes a little getting used to, but for a race car it's not that big a deal.

And yes, once you get out of the paddock you won't notice it aside from the faster revving and easy shifting.

[SirAndy]

Make sure you have enough clamping force on the pressure plate.

Not sure what your torque numbers are but when i went to a puck style racing clutch i had problems with it slipping under hard acceleration.
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[BlueRidge914]

Thank you all for the useful advice.
And to Brant , whose build I followed from the beginning with inspiration when I was last on this forum. Coming up for 25yrs on my car - not getting faster, but still having fun.
Gavin

[Cracker]

Learn to drive it correctly and you will be fine. If you get the proper equipment you will have no slippage as Andy is saying...this car runs a 7.25" triple and is rated for 1,200 horsepower.

[GregAmy]

...this car runs a 7.25" triple and is rated for 1,200 horsepower.

That is an absolute beauty of work.

But I hope it's a project in progress, as that's not NEAR enough rollcage for that application.

Smaller/lighter clutches for lower rotational momentum (faster acceleration) versus sufficient clamping force (for no slipping). Pick your compromise.

I'd suggest leaning toward the latter. We're not F1 here, and we're not going to win any money and chicks and job opportunities doing this. And dealing with a slipping clutch on race weekends sucks.

[brant]

These clutches work with multiple plates
Although they are small in diameter there does not to be any slip
They can handle any HP with the right stack of clutch plates
It’s not a compromise scenario

[GregAmy]

Then pick how fast you want to spend.

I've been doing this racing-thing long enough (over a third of a century) to recognize that the juice sometimes just ain't worth the squeeze. Especially when we're talking about historics/vintage racing where your speed is not limited by prep regs, rather by how much you want to spend, and there's no prize at the end except for pride. Plus, there's always someone whose wallet is a whole lot more prouder than mine.

But other wallets clearly disagree with mine...

[brant]

Then pick how fast you want to spend.

I've been doing this racing-thing long enough (over a third of a century) to recognize that the juice sometimes just ain't worth the squeeze. Especially when we're talking about historics/vintage racing where your speed is not limited by prep regs, rather by how much you want to spend, and there's no prize at the end except for pride. Plus, there's always someone whose wallet is a whole lot more prouder than mine.

But other wallets clearly disagree with mine...

Very true
May not change any of the fun
But we all spend money trying different things
Sometimes it’s tires or a different build of the motor
None will win cash prize money
This is just something else to play with

[BlueRidge914]

With slightly more modest power output than the example above , I should be good to go with 5.5” single.
To the gearbox I years ago added the PMS intermediate plate, side cover, and mainshaft bearing retainer, Tangerine’s shift linkage and console, and J West’s shifter. This after learning the expensive way that eventually the mainshaft starts to dance in the stock intermediate plate and then it all seizes up mid race. More durable now, but how I still envy friends who can shift fast. Don’t know what else can be done!
Gavin

[stownsen914]

With slightly more modest power output than the example above , I should be good to go with 5.5” single.

If you use a Tilton clutch, I recall there are different clutch spring options, the heaviest of which gives something like 250 ft-lbs slip threshold. Sounds like plenty for a 2.0. One thing to keep in mind is that these tiny clutches wear quickly. I recall asking Tilton about this once, and was told that even for lower hp applications like formula V or maybe it was formula Ford, that a single plate 5.5" wears pretty quickly and doesn't hold up for long. Might be worth asking.

[brant]

What happens is that they warp
The more you slip them, the more heat
The plates warp
And there are specs for measuring the tolerances

I’ve only replaced mine 1 time from wear

[stownsen914]

What happens is that they warp
The more you slip them, the more heat
The plates warp
And there are specs for measuring the tolerances

I’ve only replaced mine 1 time from wear

True. They overheat easily and don't tolerate slippage like a stock clutch. Probably they "wear out" more from that, than from thinning.