Clutch pedal feeling weird occasionally.

rabbitstew · 29 Mar 2018

As a bit of background, I use my 997 turbo as my daily, ive done nearly 30,000 miles in it over the last 2 years and its left on my drive in all weathers.

Ive not had any issues at all, but a few weeks back, and again this morning, the clutch pedal has felt really weird first thing in the morning. Now it was quite cold, damp and frosty this morning and id left the car parked on my front lawn - so not ideal conditions.

The car started immediately, but the clutch pedal felt really weird. When you pushed it down, there was about 2 inches of completely free movement until you could feel it starting to work and then when it did, it felt a lot lighter than normal. It made no difference to engaging or changing gear as you drove along, but just felt really strange.

Once the car was warmed up, after about 10/15miles of driving, the clutch pedal returned back to normal. i.e. no free movement and feeling how it normally feels.

I wonder if something is sticking somewhere due to the weather? Anyone else experienced this?

Nomar · 29 Mar 2018

I experienced something similar with my 997 C2 before my clutch started to slip and subsequently replaced at 70k miles, so it may be worn clutch like mine.

Poker2009 · 29 Mar 2018

Different symptoms, but my clutch pedal vibrated, and then didn't last much longer, before it started slipping. I was also advised (will never know rightly or wrongly) that if I didn't change my flywheel it might judder and I wouldn't like the way it felt, so I changed that aswell. This was at 40k miles.

Your mileage since it was last changed should give you an indicator (~40k-70k miles maybe??).

I would get it looked at least and changed if necessary, and possibly save your flywheel.

Phil 997 · 29 Mar 2018

just changed the clutch on my gen2 it felt heavy not light then started to slip. my feeling is its the clutch I would get it at least checked out before it costs you a flywheel as well . it maybe something else but at least you can then discount the clutch as the issue. :thumb: :thumb:

deMort · 29 Mar 2018

I dont have a set answer for you but i thought i would do one of my long boring Logical answers which i doubt anyone actually reads but im bored so what the hell ...

if you have a heavey weight on the floor .. say an engine on a pallet and you wanted to lift it .. you would jam a lever bar under it and press down .. you would then lift something thats far too heavey for you to manually lift it .

You create a fulcrum basically .

You can do this when its hot .. you can do this when its cold .. it will either work or it wont .. more leverage required .

Thats how a clutch works .

Every Porsche has the same clutch ( cover and friction plate not the same size or shape obviously ) .

No other Porsche acts like this so for my way of thinking its not the clutch .

However .. the Turbo is different .. it uses a power assisted hydraulic system with the pressure being generated by the Power steering pump .

There are several valves that allow pressurised fluid to act on the slave cyl to increase the force to operate the clutch .. More Leverage basically !

Now .. i have watched air craft crash investigations .. excellent programs if like me you dont fly .. not sure i would want to watch them if i did but thats another question .

Hydraulic valves can operate differently under temprature changes , at least the episode i watched it did .. mind you everyone died so thats not so good .

My suspicion is a valve and probably in the slave cyl wasnt acting like it should and once warmed up was fine .

This might be the sign of an early failure or nothing to worry about at all ..

If it was me i would check the clutch resevoir and make sure its not full to the brim as thats a sign of a valve failure and if that was ok then i would just keep an eye on it .. its getting warmer these days after all and i hate spending money on something now that i may not need to .

My 2 pennys anyways .

pcat · 29 Mar 2018

Demort said:
I dont have a set answer for you but i thought i would do one of my long boring Logical answers which i doubt anyone actually reads but im bored so what the hell ...

if you have a heavey weight on the floor .. say an engine on a pallet and you wanted to lift it .. you would jam a lever bar under it and press down .. you would then lift something thats far too heavey for you to manually lift it .

You create a fulcrum basically .

You can do this when its hot .. you can do this when its cold .. it will either work or it wont .. more leverage required .

Thats how a clutch works .

Every Porsche has the same clutch ( cover and friction plate not the same size or shape obviously ) .

No other Porsche acts like this so for my way of thinking its not the clutch .

However .. the Turbo is different .. it uses a power assisted hydraulic system with the pressure being generated by the Power steering pump .

There are several valves that allow pressurised fluid to act on the slave cyl to increase the force to operate the clutch .. More Leverage basically !

Now .. i have watched air craft crash investigations .. excellent programs if like me you dont fly .. not sure i would want to watch them if i did but thats another question .

Hydraulic valves can operate differently under temprature changes , at least the episode i watched it did .. mind you everyone died so thats not so good .

My suspicion is a valve and probably in the slave cyl wasnt acting like it should and once warmed up was fine .

This might be the sign of an early failure or nothing to worry about at all ..

If it was me i would check the clutch resevoir and make sure its not full to the brim as thats a sign of a valve failure and if that was ok then i would just keep an eye on it .. its getting warmer these days after all and i hate spending money on something now that i may not need to .

My 2 pennys anyways .

I *always* read your posts in full. Sometimes twice.

If you were a rock star, you would have groupies

deMort · 29 Mar 2018

:floor:

I can honestly say ive never thought of myself as that .. grinning ear to ear though :thumb:

monster · 30 Mar 2018

lol - Yes great post Demort, I always take note to read whatever you write, we are all very lucky to have you on here mate! :thumbs:

silvermilnec · 30 Mar 2018

monster said:
lol - Yes great post Demort, I always take note to read whatever you write, we are all very lucky to have you on here mate! :thumbs:

:agree:

rabbitstew · 31 Mar 2018

Demort said:
Hydraulic valves can operate differently under temprature changes , at least the episode i watched it did .. mind you everyone died so thats not so good

Excellent post. Your logic makes sense and I think the fact it all is fine once the car is warmed up, tends to make me think its something similar.

I actually just moved the car for the first time since Thursday night and sure enough it happened again. Temperature is around 6 degrees, but still very damp etc.

Im planning on having an updated clutch fitted at some point this year when I have the car remapped, so that may have to happen sooner rather than later.

I did hear that the clutch accumulator(?) is prone to failure, so i wonder if that exibits similar symptoms?

deMort · 31 Mar 2018

Start the car up then turn it off .. depress the clutch untill it goes hard .. you should get about 20 depresses untill it goes rock hard.

If you get about 20 then the accumilator should be fine , normally when it fails you only get a couple untill its hard .

If the valves fail in the slave cyl or pump ( normally the slave cyl ) then it pressurises the resevoir side so fluid will end up coming out of the clutch resevoir .

Its o/s/f next to the battery .. just check its not leaking or filled to the brim as this indicates a valve failure.

Ive just done a similar job on a 996 turbo .. rock hard pedal with no clutch depresses so i new it needed an accumilator plus it leaked from the clutch resevoir so i new it was slave / pump and also .. the pedal felt "weird ! "

Slave cyl and accumilator .. job done .

Slave cyl replacement in situe .. not a pleasent job , 3 hours .

rabbitstew · 2 Apr 2018

Cheers. It does seem to be getting worse each day. I've got it booked in with my Indy on Friday so will see. They seem to think it will be the slave cylinder but will find out then.

I was planning to do the gt2 slave cylinder conversion at some point but after just seeing the difference in price between that and an oem 997 slave cylinder I think I won't bother with it.

Clutch pedal feeling weird occasionally.

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