Hydraulic push or clutch fork pull decision

[Chris]

Right so i have two directions i can go with my setup.
I have a Porsche G50/52 transaxle which as default is a pull style clutch utilising external hydraulic slave and internal clutch fork and release bearing etc.

I am going to be running a Kennedy adaptor and flywheel etc but have two options for clutches.

Option 1:
Kennedy organic twin plate retaining original Porsche style pull fitment.

Option 2:
Spec will modify their organic twin plate for an internal hydraulic release bearing to convert to a push setup.

Both clutches are more than adequate for my torque etc, what i was wondering was from all of your experience would you rather run an internal hydraulic release bearing or the regular clutch fork pull setup? I am aware that the ford v8 was designed for a push style clutch rather than a pull.
Cost wise it is the same, if not slightly cheaper for the hydraulic push due to me needing to buy the clutch forks etc. Spec can machine the Kennedy flywheel to suit the changes.

What would you choose and why?

Chris

 

[Neil]

How many posts have I seen on the internet from people who lament their choice of an internal hydraulic release bearing? LOTS! Those make replacing a leaking cylinder a nightmare, .... not even mentioning the increased difficulty of bleeding the clutch line. Your choice, though.

 

[Chris]

How many posts have I seen on the internet from people who lament their choice of an internal hydraulic release bearing? LOTS! Those make replacing a leaking cylinder a nightmare, .... not even mentioning the increased difficulty of bleeding the clutch line. Your choice, though.

This was my main concern that it is harder to work on if there is a problem but less potential fail points compared to a full mechanical system?
If i do have issues with the bearing its being supplied from the US also which is not where the car is going to be . . . .

At the end of the day they should both give a decent pedal feel, the twin plate will be much easier on the leg and gearbox than a higher stage single plate, i'm just after the most reliable and easiest to set up option. For access naturally the slave is a winner hands down there.

 

[Chris]

Just seen that this discussion has been had a few times on FFcars etc and i think ill stay external slave you werent kidding about how many complain about leaking bearings!

 

[Neil]

The choice of clutch disk is a little complicated. A clutch with an organic friction disk is the most common but for higher torque capacity, a twin disk is a good choice. There are other high friction disk materials that keep a single plate clutch in the running, however. I originally used a Sachs Porsche clutch disk in my car. It had about 520 BHP at the time and the adapter & transaxle is a KEP and a Porsche G50/01 from an '88/'89 Carerra. It was fine but when I rebuilt my engine last time it bumped up to around 600 BHP so I thought it was time to give it a clutch that would handle the increased power without question. I replaced the Sachs organic disk with a KEP bronze metallic puck disk and it has worked out very well. My car is fairly light, 1950 lbs, so that helps.

The KEP metallic disk is different from most others with non-organic disks- it has a spring hub and the friction pucks have "marcel" instead of being solidly mounted to the disk. Marcel is a wavy spring that makes the clutch engagement smooth; without marcel the clutch is rather sudden- it grabs. The spring hub also helps the smooth clutch engagement.

Multi-disk clutches do allow a softer pedal. One thing I remember about the multi- plate clutch in Bob Peckhams McLaren M8C Can-Am car- when the clutch was pushed in driving through the paddock, it rattled. Loudly.

 

[Chris]

The choice of clutch disk is a little complicated. A clutch with an organic friction disk is the most common but for higher torque capacity, a twin disk is a good choice. There are other high friction disk materials that keep a single plate clutch in the running, however. I originally used a Sachs Porsche clutch disk in my car. It had about 520 BHP at the time and the adapter & transaxle is a KEP and a Porsche G50/01 from an '88/'89 Carerra. It was fine but when I rebuilt my engine last time it bumped up to around 600 BHP so I thought it was time to give it a clutch that would handle the increased power without question. I replaced the Sachs organic disk with a KEP bronze metallic puck disk and it has worked out very well. My car is fairly light, 1950 lbs, so that helps.

The KEP metallic disk is different from most others with non-organic disks- it has a spring hub and the friction pucks have "marcel" instead of being solidly mounted to the disk. Marcel is a wavy spring that makes the clutch engagement smooth; without marcel the clutch is rather sudden- it grabs. The spring hub also helps the smooth clutch engagement.

Multi-disk clutches do allow a softer pedal. One thing I remember about the multi- plate clutch in Bob Peckhams McLaren M8C Can-Am car- when the clutch was pushed in driving through the paddock, it rattled. Loudly.

Kennedy's organic twins are rated to 700lbft which is more than enough for me (likely 550 tops). Id like to stick with organic because of the stock pedal like engagement. Their stage 2 single they rate for 640ftlb, am unsure of the plate type but likely metallic as you mention above.

I had an organic twin on my 600hp gtr which had a light but noticeable rattle upon depression and the triple plate in my other gtr actually had less of one. I quite like it to be honest #racecar haha. I remember when a garage wanted to buy the car but thought the clutch was broken

 

[Neil]

"I remember when a garage wanted to buy the car but thought the clutch was broken ..."

 

[flatchat(Chris)]

You'll need an adapter plate, flywheel and pilot bearing + assorted fastener pak - these are custom made bits that suit your application
the rest is off the shelf Porsche stuff - clutch plate, clutch pressure plate, ring gear, starter, release fork and slave cyl etc
Streetable and good for ~600 hp
Run with this combo and you'll be fine
After 20+ years exp. this is the best starting point till you know better