7 1\2" mult-disc vs. std single disc clutch

Tim Kay · 05-17-05, 08:36 PM

Would like some input for the following:

1) Is the now popular 7 1/2" multi-disc clutch prefered over the standard (240mm?) disc.

2) Is Kennedy Eng. the main supplier of adapters, clutches, pressure plates for GT40 setups?

3) Any typical clutch, pressure plate specs?

Application is street 70%, track 30%, 500+ ft\lb torque, g50, alum. flywheel

Bill Bayard · 05-17-05, 09:11 PM

Tim,

Kennedy builds racing clutch discs "in house", to various different specs. They are THE guys to talk to, if you're looking for a track/street clutch setup.

The 240mm clutch is pretty damn tough.

I believe that the stock PP is 2200 lbs.

Kennedy has one available that's 3300 lbs.

Better start getting the left leg pumped up!

Bill

Russ Noble · 05-18-05, 02:49 AM

I think the pedal pressure of the 7" multiplate will be miles less.Someone with one may care to comment. Also, if you've spent the money on an aluminium flywheel, why hang a heavy large diameter clutch on it? Just a thought.

Regards

Tim Kay · 05-18-05, 03:25 AM

[ QUOTE ]
Better start getting the left leg pumped up!

[/ QUOTE ] Bill, I'll start doing double sets of left side lunges at the gym [img]/ubbthreads/images/graemlins/crazy.gif[/img] [img]/ubbthreads/images/graemlins/grin.gif[/img]

[ QUOTE ]
.........if you've spent the money on an aluminium flywheel, why hang a heavy large diameter clutch on it?

[/ QUOTE ] Russ, the very reason for my inquiry. Like to hear from someone using a 7 1/2"

Julian West · 05-18-05, 07:11 AM

Tim,

here's my 2c!

I see no reason why you couldn't 'adjust' the pedal pressure by changing the MC size.

FWIW I've fitted a 184mm twin plate clutch. It will be noisy & harsh in use & probably have a short lifespan. however I've saved 35lbs in weight over the standard flywheel & clutch!

Part of the reason the 184mm clutch is so harsh is due to the fact it has not got a sprung centre. During my research I couldn't find a 184mm clutch with a sprung centre (with an adequate torque spec).

I'm told that twin organic plate clutches are a bit more forgiving than the cerametallic I'm using.

Re the release mech, have you considered using a concentric release? this mech works much better than a 'fork' & has an added advantage of keeping the slave cylinder well away from the exhaust manifold.

I'm a little way off driving my car so I can't tell you how it drives yet!! [img]/ubbthreads/images/graemlins/grin.gif[/img]
Hope this helps!

Julian West · 05-18-05, 07:12 AM

concentric release mech...

Tim Kay · 05-18-05, 01:22 PM

Julian,

It was under a 'search' that I saw your flywheel and clutch in another thread prior to starting this one. I was hoping to hear from you, thanks.

From what little I have researched so far, the 2 disc is supposed to be pretty tame, but a multi-three disc is rather harsh for street. It's like a light switch, on or off.

I can see you have an AP clutch, who made the flywheel?

Tim

Tim Kay · 05-18-05, 02:33 PM

Potential hurdles I see coming are:

1) Kennedy says an aluminum flywheel wheel won't hold up to their pressure plate

2) Supposedly, no one makes a "pull" type pressure plate (porshce) in the mult-disc style - 7 1/2" (Julian, is that a ZF in your pics?)

Lee · 05-18-05, 03:54 PM

Tim
I believe Julian is using the Renault, but I could be wrong.
I also looked at that avenue. GD cars in UK fit a concentric release and triple plate clutch to the G50 for their T70. But they use the Chevy engine. On the chevy the starter is mounted to the engine so easy to get a starter to mount to engage the flywheel with ring gear near the engine. Problem is that with the Ford the starter mounts on the Porsche gearbox, so you need to find a high torque starter for the Porsche with the long reach of the standard LATE Turbo gearbox (91 onwards) (no-one does one) or mount the ring gear standing off from the flywheel like on the 88 model (more flywheel machining so possible without too much hassle).
Then you need to sort out the bellhousing to fit the concentric clutch, and find the relevant clutch pack and a flywheel to suit which you can also machine for the stand off ring gear.
In the end I went with the standard set up from GT40 Australia, which I am sure will work straight off the shelf, using mainly standard Porsche components, with GT40 Australia's lightweight flywheel and adaptor plate. If I run into problems after a few track days, then I can look at changing it then, rather than having another headache to worry about while I am trying to get the car through it's SVA test. Remaber the old adage 'KISS'. Keep It Simple, Stupid or words to that effect.

Julian West · 05-18-05, 03:56 PM

Tim,

My flywheel is nitrided steel. I'm using a R21 UN-1 trans with the Quaife conversion.

The bellhousing is R30, but had to be machined to accept the release bearing and the nose of the starter motor. Also, the input shaft runs in a thin steel tube & this had to be shortened.

I'll pm you with details of the manufacturer, altho it may be difficult for you to get the parts made 'across the pond'.

Tim Kay · 05-18-05, 07:44 PM

Thanks Lee & Julian,

Turns out the "hitch in my get-a-long" will be the Porsche offset ring gear, as Lee decribed above.

Tilton makes a nice 2 disc 7.25" clutch with the concentric hydraulic slave cylinder, very similar to Julian's setup. They can make a 'custom - one off' flywheel albeit quite costly [img]/ubbthreads/images/graemlins/smirk.gif[/img]

Tim Kay · 05-19-05, 05:19 PM

[ QUOTE ]
....using mainly standard Porsche components, with GT40 Australia's lightweight flywheel and adaptor plate.

[/ QUOTE ]
Lee, anymore specifics on flywheel(porsche ring gear?), presure plate and disc (240mm?)

BTW, does your starter mount on the trans or did DRB's adapter plate allow for engine side mounting of the starter?