Clutch replacement price check
01-06-2019, 11:09 PM
#61
+1, this:
and always want the parking brake to be the primary 'holder'
!["02996ttx50's Avatar](data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 50 50'><circle class='avatar-circle-default' fill='%23759d7b' cx='25px' cy='25px' r='20px'></circle><text class='avatar-text-default' x='49%' y='53%' fill='white' text-anchor='middle' alignment-baseline='middle'>"</text></svg>)
01-07-2019, 07:00 PM
#64
Rennlist Member
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.
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.
01-07-2019, 07:47 PM
#65
Three Wheelin'
fresh pentosin flush/bleed keeps clutch pick up consistent, when ever pick up begins to feel weird a quick flush/bleed and alls good. along with the electrical jump I have no desire to update. I prefer the feel of the assist I can heel toe much quicker.
01-07-2019, 08:06 PM
#66
RL Community Team
Rennlist Member
Rennlist Member
Obviously results may vary, but with my stock accumulator, and without the clutch switch modification, I haven't experienced "...tons of variance in clutch feel..." (reference pfbz's post you quoted). As a matter of fact, outside the standard clutch pedal stiffness when depressing the clutch on start when the accumulator went bad, I haven't had any variance in clutch feel at all.
01-07-2019, 10:05 PM
#68
OUCH! glad i sent my porsche tech pal an xmas gift. sheesh.
back to the clutch in/out "switch" the whole point of disconnecting it ( jumping it ) is that doing so will eliminate accumulator issues. it's the stress on that toilet plunger when the motor is off, and no hyd fluid is pressurized that causes premature failure of it. which is of course connected to the slave leading to... jumping the switch does nothing to the "feel" of startup or clutch "action" as once the motor is running, the system feels the same as it always had.
i have mine disconnected for years now. the only way i can "ruin" the accumulator is by regularly engaging the clutch with engine off. ( which is no longer necessary lol )
back to the clutch in/out "switch" the whole point of disconnecting it ( jumping it ) is that doing so will eliminate accumulator issues. it's the stress on that toilet plunger when the motor is off, and no hyd fluid is pressurized that causes premature failure of it. which is of course connected to the slave leading to... jumping the switch does nothing to the "feel" of startup or clutch "action" as once the motor is running, the system feels the same as it always had.
i have mine disconnected for years now. the only way i can "ruin" the accumulator is by regularly engaging the clutch with engine off. ( which is no longer necessary lol )
03-29-2022, 02:18 AM
#69
once again, thank Kevin @ UMW for providing this info in another thread which i finally located lol.. https://rennlist.com/forums/996-turb...45-00-a-2.html
"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".
"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".
“Copper (47 ppm) is still the hot topic for your Porsche. On the plus side, copper hasn't increased much since
the last sample taken in July of 2021, so brass/bronze wear isn't getting rapidly worse. That said,
brass/bronze parts like wrist pin/rocker arm bushings are still wearing more than they should be, even if
they're wearing in a stable manner, so copper at least warrants continued monitoring. All the other metals
look good, which is a bit reassuring, since we'd expect one or more other metals to also read high if there
were a major issue.”
Obviously Blackstone tech isn’t familiar with the clutch set up and safety switch system on my 996 Turbo and he’s mentioned other possible causes, but as you mentioned the #1 main bearing thrust surface is the likely culprit, can this (along with higher copper level in Oil analysis ) be detrimental to engine in the long run without any other values elevated?
Last edited by jmrosen; 03-29-2022 at 02:23 AM.
03-29-2022, 09:21 AM
#70
03-31-2022, 11:36 AM
#71
Three Wheelin'
