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"Public service announcement. I recommend that "long term" enthusiast remove the clutch/start switch. This is a 5 minute job, with a male to male spade. In a pinch you can use a spare fuse. Remove the two wires and connect them to the two spade terminals (fuse)..
This mod will reduce the wear on the #1 main bearing thrust surface. Increase copper from oil samples points to this area. This mod reduces the excessive pressure on start up, by reducing the pressure from the slave/clutch."
also. GT2 ROB has a pic of the clutch switch under the dash but i was unable to link it for some reason. its in that thread for a "how to".
Replaced my clutch PP, clutch disc, throw out bearing, flywheel bolts, pressure plate bolts, crankshaft seal for just under $3200 in Northern CA (Bay Area) at an Indy Shop back in Janary of 2016. I was quoted 11 hours of work.
It's likely obvious to most if not all, but just to be clear... The improvement in clutch consistency with the switch mod on a stock clutch slave setup is from never depressing the clutch when the engine isn't running. The mod just makes that possible.
In stock form:
1) When the engine isn't running, there is no pressure from the power steering pump, which doubles as a clutch assist hydraulic pump.
2) The accumulator tries to compensate by retaining pressure from the last time the engine was running.
3) Depressing the clutch pre-start (required with the interlock) depletes pressure from the accumulator.
4) Without consistent pressure from the accumulator, clutch feel varies...
5) Couple the above with frequent accumulator pressure leaks anyway, and you have wonky, varying feel.
By jumpering the lower clutch switch, you simply remove the need to depress the clutch to start the car. Combine this with the discipline to never depress the clutch pre-start, and to always check for neutral before start, and you can greatly improve the consistancy, if not the actual feel, of the stock clutch hydraulics...
On my car, 60K miles on the original clutch. I had tons of variance in clutch feel before the mod. Probably needed a new accumulator. But doing the switch mod gave the clutch setup new life, and as I said, I used it for another year and was happy enough until it really started to go... Once I pulled the transmission, it was clear the slave was now leaking as well, so instead of replacing the stock slave and stock accumulator, I spent the extra $500 or so to do the full, factory style (drill, tap, new shift fork) conversion.
By the way, much thanks to Powdrhound and Cervelli Technical Services for guiding me through the process.
It's likely obvious to most if not all, but just to be clear... The improvement in clutch consistency with the switch mod on a stock clutch slave setup is from never depressing the clutch when the engine isn't running. The mod just makes that possible.
In stock form:
1) When the engine isn't running, there is no pressure from the power steering pump, which doubles as a clutch assist hydraulic pump.
2) The accumulator tries to compensate by retaining pressure from the last time the engine was running.
3) Depressing the clutch pre-start (required with the interlock) depletes pressure from the accumulator.
4) Without consistent pressure from the accumulator, clutch feel varies...
5) Couple the above with frequent accumulator pressure leaks anyway, and you have wonky, varying feel.
By jumpering the lower clutch switch, you simply remove the need to depress the clutch to start the car. Combine this with the discipline to never depress the clutch pre-start, and to always check for neutral before start, and you can greatly improve the consistancy, if not the actual feel, of the stock clutch hydraulics...
On my car, 60K miles on the original clutch. I had tons of variance in clutch feel before the mod. Probably needed a new accumulator. But doing the switch mod gave the clutch setup new life, and as I said, I used it for another year and was happy enough until it really started to go... Once I pulled the transmission, it was clear the slave was now leaking as well, so instead of replacing the stock slave and stock accumulator, I spent the extra $500 or so to do the full, factory style (drill, tap, new shift fork) conversion.
By the way, much thanks to Powdrhound and Cervelli Technical Services for guiding me through the process.
Great seeing you and your car at the shop Paul. I knew you'd love the GT2 clutch mod. It simply changes the car for the better all around and changes the driving experience for the better.
Last edited by powdrhound; 01-04-2019 at 04:35 PM.
"Public service announcement. I recommend that "long term" enthusiast remove the clutch/start switch. This is a 5 minute job, with a male to male spade. In a pinch you can use a spare fuse. Remove the two wires and connect them to the two spade terminals (fuse)..
This mod will reduce the wear on the #1 main bearing thrust surface. Increase copper from oil samples points to this area. This mod reduces the excessive pressure on start up, by reducing the pressure from the slave/clutch."
also. GT2 ROB has a pic of the clutch switch under the dash but i was unable to link it for some reason. its in that thread for a "how to".
I don't recall on my 6tt, but on my C2 this mod (clutch interlock) has disabled my cruise control. No big deal, but if I ever road trip the tt, i'll probably add a switch for starting, then cruising.
I don't recall on my 6tt, but on my C2 this mod (clutch interlock) has disabled my cruise control.
Bypassing the lower clutch switch (the one shown above) does NOT affect cruise control on the 996 turbo... Cruise control uses the upper clutch switch, which you are not modifying.
Bypassing the lower clutch switch (the one shown above) does NOT affect cruise control on the 996 turbo... Cruise control uses the upper clutch switch, which you are not modifying.
Gotcha. Maybe I did the upper on the C2, and it allows clutchless starts also. I know I did the lower on the 6TT, just haven't used the cruise since.
Thanks!
Gotcha. Maybe I did the upper on the C2, and it allows clutchless starts also. I know I did the lower on the 6TT, just haven't used the cruise since.
Thanks!
That might be the case...
I think the lower switch is closes on clutch pedal is fully engaged while the upper switch closes at slightest press of clutch.
You would want cruise control to kick off with even the slightest push of clutch, but want the starter interlock to require full push.
Yes, on the clutch pedal arm. Pretty easy to spot the switch if you stick your head down in the footwell and look up.
Just take two male spade connectors and a short piece of wire to make a jumper. Pull both female wires off the switch, jumper them together, zip tie out of the way. Removing the air duct gives a bit more room to work if it's too tight down there.
^thanks for that info, pfbz. Good pics. So simple.
I know my accumulator is bad now. I planned on replacing it OEM sometime this year. Would it be recommended that this jumpering occur after that?
Guess what I'm asking, is there any problems to doing it now when the accumulator is bad--because the slave could be bad, too? I can't tell if the slave is bad and never see fluid leaking from anywhere.
01-03-2019, 02:02 PM
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