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914World.com _ 914World Garage _ Why is twin/multiple disc clutch better??

Posted by: Mueller Jun 19 2003, 05:07 PM

What am I missing here?

The friction material and contact surface area of the 1st disc and the flywheel remain the same (or are made smaller) when going to a twin or mutiple disc setup

Is the gain from a smaller diameter clutch/pressure plate and more clamping force??

I thought I had read that Porsche is considering twin disc clutches in some of the newer cars, something about being able to upshift while under power??

Hayden or anyone else, care to enlighten us??
(or maybe just me since everyone else might "get-it" )

Posted by: TimT Jun 19 2003, 05:24 PM

With twin discs you get double the contact area.

You can reduce the diameter of the rotating mass (clutch/pp/flywheel) and reduce the MOI (moment of inertia) and your engine with rev more freely, and some of the hp stored in the flywheel may be available to accelerate the car more quickly. You dont gain hp, but hp is free to accelerate the car instead of the rotating mass ( flywheel)

Some manufacturers (tilton, quartermaster,coleman) make up for the area lost by reducing the diameter of the rotating mass by doubling,or even quadrupling the number of driven discs.

Rev a car with a dual mass flywheel someday, takes forever to settle back to idle, then rev a car with a light flywheel/clutch package returns to idle quickly.

The car is more responsive with a light flywheel and clutch. I think Tilton songle plate clutches are good to almost 500 ft/lbs, but you cannot slip them at all..

Lighter is Faster

Posted by: Brad Roberts Jun 19 2003, 05:37 PM

Tim nailed it.

I just called and ordered the complete setup from WEVO earlier today for the silver tube car. It will get the new 3.2 short stroke engine and WEVO 915 before the end of summer.

Next phone call will be to Paul Guard to order all custom ratios and a main shaft that allows the use of any gears. The plan will be to go full straight cut gears this winter.

B

Posted by: kdfoust Jun 19 2003, 05:55 PM

Well not to clarify but to add to the confusion...

I acutually thought that the Porsche twin clutch setup was because the tranny had two main shafts and an "extra" set of gears which allows preselection of a gear. To shift you just engage one clutch and disengage the other. But, I think having four pedals on the floor will be confusing...

Have fun,
Kevin

Posted by: Mueller Jun 19 2003, 05:59 PM

I still don't see how the surface area is increased at the flywheel and clutch mating surface???

Posted by: Brad Roberts Jun 19 2003, 06:07 PM

Mike.. the clutch has two (twin disc setup) steel friction area's. You get 2-3-4 disc setups. It will have multiple friction discs and multiple steel discs..

Have you never had a automatic tranny apart ?? The clutch packs in a automatic tranny are almost idetical to the Tilton setup.

B

Posted by: Brad Roberts Jun 19 2003, 06:14 PM

In between each steel plate is a friction plate.

B

Posted by: Mueller Jun 19 2003, 06:22 PM

Now I get it

http://www.tiltonracing.com/pdfs/winnerschoice/pg26metclutches.pdf

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Posted by: Brad Roberts Jun 19 2003, 06:23 PM

Here you go.. better shot of the parts.

B

Posted by: Brad Roberts Jun 19 2003, 06:23 PM

You can see the "steels" and the "frictions".

B

Posted by: Mueller Jun 19 2003, 06:24 PM

I didn't know the "friction or "floater" plate was there to transmit the power......

Learn something new everyday

Posted by: Mueller Jun 19 2003, 06:25 PM

Thanks for not reaching thru your monitor and choking me !!!! LOL

Posted by: Brad Roberts Jun 19 2003, 06:26 PM

Do you have a new cover for the roller bearings ?? You changed your avatar and added another step or two.

B

Posted by: TimT Jun 19 2003, 06:27 PM

You stall the car alot getting to learn how to drive with these clutches LOL

Posted by: seanery Jun 19 2003, 06:28 PM

y?
is it more like an on/off switch?

Posted by: Brad Roberts Jun 19 2003, 06:33 PM

It is basically a on/off switch. You have to spin the tires to get the car to move forward.

Here is what happens when you "bounce" the car on the clutch thru the pits. (I figured out why we broke the Ford 9 inch in the Winston Cup car)

B

Posted by: Mueller Jun 19 2003, 06:35 PM

I "had" a rubber cover for the thrust bearings...looked great on Pro/E, came out like cr@p when made, they don't protect like I want them to.

The silicon will have to do until I get back from "vacation" in two weeks.........

Does Tilton make organic clutches for the multiple disc units??
(I saw the 8.5" units for Imports)

Would the Multi-disc clutches work better with an organic friction material??

Posted by: Mueller Jun 19 2003, 06:36 PM

DAMN.....that takes a lot of force to break one of those nodular iron carriers!!!!

Posted by: Brad Roberts Jun 19 2003, 06:39 PM

Try and drive 750hp that spins to 9k RPM thru the pits with a Tilton 7inch multi disc clutch. I couldnt figure out why/how we broke it. I just figured it out. Once you get the car rolling with the Tilton.. the car will tend to "bounce" or buck as it moves forward until you push in the clutch and match the speed of the engine with the slow movemnet forward of the car. Its hard to describe.. but you can tell which cars have the small clutches in the pits..

Combine this bucking with 3400 pounds of Winston Cup car and it play's hell on the 3rd member (pic above)

B

Posted by: TimT Jun 19 2003, 06:43 PM

We have a 900+ hp turbo 935 clone in our group, the car only weighs 2100 but getting it rolling is a pain in the balls...... g-50 trans with 1st good to about 60 the car doesnt make power at all till on boost..

lots of clutch discs go into that car (RSR clutch not Tilton)

QUOTE

Its hard to describe.. but you can tell which cars have the small clutches in the pits..

yeap

Posted by: Mueller Jun 19 2003, 06:44 PM

I guess you found the weak link in the system

Posted by: Brad Roberts Jun 19 2003, 06:47 PM

The cup cars are bitchin..

Lift throttle upshifts without the clutch at 9kRPM down the straight at Thunderhill. Nothing quite like it.

I was actually sad to see it go.

B

Posted by: Brad Roberts Jun 19 2003, 06:50 PM

Oh.. basically you couldnt tell that he was lifting throttle to make the upshift. Its not like he was coming off the throttle completely to make the upshift. Maybe 300-400 rpm "lift"

B

Posted by: drew365 Jun 19 2003, 07:13 PM

Brad; could you post contact info for Paul Guard, I'd like to inquire about his limited slip units.

Posted by: TMorr Jun 19 2003, 10:04 PM

Mike,

Looks like you understand the multiplate clutch now....
In answer to the organic plates from Tilton, No, they don't.
We are having to work with Sachs to get organic friction surfaces. They have what we want, a 200mm Ø organic, single plate, 6.0lbs clutch that can handle about 330 lbs/ft torque. This is pretty much a direct replacement for the soon to be NLA available 911 Aluminum covers.
I could not find a domestic clutch company (name company) that could supply what we wanted, so at this stage our new HiPo street clutch will be based on the above unit in conjunction with a unique aluminum / steel composite flywheel.

Regards

Hayden PTBT

Posted by: seanery Jun 19 2003, 10:43 PM

Hayden,

I don't know if anyone has said this publicly to you, but it's pretty cool that you are a member here, and post like you do.

Thanks A lot!

by the way, love your shifter!

Posted by: MJHanna Jun 20 2003, 07:15 AM

tilton flywheel has very little weight

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Posted by: MJHanna Jun 20 2003, 07:16 AM

this is a "rally" pack on a 3.0L

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Posted by: MJHanna Jun 20 2003, 07:17 AM

tilton throw-out bearing on a G-50 with a tilton starter

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Posted by: Dave_Darling Jun 20 2003, 11:42 AM

Contact for Paul Guard: gears (at) gte (dot-net).

The little blurb I saw recently sounded like Porsche was considering using the same transmission that Audi is putting into some of their cars. The Audi one has two input shafts and two gear stacks, one for even gears and one for odd gears. (It's an auto-manual box.) The controller pre-selects the next gear for you, then when either you tell it to shift or it decides you need to shift, it will disengage the one clutch and engage the other one. Shifts faster than Luhr or Massen or Tazio Nuvolari himself!

Note that this is rather different from the multiple-plate clutch setup that we've seen such a good explanation of...

--DD
(Ugly problem here at work so I'm avoiding it. )

Posted by: need4speed Jun 20 2003, 05:41 PM

Speaking of neat drive-train stuff;

How about NO clutch?
Buddy of mine just bought a Nissan Murano SUV -
But it's got a 3.5l engine with a Continuously Variable Transmission.
(It's actually an Altima with a body that looks like a truck).

It's like kind of a belt drive (apparently, it's really a fine-mesh-chain of some sort, made of a really hard alloy), that runs between two cone-shaped pullies, and a computer pushes the cones back and forth to adjust the drive ratio continuously as the vehicle accelerates. It's very weird driving it, you step on the gas, and the engine revs up, but you never hear or feel a shift as the car just keeps accelerating. Apparently, it does away with all the losses and problems of automatic transmissions. It was hard to tell though, in a truck. I just don't know how they keep that belt from slipping when the engine starts to get serious. It's a pretty torquey engine.

Since it's front-wheel drive, I climbed underneath to get a look at it to see if it could be bolted onto a rear or mid engine setup.

Didn't look very promising tho.