Clutch tech

[Airspeed]

Found a pic of my latest set-up which holded 465hp (I launch soft I must admit, but car is very heavy):

[Shag55]

Those were the std thin disks, right? Also you drove the streets with this set up?

[Airspeed]

Yes and yes. Car never rides on a trailer as you know, more trackday (circuit) then drag. Very quick shifting possible due to very light clutch rotating mass (thin = light), which the synchros like.
Thicker disks are better for drag racing though as they cope better with heat. Drag starts = clutch slip on full torque (launch) = mucho heat.
Nothing new ^^ , its just finding something that does it all which is the hardest. Amount of compromise also relates to the investment (think carbon clutches).

[Shag55]

Yes, multi carbon clutches = $5k

[Mike Lawless]

Airspeed, that clutch pictured is the one I was seriously considering. If I wasn't already over-budget on my build, I'd just go with it. They are available as single, double and triple disc, with different type friction discs available too. The spec sheet seems it indicate that a dual disk version will fit comfortably in a VW bellhousing.

It's not counterweighted like the RLR Rev6 is though.

Once I get my turbo combo somewhat sorted, it'll be time to look at clutch options.

This is a very good thread with good discussion!

[bedjo78]

great topic. learned a  lot

[MeXX]

Hi

This is final call to all the:

Top Racers
Big Guns
Big Dogs
&
Big Turbos
&
Bottle Babies

Let us know what U are running

What works and what sucks

MeXX

[dangerous]

I have always been a fan of 3-puck discs.

When I ran a supercharged engine,
I went low 10s with a single 200mm 3-puck and real 2700lb diafragm.

The pressure plate was a home made floater style deal with steel materials,
and used a generic replacement diafragm.
Car was about 1830 with the single blower.

When I stepped up to two blowers,
I went dual 3-pucks with an extra floater, and reduced the diameter to 180mm.
This worked very well. Car was 1870lbs by then and ran 9's at 147mph(236km/h)

Now I am back playing normally aspirated,
I took out one floater and disc and it works great.

I get 40 good runs from the discs, and then it begins to lose sixty ET if I dont take some shim out.
Last time I went 50 passes, since I was to lazy to pull the engine.

Our dragracing sanctioning body does not allow "made from iron" pressure plates once you go 10.99 or quicker.
While I have made various floaters and flywheels over the years,
I am still using the very same diafragm and cover from nearly 20 years ago.

[Frallan]

This is funny...
I have never liked three puck. Sorry Dangerous. I still like you.

My first ever experience was a Gene Berg setup with welded counterweighted 78 mm crank.
The flywheel was wedgemated.
A green 2700 Kennedy
....and the three puck.
The year was 1977.
First raced it in 1978
- Race one....problem with camshafts.
- Race two....slipping clutch and distorted flywheel.
Did we learn the hard way on how to separate the two...Wedgemate is tough.
- Race three...now with a super flat flywheel, pressure plate disassmbeled and ground flat, three puck slightly surfaced. All OK
- Race four...same thing. All slipping and distorted.
The coming years, whenever we tried the three puck after all new different recommnedations, no go. Back in went the fiber disc and we went quicker and quicker.
This has formed my life for loving fiber discs.

I had a six puck Porsche setup (with a 915 four speed gearbox) in my supercharged street beetle. It held well BUT it would just not slip.
One day with a friend in downtown Malmö Sweden, my friend warned me to be careful as a police car was parked and seemed to check out the stop discipline.
I got so nervous that my start rpm flew way too high and the left foot dropped.........well you can guess what happened.
I was told to be an idiot and stupid and maybe a bit Macho by my friend. Now I was lucky as the police did nothing.
Soon after, I replaced the six puck with an orginal Porsche fiber disc and we lived together all happily after!

[dangerous]

That is OK Frallan, we all can have different experiences!
But I can add that I never liked thhose 3-arm style pressure plates,
and the 2700lb one I had only had 1600lbs!

[bedjo78]

I used to use this clutch on NA . Now we install turbo and change to Pauter flywheel with kennedy double discs with stage 4 PP




picture hosting


Current stage


free photo hosting

[Turbo_Rich]

Not sure if this info is much use as I'm using a 915 gearbox and turbo type 4 though normal UK street treads. I switched to a 4 puck Helix cerametallic disc with standard 911 clutch cover and it works well for me and 250ft/lbs torque. I guess the limiting factor is the tyres on launch but it holds the power well so far.

[Fast54]

Well, I have always used Kennedy PP and "Black Magic" single disc with good results. I ran 9.18@248km and 900kg with stage 1 and 9.04@255km and 950kg with stage 2.
The only problem I had was that the disc cracks after one season. I did not have any clutch management.

/Håkan

[richie]

Also flywheel material is super important,some are too hard,thats were a single floater set up gains, you can make the floater from a softer material and just replace it regularly, with a double disc I have found the floater needs to be as thick as possible to stop distortion, most of what is offered off the shelf are to thin really and need regular re surfacing or replacing if you slip them at all

cheers richie

[Bernard Newbury]

Also flywheel material is super important,some are too hard,thats were a single floater set up gains, you can make the floater from a softer material and just replace it regularly, with a double disc I have found the floater needs to be as thick as possible to stop distortion, most of what is offered off the shelf are to thin really and need regular re surfacing or replacing if you slip them at all

cheers richie

I have this situation now, but always thought floaters to be a consumable item anyway. The discs, flywheel, and top plate all good but floater needs replacing but I consider it a good trade after a couple of seasons with clutch problems (disc pads coming off, pressurre plate breaking into 2 pieces, broken pressure plate springs breaking etc etc). I now run a RLR twin disc. 

[MeXX]

I have this situation now, but always thought floaters to be a consumable item anyway. The discs, flywheel, and top plate all good but floater needs replacing

Hi Berni

In a twin disc application the floater is the most stressed part and has to handle an enormous amount of heat, so material and thickness is very important. The latest evolution are the sintered floater which can handle the heat and have the right friction coefficient.

Sintered floater
[ Attachment: You are not allowed to view attachments ]


Bronce floater
[ Attachment: You are not allowed to view attachments ]


Slotted floater
[ Attachment: You are not allowed to view attachments ]

I like this slotted floaters which really help to avoid distortion


MeXX

[Shag55]

Nice! Slotted is a good idea. Also one could possibly be made like a rotor with grooves.

[Tekken]

First thing I did was to buy a data logger so I could see what really happens, I have learned a lot from it too.In the previous pan/torsion bar car I used single disc J&G and black magic with no clutch management.The biggest problem was the floater getting distorted, the result was change in the clutch slip.If we where lucky we got like two runs before the slip started to change, best 60-fot with that car was 1.32.Pulling the engine like 2-3 times in a weekend changing floater and adjusting break away is'nt that fun..

Now I use double disc Kennedy and hydraulic clutch management,has been a good experience so far.Not that expensive and pretty much maintenance free.We can also see that the slip is a lot more consistent now.I got some grease on the discs from the flywheel needle bearing at the first test and tune session this year (my fault.. ) , after that not touched it the rest of the season.Launch with 2 bars+ of boost, car weight race ready with driver is 852kg.Best 60-fot with new car is 1.206

Here you have a video shot from the side at SCC this year,our first run at the event.Driver sleeping when shifting to second  ,but you can see the clutch doing the job at the launch.
<a href="http://www.youtube.com/v/Rv6kogU7uks" target="_blank">http://www.youtube.com/v/Rv6kogU7uks</a>

[Fastbrit]

Kennedy 2400lb (or was it 2700? Can't remember) pressure plate, Scat four-puck solid feramic disc. Same clutch three seasons, no breakages. Prior to that, used a three-puck. Never did get my head round all this modern clutch technology... but then I gues my car was so slow and underpowered it didn't need it! 

[MeXX]

Hi

Took allot longer than i thought but the prototype of my new clutch is ready now.

The problem:
[ Attachment: You are not allowed to view attachments ]
The old clutch
[ Attachment: You are not allowed to view attachments ]
The solution the new centrifugal enhanced pressure plate
[ Attachment: You are not allowed to view attachments ]
There are 12 counterweights to enhance pressure when RPM goes up.
[ Attachment: You are not allowed to view attachments ]

MeXX

[dangerous]

Wow that is a lot of work there Mexxi!
Should have pickup now!

[MeXX]

Wow that is a lot of work there Mexxi!
Should have pickup now!

Dear Dave

To be honest if the clutch works like expected
1.35 60 feet should be possible which would bring me in the 8 th easily

MeXX

[Frallan]

Very nice! 
No disc positioned in between the pressure plate and the flywheel in that picture, right?

[MeXX]

Very nice! 
No disc positioned in between the pressure plate and the flywheel in that picture, right?

Right


MeXX

[Shag55]

Very nice Mexx! What disks with that one?

[MeXX]

Very nice Mexx! What disks with that one?

Dear Shag

The disc I will run will definitely be a Black Magic 5135 compound which is the harder and more aggressive.
The floater plates will be sintered bronce which are in design at the moment.

MeXX

[Ragtop]

Man thats pure art!

[MeXX]

Man thats pure art!

Dear Johan

THX for the kind words
Would be great to know more about your clutch setup;
maybe some pix 

MeXX

[MeXX]

Hi

Here is a pix from the different counterweights I will use:
[ Attachment: You are not allowed to view attachments ]

They are lasered from hardened steel and weight 4,2 g and 7,1 g (counterweight only)
Base setup will be:

Base pressure 4000N with 12 light counterweights

328Nm @ 4000 RPM
366Nm @ 5000 RPM
412Nm @ 6000 RPM
466Nm @ 7000 RPM
529Nm @ 8000 RPM
564Nm @ 8500 RPM


Base pressure 4000N with 12 heavy counterweights

370Nm @ 4000 RPM
430Nm @ 5000 RPM
505Nm @ 6000 RPM
593Nm @ 7000 RPM
695Nm @ 8000 RPM
750Nm @ 8500 RPM

As there are 12 ones any combination of light and heavy counterweights like  12, 2+10, 3+9, 4+8, 6+6, 8+4, 9+3, 10+2, 12;
will be possible to adjust the clutch

MeXX

[modnrod]

I've used them on bikes, but for a car that is a very elegant solution! Well done Mexx!
How much clearance will you expect to have between the opposite end of the counterweight (the one not on the disc) and the outer edge of the flywheel recess?
Will you still have enough clutch slip on launch, or will you have to lower the launch revs and initial clutch plate preload to allow it to "give" a bit out the hole?